Adsorption of arsenic using chitosan magnetic graphene oxide nanocomposite

Synthesis and characterization of cellulose fibers modified zinc phosphate/hydroxyapatite core-shell as enhanced carrier of cisplatin: Loading, release, and cytotoxicity

The uncontrolled administration of the cisplatin drug (CPTN) resulted in numerous drawbacks. Therefore, effective, affordable, and biocompatible delivery systems were suggested to regulate the loading, release, and therapeutic effect of CPTN. Zinc phosphate/hydroxyapatite hybrid form (ZP/HP) and core-shell nano-rod morphology, as well as its functionalized derivative with cellulose (CF@ZP/HP), were synthesized by the facile dissolution precipitation method followed by mixing with cellulose fibers, respectively. The developed CF@ZP/HP displayed remarkable enhanced CPTN loading properties (418.2 mg/g) as compared to ZP/HP (259.8 mg/g). The CPTN loading behaviors into CF@ZP/HP follow the Langmuir isotherm properties (R2 > 0.98) in addition to the kinetic activities of the pseudo-first-order model (R2 > 0.96). The steric assessment validates the notable increase in the existing loading receptors after the functionalization of ZP/HP with CF from 57.7 mg/g (ZP/HP) to 90.5 mg/g. The functionalization also impacted the capacity of each existing receptor to be able to ensure 5 CPTN molecules. This, in addition to the loading energies (<40 kJ/mol), donates the loading of CPTN by physical multi-molecular processes and in vertical orientation. The CPTN releasing patterns of CF@ZP/HP exhibit slow and controlled properties (95.7 % after 200 h at pH 7.4 and 100 % after 120 h at pH 5.5), but faster than the properties of ZP/HP. The kinetic modeling of the release activities together with the diffusion exponent (>0.45) reflected the release of CPTN according to both erosion and diffusion mechanisms. The loading of CPTN into both ZP/HP and CF@ZP/HP also resulted in a marked enhancement in the anticancer activity of CPTN against human cervical epithelial malignancies (HeLa) (cell viability = 5.6 % (CPTN), 3.2 % (CPTN loaded ZP/HP), and 1.12 % (CPTN loaded CF@ZP/HP)).

Insight into the integration effect of chitosan and β-cyclodextrin on the properties of zinc-phosphate/hydroxyapatite hybrid as delivery structures for 5-fluorouracil: loading and release profiles

Zinc-phosphate/hydroxyapatite hybrid form (ZP/HP) in core-shell nanostructure was developed and functionalized with both chitosan (CS@ZP/HP) and β-cyclodextrin (CD@ZP/HP) as bio-composite of enhanced physicochemical and biological properties. These structures were assessed as potential deliveries of 5-fluorouracil, exhibiting enhanced loading, release, and anti-cancer behaviors. The functionalization strongly prompted the loading effectiveness to be 301.3 mg/g (CS@ZP/HP) and 342.8 mg/g (CD@ZP/HP) instead of 238.9 mg/g for ZP/HP. The loading activities were assessed based on the hypotheses of traditional kinetic and isotherm models, alongside the computational variables of the monolayer model with a single energetic site as an advanced isotherm model. The functionalized versions exhibit much greater loading efficacy compared to ZP/HP as a result of the increment in the density of the existing loading sites [Nm(5-Fu) = 78.85 mg/g (ZP/HP), 93.87 mg/g (CS@ZP/HP), and 117.8 mg/g (CD@ZP/HP)]. Furthermore, the loading energies of approximately 40 kJ/mol, together with the loading potential of each receptor (n > 1) and Gaussian energies of approximately 8 kJ/mol, indicate the physical entrapment of 5-Fu molecules according to a vertical orientation. The materials mentioned verify long-term and continuous release characteristics. Following the modification processes, this behavior became faster as both CS@ZP/HP and CD@ZP/HP displayed complete release within 120 h at pH 1.2. The kinetic studies and diffusing exponent (>0.45) indicate that release characteristics are controlled by both diffusion and erosion processes. These carriers also markedly increase the cytotoxicity of 5-Fu against HCT-116 colorectal cancer cell lines: 5-Fu-ZP/HP (3.2% cell viability), 5-Fu-CS@ZP/HP (1.12% cell viability), and 5-Fu-CD@ZP/HP (0.63% cell viability).

Synergetic studies on the thermochemical activation and polyaniline integration on the adsorption properties of natural coal for chlorpyrifos pesticide: steric and energetic studies

Three types of synthetic coal-derived adsorbents were characterized as potential enhanced structurers during the removal of chlorpyrifos pesticide. The raw coal (CA) was activated into porous graphitic carbon (AC), and both CA and AC were blended with polyaniline polymers (PANI/CA and PANI/AC) forming two advanced composites. The adsorption performances of the modified structures in comparison with CA were evaluated based on both the steric and energetic parameters of the applied advanced isotherm model (the monolayer model of one energy). The uptake performances reflected higher capacities for the PANI hybridized form (235.8 mg/g (PANI/CA) and 309.75 mg/g (PANI/AC) as compared to AC (156.9 mg/g) and raw coal (135.8 mg/g). This signifies the impact of activation step and PANI blending on the surface and textural properties of coal. The steric investigation determined the saturation of the coal surface with extra active sites after the activation step (Nm(AC) = 62.05 mg/g) and the PANI integration (Nm(PANI/CA) = 113.5 mg/g and Nm(PANI/AC) = 169.7 mg/g) as compared to raw coal (Nm(CA) = 39.6 mg/g). This illustrated the reported uptake efficiencies of the modified samples, which can be attributed to the enhancement in the surface area and the incorporation of additional chemical groups. The results also reflect that each site can be loaded with 3-4 molecules of chlorpyrifos, which are arranged vertically and adsorbed by multi-molecular mechanisms. The energetic studies (< 40 kJ/mol) suggested the physical uptake of pesticide molecules by dipole bonding and hydrogen bonding processes. The thermodynamic functions donate the exothermic properties of 47reactions that occur spontaneously.

Enhanced remediation of U(vi) ions from water resources using advanced forms of morphologically modified glauconite (nano-sheets and nano-rods): experimental and theoretical investigations

Two forms of morphologically transformed glauconite (GL) involved exfoliated nanosheets (EXG) and nanorods (GRs), which were synthesized by facile exfoliating and scrolling modification under sonication. The two advanced forms (EXG and GRs) were applied as enhanced adsorbents for U(vi) ions and compared with using raw glauconite. The developed GRs structure displays higher saturation retention properties (319.5 mg g-1) in comparison with both EXG (264.8 mg g-1) and GL (237.9 mg g-1). This enhancement is assigned to the noticeable increment in the surface area (32.6 m2 g-1 (GL), 86.4 m2 g-1 (EXG), and 123.7 m2 g-1 (GRs)) in addition to the surface reactivity and exposure of effective siloxane groups. This was supported by the steric investigation based on the isotherm basics of the monolayer model of one energy site. The steric functions declared a strong increase in the density of the existing effective uptake receptors throughout the modification stages (GRs (112.1 mg g-1) > EXG (87.7 mg g-1) > 72.5 mg g-1 (GL)). Also, each active site can be filled with 4 U(vi) ions, donating the parallel orientation of these ions and the operation of multi-ionic mechanisms. The energetic functions, either the uptake energy (<13 kJ mol-1) or Gaussian energy (<5 kJ mol-1), validate the retention of U(vi) by physical reactions. These reactions displayed spontaneous properties and exothermic behaviors based on the investigated thermodynamic functions, including entropy, enthalpy, and internal energy. The structures also showed significant recyclability, indicating potential application on a realistic and commercial scale.

Advancing Antimony(III) Adsorption: Impact of Varied Manganese Oxide Modifications on Iron-Graphene Oxide-Chitosan Composites

Antimony (Sb) is one of the most concerning toxic metals globally, making the study of methods for efficiently removing Sb(III) from water increasingly urgent. This study uses graphene oxide and chitosan as the matrix (GOCS), modifying them with FeCl2 and four MnOx to form iron-manganese oxide (FM/GC) at a Fe/Mn molar ratio of 4:1. FM/GC quaternary composite microspheres are prepared, showing that FM/GC obtained from different MnOx exhibits significant differences in the ability to remove Sb(III) from neutral solutions. The order of Sb(III) removal effectiveness is MnSO4 > KMnO4 > MnCl2 > MnO2. The composite microspheres obtained by modifying GOCS with FeCl2 and MnSO4 are selected for further batch experiments and characterization tests to analyze the factors and mechanisms influencing Sb(III) removal. The results show that the adsorption capacity of Sb(III) decreases with increasing pH and solid-liquid ratio, and gradually increases with the initial concentration and reaction time. The Langmuir model fitting indicates that the maximum adsorption capacity of Sb(III) is 178.89 mg/g. The adsorption mechanism involves the oxidation of the Mn-O group, which converts Sb(III) in water into Sb(V). This is followed by ligand exchange and complex formation with O-H in FeO(OH) groups, and further interactions with C-OH, C-O, O-H, and other functional groups in GOCS.

Adsorption Study of Neodymium from the Aqueous Phase Using Fabricated Magnetic Chitosan-Functionalized Graphene Oxide Composites

This work reports the performances of the magnetic chitosan@graphene oxide composite (MCh@GO) for the sorption of Nd(III) from aqueous medium. The prepared composite was synthesized by a coprecipitation method and then examined by FT-IR, XRD, SEM, and TGA. XRD analysis proved physical interactions between magnetic chitosan and graphene oxide through (inter- and intramolecular H-bonding and peptide bonding). TGA data approved the thermal stability of the prepared MCh@GO nanocomposite over their constituents. The optimum pH for the sorption process was 4.5. The Langmuir model and PSO fitted the experimental data. The adsorption process was found to be endothermic and spontaneous with a Q max of 56.6 mg g-1. Indeed, the MCh@GO composite proved to be an excellent adsorbent for the purification, remediation, and separation of Nd due to its promising properties.

