Performance of montmorillonite/graphene oxide/CoFe2O4 as a magnetic and recyclable nanocomposite for cleaning methyl violet dye-laden wastewater

Adsorptive removal of orange G dye from aqueous solution by ultrasonic-activated peanut shell powder: isotherm, kinetic and thermodynamic studies

The current study is to develop surface-modified peanut shell granules by incorporating activated carbon to enhance the removal efficiency of Orange G dye (OGD) through adsorption. Activated carbon was prepared from Arachis hypogaea shell (Peanut shell) using a chemical activation method. Ultrasonic Activated Peanut Shell Powder (UAPSP) was characterised using FT-IR and SEM analysis to identify functional groups and assess surface morphology. To determine the optimal conditions, a batch adsorption study was conducted. The results indicated a maximum removal efficiency of 99.5% and a maximum adsorption capacity of 298.36 mg/g under the following parameters: pH 5, temperature 303 K, interaction period of 60 min, a dosage of 0.5 g/L for an OGD concentration of 10 mg/L. The adsorption mechanism in the current system was evaluated using the Langmuir, Freundlich, Sips, Temkin, and D-R isotherms models. Among these, the Langmuir isotherm exhibited the best fit with an R2 value of 0.997. UAPSP demonstrated a monolayer adsorption capacity of 1.9 mg/g for OGD removal. The pseudo-second-order kinetic model provided the most effective fit with an R2 value of 0.998. Thermodynamic studies revealed that the adsorption process was spontaneous and exothermic, as evidenced by the negative values of ΔG° ( -1.497) and ΔS° (16.4052) at 303 K. Additionally, the mean free energy value (E) in the D-R isotherm increased to 10.58 KJ/mol with a temperature rise from 303 K to 343 K. The characterisation results confirmed that UAPSP is an effective, cost-free, and commercial alternative adsorbent for the removal of hazardous dyes from wastewater.

Polypyrrole-decorated bentonite magnetic nanocomposite: A green approach for adsorption of anionic methyl orange and cationic crystal violet dyes from contaminated water

In the presented study, a novel polypyrrole-decorated bentonite magnetic nanocomposite (MBnPPy) was synthesized for efficient removal of both anionic methyl orange (MO) and cationic crystal violet (CV) dyes from contaminated water. The synthesis of this novel adsorbent involved a two-step process: the magnetization of bentonite followed by its modification through in-situ chemical polymerization. The adsorbent was characterized by SEM/EDX, TEM/SAED, BET, TGA/DTA-DTG, FTIR, VSM, and XRD studies. The investigation of the adsorption properties of MBnPPy was focused on optimizing various parameters, such as dye concentration, medium pH, dosage, contact time, and temperature. The optimal conditions were established as follows: dye concentration of Co (CV/MO) at 100 mg/L, MBnPPy dosage at 2.0 g/L, equilibrium time set at 105 min for MO and 120 min for CV, medium pH adjusted to 5.0 for MO dye and 8.0 for CV dye, and a constant temperature of 303.15 K. The different kinetic and isotherm models were applied to fit the experimental results, and it was observed that the Pseudo-2nd-order kinetics and Langmuir adsorption isotherm were the best-fitted models. The maximal monolayer adsorption capacities of the adsorbent were found to be 78.74 mg/g and 98.04 mg/g (at 303.15 K) for CV and MO, respectively. The adsorption process for both dyes was exothermic and spontaneous. Furthermore, a reasonably good regeneration ability of MBnPPy (>83.45%/82.65% for CV/MO) was noted for up to 5 adsorption-desorption cycles with little degradation. The advantages of facile synthesis, cost-effectiveness, non-toxicity, strong adsorption capabilities for both anionic and cationic dyes, and easy separability with an external magnetic field make MBnPPy novel.

Enhanced dye removal using montmorillonite modified with graphene quantum dots in sustainable salep nanocomposite hydrogel

This research investigated the utilization of graphene quantum dot/montmorillonite (GQD/MMT) as an effective nanofiller in a hydrogel composed of salep biopolymer. The semi-IPN hydrogel was synthesized using salep as the substrate, acrylamide (AAm) as the monomer, ammonium persulfate (APS) as an initiator in free radical polymerization, and N,N'-methylenebisacrylamide (MBA) as a cross-linking agent. The hydrogels were applied to remove safranin (SA), methylene blue (MB), crystal violet (CV), methyl green (MG), congo red (CR), and malachite green (MG) dyes from the water. The diverse properties were analyzed using a scanning electron microscope, fourier infrared spectroscopy, mapping, energy dispersive spectroscopy, weighing analysis, X-ray diffraction, and thermal stability analyses. The optimism of the prepared adsorbent in dye absorption was evaluated by measuring the swelling amount, pH impact, adsorbent dosage, and contact time. The adsorption calculations were described using kinetics and isotherm models. The results indicated that the Langmuir isotherm model (R2 = 99.6) and the pseudo-second-order kinetic model (R2 = 99.9) provided the best fit for the absorption process of MB. The presence of additional amounts of GQD/MMT had a reciprocal effect on the adsorption efficiency due to the accumulation of GQD/MMT in the semi-interpenetrating polymer network (semi-IPN (structure. The findings revealed that the samples exhibited high thermal stability, and the absorption process was primarily chemical. Furthermore, the nanocomposite hydrogels demonstrated distinct mechanisms for absorbing anionic dye (CR) and cationic dye (MB). Under optimal conditions, using 7 wt% GQD/MMT at a concentration of 5 ppm, pH = 7, an adsorbent dosage of 50 mg, at room temperature, and a contact time of 90 min, the maximum removal efficiencies were achieved: MB (96.2%), SA (98.2%), MG (86%), CV (99.8%), MG (95.8%), and CR (63.4%). These results highlight the adsorbent's high absorption capacity, rapid removal rate, and reusability, demonstrating its potential as an eco-friendly and cost-effective solution for removing dyes from water.

