3D porous bioadsorbents based on chitosan/alginate/cellulose nanofibers as efficient and recyclable adsorbents of anionic dye

Cellulose-citric acid-chitosan@metal sulfide nanocomposites: Methyl orange dye removal and antibacterial activity

In this study, to develop efficient adsorbents in removing water pollution, new cellulose-citric acid-chitosan@metal sulfide nanocomposites (CL-CA-CS@NiS and CL-CA-CS@CuS) were synthesized by one-pot reaction at mild conditions and characterized using X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Energy Dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) isotherm. The results of characterization techniques confirm that the desired compounds have been successfully synthesized. The as-prepared composites were applied for the removal of methyl orange (MO) dye from aqueous solutions using a batch technique, and the effect of key factors such as initial pH, shaking time, MO concentration, temperature and adsorbent dose were investigated and discussed. Adsorption results exhibited positive impact of temperature, shaking time and adsorbent dose on the MO removal percent. The MO removal percent has been increased over a wide range of pH from 2 (27.6 %) to 6 (98.8 %). Also, almost being constant over a wide range of MO concentration (10-70 mg/L). The results demonstrated that the maximum removal percentage of MO dye (98.9 % and 93.4 % using CL-CA-CS@NiS and CL-CA-CS@CuS, respectively) was achieved under the conditions of pH 6, shaking time of 120 min, adsorbent dose of 0.02 g, MO concentration of 70 mg/L and temperature of 35 °C. The pseudo-second-order (PSO) and Langmuir models demonstrated the best fit to the kinetic and equilibrium data. Also, the thermodynamic results showed that the MO removal process is endothermic and spontaneous in nature. The MO adsorption can be happened by different electrostatic attraction, n-π and π-π stacking and also hydrogen bonding interaction. In addition, antibacterial activity of CL-CA-CS@NiS and CL-CA-CS@CuS nanocomposites exhibited a superior efficiency against S. aureus.

Chitosan-based aerogels: A new paradigm of advanced green materials for remediation of contaminated water

Chitosan (CS) aerogels are highly porous (∼99 %), exhibit ultralow density, and are excellent sorbents for removing ionic pollutants and oils/organic solvents from water. Their abundant hydroxyl and amino groups facilitate the adsorption of ionic pollutants through electrostatic interaction, complexation and chelation mechanisms. Selection of suitable surface wettability is the way to separate oils/organic solvents from water. This review summarizes the most recent developments in improving the adsorption performance, mechanical strength and regeneration of CS aerogels. The structure of the paper follows the extraction of chitosan, preparation and sorption characteristics of CS aerogels for heavy metal ions, organic dyes, and oils/organic solvents, sequentially. A detailed analysis of the parameters that influence the adsorption/absorption performance of CS aerogels is carried out and their effective control for improving the performance is suggested. The analysis of research outcomes of the recently published data came up with some interesting facts that the unidirectional pore structure and characteristics of the functional group of the aerogel and pH of the adsorbate have led to the enhanced adsorption performance of the CS aerogel. Finally, the excerpts of the literature survey highlighting the difficulties and potential of CS aerogels for water remediation are proposed.

Effective removal of Cu(II) from water by three-dimensional composite microspheres based on chitosan/sodium alginate/silicon dioxide: Adsorption performance and mechanism

Chitosan (CS) is commonly used as an adsorbent for removing Cu(II) from water, but it has drawbacks such as solubility in dilute acid, difficulty in recycling in powder form, and short service life. This study utilized sodium alginate (SA) as a gel carrier to encapsulate CS, combined with silicon dioxide (SiO2) to improve mechanical stability. The preparation of CS/SA/SiO2 (SSC1.0) involved physical blending, CaCl2 cross-linking, and freeze-drying. Characterization methods such as SEM-EDS, FTIR, BET, and XRD were used to analyze the structural composition of SSC1.0. The material exhibited a folded surface, porous internal cross-section, nitrogen/oxygen-containing functional groups, and thermal stability in high temperatures and various aqueous environments. The adsorption performance of SSC1.0 on Cu(II) was evaluated under different conditions, showing a maximum adsorption capacity of 47.50 mg/g. The material maintained a removal rate above 70 % after 5 cycles. SSC1.0 also showed the highest removal rate of Cu(II) when applied to mine wastewater treatment. Adsorption modeling indicated that the process was driven by chemical reactions and was spontaneous and heat-absorbing.'

