Cobalt promoted bifunctional graphene composite (Co@pGSC) for heterogeneous peroxymonosulfate activation

Abstract

We report, synthesis of Co@graphene on common grinded river sand for peroxymonosulphate (PMS) activation. As prepared catalysts characterized in TEM, XPS, Raman, BET and XRD for their surface and bulk properties confirmed that the composite material has enough surface area, and Co3O4 nanoparticles are well dispersed (20-40 nm) on graphene sand composite (pGSC). The PMS activation and its oxidation efficiency of prepared catalysts were evaluated for Bisphenol-A (BPA) as a model organic pollutant in aqueous phase. The formation of SO4 center dot- and (OH)-O-center dot radical in the PMS with catalysts system proved using DMPO radical trapping agent by EPR technique. The catalyst (Co@pGSC_0.02) loaded with 0.02 M cobalt concentration showed higher percentage (98.1%) of BPA removal efficiency among the studied concentration. The oxidative-cleavage of BPA and its intermediate by-products were further verified by GC-MS analysis. The reusability of catalyst depicted greater than 90% removal efficiency and the surface, crystalline properties remained same as fresh catalyst (evidenced spent catalyst XRD and XPS analyses) over 12 cycles. The significant catalytic performance may be ascribed to synergetic effect of electron transfer between graphene and Co3O4 over sand.