Recent Advancements in the Field of Chitosan/Cellulose-Based Nanocomposites for Maximizing Arsenic Removal from Aqueous Environment

Water remediation, acknowledged as a significant scientific topic, guarantees the safety of drinking water, considering the diverse range of pollutants that can contaminate it. Among these pollutants, arsenic stands out as a particularly severe threat to human health, significantly compromising the overall quality of life. Despite widespread awareness of the harmful effects of arsenic poisoning, there remains a scarcity of literature on the utilization of biobased polymers as sustainable alternatives for comprehensive arsenic removal in practical concern. Cellulose and chitosan, two of the most prevalent biopolymers in nature, provide a wide range of potential benefits in cutting-edge industries, including water remediation. Nanocomposites derived from cellulose and chitosan offer numerous advantages over their larger equivalents, including high chelating properties, cost-effective production, strength, integrity during usage, and the potential to close the recycling loop. Within the sphere of arsenic remediation, this Review outlines the selection criteria for novel cellulose/chitosan-nanocomposites, such as scalability in synthesis, complete arsenic removal, and recyclability for technical significance. Especially, it aims to give an overview of the historical development of research in cellulose and chitosan, techniques for enhancing their performance, the current state of the art of the field, and the mechanisms underlying the adsorption of arsenic using cellulose/chitosan nanocomposites. Additionally, it extensively discusses the impact of shape and size on adsorbent efficiency, highlighting the crucial role of physical characteristics in optimizing performance for practical applications. Furthermore, this Review addresses regeneration, reuse, and future prospects for chitosan/cellulose-nanocomposites, which bear practical relevance. Therefore, this Review underscores the significant research gap and offers insights into refining the structural features of adsorbents to improve total inorganic arsenic removal, thereby facilitating the transition of green-material-based technology into operational use.

Adsorption efficiency of chitosan/clinoptilolite (CS/CZ) composite for effective removal of Cd+2 and Cr+6 ions from wastewater effluents of dairy cattle farms

The wastewater effluent is responsible for the major ecological impact of the dairy sectors. To avoid the negative consequences of heavy metal pollution on the ecosystem, creative, affordable, and efficient treatment methods are now required before the effluent flows into the surrounding area. This study was aimed at assessing the effectiveness of three different adsorbents for Cd+2 and Cr+6 ions from wastewater effluents of dairy farms, including chitosan (CS), clinoptilolite zeolite (CZ), and chitosan/clinoptilolite zeolite (CS/CZ) composite. The adsorption kinetics of the CS/CZ composite were established using the effects of the key variables (pH, agitation speed, adsorbent concentrations, and contact durations). The removal (%) and adsorption capacities, qe (mg/g), were calculated using the data from the adsorption kinetics. Wastewater samples (n = 60) were collected from the wastewater effluents of five farms. Cd+2 and Cr+6 ion concentrations in all collected samples were determined. Following the CS/CZ composite creation, it was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (X-RD), and Fourier-transform infrared spectrum (FT-IR). The CS/CZ composite had an adsorption capacity of 92.4 and 96.5 mg/g for both Cd+2 and Cr+6 ions at a concentration of 2.0 g/100 ml, respectively, while the CZ adsorption capacities for the two ions were 87.5 mg/g and 61.0 mg/g, respectively, at 4.0 g/100 ml concentration. The CS was achieved at 55.56 mg/g and 33.3 mg/g, respectively, at the same concentration. The efficiency of heavy metal removal was enhanced by increasing adsorbent concentration, agitation speed, and contact duration. Using CS/CZ composite at 2.0 g/100 ml concentration, 180 min of contact time, and 300 rpm agitation speed, the greatest removal efficiencies for Cd+2 and Cr+6 ions (96.43 and 98.75%, respectively) were demonstrated.

Remediation of arsenic and fluoride from groundwater: a critical review on bioadsorption, mechanism, future application, and challenges for water purification

In the past few decades, the excessive and inadequate use of technological advances has led to groundwater contamination, mainly caused by organic and inorganic pollutants, which are highly harmful to human health, agriculture, water bodies, and aquaculture. Among all toxic pollutants, As and F- play a significant role in groundwater contamination due to their excellent reactivity with other elements. To mitigate the prevalence of arsenic and fluoride within the water system, the use of biochar gives an attractive strategy for removing them mainly because of the substantial surface area, pore size, pH, aromatic structure, and functional groups inherent in biochar, which are primarily dependent upon its raw material and pyrolysis temperature. Researcher develops different methods like physiochemical and electrochemical for treating arsenic and fluoride contamination. Among all removal methods, bioadsorption using agricultural waste residues shows effective/feasible removal of As and F- due to its low cost, ecofriendly nature, readily available, and efficient reuse compared with several other harmful synthetic materials that demand costly design specifications. This study discusses current developments in bioadsorption methods for As and F- that use agricultural-based biomaterials and describes the prevailing state of arsenic and fluoride removal strategies that use biomaterials precisely.

Characterization of chitosan- and β-cyclodextrin-modified forms of magnesium-doped hydroxyapatites as enhanced carriers for levofloxacin: loading, release, and anti-inflammatory properties

An advanced form of magnesium-rich hydroxyapatite (Mg·HAP) was modified with two types of biopolymers, namely chitosan (CH/Mg·HAP) and β-cyclodextrin (CD/Mg·HAP), producing two types of bio-composites. The synthesized materials were developed as enhanced carriers for levofloxacin to control its loading, release, and anti-inflammatory properties. The polymeric modification significantly improved the loading efficiency to 281.4 mg g-1 for CH/Mg·HAP and 332.4 mg g-1 for CD/Mg·HAP compared with 218.3 mg g-1 for Mg·HAP. The loading behaviors were determined using conventional kinetic and isotherm models and mathematical parameters of new equilibrium models (the monolayer model of one energy). The estimated density of effective loading sites (Nm (LVX) = 88.03 mg g-1 (Mg·HAP), 115.8 mg g-1 (CH/Mg·HAP), and 138.5 mg g-1 (CD/Mg·HAP)) illustrates the markedly higher loading performance of the modified forms of Mg·HAP. Moreover, the loading energies (<40 kJ mol-1) in conjunction with the capacity of each loading site (n > 1) and Gaussian energies (<8 kJ mol-1) signify the physical trapping of LVX molecules in vertical orientation. The addressed materials validate prolonged and continuous release behaviors. These behaviors accelerated after the modification procedures, as the complete release was identified after 160 h (CH/Mg·HAP) and 200 h (CD/Mg·HAP). The releasing behaviors are regulated by both diffusion and erosion mechanisms, according to the kinetic investigations and diffusion exponent analysis (>0.45). The entrapping of LVX into Mg·HAP induces its anti-inflammatory properties against the generation of cytokines (IL-6 and IL-8) in human bronchial epithelia cells (NL20), and this effect displays further enhancement after the integration of chitosan and β-cyclodextrin.

Steric, Synergetic, Energetic Studies on the Impact of the Type of the Hybridized Polymers (Chitosan and β-Cyclodextrin) on the Adsorption Properties of Zeolite-A for Congo Red Dye

Zeolite-A was synthesized successfully from kaolinite and hybridized with two species of biopolymers (chitosan (CH/Z) and β-cyclodextrin (CD/Z)). The obtained hybridized forms were assessed as potential adsorbents of Congo red synthetic dye (CR) with enhanced affinities and elimination capacities. The synthesized CD/Z and CH/Z hybrids demonstrated uptake capacities of 223.6 and 208.7 mg/g, which are significantly higher than single-phase zeolite-A (140.3 mg/g). The integrated polymers change the surface area, surface reactivity, and number of free active receptors that are already present. The classic isotherm investigations validate Langmuir equilibrium behavior for ZA and Freundlich properties for CD/Z and CH/Z. The steric parameters validate a strong increase in the existing active receptors after the incorporation of CD (CD/Z) to be 98.1 mg/g as compared to 83 mg/g for CH/Z and 60.6 mg/g for ZA, which illustrate the detected uptake behaviors. Moreover, the CR dye was adsorbed as several molecules per single site, reflecting the vertical uptake of these molecules by multimolecular mechanisms. The energetic assessment, considering both Gaussian energies and adsorption energies (<40 kJ/mol), validates the dominant impact of the physical mechanism during the sequestration of CR (dipole binding interactions (2-29 kJ/mol) and hydrogen bonds (<30 kJ/mol)), in addition to the considerable effect of ion exchange processes. Based on the thermodynamic parameters, the CR molecules were adsorbed by exothermic and spontaneous reactions.

Enhanced arsenic removal by graphene oxide chitosan composites through FeOx decoration: Influences and mechanism

Iron decoration has been recognized as one of the most important paths to enhance contaminant adsorption by carbon-based composites. In this study, varying amounts of Fe (II) are used for the modification of graphene oxide chitosan (GOCS) materials to assess the impact of iron oxide (FeOx) morphology on the composites and their efficiency in arsenic (As) removal. Results show that incorporating 0.08 mol Fe(II) into GOCS yields better As removal performance, leading to a remarkable enhancement by 5 times for As(V) and 6 times for As(III). The iron minerals in the material consist of goethite (FeO(OH)) and magnetite (Fe3O4), with FeO(OH) playing a predominant role in As removal through the complexation and electrostatic attraction of -OH and Fe - O groups. The adsorption capacity for As (Qe) decreases with the increasing pH and the mass and volume ratio (m/v) but increases with the increasing initial concentration (C0). Besides, the presence of SO42- and HPO42- can significantly reduce As removal by the FeOx-modified GOCS. Under the conditions of pH = 3, m/v = 1.0 g/L, and C0 = 10 mg/L, a maximum Qe value reaches 61.94 mg/g. The adsorption is well-fitted to a pseudo-second-order kinetic model and is an endothermic, spontaneous, and monolayer adsorption process.

