Magnetic Chitosan Composites Research Articles

Synthesis and fabrication of magnetically separable phosphate-modified magnetic chitosan composites for lead(II) selective removal from wastewater

To address the urgent need for efficient removal of lead-containing wastewater and reduce the risk of toxicity associated with heavy-metal wastewater contamination, materials with high removal rates and easy separation must be developed. Herein, a novel organic-inorganic hybrid material based on phosphorylated magnetic chitosan (MSCP) was synthesized and applied for the selective removal of lead (II) from wastewater. From the characterization and the experimental results can be obtained that the magnetic saturation strength of MSCP reaches 14.65 emu/g, which can be separated quickly and regenerated readily, and maintains high adsorption performance even after 5 cycles, indicating that the adsorbent possesses good magnetic separation performance and durability. Also, MSCP showed high selective adsorption performance for lead in the multiple metal ions coexistence solutions at pH 6.0 and room temperature, with an adsorption coefficient SPb-MSCP of 78.85%, which was much higher than that of MSC (the SPb-MSC was 11.59%). Additionally, in the single lead system, the sorption characteristics of Pb(II) on MSCP and MCP had obvious pH-responsiveness, and their adsorption capacity increased with the increase of solution pH, reaching the maximal values of 80.19 and 72.68 mg/g, respectively. It is noteworthy that the acid resistance of MSCP with an inert layer coated on the core is significantly improved, with almost no iron leaching from MSCP over the entire acidity range, while MCP has 7.63 mg/g of iron leaching at pH 1.0. Significantly, MSCP exhibited a maximum adsorption capacity of 102.04 mg/g, which matches the Langmuir model at pH 6.0 and 298.15 K, and points to the pseudo-second-order kinetics of the chemisorption process of Pb(II) on MSCP. These findings highlight the great potential of MSCP for Pb(II) removal from aqueous solution, making it a promising solution for Pb(II) contamination in wastewater.

Fluoranthene adsorption by graphene oxide and magnetic chitosan composite (mCS/GO).

The oil industry faces the challenge of reducing its high polluting potential, due to the presence of aromatic pollutants, such as polycyclic aromatic hydrocarbons (PAHs). Efforts have been made to mitigate the impact of PAHs in industry through the development of detection technologies and the implementation of mitigation strategies. This study presents the adsorption of fluoranthene, through a magnetic composite of graphene oxide and chitosan as a method of remediation of produced water. The efficiency of the process was evaluated through kinetic, equilibrium, thermodynamic, and characterization analyses. The nanocomposite was able to remove 90.9% of FLT after 60 min and showed a maximum adsorption capacity of 28.22 mg/g, demonstrating that they can be implemented to remove fluoranthene. Kinetic and equilibrium experimental data showed that physisorption is the predominant adsorptive mechanism; however, the process is also influenced by chemisorption, which occurs through electrostatic interactions between the surface of the material and the adsorbate. The thermodynamic study showed that fluoranthene and graphene composite have high affinity, and that the adsorption is exothermic and spontaneous. The results presented in this paper indicate that the magnetic composite is a potential and sustainable adsorbent for fluoranthene remediation.

Myrica esculenta Leaf Extract-Assisted Green Synthesis of Porous Magnetic Chitosan Composites for Fast Removal of Cd (II) from Water: Kinetics and Thermodynamics of Adsorption.

