Synthesis of ZIF8 and its composites with GO and Mg(OH)2/GO for environmental remediation

Abstract

In this study, adsorption of hexavalent chromium has been examined on ZF 8 and its various composites. ZIF8 is modified by using amine groups, GO and Mg(OH)2/GO. Trend of pure ZIF8, Mg(OH)2/GO, ZIF8/NH2, ZIF8/Mg(OH)2/GO, ZIF8/NH2/GO and ZIF8/NH2/Mg(OH)2/GO for Cr(VI) removal was studied. Several characterization techniques were conducted for structural and surface characterization i.e. Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. The influence of different adsorption parameters (contact time, pH, initial concentration of Cr(VI) and absorbent dosage) were studied in batch experiments. Different kinetic and isotherm models were applied on equilibrium data.The adsorption process of ZIF8 and its composites was better described by pseudo-second-order kineticmodel and Langmuir isotherm, with maximum removal efficiency of 98% for Cr(VI) by ZIF8/NH2/Mg(OH)2/GO, whose adsorption capacity has greatly improved when compared witha single ZIF 8 or Mg(OH)2/GO.