Magnetic Chitosan Research Articles

Synthesis of a novel magnetic chitosan-mediated GO dual-template imprinted polymer for the simultaneous and selective removal of Cd(Ⅱ) and Ni(Ⅱ) from aqueous solution

With the uptrend of the energy industry and Cadmium-Nickel batteries, the development and comprehensive utilization of highly efficient adsorptive material for simultaneous and selective capture of Cd(II) and Ni(II) ions are of great significance, but formidable. Herein, a dual-template imprinted nanoparticle material (MCTS@GO@DIIP) was synthesized on GO slice structure coated with MnFe2O4 magnetic chitosan film via surface ion-imprinted technique for selective removal of Cd(II) and Ni(II) from aqueous solution. The material was based on ion-imprinted condensates of chitosan, L-histidine and GO as ion recognition layer with Cd(II) and Ni(II) as dual-template ions, L-histidine as monomer and glutaraldehyde as crosslinking agent. The obtained MCTS@GO@DIIP was characterized by SEM, FT-IR, XRD and TGA to study the surface structure, group distribution, crystal structure and thermal property. The adsorption experiments exhibited the MCTS@GO@DIIP achieved adsorption equilibrium for Cd(II) and Ni(II) ions in 30 min with the maximum adsorption capacities of 33.91 and 39.35 mg g−1, respectively. The adsorption process was agreed with the pesudo-second-order kinetic model and Langmuir isotherm adsorption model, proclaiming monolayer chemisorption on homogeneous sites was the rate-limiting step. Meanwhile, the MCTS@GO@DIIP also showed a specificity recognition ability for Cd(II) and Ni(II) using analogues Co(II), Zn(II), Mg(II) and Pb(II) as interference. Moreover, the MCTS@GO@DIIP based MSPE could extract approximately 95.5–104.6% of Cd(II) with a RSD of 3.34–8.27%, and 90.0–103.4% of Ni(II) with a RSD of 3.21–7.03% in real water samples, which indicated the polymer had the high stability and reproducibility and presented itself a promising material for the Cd(II) and Ni(II) adsorption and detection from aqueous solution.

Determination of bioactive flavonoids using β-cyclodextrin combined with chitosan-modified magnetic nanoparticles

To accurately determine flavonoids (rutin, quercetin or kaempferol), it is necessary to extract them from complex matrices. The ultrasound-assisted magnetic dispersion microsolid phase extraction technique has been predominantly used for separation and enrichment of the target analytes. The combination of magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent (DESP) is likely to enhance the efficiency of flavonoid extraction from food. In this study, adsorbents were prepared by modifying chitosan with magnetic nanoparticles, and the eluent was a DESP derived from β-cyclodextrin and an organic acid. The successful preparation of these materials was confirmed by FTIR, XRD, FE-SEM and 1H NMR. The extraction recovery rates exceeded 93%, with limits of detection and quantitation ranging from 0.9 to 2.4μg/L and 2.7 to 7.2μg/L, respectively, and the flavonoid clearance rates for ABTS and DPPH radicals reached 100%. Therefore, the integration of magnetic chitosan nanoparticles with the DESP provides a new and efficient method for the extraction of flavonoids while also presenting a potential application of the DESP in separations.

Reaction–Diffusion Process for Hydrogels with a Tailored Layer Structure

The architecture of hydrogel composites results in not only synergistic property enhancement but also superior functionality. The reaction–diffusion (RD) process is acommon phenomenon throughout nature which induced ordered structure on a length scale from microscopic to macroscopic. Different from commonly used inorganic salts or oppositely charged nanoparticles for the RD process, a modified RD process was used for layered chitosan hydrogel (L-CH) and layered magnetic chitosan hydrogel (L-MCH). During the modified RD process reported in this paper, the protonated chitosan (CS-NH3+) with iron ions (Fe3+ and Fe2+) was used as an inner-reactant and hydroxide ion (-OH−) was used as an out-reactant. The protonated chitosan (CS-NH3+) not only played the role of an inner-reactant but also the reaction medium which controlled the diffusion behavior of the out-reactant (-OH−). A series of ordered layers were constructed and the ordered layers were parallel with the longitudinal axis. The layer width of L-CH and L-MCH can be tailored by varying interval time T. The mean layer width of L-MCH increased from 50 ± 5.8 μm to 90 ± 6.4 μm when the interval time T increased from 2 min to 5 min. The tailored layer structure of L-CH and L-MCH obeyed the time law and spacing law, which declared that the L-CH and L-MCH were constructed via the reaction–diffusion process. We also show that the tailored layer structure endows hydrogel with enhanced mechanical properties, especially toughness. The yield strength of magnetic chitosan hydrogel was improved significantly (from 95.1 ± 7.6 kPa to 401.7 ± 12.1 kPa, improved by about 4 times) when 10 wt. % magnetite nanoparticles were involved. The enhancement of the mechanical propertieswas due to a physical crosslinking effect of magnetite nanoparticles on chitosan. For L-MCH, the probe displacement reached 28.93 ± 2.6 mm when the rupture occurred, which was as high as 284.7% compared with that of the non-layered hydrogel. The tailor-made hydrogels might be possible for application as a tough implantable scaffold.