Comprehensive assessment of carbon-, biomaterial- and inorganic-based adsorbents for the removal of the most hazardous heavy metal ions from wastewater

Owing to the high cost of recycling waste, underdeveloped countries discharge industrial, agricultural, and anthropogenic effluents without pretreatment. As a result, pollutant-loaded waste enters water bodies. Among the diverse toxic contaminants, heavy metal ions are the most detrimental because of their chronic toxicity, non-degradability, prevalence, and bioaccumulation. The growing shortage of water resources demands the removal of heavy metal ions from wastewater. Three SDGs of the sustainability agenda of the United Nations appeal for clean water to protect life beneath water and on land depending on the water sources. Therefore, efficient environmentally friendly approaches for wastewater treatment are urgently required. In this regard, several methods have been developed for the removal of heavy metal ions from wastewater, including adsorption as the most widely used method owing to its eco-friendly, cost-effective, and sustainable nature. The present review discusses the progress in the preparation and application of various adsorbents based on carbon, micro-organisms, agricultural waste and inorganic materials for the extraction of toxic metal ions such as Pb2+, Cr6+, As3+, As5+, Hg2+ and Cd2+. Herein, we provide information on the role of the homogeneity and heterogeneity of adsorbents, kinetics of the adsorption of an adsorbate on the surface of an adsorbent, insights into adsorption reaction pathways, the mechanism of the sorption process, and the uptake of solutes from solution. The present review will be useful for researchers working on environmental protection and clean environment.

Steric and energetic studies on the influence of cellulose on the adsorption effectiveness of Mg trapped hydroxyapatite for enhanced remediation of chlorpyrifos and omethoate pesticides

Magnesium-trapped hydroxyapatite (Mg.HP) was hybridized with cellulose fiber to produce a bio-composite (CLF/HP) with enhanced adsorption affinities for two types of toxic pesticides (chlorpyrifos (CF) and omethoate (OM)). The enhancement influence of the hybridized cellulose on the adsorption performances of Mg.HP was illustrated based on the determined steric and energetic factors. The computed CF and OM adsorption performances of CLF/HP during the saturation phases are 279.8 mg/g and 317.9 mg/g, respectively, which are significantly higher than the determined values using Mg/HP (143.4 mg/g (CF) and 145.3 mg/g (OM)). The steric analysis demonstrates a strong impact of the hybridization process on the reactivity of the surface of the composite. While CLF/HP reflects effective uptake site densities (Nm) of 93.3 mg/g (CF) and 135.3 mg/g (OM), the estimated values for Mg.HP are 51.2 mg/g (CF) and 46.11 mg/g (OM), which explain the reported enhancement in the adsorption performances of the composite. The capacity of each uptake site to be occupied with more than one molecule (n (CF) = 3-3.74 and n (OM) = 2.35-3.54) suggests multimolecular uptake. The energetic factors suggested physical mechanistic processes of spontaneous and exothermic behaviors either during the uptake of CF or OM.

Synergetic and advanced isotherm investigation for the enhancement influence of zeolitization and β-cyclodextrin hybridization on the retention efficiency of U(vi) ions by diatomite

In synergetic investigations, the adsorption effectiveness of diatomite-based zeolitic structure (ZD) as well as its β-cyclodextrin (CD) hybrids (CD/ZD) towards uranium ions (U(vi)) was evaluated to examine the influence of the transformation procedures. The retention behaviors and mechanistic processes have been demonstrated through analyzing the steric and energetic factors employing the modern equilibrium approach (a monolayer model with a single energy level). After the saturation phase, the uptake characteristics of U(vi) were dramatically improved to 297.5 mg g-1 after the CD blending procedure versus ZD (262.3 mg g-1) or 127.8 mg g-1. The steric analysis indicated a notable increase in binding site levels after the zeolitization steps (Nm = 85.7 mg g-1) as well as CD implementation (Nm = 91.2 mg g-1). This finding clarifies the reported improvement in the ability of CD/ZD to effectively retain the U(vi) ions. Furthermore, every single active site of the CD/ZD material has the capacity to adsorb around four ions, which are aligned according to a vertical pattern. The energetic aspects, specifically Gaussian energy (<8 kJ mol-1) along with retention energy (<40 kJ mol-1), validate the regulated influences of the physical mechanistic processes. The physical adsorption of U(vi) seems to depend on various intermolecular forces, such as van der Waals forces, in conjunction with zeolitic ion exchanging pathways (0.6-25 kJ mol-1). The thermodynamic assets have been evaluated to confirm the exothermic together with spontaneous adsorption U(vi) by ZD and its blend with CD (CD/ZD).

Enhanced Retention of Cd(II) by Exfoliated Bentonite and Its Methoxy Form: Steric and Energetic Studies

Synergistic studies were conducted to evaluate the retention potentiality of exfoliating bentonite (EXBEN) as well as its methanol hybridization derivative (Mth/EXBEN) toward Cd(II) ions to be able to verify the effects of the transformation processes. The adsorption characteristics were established by considering the steric and energetic aspects of the implemented advanced equilibrium simulation, specifically the monolayer model with a single energy level. Throughout the full saturation states, the adsorption characteristics of Cd(II) increased substantially to 363.7 mg/g following the methanol hybridized treatment in comparison to EXBEN (293.2 mg/g) as well as raw bentonite (BEN) (187.3 mg/g). The steric analysis indicated a significant rise in the levels of the active sites following the exfoliation procedure [retention site density (Nm) = 162.96 mg/g] and the chemical modification with methanol [retention site density (Nm) = 157.1 mg/g]. These findings clarify the improvement in the potential of Mth/EXBEN to eliminate Cd(II). Furthermore, each open site of Mth/EXBEN has the capacity to bind approximately three ions of Cd(II) in a vertically aligned manner. The energetic investigations, encompassing the Gaussian energy (less than 8 kJ/mol) plus the adsorption energy (less than 40 kJ/mol), provide evidence of the physical sequestration of Cd(II). This process may involve the collaborative impacts of dipole binding forces (ranging from 2 to 29 kJ/mol) and hydrogen binding (less than 30 kJ/mol). The measurable thermodynamic functions, particularly entropy, internal energy, and free enthalpy, corroborate the exothermic and spontaneous nature of Cd(II) retention by Mth/EXBEN, as opposed to those by EXBEN and BE.

New sulfonated covalent organic framework for highly effective As(III) removal from water

The goal of taking out As(III) from water is to reduce the detriment that poisonous metals can do to people and nature. A substance that can absorb As(III), TFPOTDB-SO3H, was made by combining 2,5-diaminobenzenesulfonic acid and 2,4,6-tris-(4-formylphenoxy)-1,3,5-triazine in a reaction that joins molecules together. This substance can adsorb As(III) very well and has excellent qualities like being easy to use again, separate substances, and filter out liquids. At pH = 8 and at room temperature, TFPOTDB-SO3H adsorbed a lot of As(III). It achieved a removal rate of 97.1 % within 10 min and could adsorb up to 344.8 mg/g. A research was conducted to investigate the effect of co-existing anions on the elimination of arsenic. The findings indicated that the presence of anions had a minimal adverse impact, reducing As(III) uptake by approximately 1-7 %. The kinetics of the uptake process were found to be controlled by the quasi-second order kinetic model, while the Langmuir isotherm model validated that the mechanism for As(III) removal was monolayer chemisorption. According to the thermodynamic analysis, the adsorption process was endothermic and occurred spontaneously. Moreover, even after 4 successive adsorption-desorption cycles, the adsorbent preserved a substantial uptake productivity of 88.86 % for As(III). The results collectively indicate that TFPOTDB-SO3H holds considerable promise for the efficient adsorption and elimination of As(III) ions from wastewater.

Chitosan-based adsorptive membrane modified by carboxymethyl cellulose for heavy metal ion adsorption: Experimental and density functional theory investigations

Low adsorption capacity and weak mechanical stability are the main drawbacks of chitosan (CS)-based adsorptive membranes for heavy metal ion removal. Polyvinyl alcohol (PVA) has been used to improve the mechanical stability of CS membranes, but adsorption capacity is disregarded. In the current study, the surface of the chitosan/polyvinyl alcohol (CP) membrane was modified using carboxymethyl cellulose (CMC) to increase its heavy metal ion adsorption capacity. Experimental and density functional theory (DFT) calculations were used to evaluate the heavy metal ion (As3+ and Cr3+) adsorption capabilities of CP and carboxymethyl cellulose-functionalized CP (CMC-CP) membranes. The batch adsorption process presented a higher heavy metal adsorption capacity of the CMC-CP membrane (As3+/CMC-CP = 234.78 mg/g and Cr3+/CMC-CP = 230.12 mg/g) compared to the CP membrane (As3+/CP = 89.02 mg/g and Cr3+/CP = 75.61 mg/g). The heavy metal/CMC-CP complexes confirmed higher adsorption energies (As3+/CMC-CP = -23.62 kcal/mol and Cr3+/CMC-CP = -23.21 kcal/mol) than the heavy metal/CP complexes (As3+/CP = -3.47 kcal/mol and Cr3+/CP = -2.92 kcal/mol). The electronic band structure was higher for CMC-CP (5.42 eV) compared to CP (4.43 eV). Experimental and theoretical findings were close, implying that the CMC-CP membrane has superior heavy metal adsorption capability than the CP membrane.

Efficient multi-ion adsorption using chitosan-malonic acid film: Enhancement using response surface methodology

The objective of this research is to conduct a comprehensive characterization of chitosan while also improving its attributes by crosslinking with malonic acid, with a focus on its efficacy in removing hexavalent chromium, arsenite and fluoride ions. Crosslinking chitosan in 1:0.5 mass ratio forming a film led to substantial enhancement in confiscation of these target pollutants. The characterization of the adsorbent involved several techniques, including FT-IR, TGA-DSC, SEM-EDX, XRD, and BET surface area analysis. In batch adsorption experiments, Chitosan-malonic acid (CMA) was employed to remove CrVI, AsIII and F- from aqueous solutions. These experiments were conducted while varying conditions such as pH, dosage, concentration, temperature, and time. Through the implementation of response surface methodology (RSM), parameters were optimized, resulting in over 95% removal of CrVI, AsIII and F- ions. The isotherm and kinetics data demonstrated a good fit with the Langmuir isotherm model and pseudo second-order kinetics, respectively. According to the Langmuir isotherm, the maximum adsorption capacities on CMA for CrVI, AsIII and F- were determined to be 687.05 mg g-1, 26.72 mg g-1 and 51.38 mg g-1 respectively under optimum pH of 4.0, 7.0 and 5.0 respectively under ambient temperature of 303 K. Thermodynamic analysis indicated that the adsorption process was spontaneous and driven by enthalpy. The regenerability of the adsorbent was validated through five adsorption-desorption cycles, signifying its reusability. An assessment of the adsorbent's sustainability indicated an eco-friendly synthesis, as reflected by the low E-factor value of 0.0028.

