Synergistic low-temperature plasma degradation of tetracycline with ferrocene

Low-temperature plasma technology has been successfully applied to the treatment of persistent organic pollutants in water. By combining catalysts with low-temperature plasma, the degradation efficiency and energy utilization efficiency of pollutants can be effectively improved. In this study, ferrocene (Fc) was added as a new catalyst to the low-temperature plasma system to treat tetracycline (TC) found in wastewater. The degradation efficiency of TC after 60 min of plasma treatment, Fc adsorption, and Fc/plasma treatment was compared, indicating that Fc/plasma improved the removal compared with using plasma alone. The effects of primary parameters such as Fc dosage, initial pH, discharge voltage, and anions in wastewater on TC removal efficiency were investigated. Under the conditions of Fc dosage of 400 mg/L, pH of 9, and discharge voltage of 20 kV, the degradation efficiency of TC was 76.59%. Results of free quenching experiments indicated that hydroxyl radicals played an important role in the treatment of TC. The characterizations of Fc showed that the structure of Fc before and after use in the plasma system changed little. In addition, toxicity testing using toxicity assessment software showed that only two to three degradation intermediate products had slightly higher toxicity than TC. The iron leaching concentration was 2.5 mg/L, and the Fc dissolution concentration was 1.72 mg/L after the reaction.