Biopolymer-based beads for the adsorptive removal of organic pollutants from wastewater: Current state and future perspectives

Among biopolymer-based adsorbents, composites in the form of beads have shown promising results in terms of high adsorption capacity and ease of separation from the effluents. This review addresses the potential of biopolymer-based beads to remediate wastewaters polluted with emerging organic contaminants, for instance dyes, active pharmaceutical ingredients, pesticides, phenols, oils, polyaromatic hydrocarbons, and polychlorinated biphenyls. High adsorption capacities up to 2541.76 mg g-1 for dyes, 392 mg g-1 for pesticides and phenols, 1890.3 mg g-1 for pharmaceuticals, and 537 g g-1 for oils and organic solvents have been reported. The review also attempted to convey to its readers the significance of wastewater treatment through adsorption by providing an overview on decontamination technologies of organic water contaminants. Various preparation methods of biopolymer-based gel beads and adsorption mechanisms involved in the process of decontamination have been summarized and analyzed. Therefore, we believe there is an urge to discuss the current state of the application of biopolymer-based gel beads for the adsorption of organic pollutants from wastewater and future perspectives in this regard since it is imperative to treat wastewater before releasing into freshwater bodies.

A colorimetric and fluorescent probe of lignocellulose nanofiber composite modified with Rhodamine 6G derivative for reversible, selective and sensitive detection of metal ions in wastewater

Heavy metal ions have extremely high toxicity. As the top of food chain, human beings certainly will accumulate them by ingesting food and participating other activities, which eventually result in the damage to our health. Therefore, it is very meaningful and necessary to design a simple, portable, stable and efficient material for heavy metal ions detection. Based on the spirolactam Rhodamine 6G (SRh6G) fluorescent probe, we prepared two types of nanocomposite materials (membrane and aerogel) by vacuum filtration and freeze-drying methods with lignocellulose nanofiber (CNF) as a carrier, polyvinyl alcohol (PVA) and glutaraldehyde (GA) as the cross-linkers. Then the microstructure, chemical composition, wetting property, fluorescence intensity and selectivity of as-prepared SRh6G/PVA/CNF would be characterized and analyzed. Results showed that SRh6G/PVA/CNF nanocomposites would turn red in color under strong acidic environment and produced orange fluorescence under ultraviolet light. Besides, they were also to detect Al3+, Cu2+, Hg2+, Fe3+ and Ag+ through color and fluorescence variations. We had further tested its sensitivity, selectivity, adsorption, fluorescence limits of detection (LOD) to Fe3+ and Cu2+. The test towards real water samples (hospital wastewater, Songhua River and tap water) proved that SRh6G/PVA/CNF nanocomposites could detect the polluted water with low concentrations of Fe3+ and Cu2+. In addition, SRh6G/PVA/CNF nanocomposites have excellent mechanical property, repeatability, superhydrophilicity and underwater superoleophobicity, which may offer a theoretical reference for the assembly strategy and detection application of cellulose-based fluorescent probe.

Cellulose-alginate hydrogels and their nanocomposites for water remediation and biomedical applications

In the last decade, both cellulose and alginate polysaccharides have been extensively utilized for the synthesis of biocompatible hydrogels because of their alluring characteristics like low cost, biodegradability, hydrophilicity, biodegradability, ease of availability and non-toxicity. The presence of abundant hydrophilic functional groups (like carboxyl and hydroxyl) on the surface of cellulose and alginate or their derivatives makes these materials promising candidates for the preparation of hydrogels with appealing structures and characteristics, leading to growing research in water treatment and biomedical fields. These two polysaccharides are typically blended together to improve hydrogels' desired qualities (mechanical strength, adsorption properties, cellulose/alginate yield). So, keeping in view their extensive applicability, in the present review article, recent advances in the development of cellulose/nanocellulose-alginate-based hydrogels and their relevance in water treatment (adsorption of dyes, heavy metals, etc.) and biomedical field (wound healing, tissue engineering, drug delivery) has been reviewed. Further, impact of other inorganic/organic additives in cellulose/nanocellulose-alginate-based hydrogels properties like contaminants adsorption, drug delivery, tissue engineering, etc., has also been studied. Moreover, the current difficulties and future prospects of nanocellulose-alginate-based hydrogels regarding their water purification and biomedical applications are also discussed at the end.

