Performance of chlorobenzene removal in a nonthermal plasma catalysis reactor and evaluation of its byproducts

• Chlorobenzene removal efficiency and CO2 selectivity were improved in plasma-catalysis system.
• The order of chlorobenzene removal in plasma-catalysis system followed as CeO2/HZSM-5 > CuO/MnO2 > Ag/TiO2.
• The main products were O3, COx, benzene ring derivatives and nitrogenous organics.
• DBD-catalysis resulted in greater enhancements of solubility and biodegradability.
• DBD-catalysis is an alternative pretreatment of biological treatment.

A nonthermal plasma catalysis reactor was developed as pretreatment technology for a biotrickling filter (BTF), which was adopted to enhance removal of poorly soluble and recalcitrant volatile organic compounds. The performance of this pretreatment process was evaluated under various technological parameters, including discharge voltage, initial concentration, and residence time. Experimental results show that the system afforded higher efficiency of removal and selectivity to CO2 compared with those obtained with the control plasma process at discharge voltages of 5–9 kV and residence times of 3–15 s. Increasing the discharge voltage and residence time increased the removal efficiency. The activity of catalysts followed the order CeO2/HZSM-5 > CuO/MnO2 > Ag/TiO2. Furthermore, the solubility and biodegradability of degradation products were examined and analyzed. The main products of chlorobenzene degradation were O3, COx, benzene derivatives, and nitrogenous organics. The amounts of nitrogenous byproducts and O3 concentration during the reaction decreased significantly in the plasma catalysis reactor. This pretreatment technology greatly enhanced the solubility and biodegradability of byproducts. The results provide fundamental data for a feasible plasma catalytic system used as pretreatment technology for a BTF.