Magnetic Chitosan Research Articles

Modified magnetic chitosan materials for heavy metal adsorption: a review.

Magnetic chitosan materials have the characteristics of both chitosan and magnetic particle nuclei, showing the characteristics of easy separation and recovery, strong adsorption capacity and high mechanical strength, and have received extensive attention in adsorption, especially in the treatment of heavy metal ions. In order to further improve its performance, many studies have modified magnetic chitosan materials. This review discusses the strategies for the preparation of magnetic chitosan using coprecipitation, crosslinking, and other methods in detail. Besides, this review mainly summarizes the application of modified magnetic chitosan materials in the removal of heavy metal ions in wastewater in recent years. Finally, this review also discusses the adsorption mechanism, and puts forward the prospect of the future development of magnetic chitosan in wastewater treatment.

Nanoparticle-mediated CRISPR/dCas9a activation of multiple transcription factors to engineer insulin-producing cells.

Insulin may help to control blood glucose levels in diabetes; however, the long-term release of insulin is important for therapy. In this work, four guide RNAs (gRNA) for factors that promote specification and maturation of insulin-producing cells were synthesized: pancreatic and duodenal homeobox 1 (PDX1), protoendocrine factor (neurogenin 3, NGN3), NK6 homeobox 1 (NKX6.1), and musculoaponeurotic fibrosarcoma oncogene family A (MAFA). These gRNAs were used to form ribonucleoproteins (RNPs) with tracRNA and dCas9-VPR, and were then immobilized on magnetic peptide-imprinted chitosan nanoparticles, which enhanced transfection. The production and release of insulin from transfected cells were then measured using ELISA and staining with anti-insulin antibodies. The expression of the genes was evaluated using qRT-PCR; this was also used to investigate the cascade of additional transcriptional regulators. The magnitude and duration of insulin production were evaluated for single and repeated transfections (using different transfection schedules) to identify the most promising protocol.

Development of magnetic dispersive micro-solid phase extraction of four phenolic compounds from food samples based on magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent

A magnetic dispersive micro-solid phase extraction technique (CS@Fe3O4-MD-μSPE-DESP) based on magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent was developed and applied to determinations of four phenolic compounds in food samples. To prevent environmental pollution and the introduction of toxic substances, deep eutectic supramolecular solvents (DESPs), which exhibited greater desorption capacities than conventional organic solvents and deep eutectic solvents, were used as novel green eluents for the first time. Some important parameters were screened by the Plackett–Burman method and then further optimized with response surface methodology (RSM). Under the optimal conditions, the proposed method showed excellent methodological indices with linearity over the range 0.1–200.0 µg·mL-1, R2 > 0.9988, extraction recoveries above 94.8 %, and precision (RSD%) below 2.9 %. The established method finishes the process of adsorption and desorption in approximately 3 min and enhances the efficiency for determination of phenolic compounds.

Efficient biodiesel production from waste cooking oil by fast co-immobilization of lipases from Aspergillus oryzae and Rhizomucor miehei in magnetic chitosan microcapsules

To achieve an efficient and cost-effective conversion from waste cooking oil (WCO) to biodiesel, a facile one-pot co-immobilization of Aspergillus oryzae lipase (AOL) and Rhizomucor miehei lipase (RML) was developed by rapid encapsulation of magnetic chitosan microcapsules. The encapsulation process was accomplished by self-assembly of negatively charged magnetic nanoparticles (citrate modified Fe3O4) on ionic cross-linked chitosan-citrate aggregates containing lipases. Integrating Tween 80 bio-imprinting of lipases, the co-immobilized AOL@RML (co-im Tween 80-AOL@RML) achieved a significant increase in activity and reached 98.5 % biodiesel yield under optimal conditions, which was 1.3 and 1.6 times higher than that of single immobilized AOL and RML, respectively. Notably, owing to the beneficial synergistic impact of methanol-tolerable AOL and thermal-stable RML, co-im Tween 80-AOL@RML displayed superior activity over single lipase counterparts under excess methanol and variable temperatures. The co-im Tween 80-AOL@RML could maintained 96 % activity after 3 cycles of biodiesel production; however, showed an obvious inactivation after continued reuse. Moreover, methanol-induced denaturation of lipases and glycerol-caused agglomeration of the magnetic nanoparticles during continued transesterification were ascertained by fourier transform infrared analysis and scanning electron microscopy. This study provides new pathways for constructing multi-lipase co-immobilzation as well as an economical and effective biocatalyst for biodiesel production from WCO.