Bifunctional of Fe3O4@chitosan nanocomposite as a clarifying agent and cationic flocculant on different sugar solutions as a comprehensive semi industrial application

In the sugar industry, eliminating side impurities throughout the manufacturing process is the most significant obstacle to clarifying sugar solutions. Herein, magnetic chitosan (MCS) nanocomposite was Fabricated to be used as a biodegradable, environmentally friendly clarifying agent throughout the cane juice and sugar refining processes. Fe3O4 was synthesized using the coprecipitation procedure, and then MCS was combined using a cross-linking agent. Furthermore, 14.76 emu g-1 was the maximum saturation magnetization (Ms) value. Because MCS is magnetically saturated, it may be possible to employ an external magnetic field to separate the contaminant deposited on its surface. Additionally, zeta potential analysis showed outstanding findings for MCS with a maximum value of (+) 20.7 mV, with improvement in color removal % up to 44.8% using MCS with more than 24% in color removal % compared to the traditional clarification process. Moreover, utilizing MCS reduced turbidity from 167 to 1 IU. Overall, we determined that MCS nanocomposite exhibits considerable effectiveness in the clarifying process for different sugar solutions, performing as an eco-friendly bio-sorbent and flocculating material.

Effect of biocomposite production factors on the development of an eco-friendly chitosan/alginate-based adsorbent with enhanced copper removal efficiency

Nowadays, wastewater treatment is a critical concern, particularly regarding the removal of heavy metals through adsorption methods. Extensive research has been conducted on obtaining high-yield and environmentally friendly adsorbents. Natural polymer adsorbents especially have shown promise in ion and organic molecule adsorption. To enhance the practical applicability of adsorbents, the combination of biopolymers to form biocomposites is a promising alternative. In this study, adsorbents based on a 1:1 wt./wt. of chitosan (CS) and alginate (SA) were prepared. The influence of the regeneration route and drying conditions on the copper adsorption capacity was investigated, along with reaction parameters such as contact time, adsorbent particle size, and pH. The highest adsorption capacity was observed in the composite material obtained through a one-pot regeneration process and freeze-dried. The CSAR3L sample exhibited a remarkable adsorption capacity of 288 mg Cu(II)/g after 360 min at 25 °C. The synergistic effect between the CS and SA precursors was confirmed by analyzing the individual precursors and their mechanical mixture. The initial adsorption rates at pH 6 followed the order: CSAR3-L > Bk-CSR3L > Bk-SAR3L + Bk-CSR3L > Bk-SAR3L. The physicochemical and morphological properties of the materials were studied by FTIR, XRD, DLS, XPS, optical microscopy, EDS-SEM, elemental chemical analysis, and TGA-DTG. The utilization of different drying methods resulted in the formation of calcium carbonate crystalline phases in the as-prepared materials, thus creating substantial adsorption active sites. After the adsorption process, hydroxylated copper sulfate phases and a significant decrease in calcium concentration were observed, indicating that an ion exchange adsorption mechanism occurred. The analysis of adsorption kinetics and the shape of the adsorption isotherms, in agreement with the characterization results, suggested the presence of multiple active sites and the formation of a chemisorption monolayer.

The Effect of Silver Nanoparticles/Titanium Dioxide in Poly(acrylic acid-co-acrylamide)-Modified, Deproteinized, Natural Rubber Composites on Dye Removal