Study on the polypeptide-functionalized magnetic chitosan microspheres that specifically adsorb Hg (II) ions

Here, we present an effective and environmentally friendly approach for fabricating polypeptide functionalized magnetic chitosan microspheres (Fe3O4@CTS@PS) based on the effective binding of polypeptide (GCTCWCSGE) with mercury ions (Hg (II)). The morphology and component of the prepared Fe3O4@CTS@PS was characterized via scanning electronic microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer. Effects of the polypeptide sequence, pH, adsorption time, initial concentration, temperature on the adsorption performance and anti-interference ability and reusability were studied. The Fe3O4@CTS@PS had excellent adsorption selectivity for Hg (II) and the adsorption capacity can reach to 218.8 mg·g−1 at 318 K and pH5.0. Kinetic data was correlated well with the pseudo-second-order model and adsorption isotherm agreed well with the Langmuir isotherm model. The reusability of Fe3O4@CTS@PS was also investigated and the adsorption capacity of Fe3O4@CTS@PS for Hg(II) still remained 92% of the initial values after four adsorption-elution cycles (eluting agent was Na2S2O3). The prepared Fe3O4@CTS@PS showed excellent adsorption performance for Hg (II) in real samples (lake water, milk and nori) and was a promising adsorbent in practical applications.

Magnetic chitosan oligomer-sulfonate-stearic acid triple combination as cisplatin carrier for site-specific targeted on MCF-7 cancer cells: Preparation, characterization and in vitro experiments.

In this study, a new amphiphilic target-specific adsorbent, chitosan oligomer-sulfonate-stearic acid triple combination (S-Cho-SA), and magnetic chitosan oligomer-sulfonate-stearic acid triple combination (M-S-Cho-SA) by oleic acid (OA)-modified Fe3 O4 via hydrophobic interaction are fabricated. By modifying the nanoparticle surfaces and having the ability to magnetically allow the target region, these particles attract attention as important particles used in targeting mechanisms in cancer therapy. With magnetic nanoparticles and an external magnetic field, it is possible to transport therapeutic agents to the target site and keep them in the desired effect zone for a longer period of time. These new adsorbents are characterized by scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy, nuclear magnetic resonance (NMR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and thermogravimetric analysis (TG/DTA). After chemical characterization, it is complexed with cisplatin (CDDP). The magnetic adsorbents were loaded with high efficiency (>50%), and the release experiments exhibited that cisplatin is released more at pH 4.5 compared with pH 7.4 at 37°C. It showed better drug release results under a magnetic field for magnetic adsorbents (36% for pH 4.5 and 3.6% for pH 7.4). The biocompatibility of the prepared adsorbents was demonstrated via the XTT assay in MCF-7 cell lines. The results also exhibited that S-Cho-SA and M-S-Cho-SA were biocompatible, and free cisplatin and cisplatin-complexed adsorbents showed an antiproliferative effect. The results showed that these new cisplatin-loaded (M-S-Cho-SA) nanoparticles are good candidates for thermotherapy in cancer treatment in the future, as they can provide selectivity by site-specific targeting and hold onto an alternative magnetic field due to the magnetic nature of the nanoparticles.

