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. (C) 2019 Elsevier B.V. All rights reserved.