Sustainable superior function of the synthesized NixCo1-xFe2Oz nanosphere on the destruction of chlorinated biphenyls in the effluent

Abstract

NixCo1-xFe2Oz composite oxide nanosphere was successfully prepared, to degrade 2-monochlorobiphenly (CB-1) in continuous-flow fixed-bed microreactor at GHSV of 20000h−1. The five cycles of temperature-dependent run experiments between 150 and 350°C showed its superior activity with a CB-1 conversion of more than 95% above 300°C over Ni0.5Co0.5Fe2Oz. Importantly, the sustainable higher reactivity could be observed over prolonged 600min reaction times after the 5th run test. The degradation products detected as biphenyl and monochlorobenzene with yield ratio of 129, account for 0.24% and 0.0011% of initial CB-1 respectively. This indicated the weak occurrence of hydrodechlorination and breakage of CC bridge bond during the degradation of CB-1. The possibly dominant occurrence of oxidative degradation probably follows Mars–van Krevelen mechanism, resulting in the generation of the formic, acetic, propanoic and butyric acids and so on. Due to the high oxygen mobility over Ni0.5Co0.5Fe2Oz nanosphere, the consumed oxygen species could be compensated rapidly by the gas phase oxygen via O2→O2− → 2O− → 2O2−. The interaction among different elements in Ni0.5Co0.5Fe2Oz nanosphere confirmed by the derivation of the electron cloud, enhanced the mobility of the reactive oxygen species, which would be beneficial for the oxidation of chlorinated biphenyls.