An Updated Overview of Magnetic Composites for Water Decontamination

Water contamination by harmful organic and inorganic compounds seriously burdens human health and aquatic life. A series of conventional water purification methods can be employed, yet they come with certain disadvantages, including resulting sludge or solid waste, incomplete treatment process, and high costs. To overcome these limitations, attention has been drawn to nanotechnology for fabricating better-performing adsorbents for contaminant removal. In particular, magnetic nanostructures hold promise for water decontamination applications, benefiting from easy removal from aqueous solutions. In this respect, numerous researchers worldwide have reported incorporating magnetic particles into many composite materials. Therefore, this review aims to present the newest advancements in the field of magnetic composites for water decontamination, describing the appealing properties of a series of base materials and including the results of the most recent studies. In more detail, carbon-, polymer-, hydrogel-, aerogel-, silica-, clay-, biochar-, metal-organic framework-, and covalent organic framework-based magnetic composites are overviewed, which have displayed promising adsorption capacity for industrial pollutants.

Efficacious adsorption of divalent nickel ions over sodium alginate-g-poly(acrylamide)/hydrolyzed Luffa cylindrica-CoFe2O4 bionanocomposite hydrogel

Existing Ni2+ heavy metal ions in an aqueous medium are highly hazardous for living organisms and humans. Therefore, designing low-cost adsorbents with enhanced effectiveness is essential for removing nickel ions to safeguard public health. In this study, a novel green nanocomposite hydrogel was synthesized through the free radical solution and bulk polymerization method, and its capability to remove divalent nickel ions from aqueous media was examined. The bionanocomposite hydrogel named as SA-g-poly(AAm)/HL-CoFe2O4 was produced by grafting polyacrylamide (AAm) onto sodium alginate (SA) in the presence of a magnetic composite recognized as HL-CoFe2O4, where HL represents hydrolyzed Luffa Cylindrica. By employing FT-IR, XRD, VSM, SEM, EDX-Map, BET, DLS, HPLC, and TGA techniques, morphological evaluation and characterization of the adsorbents were carried out. The performance of the adsorption process was studied under varying operational conditions including pH, temperature, contact duration, initial concentration of pollutant ions, and adsorbent dosage. HPLC analysis proved the non-toxic structure of the bionanocomposite hydrogel. The number of unreacted acrylamide monomers within the hydrogel matrix was measured at 20.82 mg/kg. The optimum conditions was discovered to be pH = 6, room temperature, adsorbent dosage of 1 of g.L-1, initial Ni2+ concentration of 10 mg.L-1, and contact time of 100 min, and the maximum adsorption efficiency at optimal state was calculated as 70.09, 90.25, and 93.83 % for SA-g-poly (AAm), SA-g-poly(AAm)/HL, and SA-g-poly(AAm)/HL-CoFe2O4 samples, respectively. Langmuir isotherm model was in good agreement with the experimental data and the maximum adsorption capacity of SA-g-poly(AAm), SA-g-poly(AAm)/HL, and SA-g-poly(AAm)/HL-CoFe2O4 samples was calculated to be 31.37, 43.15, and 45.19 mg.g-1, respectively. The adsorption process, according to kinetic studies, follows a pseudo-second-order kinetic model. Investigations on thermodynamics also demonstrated that the process is exothermic and spontaneous. Exploring the interference effect of co-existing ions showed that the adsorption efficiency has decreased with concentration enhancement of Ca2+ and Na+ cations in aqueous medium. Furthermore, the adsorption/desorption assessments revealed that after 8 consecutive cycles, there had been no noticeable decline in the adsorption effectiveness. Finally, actual wastewater treatment outcomes demonstrated that the bionanocomposite hydrogel successfully removes heavy metal pollutants from shipbuilding industry effluent. Therefore, the findings revealed that the newly fabricated bionanocomposite hydrogel is an efficient, cost-effective, easy-separable, and green adsorbent that could be potentially utilized to remove divalent nickel ions from wastewater.

Polymeric Networks Derived from UV-Curing of Bio-Based Polyesters for Methyl Violet Removal

In this study, firstly, the syntheses and characterizations of biobased polyesters with different acid values obtained from the condensation reaction of biobased itaconic acid and polyethylene glycol were investigated. Then, UV curing was applied to form polymeric networks as adsorbent material from these polyesters containing different acids. Fourier transform infrared spectrometry (FTIR), Nuclear Magnetic Resonance Spectroscopy (NMR), X-ray Photoelectron Spectroscopy (XPS), Gel Permeation Chromatography (GPC) and scanning electron microscope (SEM) were used for the characterization of polymeric networks. The effects of the parameters of contact time, initial dye concentration, pH, temperature, amount of adsorbent on adsorption were investigated by batch method. In addition, adsorption equilibrium data were analyzed by Langmuir, Freundlich, Tempkin, Elovich, Redlich-Peterson, Harkin-Jura and Jossens adsorption models. Kinetic and thermodynamic studies were performed at 298, 308, 318 and 328 K and desorption studies were also examined. Comparison studies for the effects of the acid values of the adsorbent materials on the removal of methyl violet (MV) organic pollutant from aqueous solutions were analyzed. According to the pseudo-second-order model, the adsorption capacities were found to be ≥ 357.14 mg/g for the adsorbents. From the thermodynamic data, it was determined that the mechanism was exothermic and spontaneous. As a result of the third reuse, it was found that the adsorbents had a removal efficiency of ≥ 72.36%. According to the results observed the increase in the acidities in the chemical structure of bio-based polymeric networks enhances the adsoption properties.