This work aims to enhance the dye-removal performance of prepared poly(acrylic acid-co-acrylamide)-modified, deproteinized, natural rubber ((PAA-co-PAM)-DPNR) through incorporation with silver nanoparticles/titanium dioxide. The (PAA-co-PAM)-DPNR was prepared by emulsion-graft copolymerization with a grafting efficiency of 10.20 ± 2.33 to 54.26 ± 1.55%. The composites based on (PAA-co-PAM)-DPNR comprising silver nanoparticles and titanium dioxide ((PAA-co-PAM)-DPNR/Ag-TiO2) were then prepared by latex compounding using the fixed concentration of AgNO3 (0.5 phr) and varying concentrations of TiO2 at 1.0, 2.5, and 5.0 phr. The formation of silver nanoparticles was obtained by heat and applied pressure. The composites had a porous morphology as they allowed water to diffuse in their structure, allowing the high specific area to interact with dye molecules. The incorporation of silver nanoparticles/titanium dioxide improved the compressive modulus from 1.015 ± 0.062 to 2.283 ± 0.043 KPa. The (PAA-co-PAM)-DPNR/Ag-TiO2 composite with 5.0 phr of TiO2 had a maximum adsorption capacity of 206.42 mg/g, which increased by 2.02-fold compared to (PAA-co-PAM)-DPNR. The behavior of dye removal was assessed with the pseudo-second-order kinetic model and Langmuir isotherm adsorption model. These composites can maintain their removal efficiency above 90% for up to five cycles. Thus, these composites could have the potential for dye-removal applications.

Progress in the Preparation of Stimulus-Responsive Cellulose Hydrogels and Their Application in Slow-Release Fertilizers

Agriculture is facing challenges such as water scarcity, low fertilizer utilization, food security and environmental sustainability. Therefore, the development of slow-release fertilizer (SRF) with controlled water retention and release is particularly important. Slow-release fertilizer hydrogel (SRFH) has a three-dimensional (3D) network structure combined with fertilizer processing, displaying excellent hydrophilicity, biocompatibility and controllability. Cellulose has abundant hydroxyl groups as well as outstanding biodegradability and special mechanical properties, which make it a potential candidate material for the fabrication of hydrogels. This work would analyze and discuss various methods for preparing stimulus-responsive cellulose hydrogels and their combinations with different fertilizers. Moreover, the application and release mechanism of stimulus-responsive cellulose hydrogels in SRF have been summarized as well. Finally, we would explore the potential issues of stimulus-responsive cellulose hydrogels serving as an SRF, propose reasonable solutions and give an outlook of the future research directions.

Nanoremediation strategies to address environmental problems

A rapid rise in population, extensive anthropogenic activities including agricultural practices, up-scaled industrialization, massive deforestation, etc. are the leading causes of environmental degradation. Such uncontrolled and unabated practices have affected the quality of environment (water, soil, and air) synergistically by accumulating huge quantities of organic and inorganic pollutants in it. Environmental contamination is posing a threat to the existing life on the Earth, therefore, demands the development of sustainable environmental remediation approaches. The conventional physiochemical remediation approaches are laborious, expensive, and time-consuming. In this regard, nanoremediation has emerged as an innovative, rapid, economical, sustainable, and reliable approach to remediate various environmental pollutants and minimize or attenuate the risks associated with them. Owing to their unique properties such as high surface area to volume ratio, enhanced reactivity, tunable physical parameters, versatility, etc. nanoscale objects have gained attention in environmental clean-up practices. The current review highlights the role of nanoscale objects in the remediation of environmental contaminants to minimize their impact on human, plant, and animal health; and air, water, and soil quality. The aim of the review is to provide information about the applications of nanoscale objects in dye degradation, wastewater management, heavy metal and crude oil remediation, and mitigation of gaseous pollutants including greenhouse gases.

Chitosan-cellulose nanocomposite: Preparation, characterization, and evaluation as cationic color precipitant in sugar clarification process

The present paper aims to use natural biodegradable polymers of chitosan (CS) and cellulose (CEL) to synthesize green chitosan-cellulose (CS-CEL) nanocomposite as a new clarifying agent. This is the cutting-edge of the sugar industry's clarification process. The CS-CEL nanocomposite showed outstanding results in zeta potential analysis, with a maximum value (+) 57.73 mV, leading to remarkableresults in coloradsorption via electrostatic attraction. It was also observed that CS-CEL has high mechanical stability. When CS and CS-CEL nanocomposite were used in the clarification of sugarcane (MJ), the findings demonstrated an improvement in colorremoval of up to 8.7% using CS and 18.1%using CS-CEL nanocomposite compared to currently phosphotation clarification process. Also, Turbidity decreased using CS-CEL nanocomposite compared to the traditional phosphotation clarification process. Overall, we can conclude that CS-CEL nanocomposite has considerable efficiency in sugarcane juice clarification process as a green biodegradable adsorbent and flocculating material to produce sulfur-free sugar.

