Catalytic performance of graphene-bimetallic composite for heterogeneous oxidation of acid orange 7 from aqueous solution.

In this study, reduced graphene oxide (rGO) embedded with bimetallic nanoparticles of cobalt-manganese oxide (CoMn2O4) was fabricated by hydrothermal treatment. The obtained product was characterized and applied for the heterogeneous activation of peroxymonosulfate (PMS) to degrade acid orange 7 (AO7). The characterization results revealed that 10-20 nm nanosized CoMn2O4 was homogenously decorated on the surface of rGO. The effect of different CoMn2O4 loadings showed that catalyst with a CoMn2O4 contents higher than 20% performs stronger capability for catalytic degradation of AO7 compared to pure CoMn2O4. In a system containing 4 mM PMS and 0.05 g/L 50% CoMn2O4/rGO, 100% conversion of AO7 (70 mg/L) and 43% mineralization could be achieved within 12 and 60 min, respectively. Recycling experiment along with XRD data demonstrates good stability of the catalyst for five successive runs. Inhibition confirmation results suggest that surface-bound SO4•- and HO• radicals both played a key role in degradation of AO7. Therefore, this material demonstrates a very efficient catalytic performance for the degradation of organic dyes.