Fabrication of chitosan-based MCS/ZnO@Alg gel microspheres for efficient adsorption of As(V).

Groundwater contaminated by arsenic endangers our health. Therefore, in this work, a novel composite adsorbent consisting of magnetic chitosan (MCS), zinc oxide (ZnO), and sodium alginate (Alg) was prepared to remove arsenic from groundwater. First, chitosan was coated on the surface of Fe3O4 nanoparticles by coprecipitation. Then, MCS/ZnO@Alg gel beads were fabricated by combining MCS with ZnO and Alg, and crosslinking the composite material in the presence of Ca2+ ions. The MCS/ZnO@Alg beads were characterized by SEM, FTIR spectroscopy, XRD, VSM, and XPS. The adsorption experiments revealed that the MCS/ZnO@Alg magnetic gel beads have high stability and As(V) adsorption capability, and adsorbed As(V) through chemical adsorption. The maximum As(V) adsorption capacity as determined from the Langmuir model was 63.69 mg/g. In addition, MCS/ZnO@Alg exhibited good recyclability and high sustainability. This work proves that the MCS/ZnO@Alg gel beads are an ideal candidate for addressing the grievous environmental threats caused by water pollution.

Efficient adsorption of Pb(II) from aqueous solutions using aminopropyltriethoxysilane-modified magnetic attapulgite@chitosan (APTS-Fe3O4/APT@CS) composite hydrogel beads.

The performance of Fe3O4/attapulgite (APT) nanoparticles in Pb(II) adsorption from aqueous solutions could be improved by modifying the particles with aminopropyltriethoxysilane (APTS) and then combining with chitosan (CS) into beads. After preparing the APTS-Fe3O4/APT@CS beads, their surface morphology and crystal phases were analyzed by Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The magnetic properties of APTS-Fe3O4/APT@CS were studied by a vibrating sample magnetometer, while their heat resistance and stability were characterized by thermal weight analysis. A recycling test and comparison of adsorption capacities were also carried out. The adsorption capacity of Fe3O4/APT was improved by the modification with APTS and CS. The adsorption process conforms to the pseudo-second-order kinetic and Langmuir adsorption isotherm models. The adsorption of Pb(II) reaches a maximum of 625.34 mg/g, which compares favorably with other reported adsorbents. The results show that APTS-Fe3O4/APT@CS is a promising hybrid adsorbent for effective removal of Pb(II) from water.

Efficient adsorption of diclofenac sodium from aqueous solutions using magnetic amine-functionalized chitosan.

In this study, we prepared a magnetic composite based on amine-functionalized chitosan (aminochitosan; AmCS) and Fe3O4 to remove diclofenac sodium (DS) from water. The fabricated AmCS@Fe3O4 composite was characterized using Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometry, X-ray diffraction, and thermogravimetric analysis. Furthermore, we investigated the influence of pH, initial DS concentration, and adsorbent dosage on the adsorption of DS. Through thermodynamic analysis, we found that the data corresponded with the Langmuir adsorption isotherm model. The maximum adsorption capacity reached 469.48 mg g-1, and the adsorption process followed the pseudo-second-order kinetic model. Finally, the AmCS@Fe3O4 composite retained good adsorption characteristics after four consecutive cycles, with removal efficiency exceeding 70%. Therefore, the developed adsorbent could be used for efficient adsorptive removal of trace drugs and personal care products from water bodies.

Facile Preparation of Metal-Organic Framework (MIL-125)/Chitosan Beads for Adsorption of Pb(II) from Aqueous Solutions.

In this study, novel composite titanium-based metal-organic framework (MOF) beads were synthesized from titanium based metal organic framework MIL-125 and chitosan (CS) and used to remove Pb(II) from wastewater. The MIL-125-CS beads were prepared by combining the titanium-based MIL-125 MOF and chitosan using a template-free solvothermal approach under ambient conditions. The surface and elemental properties of these beads were analyzed using scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopies, as well as thermal gravimetric analysis. Moreover, a series of experiments designed to determine the influences of factors such as initial Pb(II) concentration, pH, reaction time and adsorption temperature was conducted. Notably, it was found that the adsorption of Pb(II) onto the MIL-125-CS beads reached equilibrium in 180 min to a level of 407.50 mg/g at ambient temperature. In addition, kinetic and equilibrium experiments provided data that were fit to the Langmuir isotherm model and pseudo-second-order kinetics. Furthermore, reusability tests showed that MIL-125-CS retained 85% of its Pb(II)-removal capacity after five reuse cycles. All in all, we believe that the developed MIL-125-CS beads are a promising adsorbent material for the remediation of environmental water polluted by heavy metal ions.