Fabrication of Bacterial Cellulose/Chitosan-MIL-100(Fe) Composite for Adsorptive Removal of Dacarbazine

In this research, a polymeric composite based on a chitosan/bacterial cellulose (CS/BC) matrix filled with MIL-100(Fe) particles was prepared to solve the recyclability of issue MIL-100(Fe) particles and utilized as an efficient adsorbent for removing dacarbazine (DTIC) from wastewater. The adsorption capacity of the composite (CS/BC-MIL) was higher than both MIL-100(Fe) and the CS/BC polymeric matrix. The adsorption performance of the fabricated composite was evaluated through kinetics and isotherm studies. While isotherm studies revealed that the adsorption of DTIC onto the adsorbent can be well described by the Freundlich model, kinetics studies indicated that a combination of factors, rather than a single rate-limiting factor, are responsible for the adsorption rate. Thermodynamics investigation showed that the adsorption of DTIC to CS/BC-MIL composite is exothermic and occurs spontaneously. Additionally, due to the negative entropy change, it was established that the adsorption is governed by the enthalpy change. Exploring the solution chemistry revealed that the optimum pH for the adsorption process was about 4. Moreover, the CS/BC-MIL can selectively adsorb DTIC in the presence of other pharmaceuticals like doxorubicin (DOX). Furthermore, regeneration investigations disclosed that the composite holds its structural features and has an acceptable adsorption capacity after several cycles of adsorption/desorption.

Effective retention of cesium ions from aqueous environment using morphologically modified kaolinite nanostructures: experimental and theoretical studies

Kaolinite can undergo a controlled morphological modification process into exfoliated nanosilicate sheets (EXK) and silicate nanotubes (KNTs). The modified structures were assessed as potential effective adsorbents for the retention of Cs+ ions. The impact of the modification process on the retention properties was assessed based on conventional and advanced equilibrium studies, considering the related steric and energetic functions. The synthetic KNTs exhibit a retention capacity of 249.7 mg g-1 as compared to EXK (199.8 mg g-1), which is significantly higher than raw kaolinite (73.8 mg g-1). The kinetic modeling demonstrates the high effectiveness of the pseudo-first-order kinetic model (R2 > 0.9) to illustrate the sequestration reactions of Cs+ ions by K, EXK, and KNTs. The enhancement effect of the modification processes can be illustrated based on the statistical investigations. The presence of active and vacant receptors enhanced greatly from 19.4 mg g-1 for KA to 40.8 mg g-1 for EXK and 46.9 mg g-1 for KNTs at 298 K. This validates the significant impact of the modification procedures on the specific surface area, reaction interface, and reacting chemical groups' exposure. This also appeared in the enhancement of the reactivity of their surfaces to be able to uptake 10 Cs+ ions by KNTs and 5 ions by EXK as compared to 4 ions by kaolinite. The thermodynamic and energetic parameters (Gaussian energy < 8.6 kJ mol-1; uptake energy < 40 kJ mol-1) show that the physical processes are dominant, which have spontaneous and exothermic properties. The synthetic EXK and KNT structures validate the high elimination performance of the retention of Cs+ either in the existence of additional anions or cations.

Synthesis and characterization of chitosan hybridized zinc phosphate/hydroxyapatite core shell nanostructure and its potentiality as delivery system of oxaliplatin drug

An advanced form of zinc phosphate/hydroxyapatite nanorods with a core-shell structure (ZPh/HPANRs) was made and then hybridized with chitosan polymeric chains to make a safe biocomposite (CH@ZPh/HPANRs) that improves the delivery structure of traditional oxaliplatin (OXPN) chemotherapy during the treatment of colorectal cancer cells. The qualifications of CH@ZPh/HPANRs in comparison with ZPh/HPANRs as a carrier for OXPN were followed based on loading, release, and cytotoxicity. CH@ZPh/HPANRs composite exhibits a notably higher OXPN loading capacity (321.75 mg/g) than ZPh/HPANRs (127.2 mg/g). The OXPN encapsulation processes into CH@ZPh/HPANRs display the isotherm behavior of the Langmuir model (R2 = 0.99) and the kinetic assumptions of pseudo-first-order kinetics (R2 > 0.89). The steric studies reflect a strong increment in the quantities of the free sites after the chitosan hybridization steps (Nm = 34.6 mg/g) as compared to pure ZPh/HPANRs (Nm = 18.7 mg/g). Also, the capacity of each site was enhanced to be loaded by 10 OXPN molecules (n = 9.3) in a vertical orientation. The OXPN loading energy into CH@ZPh/HPANRs (<40 KJ/mol) reflects physical loading reactions involving van der Waals forces and hydrogen bonding. The OXPN release profiles of CH@ZPh/HPANRs exhibit slow and controlled properties for about 140 h at pH 7.4 and 80 h at pH 5.5. The release kinetics and diffusion exponent (>0.45) signify non-Fickian transport and a complex erosion/diffusion release mechanism. The free CH@ZPh/HPANRs particles display a considerable cytotoxic effect on the HCT-116 cancer cells (9.53 % cell viability), and their OXPN-loaded product shows a strong cytotoxic effect (1.83 % cell viability).

Preparation of chitosan-based ternary nanocomposite hydrogel film by loading graphene oxide nanosheets as adsorbent for enhanced methylene blue dye removal

Our objective in this study is to fabricate a novel chitosan-based ternary nanocomposite hydrogel film by incorporating graphene oxide (GO) nanosheets into a chitosan/partially hydrolyzed polyacrylamide (PHPA) network to boost adsorption efficiency through one step self-assembly process in water. Basically, H-bonding interactions drive the formation of a crosslinking network structure. The Batch adsorption experiments evaluated the hydrogel nanocomposite's MB adsorption performance. By loading GO, surface roughness, swelling percentage (from 21,200 % to 35,800 %), elastic modulus of up to 73.7 Pa, and adsorption characteristics (from 282 mg/g to 468 mg/g) were enhanced. The nanocomposite displayed outstanding thermally/pH responsiveness properties. MB adsorption equilibrium was reached after 45 min and the adsorption capacity was 476.19 mg.g-1 when the initial concentration was 100 mg/L. The MB adsorption kinetics and isotherms by the nanocomposite were well correlated by the PSO and the Langmuir models (R2 > 0.99), respectively. The loaded nanocomposite was shown to be regenerative for five cycles through desorption studies. Thermodynamic analysis indicated that MB adsorption occurred spontaneously (ΔG°: -16.47 kJ/mol, 303 K) and exothermically (ΔH°: -79.49 kJ/mol). A plausible adsorption mechanism was proposed for the nanocomposite developed for MB removal. Our results can contribute to the design and fabrication of nanocomposite adsorbents to treat wastewater.

Synthesis and Characterization of Iron-Rich Glauconite Nanorods by a Facile Sonochemical Method for Instantaneous and Eco-friendly Elimination of Malachite Green Dye from Aquatic Environments

Novel glauconite nanorods (GNRs) were synthesized by the sonication-induced chemical expansion and scrolling process of natural glauconite. The synthetic nanostructure was characterized by different analytical techniques as a superior adsorbent for the malachite green dye (MG). The synthetic GNRs were detected as porous nanorods with an average length of 150 nm to 5 μm, an average diameter of 25 to 200 nm, and a specific surface area of 123.7 m2/g. As an adsorbent for MG, the synthetic GNRs showed superior uptake capacity up to 1265.6 mg/g at the saturation stage, which is higher than most of the recently developed highly adsorbent dyes. The adsorption behavior and mechanistic properties were depicted by using modern and traditional equilibrium modeling. The kinetic assumption of the pseudo-first-order model (R2 > 0.94) and the classic isotherm of the Langmuir equilibrium model (R2 > 0.97) were used to describe the adsorption reactions. The steric investigation demonstrates that each active site on the surface of GNRs can adsorb up to three MG molecules (n = 2.19-2.48) in vertical orientation involving multimolecular mechanisms. Also, the determined active site density (577.89 mg/g) demonstrates the enrichment of the surface of GNRs with numerous adsorption receptors with strong affinity for the MG dye. The energetic study, including Gaussian energy (6.27-7.97 kJ/mol) and adsorption energy (9.45-10.43 kJ/mol), revealed that GNRs had physically adsorbed the dye, which might involve electrostatic attraction, hydrogen bonding, van der Waals forces, and dipole forces. The internal energy, enthalpy, and entropy determined the exothermic and spontaneous uptake of MG.

Advanced Equilibrium Modeling for the Synergetic Effect of β-Cyclodextrin Integration on the Adsorption Efficiency of Methyl Parathion by β-Cyclodextrin/Exfoliated Kaolinite Nanocomposite

Exfoliated kaolinite nanosheets (EXK) and their hybridization with β-cyclodextrin (β-CD/EXK) were evaluated as potential-enhanced adsorbents of methyl parathion (MP) in synergetic investigations to determine the effects of the different modification procedures. The adsorption behaviors were described on the basis of the energetic steric and energetic factors of the specific advanced equilibrium models (monolayer model of one energy). The functionalization process with β-CD enhanced the adsorption behaviors of MP considerably to 350.6 mg/g in comparison to EXK (291.7 mg/g) and natural kaolinite (K) (244.7 mg/g). The steric studies revealed a remarkable improvement in the quantities of the existing receptors after exfoliation (Nm = 134.4 mg/g) followed by β-CD hybridization (Nm = 162.3 mg/g) as compared to K (75.7 mg/g), which was reflected in the determined adsorption capacities of MP. Additionally, each active free site of β-CD/EXK can adsorb about 3 molecules of MP, which occur in a vertical orientation by types of multimolecular mechanisms. The energetic investigations of Gaussian energy (<8.6 kJ/mol) and adsorption energy (<40 kJ/mol) validate the physical adsorption of MP, which might involve the cooperation of dipole bonding forces, van der Waals, and hydrogen bonding. The properties and entropy values, free enthalpy, and intern energy as the investigated thermodynamic functions declared the exothermic and spontaneous behaviors of the MP adsorption.