Design of separable magnetic chitosan grafted-benzaldehyde for azo dye removal via a response surface methodology: Characterization and adsorption mechanism

In this study, a magnetic chitosan grafted-benzaldehyde (CS-BD/Fe3O4) was hydrothermally prepared using benzaldehyde as a grafting agent to produce a promising adsorbent for the removal of acid red 88 (AR88) dye. The CS-BD/Fe3O4 was characterized by infrared spectroscopy, surface area analysis, scanning electron microscopy-energy dispersive X-ray, vibrating sample magnetometry, powder X-ray diffraction, CHN elemental analysis, and point of zero charge (pHPZC). The Box-Behnken design (BBD) was adopted to study the role of variables that influence AR88 dye adsorption (A: CS-BD/Fe3O4 dose (0.02–0.1 g), B: pH (4–10), and time C: (10–90 min)). The ANOVA results of the BBD model indicated that the F-value for the AR88 removal was 22.19 %, with the corresponding p-value of 0.0002. The adsorption profiles at equilibrium and dynamic conditions reveal that the Temkin model and the pseudo-first-order kinetics model provide an adequate description of the isotherm results, where the maximum adsorption capacity (qmax) with the AR88 dye was 154.1 mg/g. Several mechanisms, including electrostatic attraction, n-π interaction, π-π interaction, and hydrogen bonding, regulate the adsorption of AR88 dyes onto the CS-BD/Fe3O4 surface. As a result, this research indicates that CS-BD/Fe3O4 can be utilized as an effective and promising bio-adsorbent for azo dye removal from contaminated wastewater.

Optimization of lead (II) removal from water and wastewater using a novel magnetic nanocomposite of aminopropyl triethoxysilane coated with carboxymethyl cellulose cross-linked with chitosan nanoparticles

The removal of heavy metals from industrial wastewater is nowadays one of the most interesting challenges in water remediation using adsorbent nanomaterials. The present study presents a novel adsorbent (Fe3O4@CS@CMC-SiNH2) nanocomposite (NC), by functionalization of the carboxymethyl cellulose (CMC) cross-linked to magnetic chitosan nanoparticles (Fe3O4@CS NPs) with aminopropyl triethoxysilane layer (APTES), and evaluate its performance toward lead (II) removal from wastewater. The synthesized NCs were characterized using several techniques. The optimization of the adsorption process was performed using the Response Surface Methodology with the Box-Behnken Design model. The optimal conditions for lead (II) ion removal were found to be; pH of 5.1, a dose of 0.10 g/L, and a temperature of 36 ℃ using Fe3O4@CS@CMC-SiNH2 NCs which proved to have superior adsorption performance with a maximum adsorption capacity of 555.56 mgPb(II)/gNC, and fast achievement of the adsorption equilibrium (30 min). Favorable monolayer chemisorption was estimated and proved to be a coordination bond between the NH amide and lead (II) ions using FTIR, as well as up to seven adsorption–desorption cycles were effective for lead (II) ion removal from aqueous solutions. In addition, the Fe3O4@CS@CMC-SiNH2 NCs showed 98.10%, and 97.21 % removal of lead (II) ions in the absence, and the presence of other contaminants of heavy metals such as cadmium (II) and mercury (II). Moreover, the Fe3O4@CS@CMC-SiNH2 NC exhibited high efficiency in the removal of lead (II) ions from wastewater, can be easily separated from water by magnetic separation, showed satisfactory reusability for five cycles of the adsorption–desorption process of lead (II) ion removal from tap water and wastewater. Consequently, Fe3O4@CS@CMC-SiNH2 NC is a prospective adsorbent nanomaterial for lead (II) ions removal from wastewater.

Constructing a dummy-template adsorbent using magnetic molecular-imprinted chitosan for rapid enrichment of flavonoids compounds from Penthorum chinense Pursh

In this work, a novel dummy molecularly imprinted polymer (MIP/CS/Fe3O4) was successfully prepared for the selective enrichment of flavonoids in Penthorum chinense Pursh. The molecularly imprinted polymer was synthesized on the surface of chitosan-modified Fe3O4 nanoparticles with naringenin as the dummy template and then it was used as a solid adsorbent for the analyte enrichment. Compared with structural analogues, the MIP/CS/Fe3O4 presented quick binding kinetic behavior, satisfying selectivity and high adsorption capacity toward pinocembrin. The adsorption capacity and the imprinting factor of MIP/CS/Fe3O4 could reach 8.56 mg·g−1 and 1.7, respectively. Finally, MIP/CS/Fe3O4 was applied to enrich flavonoids in the crude extract from Penthorum chinense Pursh and 11 flavonoids were successfully detected, indicating the MIP/CS/Fe3O4 was a promising adsorbent for separation and enrichment of flavonoids. Many favorable properties of the synthesized dummy molecularly imprinted polymer can also provide a new direction for the simultaneous enrichment of structural similarities.