Synthesis of Magnetic Chitosan Composite Beads as an Adsorbent for Removal of Organic Matter from Peat Water

Groundwater in peatlands has the potential to be utilized as a water source, but its high organic matter content presents challenges. This study aimed to improve the quality of peat water through the adsorption of organic matter using chitosan magnetic beads composite adsorbent. Magnetic chitosan beads (KMB) composite was synthesized by mixing chitosan, acetic acid, and a mixture of Fe2+/Fe3+ solution with a mole ratio of 1:2. This mixture was then dropped into a sodium hydroxide solution. In addition to KMB, magnetic composite beads containing glutaraldehyde crosslinking agent (KMBG) were also synthesized. The results of composites analysis using a Fourier transform infrared (FTIR) spectrophotometer showed typical Fe-O absorption bands at 582 cm-1 and 578 cm-1 for KMB and KMBG. The typical C=N absorption band for glutaraldehyde in KMBG appeared at 1631 cm-1. X-ray diffraction (XRD) analysis revealed the characteristic peaks of Fe3O4 for KMB and KMBG at 2θ = 30.2°, 35.5°, 43.2°, 57.0°, and 62.8° with an amorphous structure. The adsorption of organic matter was performed by varying the pH (2, 3, 4, and 5) of peat water and the mass of the adsorbent (50, 70, 100, 200, and 300 mg). The optimum adsorption occurred at pH 2 with an absorbent mass of 0.1 g KMB and 0.07 g KMBG. Applying KMB on peat water reduces turbidity, color, and absorbance at a wavelength of 254 nm (Aλ=254), which is better than using KMBG. These three parameters’ efficiency percentages were 44%, 78%, and 74% for KMB and 17%, 30%, and 59% for KMBG.

Structural insights into mechanisms of rapid harvesting of microalgae with pH regulation by magnetic chitosan composites: A study based on E-DLVO model and component fluorescence analysis

Magnetic harvesting of microalgae depends on the interface interactions between microalgal cells and flocculants, and thus it is important to find a reasonable evaluation method understand these interface interactions. In this effort, we discussed the formation mechanism and pH regulation of microalgae magnetic harvesting via magnetic chitosan (Fe3O4@SiO2-CS) synthesized by a micro-emulsion method. The flocculation performances and mechanisms during the harvesting of microalgae by the novel flocculant were evaluated. The synthesis process and structure were determined by XRD, FT-IR, SEM and XPS, and the results indicated that Fe3O4@SiO2-CS was successfully prepared. The collection efficiency of 96.52 % was achieved for Chlorella vulgaris within 3 min using Fe3O4@SiO2-CS with the Fe3O4@SiO2 and CS mass ratio of 1:3 under pH 1.0. Moreover, this study introduced the two-dimension fractal dimension and extended Derjaguin-Landau-Verwey-Overbeek (E-DLVO) model to evaluate the harvesting performances and mechanisms of Fe3O4@SiO2-CS. Experimental results showed that a strong electrostatic interaction was formed under acidic conditions between Fe3O4@SiO2-CS and microalgae cells with D2 = 1.82 (fractal dimension value). The hydrophobic tryptophan-like amino acid was observed in the slime-extracellular polymeric substances (S-EPS) secreted by microalgae. S-EPS was found to be a significant substance to promote harvesting performance when the system was neutral or alkaline. This work provides deeper insights into microalgae harvesting by Fe3O4@SiO2-CS as well as reasonable mechanisms to illustrate the interaction of Fe3O4@SiO2-CS and microalgae under different pH values.