Novel TiO2/GO/M-MMT nano-heterostructured composites exhibiting high photocatalytic activity

This study proposed a technique to enhance the photocatalytic properties of TiO2 using graphene oxide (GO) and modified Montmorillonite (M-MMT). TiO2/GO/M-MMT nano-heterostructured composites were prepared via hydrothermal and co-precipitation. The photocatalytic performance was evaluated by investigating the photodegradation rate and absorption behavior of methyl orange (MO) under visible light irradiation. The results showed that TiO2/GO/M-MMT heterojunction exhibited excellent photocatalytic degradation performance, as the degradation rate of MO was observed to be 99.3% within 150 min. The density of adsorbed MO decreased by 62.1% after 210 min of dark adsorption using the TiO2/GO/M-MMT composite, which was significantly higher than that achieved using M-MMT, GO/M-MMT, and TiO2/M-MMT. The nano-heterostructure increased the effective interface between TiO2, GO, and MMT, which increased the charge transfer ability and prolonged the electron-hole separation time. Therefore, the results of this study can be used to design novel photocatalysts to eradicate environmental pollutants.

Adsorptive removal of Cd2+ ions using dolochar at an industrial-scale process optimization by response surface methodology

In this work, performance of laboratory-synthesized dolochar has been investigated for adsorption of Cd²⁺ ions in a large-scale process with the application of Aspen Adsorption. Moreover, the optimum values of the operating parameters (namely, flow rate, bed height, and inlet metal ion concentration) that would result into maximum amount of cadmium ion adsorption (high exhaustion capacity) in minimum time (less exhaustion time) for a fixed mass of dolochar have been calculated via the application of response surface methodology. It was found that, at optimum values of bed height (3.48 m), flow rate (76.31 m³/day), and inlet concentration (10 ppm), the optimized value of exhaustion capacity and exhaustion time for cadmium ion adsorption in dolochar packed bed is equal to 1.85 mg/g and 11.39 h, respectively. The validity of these simulation experiments can be proven by the fact that the obtained exhaustion capacity of dolochar packed bed always remained in close proximity of the experimentally obtained value of adsorption capacity of the dolochar in batch process mode (equal to 2.1 mg/g).

Enhancement of photocatalytic activities of ZnFe2O4 composite by incorporating halloysite nanotubes for effective elimination of aqueous organic pollutants

ZnFe₂O₄ is a highly desirable catalyst due to its exceptional photo-response in the visible light region, but various drawbacks, such as rapid recombination of photo-generated electron-hole pairs and severe particle agglomeration, make it difficult to use. In this study, a co-precipitation approach was used to create ZnFe₂O₄/HNT (ZF/HNTs) composites. XRD, SEM, TEM, FTIR, BET, and DRS were used to characterize the ZF/HNT composites. Furthermore, the effectiveness of removing crystal violet under simulated visible light irradiation was used to assess photocatalytic activity. The results showed that ZnFe₂O₄ with typical diameters of around 20 nm was significantly distributed on halloysite nanotubes. Because of the synergistic impact of the improved agglomeration phenomena of ZnFe₂O₄ and the decreased recombination rate of photo-generated electrons and holes, all of the composites had superior photocatalytic performance than pure ZnFe₂O₄. The ZF/HNTs-11 composite exhibited the highest removal performance, removing 96.7% of the sample in less than 150 min. In addition, the composite was very stable and reusable. Consequently, ZF/HNTs-11 composite is an effective catalyst for treating pollutants found in wastewater.

Competitive adsorption of Alizarin Red S and Bromocresol Green from aqueous solutions using brookite TiO2 nanoparticles: experimental and molecular dynamics simulation

In this work, the effective adsorption and the subsequent photodegradation activity, of TiO₂ brookite nanoparticles, for the removal of anionic dyes, namely, Alizarin Red S (ARS) and Bromocresol Green (BCG) were studied. Batch adsorption experiments were conducted to investigate the effect of both dyes' concentration, contact time, and temperature. Photodegradation experiments for the adsorbed dyes were achieved using ultraviolet light illumination (6 W, λ = 365 nm). The single adsorption isotherms were fitted to the Sips model. The binary adsorption isotherms were fitted using the Extended-Sips model. The results of adsorption isotherms showed that the estimated maximum adsorption uptakes in the binary system were around 140 mg g^-1 and 45.5 mg g^-1 for ARS and BCG, respectively. In terms of adsorption kinetics, the uptake toward ARS was faster than BCG molecules in which the equilibrium was obtained in 7 min for ARS, while it took 180 min for BCG. Moreover, the thermodynamics results showed that the adsorption process was spontaneous for both anionic dyes. All these macroscopic competitive adsorption results indicate high selectivity toward ARS molecules in the presence of BCG molecules. Additionally, the TiO₂ nanoparticles were successfully regenerated using UV irradiation. Moreover, molecular dynamics computational modeling was performed to understand the molecules' optimum coordination, TiO₂ geometry, adsorption selectivity, and binary solution adsorption energies. The simulation energies distribution exhibits lower adsorption energies for ARS in the range from - 628 to - 1046 [Formula: see text] for both single and binary systems. In addition to that, the water adsorption energy was found to be between - 42 and - 209 [Formula: see text].