Fabrication of PCL/CMARX/GO Composite Nanofibrous Mats for Dye Adsorption: Wastewater Treatment

The effluents of industrial wastewater contain several toxic organic and inorganic pollutants that may contaminate clean and freshwater sources if untreated or poorly treated. These toxic pollutants include colors; hazardous compounds; surfactants; cosmetics; agrochemicals; pharmaceutical by-products; and agricultural, pharmaceutical, and medical contaminants. Treating wastewater has become a global problem. Many projects have been started in the last two decades to treat wastewater, resultant water pollution, and associated waste management problems. Adsorbants based on graphene oxide (GO) are viable wastewater treatment materials due to their adaptability, photocatalytic action, and capacity for self-assembly. Here, we report the fabrication of nanofibrous mats from polycaprolactone (PCL), carboxymethyl arabinoxylan (CMARX), and carboxyl-functionalized-graphene oxide using an electrospinning technique. The silver nanoparticles were loaded onto the mat to enhance their photocatalytic activity. These mats were characterized using different techniques, including Fourier transform infrared (FTIR), scanning electron microscope (SEM), and transmission electron microscope (TEM). The water contact angles were used to study their hydrophilic and hydrophobic behavior. The Langmuir isotherm model and adsorption kinetics were studied to evaluate their adsorption capabilities against methylene blue (MB). Sample 2 followed the Langmuir isotherm model (R² = 0.9939). Adsorption kinetics exhibited pseudo-second order behavior (R² = 0.9978) due to their maximum correlation coefficient values. MB has excellent adsorption at room temperature and the formation of the monolayer at the surface of the adsorption mat. An enhanced PO₄^3- and MB adsorption was observed, providing recyclability up to 4-5 times. Hence, the fabricated nanofibrous mat would be a potential candidate for more effective wastewater treatment applications.

Simple synthesis of chitosan/alginate/graphene oxide/UiO-67 amphoteric aerogels: Characterization, adsorption mechanism and application for removal of cationic and anionic dyes from complex dye media

A chitosan/alginate/graphene oxide/UiO-67 (CS/SA/GO/UiO-67) amphoteric aerogel was synthesized successfully. A series of characterization experiments of CS/SA/GO/UiO-67 amphoteric aerogel was performed by SEM, EDS, FT-IR, TGA, XRD, BET, and zeta potential. The competitive adsorption properties of different adsorbents for complex dyes wastewater (MB and CR) at room temperature (298 K) were compared. Langmuir isotherm model predicted that the maximum adsorption quantity of CS/SA/GO/UiO-67 for CR and MB was 1091.61 and 1313.95 mg/g, respectively. The optimum pH values of CS/SA/GO/UiO-67 for the adsorption of CR and MB were 5 and 10, respectively. The kinetic analysis showed that the adsorption of MB and CR on CS/SA/GO/UiO-67 was more suitable for the pseudo-second-order and pseudo-first-order kinetic model, respectively. The isotherm study revealed that the adsorption of MB and CR was consistent with the Langmuir isotherm model. The thermodynamic study demonstrated that the adsorption process of MB and CR was exothermic and spontaneous. FT-IR analysis and zeta potential characterization experiments revealed that the adsorption mechanism of MB and CR on CS/SA/GO/UiO-67 depended on π-π bond, hydrogen bond, and electrostatic attraction. Repeatable experiments showed that the removal rates of MB and CR of CS/SA/GO/UiO-67 after six cycles of adsorption were 67.19 and 60.82 %, respectively.