Magnetic chitosan hydrogel beads as adsorbent for copper removal from aqueous solution

Magnetic chitosan hydrogel beads (MCHB) were synthesized by blending chitosan and magnetite (Fe3O4) in sodium alginate solution. The MCHB was used to remove Cu (II) metal ions in an aqueous solution. The performance of MCHB to remove Cu (II) ions was evaluated experimentally at different parameters (the initial pH of the solution, contact time, and various magnetite ratios of the hydrogel beads) in the batch adsorption set-up. This study indicated that MCHB managed to remove Cu (II) ions by adsorption at pH 5 at 24 h of contact time. The hydrogel beads of MCHB-0.5 (C:M:A ratio by weight of 1:0.5:2) show the highest Cu (II) ions removal efficiency of 56.51%. The addition of magnetite at the minimal ratio does not hinder the adsorption of Cu (II) ions onto MCHB. The magnetite in the beads also eases the separation of the hydrogel beads from the solution by an external magnet after treatment.

Copper Catalyst-Supported Modified Magnetic Chitosan for the Synthesis of Novel 2-Arylthio-2,3-dihydroquinazolin-4(1H)-one Derivatives via Chan–Lam Coupling

In this paper, magnetic chitosan is used as a support for the immobilization of copper catalyst (Cu@MChit). The fabricated catalyst is successfully synthesized and characterized by several techniques. The activity of Cu@MChit catalyst is evaluated in the synthesis of novel derivatives of 3-alkyl-2-arylthio-2,3-dihydroquinazolin-4(1H)-ones. The products are synthesized in three simple steps via Chan–Lam coupling reaction. The synthetic route is based on the reaction of isatoic anhydride and an amine, followed by the reaction with carbon disulfide. Cu@MChit-catalyzed reaction of the obtained intermediate with phenylboronic acid leads to the desired products. The scope of the reaction is confirmed by using various amine and phenylboronic acid derivatives and the products are obtained in high isolated yields.

Functionalization of the magnetic chitosan support with dipyridylamine as a nitrogen-rich pincer ligand for Pd immobilization and investigation of catalytic efficiency in Sonogashira coupling

Functionalization of the magnetic chitosan support with dipyridylamine as a nitrogen-rich pincer ligand for Pd immobilization and investigation of catalytic efficiency in Sonogashira coupling

Preparation and characterization of PEGDE-EDTA-modified magnetic chitosan microsphere as an eco-friendly adsorbent for methylene blue removal

Chitosan has been acknowledged as the emerging prominent pollutant remover with environmentally friendly properties. Herein, we have developed magnetic chitosan (MC) microsphere with functional group enrichment using polyethylene glycol diglycidyl ether (PEGDE) and ethylenediaminetetraacetic acid (EDTA) to remove aqueous methylene blue. The success of the functional group enrichment was proven by the characterization carried out in Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and Scanning Electron Microscope (SEM) analyses. The adsorption capacity of methylene blue onto the prepared MC increased as much as 37.62% after the addition of EDTA. The optimum adsorption parameters recorded in this study were 30minutes contact time and pH level of 10. At such optimum conditions, the adsorption capacity and removal percentage reached 5.04±0.03 mg/g and 80.64±0.12%, respectively. Adsorption studies using various models revealed that the best fit of experimental data with that of theoretical was generated by the Freundlich model equation (R2 = 0.95283; root-mean-square-errors = 27.22). Exothermic adsorption was observed according to the thermodynamic study (∆H = -124.43 kJ/mol). In conclusion, our adsorbent prepared from green materials and methods could effectively remove the methylene blue from water medium.