Advanced Equilibrium Studies for the Synergetic Impact of Polyaniline on the Adsorption of Rhodamine B Dye by Polyaniline/Coal Composite

The synergetic improvement effect of the polyaniline (PANI) hybridization process on the adsorption of rhodamine B dye (RB) by PANI/coal hybrid material (PANI/C) has been evaluated using both traditional equilibrium modeling and advanced isotherm investigations. The composite was prepared by polymerizing polyaniline in the presence of coal fractions with a surface area of 27.7 m2/g. The PANI/C hybrid has an improved capacity to adsorb RB dye (423.5 mg/g) in comparison to coal particles (254.3 mg/g). The maintained increase in the elimination properties of PANI/C has been illustrated using the steric characteristics of active site density (Nm) as well as the total number of adsorbed RB on a single active site (n). However, the incorporation of PANI did not yield any substantial impact on the existing active sites' quantity, but the hybridization processes greatly influenced the selectivity and affinity of each active site, in addition to the aggregation characteristics of the dye as it interacts with the composite's surface. Whereas raw coal can only adsorb three molecules of RB, each active site throughout the PANI/C surface can adsorb approximately eight RB molecules. This is also evidence of RB dye adsorption in a vertical arrangement, which involves multimolecular processes. The Gaussian energy (4.01-5.59 kJ/mol) and adsorption energy (-4.34-4.68 kJ/mol) revealed the controllable impact of physical mechanisms. These mechanisms may include van der Waals forces, dipole-dipole interactions, and hydrogen bonds (<30 kJ/mol). The thermodynamic functions, such as enthalpy, internal energy, and entropy, that have been assessed provide evidence supporting the exothermic and spontaneous nature of the RB uptake processes by PANI/C.

Steric and Energetic Studies on the Synergetic Enhancement Effect of Integrated Polyaniline on the Adsorption Properties of Toxic Basic and Acidic Dyes by Polyaniline/Zeolite-A Composite

The synergetic enhancement effect of the polyaniline (PANI) integration process on the adsorption properties of the PANI/zeolite-A composite (PANI/ZA) as an adsorbent for malachite green and Congo red synthetic dyes was evaluated based on classic equilibrium modelling in addition to the steric and energetic parameters of advanced isotherm studies. The PANI/ZA composite displays enhanced adsorption capacities for both methylene blue (270.9 mg/g) and Congo red (235.5 mg/g) as compared to ZA particles (methylene blue (179.6 mg/g) and Congo red (140.3 mg/g)). The reported enhancement was illustrated based on the steric parameters of active site density (Nm) and the number of adsorbed dyes per active site (n). The integration of PANI strongly induced the quantities of the existing active sites that have enhanced affinities towards both methylene blue (109.2 mg/g) and Congo red (92.9 mg/g) as compared to the present sites on the surface of ZA. Every site on the surface of PANI/ZA can adsorb about four methylene blue molecules and five Congo red molecules, signifying the vertical orientation of their adsorbed ions and their uptake by multi-molecular mechanisms. The energetic investigation of the methylene blue (-10.26 to -16.8 kJ/mol) and Congo red (-9.38 to -16.49 kJ/mol) adsorption reactions by PANI/ZA suggested the operation of physical mechanisms during their uptake by PANI/ZA. These mechanisms might involve van der Waals forces, dipole bonding forces, and hydrogen bonding (<30 kJ/mol). The evaluated thermodynamic functions, including enthalpy, internal energy, and entropy, validate the exothermic and spontaneous behaviours of the methylene blue and Congo red uptake processes by PANI/ZA.

Synthesis and characterization of Mg-hydroxyapatite and its cellulose hybridized structure as enhanced bio-carrier of oxaliplatin drug; equilibrium and release kinetics

An advanced form of magnesium-doped hydroxyapatite (Mg HAP) was synthesized and hybridized with cellulose fibers, producing a safe biocomposite (CF/Mg HAP) as an enhanced delivery structure of traditional oxaliplatin (OXPN) chemotherapy drug during the treatment stages of colorectal cancer. The qualifications of CF/Mg HAP as a carrier for OXPN were followed based on loading, release, and cytotoxicity as compared to Mg HAP. The CF/Mg HAP composite exhibits a notably higher OXPN encapsulation capacity (256.2 mg g-1) than the Mg HAP phase (148.9 mg g-1). The OXPN encapsulation process into CF/Mg HAP displays the isotherm behavior of the Langmuir model (R2 = 0.99) and the kinetic assumptions of pseudo-first-order kinetics (R2 > 0.95). The steric studies reflect a strong increment in the quantities of the free sites after the cellulose hybridization steps (Nm = 178.58 mg g-1) as compared to pure Mg HAP (Nm = 69.39 mg g-1). Also, the capacity of each site was enhanced to be loaded by 2 OXPN molecules (n = 1.43) in a vertical orientation. The OXPN encapsulation energy into CF/Mg HAP (<40 kJ mol-1) reflects physical encapsulation reactions involving van der Waals forces and hydrogen bonding. The OXPN release profiles of CF/Mg HAP exhibit slow and controlled properties for about 100 h, either at pH 5.5 or pH 7.4. The release kinetics and diffusion exponent (>0.45) signify non-Fickian transport and a complex erosion/diffusion release mechanism. The free CF/Mg HAP particles display a considerable cytotoxic effect on the HCT-116 cancer cells (21.82% cell viability), and their OXPN-loaded product shows a strong cytotoxic effect (1.85% cell viability).

Co-adsorption mechanisms of As(V) and Cd(II) by three-dimensional flower-like Mg/Al/Fe-CLDH synthesized by "memory effect"

Due to the different physical and chemical properties such as surface charge and ion morphology between As(V) and Cd(II), it is challenging to remove As(V) and Cd(II), especially at low concentrations. This study constructed a novel three-dimension nanocomposite adsorbent Mg/Al/Fe-CLDH (CFMA) by "hydrothermal + calcination method". And different initial concentration ratios (Cd: As=1: 2, 1: 1, 2: 1) were used to investigate the removal performance of CFMA for Cd(II) and As(V). When the concentration ratio Cd: As=1: 2, the residual concentrations of As(V) and Cd(II) were 8.7 μg/L and 4.2 μg/L, respectively, which met the drinking water standard; In the co-adsorption system, As(V) and Cd(II) influence each other's adsorption behavior due to the anionic bridge and shielding effect of As(V) on Cd(II), As(V) gradually changed from monolayer adsorption to multi-layer adsorption dominant, while Cd(II) gradually changed from multi-layer adsorption to monolayer adsorption dominant. In this paper, the structure-activity relationship between material structure and synchronous removal of arsenic and cadmium was clarified, and the mechanism of synchronous removal was revealed, which provided technical guidance for synchronous removal of As(V) and Cd(II) from non-ferrous metal smelting wastewater.

Enhanced arsenite removal in aqueous with Fe-Ce-Cu ternary oxide nanoparticle

Arsenite is both more harmful and challenging to get out of water than arsenate. For enhanced As (III) removal, a ternary oxide nanoparticle (FCCTO) mainly composed of iron(Fe), with a small proportion of cerium(Ce) and copper(Cu) was created using a coprecipitation-calcination process. FCCTO was found to be effective in removing As (III) from water, with factors such as adsorbent dose, pH, temperature, and coexisting anions influencing its efficiency. The surface area of FCCTO reached 180.2 m2/g and the doping significantly increased its pore volume and diameter. The adsorption process on FCCTO was endothermic and spontaneous. Ce and Cu in FCCTO were able to efficiently oxidize 81.3% As (III) to As(V). Abundant sites were provided by surface hydroxyl groups for arsenic adsorption. The maximal As(III) adsorption capacity of this adsorbent under the synergistic impact of oxidation and adsorption was 101.5 mg/g. After five cycles, the FCCTO's As(III) adsorption rate dropped to 60% as a result of tetravalent Ce consumption. Surface complexation, redox, and adsorption all had a significant impact on the adsorption process. Overall, FCCTO was an excellent adsorbent with benefits of being facile fabrication, environmentally, recyclable, and having a high As(III) adsorption capacity.

Synthesis and Characterization of Mg-Hydroxyapatite and Its β-Cyclodextrin Composite as Enhanced Bio-Carrier of 5-Fluorouracil Drug; Equilibrium and Release Kinetics

An advanced form of magnesium-doped hydroxyapatite (Mg·HAP) was integrated in composite with β-cyclodextrin producing a safe biocomposite (β-CD/HAP) as an enhanced delivery structure of traditional 5-fluorouracil (5-FU) chemotherapy during the treatment stages of colorectal cancer cells. The qualifications of β-CD/HAP as a carrier for 5-FU were followed based on the loading, release, and cytotoxicity as compared to Mg·HAP. β-CD/HAP composite exhibits notably higher 5-FU encapsulation capacity (272.3 mg/g) than Mg·HAP phase (164.9 mg/g). The 5-FU encapsulation processes into β-CD/HAP display the isotherm behavior of the Freundlich model (R2 = 0.99) and kinetic assumptions of pseudo-first order kinetic (R2 > 0.95). The steric studies reflect a strong increment in the quantities of the free sites after the β-CD integration steps (Nm = 61.2 mg/g) as compared to pure Mg·HAP (Nm = 42.4 mg/g). Also, the capacity of each site was enhanced to be loaded by 5 of 5-FU molecules (n = 4.45) in a vertical orientation. The 5-FU encapsulation energy into β-CD/HAP (<40 kJ/mol) reflects physical encapsulation reactions involving van der Waals forces and hydrogen bonding. The 5-FU release profiles of β-CD/HAP exhibit slow and controlled properties for about 80 h either in gastric fluid (pH 1.2) or in intestinal fluid (pH 7.4). The release kinetics and diffusion exponent (>0.45) signify non-Fickian transport and complex erosion/diffusion release mechanism. The free β-CD/HAP particles display a considerable cytotoxic effect on the HCT-116 cancer cells (33.62% cell viability) and its 5-FU-loaded product shows a strong cytotoxic effect (2.91% cell viability).