Heavy metal contamination in water resources is a major issue worldwide. Metals released into the environment endanger human health, owing to their persistence and absorption into the food chain. Cadmium is a highly toxic heavy metal, which causes severe health hazards in human beings as well as in animals. To overcome the issue, current research focused on cadmium ion removal from the polluted water by using porous magnetic chitosan composite produced from Kaphal (Myrica esculenta) leaves. The synthesized composite was characterized by BET, XRD, FT-IR, FE-SEM with EDX, and VSM to understand the structural, textural, surface functional, morphological-compositional, and magnetic properties, respectively, that contributed to the adsorption of Cd. The maximum Cd adsorption capacities observed for the Fe3O4 nanoparticles (MNPs) and porous magnetic chitosan (MCS) composite were 290 mg/g and 426 mg/g, respectively. Both the adsorption processes followed second-order kinetics. Batch adsorption studies were carried out to understand the optimum conditions for the fast adsorption process. Both the adsorbents could be regenerated for up to seven cycles without appreciable loss in adsorption capacity. The porous magnetic chitosan composite showed improved adsorption compared to MNPs. The mechanism for cadmium ion adsorption by MNPs and MCS has been postulated. Magnetic-modified chitosan-based composites that exhibit high adsorption efficiency, regeneration, and easy separation from a solution have broad development prospects in various industrial sewage and wastewater treatment fields.

Highly effective and selective removal of lead ions by polymer-grafted silica-coated acid-resistant magnetic chitosan composites

Separation and recovery of lead resources from lead-containing wastewater is very important to achieve reuse of lead(II) and environmental protection. Herein, a novel magnetic separation adsorbent, polymer-grafted silica-coated acid-resistant magnetic chitosan composite (PMSC), was facilely constructed and applied for the efficient and selective adsorption of Pb(II) from aqueous solutions. The adsorption results in the Pb(II) mono-contaminated system showed that the adsorption process of PMSC on Pb(II) was significantly pH-responsive and increased with increasing pH, reaching a qmax value of 88.03 mg g−1 at pH 6.0, which was more than 6 times of MSC (14.47 mg g−1). More interestingly, the adsorbent with inert silica coated on the core has a higher acid resistance, with almost no iron leaching from PMSC at pH 1.0, while PMC has 3.99 mg L−1 of iron leaching. The results of adsorption isotherms and kinetics of Pb(II) by PMSC showed that Langmuir and pseudo-second-order kinetics can better describe the adsorption behavior, indicating that the adsorption process was mainly controlled by chemisorption and the maximum monolayer adsorption capacity can reach 111.12 mg g−1 at 298.15 K. Furthermore, PMSC maintained about 80 % of the initial adsorption capacity after five cycles of repeated use, demonstrating its good regenerative cycling performance. Also, PMSC showed excellent selective adsorption of Pb(II) in the coexistence solutions of multiple metal ions with the SPb up to 85.83 %, which was far more than that of MSC (23.55 %), indicating that the polymer grafting had a significant enhancement on the selective performance of the adsorbent. This work could provide design and preparation insights for the development of novel, acid-resistant, recyclable and fast magnetic separation adsorbents for the efficient selective separation of lead ions.

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.

Preparation and characterization of magnetic bioadsorbent for adsorption of Cd(II) ions

A facile magnetic chitosan composite used for heavy metal ions removal was prepared. The adsorbents with large specific area and rich carboxyl groups exhibited good removal of Cd(II) ions and could be easily separated with magnetic separation. The adsorption capacity of Cd(II) was 48 ​mg ​g−1 and the removal efficiency reached 86.7% after five cycles. Thus, the prepared magnetic chitosan composite could act as a potential adsorbent for Cd(II) ions removal.

Sequestration of cadmium ions from aqueous phase using magnetic chitosan composite