Intelligent modelling for the elimination of lanthanides (La3+, Ce3+, Nd3+ and Eu3+) from aqueous solution by magnetic CoFe2O4 and CoFe2O4-GO spinel ferrite nanocomposites

In this research, a novel CoFe₂O₄-GO (Graphen Oxide) resulting from the combination of high applicable magnetic and organic base materials and synthesized with a simple and fast co-precipitation route was synthesized for the REEs (Rare Earth Elements) extraction. This adsorbent could remove the La³⁺, Ce³⁺, Nd³⁺ and Eu³⁺ by maximum adsorption capacity of 625, 626, 714.2, 1111.2 mg/g at optimized pH = 6, respectively. A data-driven model was obtained using Group Method of Data Handling (GMDH)-based Neural Network to estimate the adsorption capacity of these LREEs as a function of time, pH, temperature, adsorbent ζ (zeta)- potential, initial concentration of lanthanides ions, and ε which is defined by the physico-chemical properties of lanthanides. The results clearly indicated that the model estimate the experimental values with good deviation (mostly less than 10%) and it can be used for the prediction of the results from other similar researches with less than 25% deviation. The results of sensitivity analysis indicated that the adsorption capacity is more sensitive to pH of the solution, temperature, and ε. Finally, the desorption studies showed an excellent removal efficiency (97%) at least for three adsorption-desorption cycles. These results claimed that the CoFe₂O₄-GO is a highly efficient adsorbent for the REEs extraction.

Sono-Photocatalytic Activity of Cloisite 30B/ZnO/Ag2O Nanocomposite for the Simultaneous Degradation of Crystal Violet and Methylene Blue Dyes in Aqueous Media

A new nanocomposite based on Cloisite 30B clay modified with ZnO and Ag₂O nanoparticles (Cloisite 30B/ZnO/Ag₂O) was synthesized as an effective catalyst in the sono-photocatalytic process of crystal violet (CV) and methylene blue (MB) dyes simultaneously. The characteristics and catalytic activity of Cloisite 30B/ZnO/Ag₂O nanocomposite were investigated under different conditions. The specific active surface for Cloisite 30B/ZnO/Ag₂O nanocomposite was 18.29 m²/g. Additionally, the catalytic activity showed that Cloisite 30B/ZnO/Ag₂O nanocomposite (CV: 99.21%, MB: 98.43%) compared to Cloisite 30B/Ag₂O (CV: 85.38%, MB: 83.62%) and Ag₂O (CV: 68.21%, MB: 66.41%) has more catalytic activity. The catalytic activity of Cloisite 30B/ZnO/Ag₂O using the sono-photocatalytic process had the maximum efficiency (CV: 99.21%, MB: 98.43%) at pH 8, time of 50 min, amount of 40 mM H₂O₂, catalyst dose of 0.5 g/L, and the concentration of 'CV + MB' of 5 mg/L. The catalyst can be reused in the sono-photocatalytic process for up to six steps. According to the results, •OH and h⁺ were effective in the degradation of the desired dyes using the desired method. Data followed the pseudo-first-order kinetic model. The method used in this research is an efficient and promising method to remove dyes from wastewater.

Review on biopolymers and composites - Evolving material as adsorbents in removal of environmental pollutants

The presence of pollutants and toxic contaminants in water sources makes it unfit to run through. Though various conventional techniques are on deck, development of new technologies are vital for wastewater treatment and recycling. Polymers have been intensively utilized recently in many industries owing to their unique characteristics. Biopolymers resembles natural alternative to synthetic polymers that can be prepared by linking the monomeric units covalently. Despite the obvious advantages of biopolymers, few reviews have been conducted. This review focuses on biopolymers and composites as suitable adsorbent material for removing pollutants present in environment. The classification of biopolymers and their composites based on the sources, methods of preparation and their potential applications are discussed in detail. Biopolymers have the potentiality of substituting conventional adsorbents due to its unique characteristics. Biopolymer based membranes and effective methods of utilization of biopolymers as suitable adsorbent materials are also briefly elaborated. The mechanism of biopolymers and their membrane-based adsorption has been briefly reviewed. In addition, the methods of regeneration and reuse of used biopolymer based adsorbents are highlighted. The comprehensive content on fate of biopolymer after adsorption is given in brief. Finally, this review concludes the future investigations in recent trends in application of biopolymer in various fields in view of eco-friendly and economic perspectives.

Fabrication and characterization of magnetic nanomaterials for the removal of toxic pollutants from water environment: A review

The success of any sustainable growth represents an advancement of novel approaches and new methodologies for managing any ecological concern. Magnetic nanoparticles have gained recent interest owing to their versatile properties such as controlled size, shape, quantum and surface effect, etc, and outcome in wastewater treatment and pollutant removal. Developments have progressed in synthesizing magnetic nanoparticles with the required size, shape and morphology, surface and chemical composition. Magnetic nanoparticles are target specific and inexpensive compared to conventional treatment techniques. This review insight into the synthesis of magnetic nanoparticles using physical, chemical, and biological methods. The biological method of synthesizing magnetic nanoparticles serves to be cost-effective, green process, and eco-friendly for various applications. Characterization studies of synthesized nanoparticles using TEM, XRD, SARS, SANS, DLS, etc are discussed in detail. Magnetic nanoparticles are widely utilized in recent research for removing organic and inorganic contaminants. It was found that the magnetic nanosorption approach together with redox reactions proves to be an effective and flexible mechanism for the removal of pollutants from waste effluents.