Synthesis and Characterization of Methoxy-Exfoliated Montmorillonite Nanosheets as Potential Carriers of 5-Fluorouracil Drug with Enhanced Loading, Release, and Cytotoxicity Properties

Natural bentonite clay (BE) underwent modification steps that involved the exfoliation of its layers into separated nanosheets (EXBE) and further functionalization of these sheets with methanol, forming methoxy-exfoliated bentonite (Mth/EXBE). The synthetically modified products were investigated as enhanced carriers of 5-fluorouracil as compared to raw bentonite. The modification process strongly induced loading properties that increased to 214.4 mg/g (EXBE) and 282.6 mg/g (Mth/EXBE) instead of 124.9 mg/g for bentonite. The loading behaviors were illustrated based on the kinetic (pseudo-first-order model), classic isotherm (Langmuir model), and advanced isotherm modeling (monolayer model of one energy). The Mth/EBE carrier displays significantly higher loading site density (95.9 mg/g) as compared to EXBE (66.2 mg/g) and BE (44.9 mg/g). The loading numbers of 5-Fu in each site of BE, EXBE, and Mth/EXBE (>1) reflect the vertical orientation of these loaded ions involving multi-molecular processes. The loading processes that occurred appeared to be controlled by complex physical and weak chemical mechanisms, considering both Gaussian energy (<8 KJ/mol) as well as loading energy (<40 KJ/mol). The releasing patterns of EXBE and Mth/EXBE exhibit prolonged and continuous properties up to 100 h, with Mth/EXBE displaying much faster behaviors. Based on the release kinetic modeling, the release reactions exhibit non-Fickian transport release properties, validating cooperative diffusion and erosion release mechanisms. The cytotoxicity of 5-Fu is also significantly enhanced by these carriers: 5-Fu/BE (8.6% cell viability), 5-Fu/EXBE (2.21% cell viability), and 5-Fu/Mth/EXBE (0.73% cell viability).

Insight into the synergetic, steric and energetic properties of zeolitization and cellulose fiber functionalization of diatomite during the adsorption of Cd(ii): advanced equilibrium studies

The adsorption potentiality of zeolitized diatomite (ZD) frustules and their cellulose hybridized (C/ZD) product for Cd(ii) ions was assessed in synergetic studies to investigate the impact of the modification processes. The adsorption properties were illustrated based on the steric and energetic parameters of the applied advanced equilibrium modeling (monolayer model of one energy). The cellulose hybridization process increased the adsorption properties of Cd(ii) significantly to 229.4 mg g-1 as compared to ZD (180.8 mg g-1) and raw diatomite (DA) (127.8 mg g-1) during the saturation state. The steric investigation suggested a notable increase in the quantities of the active sites after the zeolitization (Nm = 62.37 mg g-1) and cellulose functionalization (Nm = 98.46 mg g-1), which illustrates enhancement in the Cd(ii) uptake capacity of C/ZD. Moreover, each active site of C/ZD can absorb about 4 ions of Cd(ii) ZD, which occur in a vertical orientation. The energetic studies, including Gaussian energy (<8 kJ mol-1) and retention energy (<8 kJ mol-1), demonstrate the physical uptake of Cd(ii), which might involve cooperating van der Waals forces (4-10 kJ mol-1), hydrophobic bonds (5 kJ mol-1), dipole forces (2-29 kJ mol-1), and hydrogen bonding (<30 kJ mol-1) in addition to zeolitic ion exchange mechanisms (0.6-25 kJ mol-1). The behaviors and values of entropy, internal energy, and free enthalpy as the assessed thermodynamic functions validate the exothermic and spontaneous properties of the Cd(ii) retention by ZD and the C/ZD composite.

Insights into the Effect of Chitosan and β-Cyclodextrin Hybridization of Zeolite-A on Its Physicochemical and Cytotoxic Properties as a Bio-Carrier for 5-Fluorouracil: Equilibrium and Release Kinetics Studies

Synthetic zeolite-A (ZA) was hybridized with two different biopolymers (chitosan and β-cyclodextrin) producing biocompatible chitosan/zeolite-A (CS/ZA) and β-cyclodextrin/zeolite-A (CD/ZA) biocomposites. The synthetic composites were assessed as bio-carriers of the 5-fluorouracil drug (5-Fu) with enhanced properties, highlighting the impact of the polymer type. The hybridization by the two biopolymers resulted in notable increases in the 5-Fu loading capacities, to 218.2 mg/g (CS/ZA) and 291.3 mg/g (CD/ZA), as compared to ZA (134.2 mg/g). The loading behaviors using ZA as well as CS/ZA and CD/ZA were illustrated based on the classic kinetics properties of pseudo-first-order kinetics (R² > 0.95) and the traditional Langmuir isotherm (R² = 0.99). CD/ZA shows a significantly higher active site density (102.7 mg/g) in comparison to CS/ZA (64 mg/g) and ZA (35.8 mg/g). The number of loaded 5-Fu per site of ZA, CS/ZA, and CD/ZA (>1) validates the vertical ordering of the loaded drug ions by multi-molecular processes. These processes are mainly physical mechanisms based on the determined Gaussian energy (<8 kJ/mol) and loading energy (<40 kJ/mol). Both the CS/ZA and CD/ZA 5-Fu release activities display continuous and controlled profiles up to 80 h, with CD/ZA exhibiting much faster release. According to the release kinetics studies, the release processes contain non-Fickian transport release properties, suggesting cooperative diffusion and erosion release mechanisms. The cytotoxicity of 5-Fu is also significantly enhanced by these carriers: 5-Fu/ZA (11.72% cell viability), 5-Fu/CS/ZA (5.43% cell viability), and 5-Fu/CD/ZA (1.83% cell viability).

Synthesis and Characterization of β-Cyclodextrin-Hybridized Exfoliated Kaolinite Single Nanosheets as Potential Carriers of Oxaliplatin with Enhanced Loading, Release, and Cytotoxic Properties

Natural kaolinite was subjected to a successful exfoliation process into separated kaolinite nanosheets (KNs), followed by hybridization with β-cyclodextrin biopolymer (β-CD), forming an advanced bio-nanocomposite (β-CD/KNs). The synthetic products were evaluated as enhanced delivery structures for oxaliplatin chemotherapy (OXAPN). The hybridization of KNs with β-CD polymer notably enhanced the loading capacity to 355.3 mg/g (β-CD/KNs) as compared to 304.9 mg/g for KNs. The loading of OXAPN into both KNs and β-CD/KNs displayed traditional pseudo-first-order kinetics (R² > 0.85) and a conventional Langmuir isotherm (R² = 0.99). The synthetic β-CD/KNs validates a greater occupied effective site density (98.7 mg/g) than KNs (66.3 mg/g). Furthermore, the values of the n steric parameter (4.7 (KNs) and 3.6 (β-CD/KNs)) reveal the vertical orientation of the loaded molecules and the loading of them by multi-molecular mechanisms. These mechanisms are mainly physical processes based on the obtained Gaussian energy (<8 KJ/mol) and loading energy (<40 KJ/mol). The release profiles of both KNs and β-CD/KNs extend for about 120 h, with remarkably faster rates for β-CD/KNs. According to the release kinetic findings, the release of OXAPN displays non-Fickian transport behavior involving the cooperation of diffusion and erosion mechanisms. The KNs and β-CD/KNs as free particles showed considerable cytotoxicity and anticancer properties against HCT-116 cancer cell lines (71.4% cell viability (KNs) and 58.83% cell viability (β-CD/KNs)). Additionally, both KNs and β-CD/KNs significantly enhanced the OXAPN's cytotoxicity (2.04% cell viability (OXAPN/KNs) and 0.86% cell viability (OXAPN/β-CD/KNs).

Insight into the Morphological Properties of Nano-Kaolinite (Nanoscrolls and Nanosheets) on Its Qualification as Delivery Structure of Oxaliplatin: Loading, Release, and Kinetic Studies

Natural kaolinite underwent advanced morphological-modification processes that involved exfoliation of its layers into separated single nanosheets (KNs) and scrolled nanoparticles as nanotubes (KNTs). Synthetic nanostructures have been characterized as advanced and effective oxaliplatin-medication (OXAP) delivery systems. The morphological-transformation processes resulted in a remarkable enhancement in the loading capacity to 304.9 mg/g (KNs) and 473 mg/g (KNTs) instead of 29.6 mg/g for raw kaolinite. The loading reactions that occurred by KNs and KNTs displayed classic pseudo-first-order kinetics (R² > 0.90) and conventional Langmuir isotherms (R² = 0.99). KNTs exhibit a higher active site density (80.8 mg/g) in comparison to KNs (66.3 mg/g) and raw kaolinite (6.5 mg/g). Furthermore, compared to KNs and raw kaolinite, each site on the surface of KNTs may hold up to six molecules of OXAP (n = 5.8), in comparison with five molecules for KNs. This was accomplished by multi-molecular processes, including physical mechanisms considering both the Gaussian energy (<8 KJ/mol) and the loading energy (<40 KJ/mol). The release activity of OXAP from KNs and KNTs exhibits continuous and regulated profiles up to 100 h, either by KNs or KNTs, with substantially faster characteristics for KNTs. Based on the release kinetic investigations, the release processes have non-Fickian transport-release features, indicating cooperative-diffusion and erosion-release mechanisms. The synthesized structures have a significant cytotoxicity impact on HCT-116 cancer cell lines (KNs (71.4% cell viability and 143.6 g/mL IC-50); KNTs (11.3% cell viability and 114.3 g/mL IC-50). Additionally, these carriers dramatically increase OXAP's cytotoxicity (2.04% cell viability, 15.4 g/mL IC-50 (OXAP/KNs); 0.6% cell viability, 4.5 g/mL IC-50 (OXAP/KNTs)).

