Adsorption and kinetic study of Cr(VI) on ZIF-8 based composites

Abstract

In this study, adsorption of hexavalent chromium has been examined on ZIF-8 and its various composites. ZIF-8 was modified by using amine groups, GO and Mg(OH)2/GO. ZIF-8, Mg(OH)2/GO, ZIF-8/NH2, ZIF-8/Mg(OH)2/GO, ZIF-8/NH2/GO and ZIF-8/NH2/Mg(OH)2/GO was studied for Cr(VI) adsorption Several characterization techniques were used for the structural and surface characterization such as Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analyzer. The impact of various adsorption parameters (contact time, pH, initial concentration of Cr(VI) and absorbent dosage) was studied in batch experiments. Different kinetic and isotherm models were applied on equilibrium data. The adsorption process of ZIF-8 and its composites was explained by pseudo-second-order kinetic model as well as Langmuir isotherm, with maximum removal efficiency of 98% for Cr(VI) by ZIF-8/NH2/Mg(OH)2/GO.