Chitosan-based composite hydrogel with a rigid-in-flexible network structure for pH-universal ultra-efficient removal of dye

Polysaccharide-based hydrogel adsorbents become popular because of their high adsorption capacity and fast adsorption rate, but their low removal rate and poor pH resistance have always been fatal shortcomings. Herein, a feasible strategy was proposed to strengthen the ability of hydrogel adsorbent to remove organic pollutants (i.e., dye) by incorporating natural rectorite (REC) into chitosan-g-poly (2-acrylamido-2-methyl-propane-sulfonic-acid) hydrogel network to form a rectorite-in-polymer network structure. The introduction of less dosage of REC (1.2 wt%) into the hydrogel facilitates to improve its adsorption capacities toward methylene blue (MB) in deionized water, tap water, seawater, Yangtze River water, and Yellow River water (1083.39-1303.49 mg/g); while incorporating higher content of REC (15.8 wt% REC) helps to improve the removal rate (99.6 % for MB in real waters), which are greatly superior to commercial activated carbons. The adsorbent keeps high adsorption efficiency in a broad pH range (2-11), and can be reused for >4 times.

Bamboo Nanocellulose/Montmorillonite Nanosheets/Polyethyleneimine Gel Adsorbent for Methylene Blue and Cu(II) Removal from Aqueous Solutions

In recent years, the scarcity of pure water resources has received a lot of attention from society because of the increasing amount of pollution from industrial waste. It is very important to use low-cost adsorbents with high-adsorption performance to reduce water pollution. In this work, a gel adsorbent with a high-adsorption performance on methylene blue (MB) and Cu(II) was prepared from bamboo nanocellulose (BCNF) (derived from waste bamboo paper) and montmorillonite nanosheet (MMTNS) cross-linked by polyethyleneimine (PEI). The resulting gel adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (SEM), X-ray photoelectron spectroscopic (XPS), etc. The results indicated that the MB and Cu(II) adsorption capacities of the resulting gel adsorbent increased with the solution pH, contact time, initial concentration, and temperature before equilibrium. The adsorption processes of MB and Cu(II) fitted well with the fractal-like pseudo-second-order model. The maximal adsorption capacities on MB and Cu(II) calculated by the Sips model were 361.9 and 254.6 mg/g, respectively. The removal of MB and Cu(II) from aqueous solutions mainly included electrostatic attraction, ion exchange, hydrogen bonding interaction, etc. These results suggest that the resulting gel adsorbent is an ideal material for the removal of MB and Cu(II) from aqueous solutions.

Facile synthesis of CoFe2O4@MIL-53(Al) nanocomposite for fast dye removal: Adsorption models, optimization and recyclability

The global occurrence of textile dyes pollution has recently emerged, posing a serious threat to ecological systems. To abate dye contamination, we here developed a novel magnetic porous CoFe₂O₄@MIL-53(Al) nanocomposite by incorporating magnetic CoFe₂O₄ nanoparticles with MIL-53(Al) metal-organic framework. This nanocomposite possessed a surface area of 197.144 m² g^-1 and a pore volume of 0.413 cm³ g^-1. The effect of contact time (5-120 min), concentration (5-50 mg L^-1), dosage (0.1-1.0 g L^-1), and pH (2-10) on Congo red adsorption was clarified. CoFe₂O₄@MIL-53(Al) could remove 95.85% of Cong red dye from water with an accelerated kinetic rate of 0.6544 min^-1 within 10 min. The kinetic and isotherm models showed the predominance of Bangham and Temkin. According to Langmuir, the maximum uptake capacities of CoFe₂O₄@MIL-53(Al), CoFe₂O₄, and MIL-53(Al) adsorbents were 43.768, 17.982, and 15.295 mg g^-1, respectively. CoFe₂O₄@MIL-53(Al) was selected to optimize Cong red treatment using Box-Behnken experimental design. The outcomes showed that CoFe₂O₄@MIL-53(Al) achieved the highest experimental uptake capacity of 35.919 mg g^-1 at concentration (29.966 mg L^-1), time (14.926 min), and dosage (0.486 g L^-1). CoFe₂O₄@MIL-53(Al) could treat dye mixture (methylene blue, methyl orange, Congo red, malachite green, and crystal violet) with an outstanding removal efficiency of 81.24% for 30 min, and could be reused up to five cycles. Therefore, novel recyclable and stable CoFe₂O₄@MIL-53(Al) is recommended to integrate well with real dye treatments systems.

