Zn-CNTs-FeO catalytic in situ generation of HO for heterogeneous Fenton degradation of 4-chlorophenol.

A novel Zn-CNTs-FeO composite was synthesized by the chemical co-precipitation combined with high sintering process at nitrogen atmosphere. The as-prepared composite was characterized by SEM, EDS, XRD, XPS, VSM and N adsorption/desorption experiments. A novel heterogeneous Fenton-like system, composed of Zn-CNTs-FeO composite and dissolved oxygen (O) in solution, which can in situ generate HO and OH, was used for the degradation of 4-chlorophenol (4-CP). The influences of various operational parameters, including the initial pH, dosage of Zn-CNTs-FeO and initial concentration of 4-CP on the removal of 4-CP were investigated. The removal efficiencies of 4-CP and total organic carbon (TOC) were 99% and 57%, respectively, at the initial pH of 1.5, Zn-CNTs-FeO dosage of 2 g/L, 4-CP initial concentration of 50 mg/L and oxygen flow rate of 400 mL/min. Based on the results of the radical scavenger effect study, the hydroxyl radical was considered as the main reactive oxidants in Zn-CNTs-FeO/O system and a possible degradation pathway of 4-CP was proposed.