Magnetic Chitosan Particles Research Articles

PAMAM Grafted Magnetic Chitosan Particles by EDTA Core for Efficient Removal of Cu (II)

PAMAM Grafted Magnetic Chitosan Particles by EDTA Core for Efficient Removal of Cu (II)

Simultaneous Removal and Extraction of Bisphenol A and 4-tert-butylphenol From Water Samples Using Magnetic Chitosan Particles

Magnetic chitosan (MC) was used as an ecofriendly and potential adsorbent for the removal of bisphenol-A and 4-tert-butylphenol from water samples. The magnetic chitosan was synthesized and characterized for functional groups, surface morphology, elemental composition, and crystallinity using spectroscopic techniques. Factors influencing the uptake such as pH, mass of adsorbent, bisphenol-A and 4-tert-butylphenol concentration, contact time, and temperature were examined thoroughly using aqueous solutions. Equilibrium, kinetic, and thermodynamic parameters were evaluated, and the results revealed that the adsorption of bisphenol-A and 4-tert-butylphenol followed pseudo-second-order kinetics and Langmuir adsorption isotherm. The adsorption processes were exothermic and spontaneous. The method was found feasible for the removal and extraction of bisphenol-A and 4-tert-butylphenol in environmental water samples. The recovery of bisphenol A and 4-tert-butylphenol in tap water ranged from 95.6% to 96.8% and 95.4% to 101.2% and in river water from 87.6% to 95.9% and 92.8% to 98.2%, respectively. The results indicate that magnetic chitosan is a potential adsorbent for easy, effective removal and extraction of bisphenol-A and 4-tert-butylphenol from environmental water samples, and the adsorbent material is chemically benign and environment friendly.

Synthesis of a novel magnetic composite based on graphene oxide, chitosan and organoclay and its application in the removal of bisphenol A, 17α-ethinylestradiol and triclosan

A new nanocomposite was synthesized from graphene oxide, magnetic chitosan and organoclay (GO/mCS/OC). Its application as an adsorbent was investigated for the removal of emerging contaminants such as bisphenol A (BPA), 17α-ethynylestradiol (EE2) and triclosan (TCS). These contaminants, even at low concentrations, cause damage to aquatic biota and have been attracting the attention of researchers around the world. The synthesis of nanocomposite comprised the preparation of GO through hummers method, followed by the aggregation of magnetic chitosan and organoclay particles. These adsorbent materials were characterized using FTIR, XRD, SEM, EDS, TGA, VSM and zeta potential. Furthermore, their adsorptive capacities were evaluated in batch system. The synthesized nanocomposite exhibited satisfactory performance and similar to that of the precursor organophilic clay under the conditions evaluated. TCS was easier to be removed, followed by EE2 and BPA, with removal percentages of about 98%, 72% and 58% and adsorptive capacities of about 40, 30 and 20 mg g−1, respectively, when using the nanocomposite. In order to unveil the chemical reactivity of the approached contaminants at a molecular level, density functional theory (DFT) was evaluated by calculating molecular chemical descriptors and evaluating the electrostatic potential maps. The chemical reactivity corroborates the affinity assays, showing a more effective adsorption of the most reactive molecule, which was the TCS. The synthesized nanocomposite performed well in removing emerging contaminants and proved to be a good alternative in the treatment of contaminated effluents.

Identification of blood plasma proteins using heparin-coated magnetic chitosan particles

Heparin was immobilized on magnetic chitosan particles to be used as a tool for human plasma protein identification. Chitosan was magnetized by co-precipitation with Fe2+/Fe3+ (MAG-CH). Heparin was functionalized with carbodiimide and N-hydroxysuccinimide and covalently linked to MAG-CH (MAG-CH-hep). X-ray diffraction confirmed the presence of chitosan and Fe3O4 in MAG-CH. This particle exhibited superparamagnetism and size between 100–300 μm. Human plasma diluted with 10 mM phosphate buffer (pH 5.5) or 50 mM Tris-HCl buffer (pH 8.5) was incubated with MAG-CH-hep, and the proteins fixed were eluted with the same buffers containing increasing concentrations of NaCl. The proteins obtained were investigated by SDS-PAGE, LC/MS, and biological activity tests (PT, aPTT, and enzymatic chromogenic assay). Inhibitors of the serpin family, prothrombin, and human albumin were identified in this study. Therefore, MAG-CH-hep can be used to purify these proteins and presents the following advantages: low-cost synthesis, magnetic separation, ion-exchange purification, and reusability.