Poly(amidoxime)-graft-magnetic chitosan for highly efficient and selective uranium extraction from seawater

Adsorbents with highly efficient and selective recovery performance towards uranium are significantly demanded for the sustainable nuclear power production. Herein, poly(amidoxime)-graft-magnetic chitosan (P(AO)-g-MC) was synthesized through functionalizing magnetic chitosan with polyacrylonitrile followed by amidoximation process. Under magnetic field, P(AO)-g-MC can be separated from the solution in 10 s. Owing to the strong affinity of high-density amidoxime groups towards uranium, P(AO)-g-MC showed remarkable adsorption capacity, rapid kinetics and good regeneration performance in uranium spiked aqueous solution. Notably, the 7-day uranium adsorption capacity of P(AO)-g-MC from natural seawater in column mode was up to 5.14 mg/g, 12 times that of vanadium. The excellent uranium uptake performance over vanadium originated from the strong coordination by N and O in amidoxime groups according to theoretical simulation. The advantages of easy separating and high selectivity make P(AO)-g-MC a very potential uranium adsorbent in natural seawater.

Highly Efficient Adsorption of Tetracycline Using Chitosan-Based Magnetic Adsorbent.

Herein, tetracycline adsorption employing magnetic chitosan (CS·Fe3O4) as the adsorbent is reported. The magnetic adsorbent was synthesized by the co-precipitation method and characterized through FTIR, XRD, SEM, and VSM analyses. The experimental data showed that the highest maximum adsorption capacity was reached at pH 7.0 (211.21 mg g-1). The efficiency of the magnetic adsorbent in tetracycline removal was dependent on the pH, initial concentration of adsorbate, and the adsorbent dosage. Additionally, the ionic strength showed a significant effect on the process. The equilibrium and kinetics studies demonstrate that Sips and Elovich models showed the best adjustment for experimental data, suggesting that the adsorption occurs in a heterogeneous surface and predominantly by chemical mechanisms. The experimental results suggest that tetracycline adsorption is mainly governed by the hydrogen bonds and cation-π interactions due to its pH dependence as well as the enhancement in the removal efficiency with the magnetite incorporation on the chitosan surface, respectively. Thermodynamic parameters indicate a spontaneous and exothermic process. Finally, magnetic chitosan proves to be efficient in TC removal even after several adsorption/desorption cycles.

Co-immobilization of electron mediator and laccase onto dialdehyde starch cross-linked magnetic chitosan nanomaterials for organic pollutants' removal.

In this study, an amino-functionalized ionic liquid-modified magnetic chitosan (MACS-NIL) containing 2,2-diamine-di-3-ethylbenzothiazolin-6-sulfonic acid (ABTS) was used as a carrier, and dialdehyde starch (DAS) was used as a cross-linking agent to covalently immobilize laccase (MACS-NIL-DAS-lac), which realized the co-immobilization of laccase and ABTS. The carrier was characterized by Fourier infrared transform spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction analysis, electron paramagnetic resonance, etc. The immobilization efficiency and activity retention of MACS-NIL-DAS-lac could reach 76.7% and 69.8%, respectively. At the same time, its pH stability, thermal stability, and storage stability had been significantly improved. In the organic pollutant removal performance test, the removal rate of 2,4-dichlorophenol (10mg/L) by MACS-NIL-DAS-lac (1 U) could reach 100% within 6h, and the removal efficiency could still reach 88.6% after six catalytic runs. In addition, MACS-NIL-DAS-lac also showed excellent degradation ability for other conventional phenolic pollutants and polycyclic aromatic hydrocarbons. The research results showed that MACS-NIL-DAS fabricated by the combination inorganic material, organic biomacromolecules, ionic liquid, and electron mediator could be used as a novel carrier for laccase immobilization and the immobilized laccase showed excellent removal efficiency for organic pollutants.

