New insight into degradation of chloramphenicol using a nanoporous Pd/Co₃O₄cathode: characterization and pathways...

The growing chloramphenicol (CAP) in wastewater brought a serious threat to the activity of activated sludge and the spread of antibiotics resistance bacteria. In this study, a highly ordered nanoporous Co₃O₄layer on Co foil through anodization was prepared as cathode for nitro-group reduction and electrodeposited with Pd particles for dechlorination to reduce CAP completely. After 3 h treatment, almost 100% of CAP was reduced. Co²⁺ions in Co₃O₄served as catalytic sites for electrons transfer to CAP through a redox circle Co²⁺-Co³⁺-Co²⁺, which triggered nitro-group reduction at first. With the presence of Pd particles, more atomic H* were generated for dechlorination, which increased 22% of reduction efficiency after 3 h treatment. Therefore, a better capacity was achieved by Pd/Co₃O₄cathode (K = 0.0245 min^-1,Kis reaction constant) than by other cathodes such as Fe/Co₃O₄(K = 0.0182 min^-1), Cu/Co₃O₄(K = 0.0164 min^-1), and pure Co₃O₄(K = 0.0106 min^-1). From the proposed reaction pathway, the ultimate product was carbonyl-reduced AM (dechlorinated aromatic amine product of CAP) without antibacterial activity, which demonstrated this cathodic technology was a feasible way for wastewater pre-treatment.