Preparation and characterization of wheat straw biochar loaded with aluminium/lanthanum hydroxides: a novel adsorbent for removing fluoride from drinking water

In this work, a novel adsorbent of aluminium/lanthanum loaded wheat straw biochar (Al-La-WSB), was prepared by using a facile approach and used for fluoride removal. The Al-La-WSB and its pristine wheat straw biochar (WSB) were characterized by scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray powder diffraction (XRD) methods. Batch adsorption experiments were carried out to investigate adsorbent performance, the highest removal rate was observed at pH 9, contact time of 7 h and Al-La-WSB dose of 1 g L^-1. Lagergren pseudo-second-order kinetics and Langmuir isotherm model fitted the experimental data well. The maximum fluoride adsorption capacity of Al-La-WSB at different experiment temperature of 298, 308 and 318 K, was 51.28 mg g^-1, 46.73 mg g^-1 and 50.25 mg g^-1, respectively, which was better than most reported adsorbents. The Al-La-WSB performed well over a considerable wide pH range of 3-10 and carried positive charge at pH < 4.8. The presence co-existing ions of SO₄^2-, HCO₃^-, Cl^- and NO₃^- had a minor impact on fluoride adsorption besides PO₄^3-. Regeneration experiment results showed that the Al-La-WSB had an excellent reusability. According to the adsorbent characterization and batch adsorption experiment, the adsorption of fluoride on the Al-La-WSB was primarily a chemisorption, involving electrostatic interactions and ion exchange, which nitrate ion and hydroxyl played a major role. The results suggested that the Al-La-WSB could be a great adsorbent for removing fluoride from drinking water.

Development of new magnetic adsorbent of walnut shell ash/starch/Fe3O4 for effective copper ions removal: Treatment of groundwater samples

The goal of this investigation was to develop a new magnetic nanocomposite of walnut shell ash (WSA)/starch/Fe₃O₄ to remove Cu (II) present in groundwater samples. The desired nanocomposites were successfully synthesized by the chemical deposition method. The specific active surface area for pristine WSA and WSA/starch/Fe₃O₄ magnetic nanocomposites was determined to be 8.1 and 52.6 m²/g, respectively. A central composite design for the response surface method was utilized to study the influence of pH, adsorbent quantity, initial content of Cu (II), temperature, and contact time. This method showed the success of the model to design process variables and to estimate the appropriate response. The P- and F-value determined for the quadratic polynomial model showed the significance and accuracy of the proposed model in examining experimental and predicted data with R² and Adj.R² of 0.994 and 0.991, respectively. The Cu adsorption onto WSA and WSA/starch/Fe₃O₄ obeyed the Freundlich and Langmuir models, respectively. The highest Cu (II) sorption capacity of 29.0 and 45.4 mg/g was attained for WSA and WSA/starch/Fe₃O₄, respectively. The free energy of Gibbs had a negative value at 25-45 °C indicating that the adsorption process is spontaneous. Also, negative ΔH values for copper adsorption showed that the processes are exothermic. The kinetic adsorption data for WSA and WSA/starch/Fe₃O₄ followed the pseudo-second order (PSO) model. The ability of the composite adsorbent to remove copper from three groundwater samples showed that it could be reused at least 3 times with appropriate efficiency, depending on the water quality.

Adsorption of methylene blue by Nicandra physaloides(L.) Gaertn seed gum/graphene oxide aerogel

In this study, a novel composite aerogel of Nicandra physaloides(L.) Gaertn seed, gum/graphene oxide (NPG/GO), was prepared by using a vacuum freeze drying method for methylene blue (MB) adsorption. The techniques, including Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), were adopted for studying the structure and surface characteristics of NPG/GO, with thermogravimetric analysis (TGA) being adopted for testing thermal properties. The effects of pH value, initial dye concentration, temperature and adsorbent dosage on adsorption performance were elaborately analysed. The adsorption kinetic studies showed that the process of adsorption follows Langmuir isotherm and a pseudo-second-order kinetic model. When the mass ratio of NPG to GO was 1.25:1, the adsorption capacity was the highest. According to Langmuir isotherm, the maximum adsorption capacity of 408.16 mg/g was higher than that of NPG. The specific surface area and average pore diameter of NPG/GO was measured as 2.70 m²/g and 4.8 nm, respectively. Thermodynamic analysis revealed that the adsorption process of methylene blue on NPG/GO was a spontaneous and endothermic process. In general, the prepared nanocomposites were excellent candidates for adsorption and removal process because of simple synthesis, low cost, high efficiency, non-toxicity, environment protection and degradability.

SnO2–Fe3O4 nanocomposites for the photodegradation of the Congo red dye

Synthesis of SnO₂–Fe₃O₄ nanocomposites was conducted. The purpose of this study was to obtain the SnO₂–Fe₃O₄ nanocomposites, the effectiveness of photodegradation Congo red by SnO₂–Fe₃O₄ nanocomposites and determine the kinetics of photodegradation. The XRD analysis showed that the SnO₂–Fe₃O₄ nanocomposite best mass ratio was 1:1 based on the highest intensity of characteristic angle (2θ), which is 26.54° and had the smallest crystal size, which is 9.662 nm. Based on the UV-Vis DRS result, the SnO₂–Fe₃O₄ nanocomposites bandgap value was 2.3 eV. The magnetization saturation value of SnO₂–Fe₃O₄ nanocomposites was 64.96 emu/g. The morphology of SnO₂–Fe₃O₄ nanocomposites showed by the TEM image, where the dark spots spread in the lighter areas. The surface of SnO₂–Fe₃O₄ nanocomposites characterized by SEM with the result was bumpy surface and many pores. The EDS result of SnO₂–Fe₃O₄ nanocomposites confirmed the presence of Fe, Sn, and O elements. The functional group of SnO₂–Fe₃O₄ nanocomposites showed by FTIR data, the stretch band of Sn–O characteristics showed at wavenumber 590 cm⁻¹, and the stretch band of Fe–O showed at wavenumber 563 cm⁻¹. The optimum condition of nanocomposites at a contact time of 90 min and the optimum concentration of 18 mg/L showed that the percent of photodegradation was 50.76%. The photodegradation rate of SnO₂–Fe₃O₄ was fitted to Pseudo-second-order.