Activation of Insulin Gene Expression via Transfection of a CRISPR/dCas9a System Using Magnetic Peptide-Imprinted Nanoparticles.

A CRISPRa transcription activation system was used to upregulate insulin expression in HEK293T cells. To increase the delivery of the targeted CRISPR/dCas9a, magnetic chitosan nanoparticles, imprinted with a peptide from the Cas9 protein, were developed, characterized, and then bound to dCas9a that was complexed with a guide RNA (gRNA). The adsorption of dCas9 proteins conjugated with activators (SunTag, VPR, and p300) to the nanoparticles was monitored using both ELISA kits and Cas9 staining. Finally, the nanoparticles were used to deliver dCas9a that was complexed with a synthetic gRNA into HEK293T cells to activate their insulin gene expression. Delivery and gene expression were examined using quantitative real-time polymerase chain reaction (qRT-PCR) and staining of insulin. Finally, the long-term release of insulin and the cellular pathway related to stimulation by glucose were also investigated.

Magnetic chitosan hydrogel induces neuronal differentiation of neural stem cells by activating RAS-dependent signal cascade

Our aim was to modulate magnetic cues to influence the differentiation of neural stem cell (NSC) into neuron during nerve repair and to explore corresponding mechanisms. Here, a magnetic hydrogel composed of chitosan matrices and magnetic nanoparticles (MNPs) with different content was prepared as the magnetic-stimulation platform to apply intrinsically-present magnetic cue and externally-applied magnetic field to NSC grown on the hydrogel. The MNP content had regulatory effects on neuronal differentiation and the MNPs-50 samples exhibited the best neuronal potential and appropriate biocompatibility in vitro, as well as accelerated the subsequent neuronal regeneration in vivo. Remarkably, the use of proteomics analysis parsed the underlying mechanism of magnetic cue-mediated neuronal differentiation form the perspective of protein corona and intracellular signal transduction. The intrinsically-present magnetic cues in hydrogel contributed to the activation of intracellular RAS-dependent signal cascades, thus facilitating neuronal differentiation. Magnetic cue-dependent changes in NSCs benefited from the upregulation of adsorbed proteins related to “neuronal differentiation”, “cell-cell interaction”, “receptor”, “protein activation cascade”, and “protein kinase activity” in the protein corona. Additionally, magnetic hydrogel acted cooperatively with the exterior magnetic field, showing further improving neurogenesis. The findings clarified the mechanism for magnetic cue-mediated neuronal differentiation, coupling protein corona and intracellular signal transduction.

Pb2+ recovery from real water samples by adsorption onto nano Fe3 O4 /chitosan-acrylamide hydrogel ions in real water samples.

This study examined the removal of Pb(II) using magnetic chitosan hydrogel adsorbent from diverse sample waters. Spectrometry was used to track the effects of magnetic acrylamide nanocomposite dose, pH extraction, and contact duration on Pb(II) removal from sample water. This research also looked at adsorption isotherm models for the sorption of Pb(II). The magnetic chitosan hydrogel adsorbent Pb(II) adsorption capability was 31.74mg/g respectively. The Freundlich isotherm model fits the removal of Pb(II) utilising magnetic chitosan hydrogel adsorbent. In addition, this adsorbent was shown to have a qmax value of 31.74mg/g of Pb2+ ions, which is considered to be of high efficiency for Pb2+ ion removal. The studied kinetic models have determined that the pseudo-second-order linear model is more suitable to explain the adsorption of lead (II) on magnetic chitosan hydrogel adsorbent. Also, chemical adsorption is the rate-limiting step in the adsorption process of lead (II) ions.

A Novel Electrochemical Sensor Based on an Environmentally Friendly Synthesis of Magnetic Chitosan Nanocomposite Carbon Paste Electrode for the Determination of Diclofenac to Control Inflammation.