Present communication reports on the synthesis, characterization and application of Fe3O4-chitosan composite (MCC). The magnetic chitosan composite are crafted by mixing Fe3O4 nanoparticles solution to chitosan solution. Fe3O4 nanoparticles have been synthesized by co-precipitation method. The synthesized composite have been extensively characterized using various techniques such as FTIR, TEM, XRD and BET analysis. The surface area analysis suggested that the materials synthesized is mesoporous in nature. Incorporation of chitosan crosslinked actively with Fe3O4 nanoparticles that results in reduction of surface area and narrower pore size distribution of the composite than pure Fe3O4 nanoparticles. TEM study demonstrated that Fe3O4 nanoparticles were found in the range of 20–25 nm. The synthesized composite is able to capture more than 89% Cd(II) from synthetic Cd(II) solution within 80 min of contact time. The adsorption equilibrium data better conformed with the Langmuir isotherm. The maximum capacity determined from Langmuir isotherm was 149.92 mg/g at 323 K. Adsorption kinetics of cadmium on MCC could be well analyzed with pseudo-second-order kinetic model. Thermodynamics investigation reveals that with the increase of solution temperature 303 K, 313 K and 323 K the ΔGo values decreases correspondingly to −87.76, −90.36 and -93.36 KJ/mol, suggesting endothermic nature of the adsorption process. The adsorbent could be successfully reused for more than five cycles. Thus, MCC can be serves as a reliable and sustainable material for efficient sequestration of Cd(II) species from aqueous environment.

Fe3O4@chitosan‐bound boric acid composite as pH‐responsive reusable adsorbent for selective recognition and capture of cis‐diol‐containing shikimic acid

Recently, shikimic acid (SA) has aroused great concern as the starting raw material for the synthesis of antiviral drug (Tamiflu) against the spread of influenza virus in the body. In this work, magnetic chitosan composite modified with boric acid and its application in SA recognition and separation was described. Chitosan (CT) with plenty of hydroxyl and amino groups was first coated on the surface of magnetic core Fe3O4, then carboxylic groups were grafted to the surface of Fe3O4@CT via anhydride modification, followed by the introduction of 3‐aminophenylboronic acid (APBA). The uniform morphology and composition analysis of the adsorbent (Fe3O4@CT‐COOH‐BA) were characterized by FT‐IR, XRD, XPS, SEM, TEM and UV–visible spectroscopy. The adsorption capacity of as‐prepared material was explored in detail by batch mode experiments. The adsorption kinetics fitted well with a pseudo‐second order model, and the adsorption isotherms was well described by the Langmuir model with a maximum adsorption capacity of 23.8 mg g−1 at 25 °C. Solution pH plays a crucial role in adsorption process and the optimized pH was 8.0. In addition, Fe3O4@CT‐COOH‐BA could be easily reused through an external magnet and the adsorption capacity reduced by only 4% after five adsorption–desorption cycles. These results prove that boric acid modified magnetic chitosan composite is an effective and practical adsorbent for specific recognition and selective adsorption of cis‐diol‐containing compounds.

Biopolymer modified transition metal spinel ferrites for removal of fluoride ions from water

In present study different nano metal ferrites such as zinc ferrite (ZnFN), nickel ferrite (NiFN) and cobalt ferrite (CoFN) were modified with chitosan (CS) biopolymer to prepare recyclable magnetic chitosan composites and used as adsorbents to remove fluoride ions from aqueous solution. Various techniques like Fourier Transform Infra-Red (FT-IR), X-Ray Diffraction (XRD), Transmission Electron Microscope (TEM), BET analysis, Thermal Gravimetric Analysis (TG-DTA) and pH of point zero charges (pHzpc) were used to study the surface characterization and morphology of different magnetic chitosan composites. Thermal studies results reveal that the different chitosan composites are thermally stable up to 400 °C. The adsorption kinetics data obtained from different magnetic composites were best fitted in Lagergren Pseudo-second-order model. Among different isotherm models, the adsorption equilibrium data were best fitted in the Langmuir isotherm model. The calculated maximum adsorption capacities of ZnFN-CS, NiFN-CS, and CoFN-CS composites were 6.9, 8.3 and 6.7 mg/g, respectively. The calculated adsorption thermodynamic parameters values confirmed that the adsorption of fluoride ions is spontaneous and exothermic in nature. The regeneration efficiency of different magnetic composites was studied up to five successive cycles. The results revealed that the regeneration efficiencies of ZnFN-CS, NiFN-CS and CoFN-CS composites toward fluoride ions were reduced to 84%, 79%, and 76%, respectively.