Pyrene-based sulfonated organic porous materials for rapid adsorption of cationic dyes in water

Porous organic polymers (POP) have gained attention because of their high specific surface area, porosity and their simplicity in synthesis, but for the most part, they are hydrophobic because of their organic backbone, making it difficult to expand their applications. Here, we have obtained poly(pyrene) porous organic polymers (PyPOP) through the polymerization of pyrene monomers catalysed by aluminium trichloride, which is a simple and inexpensive synthesis method. The sulfonated poly(pyrene) porous organic polymers (PyPOP-SO₃H) obtained showed rapid adsorption of cationic dyes, especially malachite green (MG adsorption 1607 mg/g) and methylene blue (MB adsorption 1220 mg/g) in pH = 7 aqueous solution, room temperature. The results show that the Freundlich model is more in line with the adsorption process than the Langmuir model, whether for methylene blue or malachite green. In addition, the PSO kinetic model fits better than PFO kinetic model, whether it is for the adsorption of methylene blue or malachite green. The excellent adsorption performance of PyPOP-SO3H for cationic dyes may be due to the introduction of sulfonic acid groups, which not only increases the specific surface area but also allows better dispersion in water, increasing contact points and adsorption efficiency. This research expands the scope of exploration and application of POP.

Influence of Ce3+ on the Structural, Morphological, Magnetic, Photocatalytic and Antibacterial Properties of Spinel MnFe2O4 Nanocrystallites Prepared by the Combustion Route

The present work describes the effect of Ce3+ ion doping on the structural, morphological, and magnetic properties of spinel manganese ferrite (MnFe2O4) nanocrystallites (NCs) using various instrument techniques. Rare earth element (REE) Cerium (Ce3+) doped MnFe2O4 NCs were prepared by a simple microwave combustion technique. In the present scenario, ferrites are widely used for photocatalytic dye degradation and antibacterial applications. Aiming to achieve this, we prepared Ce3+ doped MnFe2O4 NCs by microwave combustion method and urea as burning agent and the obtained powder samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), high resolution scanning electron microscope (HR-SEM), high resolution transmission electron microscope (HR-TEM) and vibration sample magnetometer (VSM) techniques. The pure spinel phase formation was confirmed by XRD analysis. FTIR spectra show two prominent absorption bands under 1000 cm−1, which confirms the formation of the spinel structure. HR-SEM and HR-TEM pictures demonstrated a sphere-shaped morphology and also expose the combination and agglomeration of grains, which are mostly due to the magnetic characteristics of the samples. The magnetic properties of the synthesized MnCexFe2−xO4 (x = 0.0, 0.1, 0.3, and 0.5) NCs were studied by VSM analysis at room temperature (RT) shows ferromagnetic behavior. The photodegradation results showed that MnFe2O4 and Ce doped MnFe2O4 NCs have a higher potential to degrade methylene blue (MB) and the sample MnCe0.3Fe1.7O4 NCs showed superb photocatalytic performance (91.53%) compared to other samples. The antibacterial activities of Gram-positive S. aureus, B. subtilis and Gram-negative K. pneumonia and E. coli were investigated using pure and Ce3+ substituted MnFe2O4 NCs and a higher activity for MnCe0.3Fe1.7O4 NCs than other samples was observed, which indicated that they can be used in biomedical applications.

Impact of ZnO and Fe3O4 magnetic nanoscale on the methyl violet 2B removal efficiency of the activated carbon oak wood

In the current study, activated carbon oak wood (ACOW600) and modified activated carbon using ZnO (ACOW600/ZnO) and Fe₃O₄ (ACOW600/ZnO/Fe₃O₄) nanoparticles were used to remove methyl violet 2B dye (MV2B) from aqueous solutions. ACOW was synthesized at different temperatures (300-700 °C), and then the maximum MV2B removal efficiency (92.76 %) was achieved using ACOW synthesized at 600 °C. The morphology and characteristics of ACOW600, ACOW600/ZnO, and ACOW600/ZnO/Fe₃O₄ were studied using surface analyzes. According to the results, the adsorbents indicated a high ability to absorb MV2B from liquid solution, and their kinetic behavior follows a pseudo-second-order kinetic. In addition, the equilibrium study revealed that the MV2B uptake by the ACOW600/ZnO/Fe₃O₄ magnetic nanocomposite followed the Freundlich model. In contrast, the Langmuir model described the MV2B adsorption process using ACOW600 and ACOW600/ZnO. The maximum adsorption capacity (q_m) of MV2B using ACOW600, ACOW600/ZnO, and ACOW600/ZnO/Fe₃O₄ was determined 26.16 mg g^-1, 37.05 mg g^-1, and 48.59 mg g^-1, respectively, indicating that modification of ACOW600 led to improve its performance in removing MV2B. The enthalpy (ΔH), entropy (ΔG), and Gibbs free energy (ΔS) parameters revealed that the decontamination of MV2B using the studied adsorbents was exothermic and spontaneous. Also, random interactions of MV2B molecules and adsorbent surfaces were reduced during the adsorption process. Textile wastewater was significantly treated by ACOW600, ACOW600/ZnO, and ACOW600/ZnO/Fe₃O₄ adsorbents. The recycling of the adsorbents was demonstrated that the investigated adsorbents could be re-utilized many times in the MV2B removal process.