A simple and eco-friendly electrochemical sensor for the anti-inflammatory diclofenac (DIC) was developed in a chitosan nanocomposite carbon paste electrode (M-Chs NC/CPE). The M-Chs NC/CPE was characterized with FTIR, XRD, SEM, and TEM for the size, surface area, and morphology. The produced electrode showed a high electrocatalytic activity to use the DIC in 0.1 M of the BR buffer (pH 3.0). The effect of scanning speed and pH on the DIC oxidation peak suggests that the DIC electrode process has a typical diffusion characteristic with two electrons and two protons. Furthermore, the peak current linearly proportional to the DIC concentration ranged from 0.025 M to 4.0 M with the correlation coefficient (r2). The sensitivity, limit of detection (LOD; 3σ), and the limit of quantification (LOQ; 10σ) were 0.993, 9.6 µA/µM cm2, 0.007 µM, and 0.024 µM, respectively. In the end, the proposed sensor enables the reliable and sensitive detection of DIC in biological and pharmaceutical samples.

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.

Superparamagnetic Multifunctionalized Chitosan Nanohybrids for Efficient Copper Adsorption: Comparative Performance, Stability, and Mechanism Insights.

To limit the dangers posed by Cu(II) pollution, chitosan-nanohybrid derivatives were developed for selective and rapid copper adsorption. A magnetic chitosan nanohybrid (r-MCS) was obtained via the co-precipitation nucleation of ferroferric oxide (Fe3O4) co-stabilized within chitosan, followed by further multifunctionalization with amine (diethylenetriamine) and amino acid moieties (alanine, cysteine, and serine types) to give the TA-type, A-type, C-type, and S-type, respectively. The physiochemical characteristics of the as-prepared adsorbents were thoroughly elucidated. The superparamagnetic Fe3O4 nanoparticles were mono-dispersed spherical shapes with typical sizes (~8.5-14.7 nm). The adsorption properties toward Cu(II) were compared, and the interaction behaviors were explained with XPS and FTIR analysis. The saturation adsorption capacities (in mmol.Cu.g-1) have the following order: TA-type (3.29) > C-type (1.92) > S-type (1.75) > A-type(1.70) > r-MCS (0.99) at optimal pH0 5.0. The adsorption was endothermic with fast kinetics (except TA-type was exothermic). Langmuir and pseudo-second-order equations fit well with the experimental data. The nanohybrids exhibit selective adsorption for Cu(II) from multicomponent solutions. These adsorbents show high durability over multiple cycles with desorption efficiency > 93% over six cycles using acidified thiourea. Ultimately, QSAR tools (quantitative structure-activity relationships) were employed to examine the relationship between essential metal properties and adsorbent sensitivities. Moreover, the adsorption process was described quantitatively, using a novel three-dimensional (3D) nonlinear mathematical model.

Neuroprotective effect of piracetam-loaded magnetic chitosan nanoparticles against thiacloprid-induced neurotoxicity in albino rats

Thiacloprid (TH) is a neurotoxic agricultural insecticide and potential food contaminant. The purpose of this study was to investigate the relationship between TH exposure and memory dysfunction in rats, as well as the potential protective effect of piracetam and piracetam-loaded magnetic chitosan nanoparticles (PMC NPs). Rats were divided into five equal groups (six rats/group). The control group received saline. Group II was treated with PMC NPs at a dose level of 200 mg/kg body weight (Bwt); Group III was treated with 1/10 LD50 of TH (65 mg/kg Bwt); Group IV was treated with TH (65 mg/kg Bwt) and piracetam (200 mg/kg Bwt); Group V was co-treated with TH (65 mg/kg Bwt) and PMC NPs (200 mg/kg Bwt). All animal groups were dosed daily for 6 weeks by oral gavage. Footprint analysis, hanging wire test, open field test, and Y-maze test were employed to assess behavioral deficits. Animals were euthanized, and brain tissues were analyzed for oxidative stress biomarkers, proinflammatory cytokines, and gene expression levels of glial fibrillary acidic protein (GFAP), amyloid-beta precursor protein (APP), B-cell lymphoma 2 (Bcl-2), and caspase-3. Brain and sciatic nerve tissues were used for the evaluation of histopathological changes and immunohistochemical expression of tau protein and nuclear factor kappa B (NF-κB), respectively. The results revealed that TH-treated rats suffered from oxidative damage and inflammatory effect on the central and peripheral nerves. The administration of PMC NPs considerably protected against TH-induced neuronal damage, increased antioxidant enzyme activity, decreased inflammatory markers, and improved behavioral performance than the group treated with piracetam. The neuroprotective effect of PMC NPs was mediated through the inhibition of GFAP, APP, caspase-3, Tau, and NF-κB gene expression with induction of Bcl-2 expression. In conclusion, TH could induce oxidative stress, inflammatory and neurobehavior impairment in rats. However, PMC NPs administration markedly mitigated TH-induced brain toxicity, possibly via oxidative and inflammatory modulation rather than using piracetam alone.

