Removal of dichloroacetic acid from aqueous solution using non-thermal plasma generated by dielectric barrier discharge and nano-pulse corona discharge

Abstract

In the present work, the efficiencies of non-thermal plasma (NTP) for the removal of dichloroacetic acid (DCA) generated by two different techniques were calculated. The techniques were dielectric barrier discharge (DBD) in a planar falling film reactor and nano-pulse corona discharge (PCD) in a longitudinal horizontal reactor design. The experiments were carried out under various gas atmospheres in the gas-liquid interface. The comparison was performed based on the energy yield (G50) and degree of mineralization measured by total organic carbon (TOC) removal. The experimental results have shown that the degradation and mineralization efficiencies are affected by the input power and the nature of gas. The results show that the decomposition of DCA under argon and helium atmospheres is the most effective method. However, in the presence of sulfobetaine surfactant in the solution a significant reduction in the degradation efficiency was observed due to the scavenging of the reactive radicals generated over the liquid solution and preventing the oxidation of pollutants in the bulk solution. With respect to the energy yield, the nano-pulse corona discharge is more efficient than DBD plasma. Formation of H2O2 under argon atmosphere and ozone generation under (Ar:O2) atmosphere in DBD reactor were investigated and discussed. In the PCD reactor the production of these species is negligible, due to the short plasma pulse period in the nanosecond-scale which decomposing the generated H2O2 and O3, that ultimately lead to enhancing the efficiency in the PCD.