The influence of Fe3O4 on Magnetic Chitosan composite preparation for Methylene blue removal from water

The influence of Fe3O4 on magnetic chitosan composite preparation for methylene blue removal from water had been studied. Fe3O4 was loaded on chitosan with various content. The prepared magnetic chitosan composites were characterized by Fourier Transform Infrared (FT-IR), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis. Results showed Fe3O4 loading on magnetic chitosan composites preparation improved methylene blue adsorption capacity of chitosan. The best ratio of chitosan/Fe3O4 obtained in this work was 0.35g / 0.5g. The methylene blue adsorption capacity of the magnetic chitosan composite was higher than pure chitosan. Magnetic composite can be used as potential adsorbent for methylene blue removal from water.

Highly efficient removal of heavy metals from waters by magnetic chitosan-based composite

Magnetic chitosan composite (MCC) made by chitosan matrix embedding magnetite/maghemite were developed for the removal of toxic Cu(II), Pb(II), and Ni(II) from water. Thermogravimetric (TGA) and Zeta potential analyses showed that MCC contains ca. 50 wt % of chitosan and presents a value of isoelectric point (pHIEP) around 8-8.5. The magnetization curve revealed a saturation magnetization of 12 emu g−1, which indicates that MCC can be easily recovered by magnetic separation. Adsorption of the heavy metals to MCC reached equilibrium within 120 min with maximum uptakes of 108.9 mg g−1, 216.8 mg g−1 and 220.9 mg g−1 for Ni(II), Cu(II) and Pb(II), respectively. The results show that the amino and hydroxyl functional groups of chitosan are involved in the adsorption process. The reported adsorption capacity from organic pollutants, such as hydrocarbons, along with the high adsorption capacity shown for heavy metals, point out MCC being a promising versatile adsorbent for wastewater treatments.

Phosphorylated chitosan/CoFe2O4 composite for the efficient removal of Pb(II) and Cd(II) from aqueous solution: Adsorption performance and mechanism studies

Phosphorylated magnetic chitosan composite (P-MCS) was successfully synthesized and applied to adsorb Pb(II) and Cd(II) from aqueous solutions. The as-prepared P-MCS composite was characterized by EDS, SEM, FTIR, XRD, XPS and zeta potential analysis. Factors affecting adsorption including adsorbent dose, pH value and contact time were optimized to improve the adsorption performance. The adsorption isotherm and kinetic model could well conform to Langmuir model and pseudo-second-order kinetic model. The as-prepared adsorbent exhibited good adsorption capacities for Pb(II) (151.06 mg g−1) and Cd(II) (71.53 mg g−1) from Langmuir isotherm. Besides, spectroscopic analysis after adsorption including FTIR and XPS were also performed to further reveal the adsorption mechanism. The results indicated that surface complexation and ion exchange between functional groups and metal ions played an important role in adsorption process. Thermodynamic studies (∆G < 0, ∆H > 0, ∆S > 0) implied that the adsorption process is an endothermic and spontaneous reaction. Furthermore, the excellent magnetic separation and regeneration performance indicated the feasibility of using P-MCS composite for Pb(II)/Cd(II)-bearing wastewater remediation.

Facile Preparation of Magnetic Chitosan Coprecipitated by Ethanol/NH3·H2O for Highly Efficient Removal toward Cr(VI)

The adsorption ability of chitosan (CS) usually decreases with the introduction of magnetic particles, and thus magnetic CS has to be chemically modified further to improve its adsorption performance. Herein, a novel magnetic chitosan composite (Fe3O4–CS3) with porous structure and evenly distributed Fe3O4 was successfully prepared via the reduction of the solubility of CS by ethanol (physical reaction), and followed the coprecipitation of the mixture of FeCl3/FeCl2/CS by ethanol/NH3·H2O. Without any modification, its maximum adsorption capacity toward Cr(VI) ions can achieve 242.1 mg/g (≈468.6 mg/g of CS). This significant progress could be ascribed to the very fast precipitate rate of CS due to the decrease in solubility induced by ethanol. Ethanol causes rigorous solidification of CS, so that there is not enough time to densify, resulting in a looser CS matrix with a larger pore size. After adsorption, this Fe3O4–CS3 could not only be easily separated but also be effectively regenerated by NaOH solution in a rather wider concentration range, showing great potential in the field of heavy metal wastewater treatment.

