Comparative investigation of argon and argon/oxygen plasma performance for Perchloroethylene (PCE) removal from aqueous solution: optimization and kinetic study.

Purpose: The aim of this study is evaluation of the perchloroethylene degradation from aqueous solutions by non-thermal plasma produced in dielectric barrier discharge reactor in two different scenarios: first plasma generated with 225 cc/min mixture of oxygen and argon flow (12% gas ratio of O2 /Ar), and in the second scenario plasma generated with 225 cc/min of pure argon gas.

Methods: Design studies were performed using response surface methodology and central composite design. All experiments with the selected levels of independent parameters including the initial concentration of perchloroethylene (5-100 mg/L), voltage (20-5 kv) and contact time (15-180 s) was implemented, and 29 tests were proposed by using response surface methodology and central composite design was performed in two experimental scenarios.

Results: Results showed that the Pseudo first-order kinetics coefficient of perchloroethylene degradation in the mixture of oxygen and argon and pure argon scenario under the optimum conditions were 0.024 and 0.016 S-1 respectively. Results conveyed that in order to achieve the highest removal efficiency (100%), the values of contact time, perchloroethylene concentration and voltage variables were predicted 169.55 s, 74.3 mg/l, 18.86 kv respectively in mixture of oxygen and argon scenario and also were predicted 203 s, 85.22 mg/l, 20.39 kv respectively in pure argon scenario.

Conclusions: In the recent study dielectric barrier discharge was an efficient method for perchloroethylene removal with both oxygen an argon mixture and pure argon as input gas. Both input voltage and reaction time has positive effect on perchloroethylene removal; but initial perchloroethylene concentration has negative effect on perchloroethylene removal. Comparison of two plasma scenarios with different input gas shown that plasma generated by mixture of oxygen and argon gas was more powerful and had higher removal efficiency and degradation kinetics than the plasma generated by pure argon gas.