Effect of Bi2WO6/g-C3N4 composite on the combustion and catalytic decomposition of energetic materials: An efficient catalyst with g-C3N4 carrier

An effective strategy involving a suitable carrier is needed to improve the dispersion, combustion and catalytic performances of catalyst nanoparticles. Herein, a Bi₂WO₆/g-C₃N₄ composite employing g-C₃N₄ as the catalyst carrier was prepared by a one-step in situ hydrothermal method, which was used as the combustion catalyst of solid propellants. The catalyst's structure, morphology and its catalytic decomposition on several energetic materials were characterized by a series of analyses. The optimal ratio of g-C₃N₄ and Bi₂WO₆ was systematically determined. The results demonstrate that Bi₂WO₆/g-C₃N₄ (4:6) composite can diminish the decomposition temperatures of ammonium perchlorate (AP), cyclotrimethylenetrinitramine (RDX), dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) and cyclotrimethylenetrinitramine + nitrocellulose (RDX + NC) by 25.0, 5.2, 24.0 and 1.2 (4.9) ° C, and reduce their apparent activation energy by 59.5, 116.7, 11.6 kJ mol^-1, respectively. Moreover, the laser ignition tests indicate that Bi₂WO₆/g-C₃N₄ can effectively promote the ignition performance of RDX and RDX + NC. A possible mechanism of Bi₂WO₆/g-C₃N₄ on AP was proposed. The g-C₃N₄ catalyst carrier is superior to GO carrier due to its low cost, simple synthesis process, improved combustion and catalytic performances, as well as high N content. These make it have broad engineering application prospects in solid propulsion and other energetic materials.

Preparation of clinoptilolite/starch/CoFe2O4 magnetic nanocomposite powder and its elimination properties for cationic dyes from water and wastewater

A new magnetic nanocomposite clinoptilolite (CLT)/Starch/CoFe₂O₄ was synthesized using co-precipitation method. The prepared magnetic composite powder was utilized for decontamination of methylene blue dye (MBD), methyl violet dye (MVD), and crystal violet dye (CVD) from water media. The BET analysis showed that CLT modification using starch and CoFe₂O₄ nanoparticles improved its specific surface and the amount of specific surface area for CLT, CoFe₂O_4, and CLT/Starch/CoFe₂O₄ powder was reported to be 18.82 m².g^-1, 151.4 m².g^-1, and 104.75 m².g^-1, respectively. Experimental results showed that pH 9 had a vital role in the adsorption process of all three types. Langmuir and Redlich-Petersen isotherm models were well fitted with experimental data. Also, the maximum adsorption capacity of CVD, MBD, and MVD to the desired composite was determined as 32.84 mg.g^-1, 31.81 mg.g^-1, and 31.15 mg.g^-1, respectively. In addition, the kinetic data of the removal process followed a pseudo-first order (PFO) kinetic model. Negative thermodynamic parameters were indicated that the process is spontaneous and exothermic. Finally, ad(de)sorption experiments' results showed that the synthesized nanocomposite adsorbent has an excellent ability to adsorb cationic dyes after several consecutive cycles.

Magnetically guided theranostics: montmorillonite-based iron/platinum nanoparticles for enhancing in situ MRI contrast and hepatocellular carcinoma treatment

In Asia, including Taiwan, malignant tumors such as Hepatocellular carcinoma (HCC) one of the liver cancer is the most diagnosed subtype. Magnetic resonance imaging (MRI) has been a typical diagnostic method for accurately diagnosing HCC. When it is difficult to demonstrate non-enhanced MRI of tumors, radiologists can use contrast agents (such as Gd3+, Fe3O4, or FePt) for T1-weighted and T2-weighted imaging remain in the liver for a long time to facilitate diagnosis via MRI. However, it is sometimes difficult for T2-weighted imaging to detect small tumor lesions because the liver tissue may absorb iron ions. This makes early cancer detection a challenging goal. This challenge has prompted current research to create novel nanocomposites for enhancing the noise-to-signal ratio of MRI. To develop a method that can more efficiently diagnose and simultaneously treat HCC during MRI examination, we designed a functionalized montmorillonite (MMT) material with a porous structure to benefit related drugs, such as mitoxantrone (MIT) delivery or as a carrier for the FePt nanoparticles (FePt NPs) to introduce cancer therapy. Multifunctional FePt@MMT can simultaneously visualize HCC by enhancing MRI signals, treating various diseases, and being used as an inducer of magnetic fluid hyperthermia (MFH). After loading the drug MIT, FePt@MMT-MIT provides both MFH treatment and chemotherapy in one nanosystem. These results ultimately prove that functionalized FePt@MMT-MIT could be integrated as a versatile drugs delivery system by combining with MRI, chemotheraeutic drugs, and magnetic guide targeting.

Zn2+ removal from the aqueous environment using a polydopamine/hydroxyapatite/Fe3O4 magnetic composite under ultrasonic waves

In this study, an easily magnetically recoverable polydopamine (PDA)-modified hydroxyapatite (HAp)/Fe3O4 magnetic composite (HAp/Fe3O4/PDA) was suitably synthesized to exploit its adsorption capacity to remove Zn2+ from aqueous solution, and its structural properties were thoroughly examined using different analytical techniques. The effect of multiple parameters like pH, ultrasonic power, ultrasonic time, adsorbent dose, and initial Zn2+ concentration on the adsorption efficiency was assessed using RSM-CCD. According to the acquired results, by increasing the adsorbent quantity, ultrasonic power, ultrasonic time, and pH, the Zn2+ adsorption efficiency increased and the interaction between the variables of ultrasonic power/Zn2+ concentration, pH/Zn2+ concentration, pH/absorbent dose, and ultrasonic time/adsorbent dose has a vital role in the Zn2+ adsorption. The uptake process of Zn2+ onto PDA/HAp/Fe3O4 followed Freundlich and pseudo-second order kinetic models. The maximum capacity of Zn2+ adsorption (q m) obtained by PDA/HAp/Fe3O4, HAp/Fe3O4, and HAp was determined as 46.37 mg g-1, 40.07 mg g-1, and 37.57 mg g-1, respectively. Due to its good performance and recoverability (ten times), the HAp/Fe3O4/PDA magnetic composite can be proposed as a good candidate to eliminate Zn2+ ions from a water solution.