Removal and environmentally safe disposal of As(III) and As(V)-loaded ferrihydrite/biosilica composites

Pure ferrihydrite and ferrihydrite-biosilica composite were synthesized and studied for the removal of As(III) and As(V). The synthesized materials have an adsorption capacity higher than some reported materials in the literature - 140 and 90 mg g^-1 for As(III) and As(V), respectively. The pH of the solution was shown to impact greatly on As(V) adsorption, but not on As (III), which is stable as a protonated, uncharged oxyanion, at pH < 9.2. The adsorption products were subjected to thermal treatment (500 °C for 2 h), promoting ferric arsenate formation. The adsorbed As on ferrihydrite (Fh) was shown to inhibit the phase transformation of Fh to hematite. More so, thermal treatment was shown to oxidize As(III) to As (V). The changes in the adsorption residues after thermal treatment also had an impact on As mobility. The As (III) associated with the Fh phase increased from 42 to 95%, according to a sequential extraction protocol. Therefore, this work presents a process for As removal, followed by thermal treatment of arsenic-loaded ferrihydrites which enables environmentally safe disposal of As residues.

Biochar modification to enhance arsenic removal from water: a review

Arsenic (As) contamination is a major threat to drinking water quality throughout the world, and the development of appropriate remediation methods is critical. Adsorption is considered the most effective method for remediation of As-contaminated water. Biochar is a promising adsorbent and widely discussed for As removal due to its potential low cost and environmental friendliness. However, pristine biochar generally exhibited relatively low adsorption capacity for As mainly due to the electrostatic repulsion between the negatively charged biochar and As. Biochar modification, especially metal modification, was developed to boost the adsorption capacity for As. A systematic analysis of As removal as affected by biochar properties and modification will be of great help for As removal. This paper presents a comprehensive review on As removal by biochars from different feedstock, preparation procedures, and modification methods, with a major focus on the possible mechanisms of interaction between As and biochar. Biochar derived from sewage sludge exhibited relatively high adsorption capacity for As. Considering energy conservation, biochars prepared at 401-500 °C were more favorable in adsorbing As. Fe-modified biochar was the most popular modified biochar for As remediation due to its low cost and high efficiency. In addition, the limitations of the current studies and future perspectives are presented. The aim of this review is to provide guidance for the preparation of low-cost, environmentally friendly, and high efficiency biochar for the remediation of As-contaminated water.

Characterization of cellulose-functionalized phillipsite biocomposite as an enhanced carrier of oxaliplatin drug during the treatment of colorectal cancer: loading, release, and cytotoxicity

Natural phillipsite (N.Ph) was hybridized with cellulose fibers to produce a safe biocomposite (CF/N.Ph) as an enhanced delivery structure of traditional oxaliplatin (OXPN) chemotherapy during the treatment stages of colorectal cancer cells. The requirements of CF/N.Ph as a carrier for OXPN were followed based on the loading, release, and cytotoxicity compared to N.Ph. CF/N.Ph composite exhibits a notably higher OXPN encapsulation capacity (311.03 mg g^-1) than the N.Ph phase (79.6 mg g^-1). The OXPN encapsulation processes into CF/N.Ph display the isotherm behavior of the Freundlich model (R² = 0.99) and the kinetic assumptions of pseudo-first order kinetic (R² > 0.95). The steric studies reflect a strong increment in the quantities of the free sites after the cellulose hybridization steps (Nm = 100.01 mg g^-1) compared to pure N.Ph (Nm = 27.94 mg g^-1). Additionally, the capacity of each site was enhanced to be loaded by 4 OXPN molecules (n = 3.11) compared to 3 by N.Ph (n = 2.85) in a vertical orientation. The OXPN encapsulation energy into CF/N.Ph (<40 kJ mol^-1) reflects physical encapsulation reactions involving electrostatic attraction, van der Waals forces, and hydrogen bonding. The OXPN release profiles of CF/N.Ph exhibit slow and controlled properties for about 150 h either at pH 5.5 or at pH 7.4. The release kinetics and diffusion exponent (>0.45) signify non-Fickian transport and a complex erosion/diffusion release mechanism. The free CF/N.Ph particles display a considerable cytotoxic effect on HCT-116 cancer cells (46.91% cell viability), and its OXPN-loaded product shows a strong cytotoxic effect (3.14% cell viability).

An all-biopolymer self-assembling hydrogel film consisting of chitosan and carboxymethyl guar gum: A novel bio-based composite adsorbent for Cu2+ adsorption from aqueous solution

A novel bio-based composite adsorbent, all biopolymer self-assembled hydrogel film has been prepared by eco-friendly amalgamating chitosan (CS) and carboxymethyl guar gum (CMGG) biopolymers in water without needing small molecules for cross-linking. Various analysis demonstrated the electrostatic interactions and hydrogen bondings within the network structure are responsible for gelling, crosslinking, and forming a 3D structure. Various experimental parameters were optimized to evaluate the CS/CMGG's potential for removing Cu²⁺ ions from aqueous solution, including pH, dosage, Cu(II) initial concentration, contact time, and temperature. The pseudo-second-order kinetic and Langmuir isotherm models are highly correlated with the kinetic and equilibrium isotherm data, respectively. Using the Langmuir isotherm model for an initial metal concentration of 50 mg/L at pH 6.0 and 25 °C, the maximum adsorption of Cu(II) was calculated to be 155.51 mg/g. A combination of adsorption-complexation and ion exchange must be involved in Cu(II) adsorption on the CS/CMGG. Five cycles of the loaded CS/CMGG hydrogel regeneration and reuse were successfully achieved without an appreciable difference in Cu(II) removal percentage. Thermodynamic analysis indicated that copper adsorption occurred spontaneously (ΔG°: -2.85 J/mol, 298 K) and exothermically (ΔH°: -27.58 J/mol). A reusable bio-adsorbent for removing heavy metal ions was developed that is eco-friendly, sustainable, and efficient.

Adsorption of Copper and Arsenic from Water Using a Semi-Interpenetrating Polymer Network Based on Alginate and Chitosan

New biobased hydrogels were prepared via a semi-interpenetrating polymer network (semi-IPN) using polyacrylamide/chitosan (PAAM/chitosan) hydrogel for the adsorption of As(V) or poly acrylic acid/alginate (PAA/alginate) hydrogel for the adsorption of Cu(II). Both systems were crosslinked using N,N'-methylenebisacrylamide as the crosslinker and ammonium persulfate as the initiating agent. The hydrogels were characterized by SEM, Z-potential, and FTIR. Their performance was studied under different variables, such as the biopolymer effect, adsorbent dose, pH, contact time, and concentration of metal ions. The characterization of hydrogels revealed the morphology of the material, with and without biopolymers. In both cases, the added biopolymer provided porosity and cavities' formation, which improved the removal capacity. The Z-potential informed the surface charge of hydrogels, and the addition of biopolymers modified it, which explains the further metal removal ability. The FTIR spectra showed the functional groups of the hydrogels, confirming its chemical structure. In addition, the adsorption results showed that PAAM/chitosan can efficiently remove arsenic, reaching a capacity of 17.8 mg/g at pH 5.0, and it can also be regenerated by HNO3 for six cycles. On the other hand, copper-ion absorption was studied on PAA/alginate, which can remove with an adsorption capacity of 63.59 mg/g at pH 4.0, and the results indicate that it can also be regenerated by HNO3 for five cycles.

Adsorption mechanism and removal efficiency of magnetic graphene oxide-chitosan hybrid on aqueous Zn(II)

Magnetic architecture incorporating graphene-chitosan has demonstrated encouraging application in wastewater purification. Herein, a ternary hybrid based on Fe₃O₄-graphene oxide-chitosan (MGOCS) was fabricated and employed as adsorbent to remove aqueous Zn(II). The adsorption mechanism was intensively inspected based on the hard and soft acid base (HSAB) theory. Results present, MGOCS removes 96.73 % of Zn(II) in 38 min, with adsorption quantity 386.92 mg·g^-1. Electron transfer and energy lowering determined by the HSAB theory illuminate the plausible adsorption sites in each component of MGOCS: O₂^- in Fe₃O₄, -C(=O)NH-, -NH₂ in chitosan and -OH in graphene oxide. The exploration was upheld by spectroscopic analyses. Thereby, following adsorption mechanism was proposed. (1) ZnO bond was formed featured by electron donation. (2) The -C(=O)NH- group formed via amidation between graphene oxide and chitosan contributes to Zn(Π) uptake. This work may inspire the development of efficient adsorbent based on magnetic graphene-chitosan for wastewater remediation.

Simple Co-Precipitation of Iron Minerals for the Removal of Phenylarsonic Acid: Insights into the Adsorption Performance and Mechanism

In this study, three kinds of iron minerals, ferrihydrite, hematite, and goethite, were prepared by a simple coprecipitation method for the adsorption and removal of phenylarsonic acid (PAA). The adsorption of PAA was explored, and the influences of ambient temperature, pH, and co-existing anions on adsorption were evaluated. The experimental results show that rapid adsorption of PAA occurs within 180 min in the presence of iron minerals, and the adsorption process conforms to a pseudo-second-order kinetic model. The isothermal adsorption of PAA by ferrihydrite, goethite, and hematite agrees with the Redlich-Peterson model. The maximum adsorption capacities of PAA are 63.44 mg/g, 19.03 mg/g, and 26.27 mg/g for ferrihydrite, goethite, and hematite, respectively. Environmental factor experiments illustrated that an alkaline environment will significantly inhibit the adsorption of PAA by iron minerals. CO32-, SiO32-, and PO43- in the environment will also significantly reduce the adsorption performance of the three iron minerals. The adsorption mechanism was analyzed by FTIR and XPS, which indicated that ligand exchange between the surface hydroxyl group and the arsine group leads to the formation of an Fe-O-As bond, and electrostatic attraction between the iron minerals and PAA played an important role in the adsorption.

Biopolymers as a versatile tool with special emphasis on environmental application

Water sources are becoming highly unsuited as potable sources due to the presence of impurities and hazardous chemicals. Although there are many conventional methods available, the development of innovative technologies is essential for the treating and recycling of wastewater. Owing to their unique and excellent qualities, polymers have recently seen extensive use across various industries. By joining the monomeric components covalently, biopolymers resemble a more natural alternative to synthetic polymers. The biopolymer and biopolymer composites integrate into many sections of the treatment process easily, making them effective, affordable, and environmentally beneficial. Due to their distinct features, biopolymers can replace traditional adsorbents. The biopolymers and composites discussed in this chapter are ideal adsorbent materials for eliminating contaminants from the environment. Based on their sources, methods of preparation, and uses, biopolymers, and their composites are categorized. This chapter also includes different research perspectives on biopolymers, especially from an ecological and financial standpoint.