Rapid determination of multiclass antibiotics and their metabolites in milk using ionic liquid-modified magnetic chitosan nanoparticles followed by UPLC-MS/MS

This research introduced a rapid and efficient method for simultaneous pre-concentration and determination of twenty-two antibiotics and their metabolites in milk samples using functional imidazole-based ionic liquid-modified magnetic chitosan nanoparticles followed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Different techniques characterized the synthesized nanoparticles. Experimental variables were studied and optimized by the one-factor-at-a-time approach and Box-Behnken design. All antibiotics showed good linearity, with correlation coefficients of more than 0.995. The matrix effects were greatly minimized using the proposed method. The range of average recoveries was from 85.9 to 107.5%, and precision values were presented as RSDs, which were below 9.2%. The limits of detection were 0.04–0.19 μg kg−1. The measurement uncertainty was estimated by the bottom-up approach. The conformity method was applied in the analysis of real milk samples. Antibiotic residues were found in 124 samples out of 241 milk samples. Nevertheless, it was found that 24 of 133 raw cow milk samples and 15 of 108 pasteurized milk samples were above maximum residue limits. Finally, the potential human health risk estimated using the hazard quotient approach, based on the estimated daily intake and acceptable daily intake, showed a negligible risk for human health from milk consumption.

Enhancement of Cerium Sorption onto Urea-Functionalized Magnetite Chitosan Microparticles by Sorbent Sulfonation-Application to Ore Leachate.

The recovery of strategic metals such as rare earth elements (REEs) requires the development of new sorbents with high sorption capacities and selectivity. The bi-functionality of sorbents showed a remarkable capacity for the enhancement of binding properties. This work compares the sorption properties of magnetic chitosan (MC, prepared by dispersion of hydrothermally precipitated magnetite microparticles (synthesized through Fe(II)/Fe(III) precursors) into chitosan solution and crosslinking with glutaraldehyde) with those of the urea derivative (MC-UR) and its sulfonated derivative (MC-UR/S) for cerium (as an example of REEs). The sorbents were characterized by FTIR, TGA, elemental analysis, SEM-EDX, TEM, VSM, and titration. In a second step, the effect of pH (optimum at pH 5), the uptake kinetics (fitted by the pseudo-first-order rate equation), the sorption isotherms (modeled by the Langmuir equation) are investigated. The successive modifications of magnetic chitosan increases the maximum sorption capacity from 0.28 to 0.845 and 1.25 mmol Ce g-1 (MC, MC-UR, and MC-UR/S, respectively). The bi-functionalization strongly increases the selectivity of the sorbent for Ce(III) through multi-component equimolar solutions (especially at pH 4). The functionalization notably increases the stability at recycling (for at least 5 cycles), using 0.2 M HCl for the complete desorption of cerium from the loaded sorbent. The bi-functionalized sorbent was successfully tested for the recovery of cerium from pre-treated acidic leachates, recovered from low-grade cerium-bearing Egyptian ore.

Synchronous reduction and removal of hexavalent chromium from wastewater by modified magnetic chitosan beads