Highly efficient removal of acid red‐17 and bromophenol blue dyes from industrial wastewater using graphene oxide functionalized magnetic chitosan composite

In present study, magnetic chitosan‐graphene oxide composite (ᶆÇ‐GO) has been synthesized and used for the removal of two common textile dyes; acid red‐17 (AR‐17) and bromophenol blue (BPB). The effect of various parameters including pH (2–8), time (10–100 min), adsorbent dosage (2–10 mg), initial dye concentration (2–30 μg mL−1) as well as temperature (303, 313, and 323 K) was investigated. The point of zero charge of composite was determined using pH drift method in an attempt to better understand the adsorption process. Present work revealed fast adsorption kinetics with removal efficiency of around 79 and 97% for AR‐17 and BPB, respectively, under optimized conditions. Besides, equilibrium relationships were studied using Langmuir and Freundlich models. Thermodynamic analysis uncovered the spontaneous and endothermic nature of dye‐composite interation. Synthesized material showed profound stability after five successive adsorption‐desorpion cycle of reuse. Importantly, spiked real water samples were used to check the suitability of composite adsorbent for practical applications. High % recoveries were obtained which indicated that complex matrix presented insignificant interference effects. Also, comparative study revealed that composite material offers superior performance for the removal of dyes relative to precursors (Ç, Fe3O4 nanoparticles, GO). Improvement in removal efficiency of synthesized composite toward selected dyes can be attributed to intrinsic qualities of Ç and incorporated functionalities; exceptionally high surface area as well as excellent mechanical properties of GO and convenience of magnetic separation because of Fe3O4 nanoparticles. POLYM. COMPOS., 39:3317–3328, 2018. © 2017 Society of Plastics Engineers

Composite particles formed by complexation of poly(methacrylic acid) — stabilized magnetic fluid with chitosan: Magnetic material for bioapplications

A simple procedure for the synthesis of magnetic fluid (ferrofluid) stabilized by poly(methacrylic acid) has been developed. This ferrofluid was used to prepare a novel type of magnetically responsive chitosan-based composite material. Both ferrofluid and magnetic chitosan composite were characterized by a combination of microscopy (optical microscopy, TEM, SEM), scattering (static and dynamic light scattering, SANS) and spectroscopy (FTIR) techniques. Magnetic chitosan was found to be a perspective material for various bioapplications, especially as a magnetic carrier for immobilization of enzymes and cells. Lipase from Candida rugosa was covalently attached after cross-linking and activation of chitosan using glutaraldehyde. Baker's yeast cells (Saccharomyces cerevisiae) were incorporated into the chitosan composite during its preparation; both biocatalysts were active after reaction with appropriate substrates.

Single-step synthesis of magnetic chitosan composites and application for chromate (Cr(VI)) removal

Magnetic chitosan composites (Fe3O4@chitosan) were synthesized in one single-step, characterized and applied in Cr(VI) removal from water. With the increase of loading proportion of chitosan, Cr(VI) adsorption capacity of Fe3O4@chitosan composites increased from 10.771 to 21.040 mg/g. The optimum adsorption capacities of Cr(VI) on Fe3O4@chitosan-3 were found in a pH range of 3.0−5.0. Kinetic study results show that the adsorption process follows pseudo-second-order model, indicating that the rate-limiting step in the adsorption of Cr(VI) involves chemisorptions. Moreover, FT-IR spectra analysis confirms that the amine and hydroxyl groups of chitosan are predominantly responsible for binding. Results from this work demonstrate that the prepared Fe3O4@chitosan composites possess great potential in Cr(VI) removal from contaminated water.