CuxNiyCo-LDH nanosheets on graphene oxide: An efficient and stable Fenton-like catalyst for dual-mechanism degradation of tetracycline

A highly efficient and stable heterogeneous Fenton-like catalyst was fabricated via growing CuxNiyCo-containing layered double hydroxide (LDH) nanosheets onto graphene oxide (GO) (CuxNiyCo-LDH/GO) by a facile co-precipitation method. The Cu2.5Ni0.5Co-LDH/GO with higher crystallinity and a larger specific surface area exhibited the highest catalytic activity in the degradation of tetracycline (TC). The TC degradation and mineralization efficiencies achieved 96.5% and 80.4%, respectively, in 40 min under the optimum conditions (60 mg/L of catalyst, 10 mM of H2O2 and pH = 10.2). The catalyst also exhibited excellent reusability with the degradation of TC remaining above 95% after 5 successive cycles. A dual-mechanism of TC degradation was proposed: attacked by ·OH primarily generated by catalyst surface and direct oxidation through the C-O-M bonds as the electron donor, leading to a high H2O2 utilization in the system. The degradation pathway of TC was also proposed based on the detected intermediates, and the overall toxicity of TC was effectively alleviated in Cu2.5Ni0.5Co-LDH/GO system according to toxicity prediction.