As one of the highly toxic heavy metal contaminants, hexavalent chromium (Cr(VI)) poses a serious hazard to the environment and public health due to its excellent solubility in aqueous environment. To synchronously reduce and remove Cr(VI) from wastewater efficiently, a class of functionalized magnetic chitosan (CS) beads (MCB-ECH-SH/SO3H) was synthesized with CS as the substrate material and in situ assembling Fe3O4 nanoparticles as the incorporated magnetic material, followed by epichlorohydrin (ECH) cross-linking and l-cysteine grafting. Results showed that Cr(VI) in aqueous solution could be rapidly adsorbed onto MCB-ECH-SH/SO3H via electrostatic attraction, meanwhile -SH groups introduced by l-cysteine grafting could not only significantly facilitate the reduction of Cr(VI) to less toxic trivalent chromium (Cr(III)), but also promote the resultant Cr(III) chelating onto adsorbent due to the proton consumption caused by Cr(VI) reduction, resulting in the synergistic enhancement of Cr(VI) detoxification and total chromium (Cr(Total)) removal. The batch adsorption experiments revealed that the well designed MCB-ECH-SH/SO3H could be applied over a wide pH range (initial pH of 1.0–7.0), and showed much higher remove efficiency (99.6 ± 0.2 %) of Cr(VI) than MCB and MCB-ECH at initial pH 5.0 (60 °C) due to the improvement of stability and reducing capacity. The Cr(Total) sorption behaviors were well according with the pseudo-second-order kinetic and Langmuir models, indicating a single-layer, exothermal, and chemical sorption process, while the maximum Cr(Total) removal capacity of MCB-ECH-SH/SO3H was estimated to be 293.46 mg∙g−1, exceeding most of previously reported related adsorbents. Moreover, MCB-ECH-SH/SO3H could still maintained strong adsorption performance after five cycles and exhibited excellent ability to remove 95 % Cr(VI) within 1 h for low concentration Cr(VI)-containing wastewater. The combination of synchronous reduction and adsorption property, high removal capacity, convenient magnetic separation and good recycling performance makes MCB-ECH-SH/SO3H an ideal candidate for chromium-containing wastewater treatment.

Heteropolyacid coupled with cyanoguanidine decorated magnetic chitosan as an efficient catalyst for the synthesis of pyranochromene derivatives

In this study, a novel nanocatalyst was successfully prepared by heteropolyacid immobilization of magnetic chitosan-cyanoguanidine composite and fully characterized by different analysis methods, including FTIR, XRD, TGA, SEM, and EDS. The catalytic activity of fabricated composite was examined in a one-pot three-component reaction, involving the diverse active methylene compounds, various aryl aldehydes, and malononitrile in water. The results revealed the efficient catalytic performance of composite, while all reactions proceeded smoothly and led to the formation of the corresponding pyranochromene derivatives in high to excellent yields.

Treatment of wastewater containing alizarin red dye: development and application of magnetic chitosan as a natural eco-friendly material

Treatment of wastewater containing alizarin red dye: development and application of magnetic chitosan as a natural eco-friendly material

Effective adsorption of Congo red dye by magnetic chitosan prepared by solvent-free ball milling

Chitosan and Fe3O4 were used as raw materials to successfully synthesize chitosan@Fe3O4 by a simple, green and friendly solvent-free ball milling method. The surface morphology, phase composition, structure and magnetic properties of the chitosan@Fe3O4 material were characterized using SEM, FT-IR, PXRD, VSM methods. The prepared material was used as an adsorbent to remove the target congo red dye. The effect of experimental factors such as solution pH and contact time on the adsorption performance were studied and optimized. The adsorption behavior of chitosan@Fe3O4 material for congo red dye was investigated, and the adsorption mechanism, recycling performance of the materials were discussed.

Positively charged covalent organic framework modified magnetic chitosan as a smart device for efficient diclofenac sodium removal from water

In the current research for the first time, the new magnetic chitosan-coated triazine-based covalent organic frameworks (CS/Fe3O4@TCOFs) were fabricated relying on the unique characteristics of chitosan (CS) and used for the adsorptive removal of diclofenac sodium (DS). The bio-adsorbent was studied by common characterization techniques. The calculated magnetic saturation (Ms 34.49 emu/g) revealed that the CS/Fe3O4@TCOFs can be easily separated by an external magnetic field. More importantly, it displayed a nanoporous structure with about 846.87 m2/g specific surface area in BET analysis. The maximum DS adsorption capacity was calculated at about 333.33 mg/g at 25 °C (pH 5) in the initial 50 mg/L concentration. The adsorption data were well fitted with the pseudo-second-order kinetics model, R2 0.9986, and also the Langmuir isotherm thermodynamic model, R2 0.9898. Additionally, the CS/Fe3O4@TCOFs showed excellent adsorption capacity after six times regeneration. These initial findings are expected to inspire further design and fabrication of effective bio-adsorbents for promising practical applications.