Immobilization of pectinase on chitosan-magnetic particles: Influence of particle preparation protocol on enzyme properties for fruit juice clarification

Magnetic-chitosan particles were prepared following three different protocols enabling the preparation of particles with different sizes – nano (Nano-CMag, Micro (Micro-CMag) and Macro (Macro-CMag) – and used for pectinase immobilization and clarification of grape, apple and orange juices. The particle size had a great effect in the kinetic parameters, Nano-CMag biocatalyst presented the highest Vmax value (78.95 mg. min−1), followed by Micro-CMag and Macro-CMag, with Vmax of 57.20 mg.min−1 and 46.03 mg.min−1, respectively. However, the highest thermal stability was achieved using Macro-CMag, that was 8 and 3-times more stable than Nano-CMag and Micro-CMag biocatalysts, respectively. Pectinase immobilized on Macro-CMag kept 85% of its initial activity after 25 batch cycles in orange juice clarification. These results suggested that the chitosan magnetic biocatalysts presented great potential application as clarifying catalysts for the fruit juice industry and the great importance of the chitosan particles preparation on the final biocatalyst properties.

Improved Thermal and Reusability Properties of Xylanase by Genipin Cross-Linking to Magnetic Chitosan Particles.

Enzymes are gradually increasingly preferred over chemical processes, but commercial enzyme applications remain limited due to their low stability and low product recovery, so the application of an immobilization technique is required for repeated use. The aims of this work were to produce stable enzyme complexes of cross-linked xylanase on magnetic chitosan, to describe some characteristics of these complexes, and to evaluate the thermal stability of the immobilized enzyme and its reusability. A xylanase was cross-linked to magnetite particles prepared by in situ co-precipitation of iron salts in a chitosan template. The effect of temperature, pH, kinetic parameters, and reusability on free and immobilized xylanase was evaluated. Magnetization, morphology, size, structural change, and thermal behavior of immobilized enzyme were described. 1.0 ± 0.1μg of xylanase was immobilized per milligram of superparamagnetic chitosan nanoparticles via covalent bonds formed with genipin. Immobilized xylanase showed thermal, pH, and catalytic velocity improvement compared to the free enzyme and can be reused three times. Heterogeneous aggregates of 254nm were obtained after enzyme immobilization. The immobilization protocol used in this work was successful in retaining enzyme thermal stability and could be important in using natural compounds such as Fe3O4@Chitosan@Xylanase in the harsh temperature condition of relevant industries.

Groundwater Purification in a Polymetallic Mining Area (SW Sinai, Egypt) Using Functionalized Magnetic Chitosan Particles

A magnetic glycine-grafted chitosan sorbent (Gly) was functionalized to produce a hydrazide derivative (HGly). The two sorbents were tested in batch mode for the sorption of a series of 10 metal ions present in the groundwater collected in three wells in the Wadi (valley) Nasib mining area (SW Sinai, Egypt). HGly is much more efficient for metal recovery than Gly. Under selected experimental conditions (sorbent dosage 1.5 g L−1), the sorption efficiency is not sufficient for achieving the standard levels for drinking water: the most problematic metal ions in terms of drinkability remain aluminum (too high metal concentration in the groundwater), cadmium, and chromium for the three wells (and nickel in the case of only one well). Increasing the sorbent dosage improves the treatment efficiency. The sorbent (HGly) was tested in fixed-bed columns. The breakthrough curves were compared for the different metals for the groundwater collected in the most contaminated of the three wells. The levels of metal concentration in the treated groundwater are too high for direct use in irrigation. However, they are consistent with the standards for livestock drinking water (based on FAO recommendations, Food and Agriculture Organization of the United Nations). The metals can be readily desorbed using 0.5 M HCl solutions with a relatively high concentrating effect (i.e., 50 times). The re-use of the sorbent for three successive cycles of sorption/desorption cycles shows a progressive but weak decrease in sorption and desorption performances.

Efficient and Green Fabrication of Porous Magnetic Chitosan Particles Based on a High-Adhesive Superhydrophobic Polyimide Fiber Mat

In this paper, an efficient and green strategy was developed to synthesize porous magnetic chitosan (PMCS) particles via a special superhydrophobic effect of a porous fluorinated polyimide (PFPI) f...