Insight into the effects of H2SO4 and HNO3 acidification processes on the properties of coal as an enhanced adsorbent for ciprofloxacin residuals: Steric and energetic studies

A sub-bituminous natural coal sample (R.C) was treated with sulfuric acid (S.C) and nitric acid (N.C) as modified products and enhanced adsorbents for obtaining ciprofloxacin (CFX) antibiotic residuals from water. The characterization studied demonstrates enhancement in the surface area and the incorporation of new active oxygenated, sulfur-bearing, and nitrogen-bearing chemical groups into the structure of coal samples. This was reflected in the adsorption capacities that were enhanced from 164.08 mg/g (R.C) to 489.2 mg/g and 518.5 mg/g for N.C and S.C, respectively. The impact of the acid modification processes was evaluated based on the energetic and steric properties of their adsorption systems considering the parameters of the advanced monolayer equilibrium model with one energy site. The determined occupied active sites’ density of R.C (46.32–61.44 mg/g), N.C (168.7–364.9 mg/g), and S.C (159.2–249.9 mg/g) reflects an increase in the quantities of active centers after the acid treatment processes, especially with HNO3. The higher efficiencies of the active sites of S.C to adsorb more CFX molecules (n = 2.08–2.31) than N.C (n = 1.41–2.16) illustrate its higher adsorption capacity. The energetic investigation [adsorption (˂40 kJ/mol) and Gaussian (˂8 kJ/mol) energies] suggested adsorption of CFX by N.C and S.C mainly by physical processes such as van der Waals forces, hydrogen bonding, dipole bonding, and π–π interactions. Moreover, the determined thermodynamic functions including entropy, internal energy, and free enthalpy reflect the spontaneous and endothermic uptake of CFX on the surfaces of N.C and S.C.

As(III) removal by a recyclable granular adsorbent through dopping Fe-Mn binary oxides into graphene oxide chitosan

Graphene oxide chitosan composite (GOCS) is recognized as an environmentally friendly composite adsorbent because of its stability and abundant functional groups to adsorb heavy metals, and Fe-Mn binary oxides (FMBO) have attracted increasing interest due to their high removal capacity of As(III). However, GOCS is often inefficient for heavy metal adsorption and FMBO suffers poor regeneration for As(III) removal. In this study, we have proposed a method of dopping FMBO into GOCS to obtain a recyclable granular adsorbent (Fe/MnGOCS) for achieving As(III) removal from aqueous solutions. Characterization of BET, SEM-EDS, XRD, FTIR, and XPS are carried out to confirm the formation of Fe/MnGOCS and As(III) removal mechanism. Batch experiments are conducted to investigate the effects of operational factors (pH, dosage, coexisting ions, etc.), as well as kinetic, isothermal, and thermodynamic processes. Results show that the removal efficiency (R_e) of As(III) by Fe/MnGOCS is about 96 %, which is much higher than those of FeGOCS (66 %), MnGOCS (42 %), and GOCS (8 %), and it increases slightly with the increasing molar ratio of Mn and Fe. This is because amorphous Fe (hydro)oxides (mainly in the form of ferrihydrite) complexation with As(III) is the major mechanism to remove As(III) from aqueous solutions, and it is accompanied by As(III) oxidation mediated by Mn oxides and the complexation of As(III) with oxygen-containing functional groups of GOCS. Charge interaction plays a weaker role in As(III) adsorption, therefore R_e is persistently high over a wide range of pH values of 3-10. But the coexisting PO₄^3- can greatly decrease R_e by 24.11 %. As(III) adsorption on Fe/MnGOCS is endothermic and its kinetic process is controlled by pseudo-second-order with a determination coefficient of 0.95. Fitted by the Langmuir isotherm, the maximum adsorption capacity is 108.89 mg/g at 25 °C. After four times regeneration, there is only a slight decrease of <10 % for the R_e value. Column adsorption experiments show that Fe/MnGOCS can effectively reduce As(III) concentration from 10 mg/L to <10 μg/L. This study provides new insights into binary polymer composite modified by binary metal oxides to efficiently remove heavy metals from aquatic environments.

Synthesis and characterization of cellulose functionalized zeolitic diatomite as an enhanced carrier of oxaliplatin drug; loading, release, and cytotoxicity

Natural diatomite frustules (D) were incorporated in zeolitization and cellulose functionalization processes to obtain zeolitized diatomite (ZD) and cellulose fibrous/zeolitized diatomite composite (CF/ZD). The modified products were assessed as potential carriers of oxaliplatin drug (OXPL) with enhanced properties. The prepared ZD (112.5 mg/g) and CF/ZD (268.3 mg/g) structures exhibit significantly enhanced encapsulation capacities as compared to raw diatomite (65.9 mg/g). The occurred encapsulation reactions follow the classic Pseudo-first order kinetic (R² > 0.93) and traditional Langmuir isotherm (R² = 0.99). The estimated effective encapsulation site density of CF/ZD is 104.8 mg/g which is a notably higher value than ZD (44.6 mg/g) and D (28.4 mg/g). Moreover, each effective site can be occupied with up to 3 molecules of OXPL molecules in vertical forms involving multi-molecular mechanisms. The encapsulation energy (<40 KJ/mol) suggested the predominant effects of the physical mechanisms during the encapsulation reactions. The release profiles of ZD as well as CF/ZD exhibit slow and controlled properties for about 100 h either at pH 5.5 or at pH 7.4. The release kinetic studies involving the obtained diffusion exponent values (>0.45) suggested non-Fickian transport and complex erosion/diffusion release mechanism. These structures exhibit enhanced cytotoxic effects on the HCT-116 cancer cell lines (D (18.78 % cell viability), ZD (9.76 % cell viability), and CF/ZD (3.16 % cell viability).

Adsorption and desorption characteristics of arsenic in calcareous soils as a function of time; equilibrium and thermodynamic study

Irrigation of carbonate-rich agricultural soils with arsenic (As)-contaminated water leads to the accumulation of As in these soils. In this regard, there is an opportunity to adsorb and fix the As in soil and decrease the As transportation to the plants and subsequently the human food chain. So, the present study aimed to investigate the adsorption-desorption characteristics of As in calcareous soils and the potential of As fixation over time. First, to achieve this purpose, 53 soil samples were gathered from the study site and after the laboratory analysis, the soils were categorized into four groups based on their physicochemical properties. Then, four representative samples of these groups were selected, namely soil 1, soil 2, soil 3, and soil 4. Afterward, the As adsorption-desorption was investigated in a lab-scale batch experiment. Next, the effect of age was assessed by incubating the As-adsorbed soils for 60 days, and to study the impact of temperature, the adsorption was performed at four temperature levels (10, 20, 30, and 40 °C). Finally, the isotherm models were fitted to experimental data, and the amount of loosely and tightly held As was quantified. Results revealed that the As adsorption isotherms were L-type, in which As adsorption increased with the increase of As loading. The double-site Langmuir (DSL) estimated that a limited amount of As was adsorbed on high-energy surfaces and a large amount of As was adsorbed on low-energy surfaces. Desorption results showed that a significant amount of As desorbed immediately; however, the desorption significantly decreased with the increase of age, especially at low equilibrium concentrations. By aging the loosely held As transformed into non-labile forms so that in soils 1, 2, 3, and 4, the fraction of As adsorbed on high-energy surfaces increased from 72.5, 93.2, 63.2, and 123 mg/kg to 167, 141, 70.6, and 196 mg/kg, respectively, and the fraction of As adsorbed on low-energy surfaces decreased from 397, 256, 202, and 317 mg/kg to 182, 238, 173, and 172 mg/kg, respectively (after aging for 60 days). Aging proved to be a promising solution for decreasing As transport into the human food chain and could be employed for crops with longer irrigation cycles. ΔH_ad values were positive and varied from 9.26 to 13.0 kJ/mol, confirming the endothermic nature of adsorption. ΔG_ad values were negative and varied from - 18.8 to - 22.8 kJ/mol at all temperatures, demonstrating the spontaneous nature of adsorption.

Nanotechnology- A ray of hope for heavy metals removal

Environmental effects of heavy metal pollution are considered as a widespread problem throughout the world, as it jeopardizes human health and also reduces the sustainability of a cleaner environment. Removal of such noxious pollutants from wastewater is pivotal because it provides a propitious solution for a cleaner environment and water scarcity. Adsorption treatment plays a significant role in water remediation due to its potent treatment and low cost of adsorbents. In the last two decades, researchers have been highly focused on the modification of adsorption treatment by functionalized and surface-modified nanomaterials which has spurred intense research. The characteristics of nano adsorbents attract global scientists as it is also economically viable. This review shines its light on the functionalized nanomaterials application for heavy metals removal from wastewater and also highlights the importance of regeneration of nanomaterials in the view of visualizing the economic aspects along with a cleaner environment. The review also focused on the proper disposal of nanomaterials with crucial issues that persist in the adsorption process and also emphasize future research modification at a large-scale application in industries.

Chitosan-the miracle biomaterial as detection and diminishing mediating agent for heavy metal ions: A mini review

Proliferation of heavy metal ions as aquatic pollutants has been a matter of growing concern now a days. Several anthropogenic activities have fueled higher concentration of heavy metal ions in aquatic bodies above threshold values, as set by World Health Organization. Of late, chitosan for its exquisite properties has been widely used in tackling this burning problem of aquatic pollution caused by heavy metal ions. Accordingly, this mini review appraises the detection as well as diminution activities where chitosan plays the major contributing part. Starting from the intrinsic properties of chitosan, the detection strategy via chitosan composites is comprehensively delineated. Likewise, the removal activities via chitosan mediating agents are also overviewed, followed by future recommendations. It is believed that this mini review will give researchers a brief appraisal of two prominent activities related to controlling of heavy metal ion pollution.