Solvent influence in decorating graphene oxide with zeolitic imidazolate framework-8 for the elimination of lead

Abstract The preparation of zeolitic imidazolate framework-8 modified graphene oxide (ZIF-8/GO) composites by varying different solvents such as RO water (ZGH), methanol (ZGM), and ammonia solution (ZGN) was investigated. The composites were characterized for their surface morphology and functional groups available, as well as investigated for their abilities in removing lead ions from aqueous solution. The results showed that all composites resembled functional groups originated from ZIF-8 with unnoticeable GO peaks, implying the homogenous attachment of ZIF-8 all over GO. The solvent effects were significant in the particle size where the smallest was obtained by ZGH, whereas ZGM obtained 103 nm, and ZGN had the greatest mean particle size of 426 nm. Furthermore, the ZIF-8 of ZGH was consisted of cubic and rhombic dodecahedron, the most stable crystalline structure of ZIF-8. With favorable physicochemical properties observed in ZGH, it also had outstanding ability in adsorbing lead ion. With only 10 mg dose used, nearly 100% lead removal was achieved by ZGH, while that of ZGM and ZGN could achieve only 94% removal. Besides that, ZGH only needed 10 minutes to achieve equilibrium in adsorption, making it the best candidate as a potential adsorbent for heavy metal.