Synthesis of novel modified magnetic chitosan particles and their adsorption performance toward Cr(VI)

Novel adsorbents, poly([2-(methacryloxy)ethyl]trimethylammonium chloride) modified magnetic chitosan particles (DMCPs), were synthesized via free radical polymerization and applied to adsorb Cr(VI) from aqueous solution. The effects of pH (2–11), Cr(VI) concentration (10–200 mg/L) and contact time (0–420 min) on the adsorption performance were evaluated. The results showed that the adsorption capacity of DMCPs was much larger than that of magnetic chitosan particles (MCPs) in the examined pH range and decreased with Cl− concentration increasing, indicating that electrostatic interaction and ion exchange are the governing mechanisms of Cr(VI) adsorption by DMCPs. The Langmuir isotherm model and pseudo-second-order kinetic model fitted the experimental data well. The maximum adsorption capacity of DMCPs is 153.85 mg/g. Besides, Cr(VI)-loaded DMCPs could be easily separated and efficiently regenerated. Therefore, DMCPs are promising candidates for Cr(VI) adsorption owing to their excellent performance in a wide pH range, easy separation and good reusability.

Concurrent reduction-adsorption of chromium using m-phenylenediamine-modified magnetic chitosan: kinetics, isotherm, and mechanism.

Magnetic chitosan particles (MCS) were chemically grafted by m-phenylenediamine (mPD) forming a distinctive shell layer with abundant nitrogenous functional groups and used as an adsorbent for the effective removal of Cr(VI) from aqueous solution. By interaction among functional groups in the facile oxidative polymerization process, the grafting of mPD and its polymers on MCS surface was innovatively realized. Through Fourier-transformed infrared spectroscopy, energy dispersive spectrometer, X-ray photoelectron spectroscopy, etc., the chemical properties of MCS before and after modification were characterized and the concurrent reduction-adsorption mechanism in Cr(VI) adsorption by mPD-MCS was carefully analyzed. The maximal Cr(VI) removal performance of mPD-MCS reached 227.27mg/g, which was significantly better than that of the original MCS. The analysis indicated that Cr(VI) could be efficiently reduced to Cr(III) and the removal of Cr(VI) and Cr(III) was through adsorption and chelation simultaneously by mPD-MCS. Results also indicated that the concurrent reduction-adsorption was enhanced by protonation of nitrogenous functional groups under low pH. The obtained results suggest that mPD-MCS has a good potential in removal and detoxication of Cr(VI) from aqueous solutions.

Uranium and europium sorption on amidoxime-functionalized magnetic chitosan micro-particles

Magnetic chitosan particles were successfully modified by amidoxime-grafting (as evidenced by FTIR analysis, SEM-EDX analysis, elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis and titration). The effect of pH was investigated showing optimum sorption at pH 4 for U(VI) and pH 5 for Eu(III). Uptake kinetics are relatively fast: the equilibrium was reached within 60–90 min; and the kinetic profiles were preferentially fitted by the pseudo-second order rate equation. Sorption isotherms are equally fitted by the Langmuir and the Sips equations; under optimal conditions maximum sorption capacity reaches 1.5 mmol U g−1 and 2.47 mmol Eu g−1. In bi-component solution, at pH close to 4.9, uranyl is enriched on the sorbent (higher selectivity coefficient) while maintaining high sorption capacities. The selectivity for Eu(III) sorption is higher at pH 2.3 but at the expense of a decrease in sorption capacities. Metal ions can be readily and fast desorbed using 0.5 M HCl solutions: 30–90 min are sufficient for achieving the complete desorption of U(VI) and about 95% of Eu(III) desorption. Sorption and desorption performances are maintained almost constant over 5 cycles of sorption/desorption: the sorbent can be efficiently recycled. Uranium was successfully recovered from alkaline leachate of a sedimentary dolostone ore material.

Preparation of cross-linked magnetic chitosan particles from steel slag and shrimp shells for removal of heavy metals

ABSTRACTIn this study, a new method for preparation of cross-linked magnetic chitosan particles (MCPs) from steel slag and shrimp shells using green tea extract as crosslinking reagent has been presented. The MCPs obtained were characterized by means of X-ray diffraction analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy and magnetic properties, and then were used to investigate the adsorption properties of Cu(II) and Ni(II) ions in aqueous solutions. The influence of experimental conditions such as contact time, pH value, adsorbent dose and initial metal concentration, and the possibility of regeneration were studied systematically. The Cu(II) and Ni(II) adsorption isotherms, kinetics and thermodynamics have been measured and discussed. The results show that the synthesized MCPs have high adsorption capacity for both metal ions (126.58 mg/g for Cu(II) and 66.23 mg/g for Ni(II)), and have excellent regeneration stability with efficiency of greater than 83% after five cycles of the adsorption–regeneration process. The adsorption process of Ni(II) and Cu(II) on MCPs was feasible, spontaneous and exothermic, and better described by the Langmuir model and pseudo-second-order kinetic equation. The MCPs can be applied as a low cost and highly efficient adsorbent for removal of heavy metals from wastewater due to its high adsorption capacity, easy recovery and good reusability.

