Removal of high-concentration 4 - Chlorophenol (4-CP) in wastewater using carbon-based heterogeneous catalytic oxidation: Performance and mechanism

The treatment of large quantities of 4-CP wastewater produced in chemical industries has attracted considerable attention due to its high biotoxicity and refractory nature. The heterogeneous Fenton system initiated by carbon-based iron material (HACO-P) was applied to degrade the high concentration 4-CP (2 g/L) wastewater under ambient condition. HACO-P presented excellent adsorption performance with 173.9 mg/g of adsorption capacity. Compared with other heterogeneous Fenton process, 4-CP (100%) and TOC (43%) were degraded within 120 min under optimal conditions of pH of 3.0, [H2O2]0/[4-CP]0 of 6.5, and 3.0 g/L of HACO-P, which demonstrated that more efficient and economical treatment was achieved. Notably, the system exhibited outstanding performance at high concentrations of SO42− and the presence of SO42− can even promote 4-CP removal. Unlike conventional 4-CP degradation mechanisms relying on qualitative analysis of products, four possible intermediates were successfully quantified and 4-CP degradation and dechlorination pathways were proposed. Meanwhile, the mortality rate and malformation rate of zebrafish hatched with three kinds of 4-CP solution decreased gradually with the 4-CP degradation time of 0min, 15min and 120min, which indicated that the toxicity of the 4-CP solution decreased with the extension of degradation time. The feasibility of the system was verified by its stable operation in consecutive rounds of experiments. Overall, this study conclusively provided strong evidence for the heterogeneous Fenton oxidation of high concentration CP wastewater with minimal consumption of reagents.