Experimental Insights into Mesoporous Polyaniline-Based Nanocomposites for Anionic and Cationic Dye Removal

This work presents the preparation of inorganic-organic hybrid nanocomposites, namely three-dimensional polyaniline (Pani)/activated silica gel (ASG) (3D Pani@ASG), their characterization, and in removing application as a potential adsorbent for cationic brilliant green (BG), crystal violet (CV), and anionic Congo red (CR), and methyl orange (MO) dyes. Pani@ASG nanocomposites have been prepared by the in situ polymerization method and characterized using various techniques such as Fourier transform infrared (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction, thermogravimetric analysis with derivative thermogravimetry, zeta potential analyses, and Brunauer-Emmett-Teller (BET). The scanning electron microscopy (SEM) study confirms the average particle size of the Pani@ASG nanocomposite is in the range of 5 nm. FESEM, TEM, FTIR, and XRD analysis proved the successful decoration of ASG over Pani. The BET result of Pani@ASG shows a mesoporous nature with a pore diameter of less than 3 nm and a surface area of 423.90 m² g^-1. Both SEM and TEM analyses show the proportional distribution of ASG over Pani's surface. The adsorption trend of BG and MO on the studied materials at pH 7 was found as follows: Pani@ASG > Pani > ASG. The highest sorption capacities of MO and BG on Pani@ASG were 161.29 and 136.98 mg/g (T = 298.15 K, and Pani@ASG dose: 0.04 g for MO and 0.06 g for BG), which were greater compared with bare Pani and bare ASG, respectively. The interaction mechanism behind the adsorption of BG and MO dyes onto the Pani@ASG nanocomposite includes electrostatic interaction, π-π interaction, and hydrogen bonding. The mechanistic pathway and the interactions between the targeted dyes and Pani@ASG were further studied using adsorption isotherm, adsorption kinetics, and thermodynamics.

Synthesis, characterization and application of new adsorbent composites based on sol-gel/chitosan for the removal of soluble substance in water

In this work, new adsorbent composites from the silica precursor tetraethyl orthosilicate (TEOS) and chitosan have been successfully synthesized, denominated 20%Chi, 30%Chi and 40%Chi. The composites presented enhanced chemical and physical characteristics, with emphasis on the high surface areas between 374.94 m²/g to 886.31 m²/g. The application of the composites in the model system (TY - Tartrazine yellow dye), presented adsorption capacities dependent on the amount of chitosan in the composite (40%Chi > 30%Chi > 20%Chi). However, from the experimental data of the constituent materials, 30%Chi provided the greatest increase in the adsorption capacity in the monolayer, with values of 36%. This demonstrates that the amount of chitosan in the compound alters the arrangement of adsorption sites. The 30%Chi composite presented life cycle superior to 10 reuse cycles.

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The addition of silica provided better physical and chemical properties to the developed composites.

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The synthesis of the 30%Chi composite enabled an increase in the adsorption capacity of the TY dye.

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The 30%Chi composite obtained a surface area of 886.31 m²/g.

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The 30%Chi composite was useful for more than 10 adsorption and desorption cycles.

Core-shell microparticles: From rational engineering to diverse applications

Core-shell microparticles, composed of solid, liquid, or gas bubbles surrounded by a protective shell, are gaining considerable attention as intelligent and versatile carriers that show great potential in biomedical fields. In this review, an overview is given of recent developments in design and applications of biodegradable core-shell systems. Several emerging methodologies including self-assembly, gas-shearing, and coaxial electrospray are discussed and microfluidics technology is emphasized in detail. Furthermore, the characteristics of core-shell microparticles in artificial cells, drug release and cell culture applications are discussed and the superiority of these advanced multi-core microparticles for the generation of artificial cells is highlighted. Finally, the respective developing orientations and limitations inherent to these systems are addressed. It is hoped that this review can inspire researchers to propel the development of this field with new ideas.