Functionalization of Magnetic Chitosan Particles for the Sorption of U(VI), Cu(II) and Zn(II)-Hydrazide Derivative of Glycine-Grafted Chitosan.

A new magnetic functionalized derivative of chitosan is synthesized and characterized for the sorption of metal ions (environmental applications and metal valorization). The chemical modification of the glycine derivative of chitosan consists of: activation of the magnetic support with epichlorohydrin, followed by reaction with either glycine to produce the reference material (i.e., Gly sorbent) or glycine ester hydrochloride, followed by hydrazinolysis to synthesize the hydrazide functionalized sorbent (i.e., HGly sorbent). The materials are characterized by titration, elemental analysis, FTIR analysis (Fourrier-transform infrared spectrometry), TGA analysis (thermogravimetric analysis) and with SEM-EDX (scanning electron microscopy coupled to energy dispersive X-ray analysis). The sorption performances for U(VI), Cu(II), and Zn(II) are tested in batch systems. The sorption performances are compared for Gly and HGly taking into account the effect of pH, the uptake kinetics (fitted by the pseudo-second order rate equation), and the sorption isotherms (described by the Langmuir and the Sips equations). The sorption capacities of the modified sorbent reach up to 1.14 mmol U g−1, 1.69 mmol Cu g−1, and 0.85 mmol Zn g−1. In multi-metal solutions of equimolar concentration, the chemical modification changes the preferences for given metal ions. Metal ions are desorbed using 0.2 M HCl solutions and the sorbents are re-used for five cycles of sorption/desorption without significant loss in performances.

Rapid separation of microalga Chlorella vulgaris using magnetic chitosan: Process optimization using response surface methodology

ABSTRACTMicroalgal flocculation using magnetic chitosan was evaluated as a technique to rapidly settle Chlorella vulgaris cells. Magnetic chitosan particles were synthetized using chemical coprecipitation of Fe2+ and Fe3+ ions by NaOH in the presence of chitosan followed by treatment under hydrothermal conditions. Using general full factorial experimental design, the influential range of solution pH, flocculant dosage, and settling time were determined to be 6–8, 10–250 ppm, and 2 min, respectively. Parallel flocculation experiments employing pure chitosan and magnetic chitosan were conducted in the influential range of factors, resulting in maximal efficiencies of 46% and 91.4%, respectively. The results of the second-order factorial design followed by response surface methodology (RSM) helped the second-order polynomial function to predict an optimum separation efficiency of 94% with a flocculant dosage of 216 ppm and pH = 7.23, which was verified by experimental results. This paper presents for the first time to our knowledge the optimization of C. vulgaris separation with magnetic chitosan particles in magnetic fields under a series of pHs, dosage, and time conditions.

Preparation of the core/shell structure of magnetic chitosan particles and application in oilfield

Contrary to the traditional surfactants, the novel magnetic NiFe2O4-chitosan nanoparticles have the advantage of excellent biodegradation. The NiFe2O4-chitosan nanoparticles with core-shell structure were prepared. The images of TEM and the SEM exhibited that the cubic-shape magnetic NiFe2O4 particles were encapsulated in the spherical chitosan nanoparticles. Sizes of all NiFe2O4-chitosan nanoparticles were below 100 nm. The saturated magnetization of NiFe2O4-chitosan nanoparticles could reach 75 emu/g and demonstrated the characteristics of superparamagnetism. Evaluation of the interfacial properties of the product indicated that the interfacial tension between crude oil and water could be reduce to ultra-low values (10−3 mN/m) upon the magnetic NiFe2O4-chitosan nanoparticles application in several blocks in Shengli Oilfield without other additives. The magnetic NiFe2O4-chitosan nanoparticles had good salt-resisting capacity.

Enhanced surface imprinting of lysozyme over a new kind of magnetic chitosan submicrospheres

Surface protein imprinting over nano- or micron-sized substrates is an effective approach for improving the biomacromolecule mass transfer and rebinding capacity. For achieving high recognition performance, it is necessary to introduce certain functional groups onto the surface of the support materials which can interact with the template protein. Herein, we report a surface protein imprinting approach using a new kind of core–shell magnetic chitosan submicrospheres as the supports. The surface of these magnetic chitosan particles is tethered with uncross-linked chitosan chains, hence bearing plenty of amino and hydroxyl groups, where a large amount of functional ligands can be readily coupled for capturing of the protein template. With lysozyme as a model print protein, the magnetic supports were functionalized with maleic acid and then coated with imprinted polymer layers. The resulting imprinted microspheres show significantly selective rebinding for lysozyme. In particular, they exhibit a specific rebinding capacity about three times higher than achieved with our previous lysozyme-imprinted particles synthesized in similar way but with maleic acid modified silica nanoparticles as the supports. This can be attributed to the much higher template binding capacity to the modified magnetic chitosan submicrospheres. Also, the resultant imprinted particles can be easily collected by a magnet. Therefore, such kind of chitosan submicrospheres may be a versatile carrier for constructing high-capacity and magnetically recyclable surface protein-imprinted particles.