Influence of tin (Sn) doping on Co3O4 for enhanced photocatalytic dye degradation

Wastewater remediation is one of the special issues that have been discussed in recent years and one of the main pollutants was dyes which totally changes the water behavior. To eradicate the organic compounds from the wastewater and reuse it, there are numerous steps have been taken into consideration. Dye degradation via photocatalysis is one of the promising technique with good efficiency. Pure and tin (Sn) doped Co₃O₄ was prepared employing co-precipitation technique. The structural, vibrational, optical and morphological analysis was done employing X-ray diffraction studies, Photoluminescence, Raman analysis and Scanning Electron Microscopic (SEM) studies. The well-defined nanoparticles were grown with 1 M Sn doped Co₃O₄. The photocatalytic activities of methylene blue dye under visible light were investigated by adding the samples (CS-1, CS-2, CS-3). 1 M Sn doped Co₃O₄ sample showed 75% efficiency towards dye degradation. The prepared 1 M Sn doped Co₃O₄ sample will be the best for photocatalytic activity. By doping Sn atoms the efficiency of the host is increased which will be the most promising candidate for the photocatalytic dye degradation applications.

Super and Selective Adsorption of Cationic Dyes onto Carboxylate-Modified Passion Fruit Peel Biosorbent

The carboxylate-functionalized passion fruit peel (PFPCS) was an efficient and rapid biosorbent for wastewater treatment. The PFPCS exhibited excellent selectivity to the cationic dyes, where the maximum adsorption capacities for methylene blue (MB) and methyl violet (MV) were 1,775.76 mg g-1 and 3,756.33 mg g-1, respectively. And the adsorption process of MB and MV on PFPCS reached equilibrium within 20 min. Moreover, the adsorption conditions and mechanisms were investigated. The adsorption process was in good agreement with the pseudo-second-order and Langmuir isotherm models. The adsorption mechanism was also proposed to be electrostatic interaction and hydrogen bond. After six cycles of desorption-adsorption, the removal efficient of MB and MV could be kept above 95%. Thus, PFPCS was considered as a highly efficient absorbent for removing cationic dyes from polluted water due to excellent adsorption characteristics, low cost and environmental friendliness.

The removal of anionic and cationic dyes from an aqueous solution using biomass-based activated carbon

In this study, two biomass-based adsorbents were used as new precursors for optimizing synthesis conditions of a cost-effective powdered activated carbon (PAC). The PAC removed dyes from an aqueous solution using carbonization and activation by KOH, NaOH, and H₂SO₄. The optimum synthesis, activation temperature, time and impregnation ratio, removal rate, and uptake capacity were determined. The optimum PAC was analyzed and characterized using Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), a field emission scanning electron microscope (FESEM), Zeta potential, and Raman spectroscopy. Morphological studies showed single-layered planes with highly porous surfaces, especially PAC activated by NaOH and H₂SO₄. The results showed that the experimental data were well-fitted with a pseudo-second-order model. Based on Langmuir isotherm, the maximum adsorption capacity for removing methylene blue (MB) was 769.23 mg g⁻¹ and 458.43 mg g⁻¹ for congo red (CR). Based on the isotherm models, more than one mechanism was involved in the adsorption process, monolayer for the anionic dye and multilayer for the cationic dye. Elovich and intraparticle diffusion kinetic models showed that rubber seed shells (RSS) has higher α values with a greater tendency to adsorb dyes compared to rubber seed (RS). A thermodynamic study showed that both dyes’ adsorption process was spontaneous and exothermic due to the negative values of the enthalpy (ΔH) and Gibbs free energy (ΔG). The change in removal efficiency of adsorbent for regeneration study was observed in the seventh cycles, with a 3% decline in the CR and 2% decline in MB removal performance. This study showed that the presence of functional groups and active sites on the produced adsorbent (hydroxyl, alkoxy, carboxyl, and π − π) contributed to its considerable affinity for adsorption in dye removal. Therefore, the optimum PAC can serve as efficient and cost-effective adsorbents to remove dyes from industrial wastewater.

Adsorption of Crystal Violet Dye Using Activated Carbon of Lemon Wood and Activated Carbon/Fe3O4 Magnetic Nanocomposite from Aqueous Solutions: A Kinetic, Equilibrium and Thermodynamic Study

Activated carbon prepared from lemon (Citrus limon) wood (ACL) and ACL/Fe₃O₄ magnetic nanocomposite were effectively used to remove the cationic dye of crystal violet (CV) from aqueous solutions. The results showed that Fe₃O₄ nanoparticles were successfully placed in the structure of ACL and the produced nanocomposites showed superior magnetic properties. It was found that pH was the most effective parameter in the CV dye adsorption and pH of 9 gave the maximum adsorption efficiency of 93.5% and 98.3% for ACL and ACL/Fe₃O₄, respectively. The Dubinin–Radushkevich (D-R) and Langmuir models were selected to investigate the CV dye adsorption equilibrium behavior for ACL and ACL/Fe₃O₄, respectively. A maximum adsorption capacity of 23.6 and 35.3 mg/g was obtained for ACL and ACL/Fe₃O₄, respectively indicating superior adsorption capacity of Fe₃O₄ nanoparticles. The kinetic data of the adsorption process followed the pseudo-second order (PSO) kinetic model, indicating that chemical mechanisms may have an effect on the CV dye adsorption. The negative values obtained for Gibb’s free energy parameter (−20 < ΔG < 0 kJ/mol) showed that the adsorption process using both types of the adsorbents was physical. Moreover, the CV dye adsorption enthalpy (ΔH) values of −45.4 for ACL and −56.9 kJ/mol for ACL/Fe₃O₄ were obtained indicating that the adsorption process was exothermic. Overall, ACL and ACL/Fe₃O₄ magnetic nanocomposites provide a novel and effective type of adsorbents to remove CV dye from the aqueous solutions.