Microfluidic preparation of magnetic chitosan microsphere and its adsorption towards Congo red

Microfluidic preparation of magnetic chitosan microsphere and its adsorption towards Congo red

Influence of temperature change on the immobilization of soil Pb and Zn by hydrochar: Roles of soil microbial modulation

Considering the potential effect of the ambient temperature on soil microorganisms during heavy metal immobilization by hydrochar, 60 days of soil incubation was conducted to explore the impact of ambient temperature (5, 25, and 35 °C) on the immobilization of Pb and Zn by chitosan-magnetic sawdust hydrochar (CMSH) and magnetic chitosan hydrochar (MCH). The results showed that soil pH was relatively high and total organic carbon (TOC) was slightly lower in the 35 °C treatment. The diethylenetriaminepentaacetic acid (DTPA) available state content decreased significantly with the temperature increasing. Meanwhile, the ratios of stable Pb and Zn in the sequential extraction method proposed by the European Community Bureau of Reference (BCR) gradually increased with increasing temperature. The heatmap based on microbial community showed that elevated temperature not only favored the enrichment of metal-stable phyla, such as Chloroflexi, but was also involved in inhibiting the growth of Firmicutes, Actinobacteriota, and Proteobacteria. Meanwhile, different genera (Fonticella and Bacillus) in the Firmicutes phylum had distinct responses to temperature as well as to heavy metal immobilization effects. Subsequently, redundancy analysis confirmed that Chloroflexi and Fonticella were positively correlated with temperature and stable state metal content, while Actinobacteriota and Bacillus were negatively correlated with temperature and were positively correlated with DTPA available metal content. Moreover, Pb and Zn indicators displayed significant correlations for the dominant genera (R2 > 0.8, p < 0.02).

Comparative study of uncoated and tetraethylorthosilicate-coated magnetic chitosan beads in the adsorption of two textile dyes

Comparative study of uncoated and tetraethylorthosilicate-coated magnetic chitosan beads in the adsorption of two textile dyes

Removal of tetracycline from water using ethylenediamine-modified magnetic chitosan

In this work, the magnetic chitosan nanoparticles were prepared by in-situ co-precipitation method and then modified by glutaraldehyde and ethylenediamine. The effect dose of crosslinking agents for adsorbent preparation on tetracycline (TC) adsorption was investigated. The experiment results showed that the modified chitosan (EMMCS-G) had the best adsorption performance, which was more than twice that of raw magnetic chitosan. EMMCS-G was characterized by SEM, TEM, VSM, FTIR, XRD and XPS. The effects of experimental parameters such as time, temperature, pH, adsorbent dosage and Cu2+ on TC adsorption by EMMCS-G were discussed. The result indicated that the optimal pH was 6.5. Under the conditions of an initial TC concentration of 50 ​mg/L and an EMMCS-G dosage of 50 ​mg, the removal rate reached an impressive 94%. The isotherm and kinetic studies of adsorption process illustrated that adsorption of TC onto EMMCS corresponded to Freundlich isotherm and pseudo-second-order kinetic models. The maximum adsorption capacity was 84 ​mg/g. Thermodynamic analysis revealed that adsorption process was both endothermic and spontaneous. The regeneration experiment suggested that the adsorbent possessed excellent reusability for further use. Moreover, the adsorption mechanisms of TC onto EMMCS-G mainly involved pore filling, π-π interactions, hydrogen bonding and electrostatic attraction.

Enhanced PMS/O2 activation by self-crosslinked amine-gluteraldehyde/chitosan-Cu biocomposites for efficient degradation of HEPES as biological pollutants and selective allylic oxidation of cyclohexene

Optimization and mechanism elucidation of the catalytic degradation of HEPES and selective aerobic oxidation of cyclohexene by Cu@cross-linked magnetic chitosan.