Two-step preparation of nano-scaled magnetic chitosan particles using Triton X-100 reversed-phase water-in-oil microemulsion system

A new two-step route for the preparation of nano-scaled magnetic chitosan particles has been developed, different from reported one-step in situ preparation and two-step preparation method of reversed-phase suspension, Triton X-100 reversed-phase water-in-oil microemulsion encapsulation method was employed in coating the pre-prepared Fe3O4 nanoparticles with chitosan. The resultant magnetic chitosan particles owned a narrow size distribution ranging from 50 to 92nm. X-ray diffraction patterns (XRD) indicated that the chitosan coating procedure did not change the spinal structure of Fe3O4 magnetic nanoparticles. The results of Fourier transform infrared (FTIR) analysis and thermogravimetric analysis (TGA) demonstrated that the chitosan was coated on Fe3O4 nanoparticles and its average mass content was ∼50%. The saturated magnetization of the magnetic Fe3O4/chitosan nanoparticles reached 18.62emu/g, meanwhile, the nanoparticles showed the characteristics of superparamagnetism. The magnetic chitosan nanoparticles showed a high recoverability of 99.99% in 10min when pH exceeded 4. The results suggested that the as-prepared magnetic chitosan particles were nano-scaled with a narrow size distribution and a high recoverability.

Core–shell magnetic chitosan particles functionalized by grafting: Synthesis and characterization

A method for preparing magnetic composite particles with a core containing iron oxide encapsulated in crosslinked chitosan (CS) and a functionalized synthetic copolymer shell is proposed and optimized. The magnetic material is produced in situ. Surface vinyl groups are introduced by attaching glycidyl methacrylate (GMA) to the hydroxyl or amino chitosan residues via ether or N-alkyl bonds in acidic medium. These groups are used in a subsequent synthesis step as starting points for free radical copolymerization of GMA, ethylene glycol dimethacrylate (EGDMA) and poly(ethylene glycol methylmethacrylate) (PEG-MMA). The epoxy rings are opened in the final step with ethylenediamine (EDA). The results confirm that a grafted polymer layer has been anchored on the surface by covalent bonds. Sorption batch experiments using copper (II) ion solutions were conducted in order to compare the performance of the synthesized materials as heavy metal adsorbents. The functionalized particles show superior adsorption capacity compared to the ungrafted material.

The Characterization and Thermal Investigation of Chitosan-Fe3O4 Nanoparticles Synthesized Via A Novel One-step Modifying Process

A novel modifying process was designed to prepare ultra small magnetic chitosan nanoparticles which exhibited unique thermal stability and decomposition mechanism. The chemical structures and physical properties of the prepared products were characterized using FTIR, TEM, XRD, TGA and DSC techniques. The results revealed that this approach eliminated the aggregation among nanoparticles. The magnetic chitosan particles were 10–15 nm in size with good dispersibility and new thermal property. To further study the decomposition process, the combined TGA-FTIR technique was used to the analysis of the evolution with the temperature of the gas products evolved in the degradation of the magnetic chitosan. The phenomena were observed directly from TGA-FTIR stack plots. From the measurements data, it suggested that the unusual thermal behavior of chitosan might be attributed to the additional bridging through metal oxide.

Hyaluronic acid interaction with chitosan-conjugated magnetite particles and its purification

The polyelectrolyte complex (PEC) effect between hyaluronic acid (HA) and chitosan was explored to recover HA from fermentation broth. Chitosan was conjugated with the magnetic nanoparticles by co-precipitation method to facilitate its recovery. The magnetic chitosan particles (chitosan–magnetite) have an average size about 5 μm and point of zero charge (PZC) around 6.5. pH lower than PZC favored the HA capture. About 39 mg of HA was captured per gram of particles at pH 6. Nearly quantitative release of captured HA was achieved at pH 8. Although HA could not be directly isolated from Streptococcus zoopedemics fermentation broth by manipulating pH between 6 and 8, HA free of contaminant protein could be purified from the crude ethanol precipitate using chitosan–magnetite.