Magnetic graphene oxide-containing chitosan‑sodium alginate hydrogel beads for highly efficient and sustainable removal of cationic dyes

Developing recyclable and efficient adsorbents for cationic dyes removal from wastewater is crucial for ensuring green ecology and drinking water safety. Herein, we demonstrated a novel magnetic gel bead adsorbent that was synthesized by employing graphene oxide (GO) modified Fe₃O₄ as magnetic nanoparticles doped sodium alginate (SA)/chitosan (CS) gel (SA/GO@Fe₃O₄/CS). The GO@Fe₃O₄ sample was prepared based on GO by the chemical co-precipitation method, which not only reduced the aggregation of Fe₃O₄ but also increases the specific surface area of the composite gel beads. The prepared gel beads were used to adsorb methylene blue (MB), neutral red (NR), and safranine T (ST). The experimental results showed that the adsorption capacity of SA/GO@Fe₃O₄/CS gel beads for MB, NR, and ST reached 21.325 mg/g, 44.654 mg/g and 44.313 mg/g. After five recycles, the removal rates could still reach more than 90% of the original, exhibiting a high recovery rate. Therefore, this paper provides a strategy for the preparation of high efficiency and recyclable cationic dye adsorbents with a large specific surface area.

Applications of chitin and chitosan based biomaterials for the adsorptive removal of textile dyes from water - A comprehensive review

The presence of pollutants in the water bodies deteriorate the water quality and make it unfit for use. From an environmental perspective, it is essential to develop new technologies for the wastewater treatment and recycling of dye contaminated water. The surface modified chitin and chitosan biopolymeric composites based adsorbents, have an important role in the toxic organic dyes from removal wastewater. The surface modification of biopolymers with various organics and inorganics produces more active sites at the surface of the adsorbent, which enhances dye and adsorbent interaction more reliable. Herein, the work brought in the thought of the application of various chitin and chitosan composites in wastewater remediation and suggested the versatility in composites for the development of rapid, selective and effective removal processes for the detoxification of a variety of organic dyes. It further emphasizes the existing obstruction and impending prediction for the deprivation of dyes via adsorption techniques.

Recent Advances in the Fabrication and Environmental Science Applications of Cellulose Nanofibril-Based Functional Materials

Cellulose is one of the important biomass materials in nature and has shown wide applications in various fields from materials science, biomedicine, tissue engineering, wearable devices, energy, and environmental science, as well as many others. Due to their one-dimensional nanostructure, high specific surface area, excellent biodegradability, low cost, and high sustainability, cellulose nanofibrils/nanofibers (CNFs) have been widely used for environmental science applications in the last years. In this review, we summarize the advance in the design, synthesis, and water purification applications of CNF-based functional nanomaterials. To achieve this aim, we firstly introduce the synthesis and functionalization of CNFs, which are further extended for the formation of CNF hybrid materials by combining with other functional nanoscale building blocks, such as polymers, biomolecules, nanoparticles, carbon nanotubes, and two-dimensional (2D) materials. Then, the fabrication methods of CNF-based 2D membranes/films, three-dimensional (3D) hydrogels, and 3D aerogels are presented. Regarding the environmental science applications, CNF-based nanomaterials for the removal of metal ions, anions, organic dyes, oils, and bio-contents are demonstrated and discussed in detail. Finally, the challenges and outlooks in this promising research field are discussed. It is expected that this topical review will guide and inspire the design and fabrication of CNF-based novel nanomaterials with high sustainability for practical applications.

A mesoporous nanocellulose/sodium alginate/carboxymethyl-chitosan gel beads for efficient adsorption of Cu2+ and Pb2

In this study, a novel mesoporous nanocellulose/sodium alginate (SA)/carboxymethyl-chitosan (CMC) aerogel was fabricated using a simple method. The adsorption of Cu²⁺ and Pb²⁺ on the aerogel in aqueous solutions was investigated. The obtained aerogel was characterized using scanning electron microscopy, fourier-transform infrared spectroscopy, transmission microscope, atomic force microscopy and N₂ adsorption-desorption. Furthermore, the fundamental Cu²⁺ and Pb^2+c adsorption behaviours of the mesoporous aerogel, including the effect of pH, adsorption equilibrium and kinetics were investigated. The adsorption isotherms and kinetics of aerogel closely followed the Langmuir model and pseudo-second-order model, respectively, indicating that the adsorption behaviours can be classified as monolayer chemical adsorption. The aerogel exhibited high efficiency for the adsorption of Cu²⁺ (169.94 mg/g) and Pb²⁺ (472.59 mg/g). The aerogel maintained a high adsorption capacity for Cu²⁺ (56 mg/g) and Pb²⁺ (245 mg/g) after five adsorption-desorption cycles. Therefore, the as-prepared mesoporous aerogel has great potential in wastewater treatment.