Remediation of p-nitrophenol and pentachlorophenol mixtures contaminated soil using pulsed corona discharge plasma

Abstract

The feasibility of remediation of p-nitrophenol (PNP) and pentachlorophenol (PCP) mixtures contaminated soil was investigated using pulsed corona discharge plasma. The influences of initial pollutant concentration, the existence of the second pollutant, and soil pH on pollutants removal were studied. The results showed that the mixed pollutants could be removed effectively by pulsed corona discharge plasma. For 600mgkg−1 mixtures contaminated soil, comprised of 300mgkg−1 PCP and 300mgkg−1 PNP, 86.0% of PNP and 94.1% of PCP were removed at the specific energy density of 485Jgsoil-1, and correspondingly, the energy yield was about 18.3% higher than for treating single PNP contaminated soil (600mgkg−1) and 6.1% lower than for treating single PCP contaminated soil (600mgkg−1). PNP and PCP degradation efficiencies both decreased with increasing initial pollutant concentration. In mixtures contaminated soil, the changes of PCP initial concentration brought obvious influences on both PNP and PCP degradation, as well as on energy yield; however, the changes of PNP initial concentration contributed to more obvious effects on PCP degradation than PNP degradation, and caused little influence on energy yield. The degradation characteristics of mixtures depend on their acid–base equilibrium constants, and alkaline condition was beneficial for both PNP and PCP removal. The differences in degradation, mineralization, dechlorination and denitrification between single pollutant contaminated soil and mixtures contaminated soil were attributed to the different reaction rates of active species with PCP and PNP molecules.