Treating Soil PCP at Optimal Conditions Using Heme and Peroxide

The environmental impact of pentachlorophenol (PCP) has been the subject of extensive research in recent years. Investigations of PCP degradation using both biotic and abiotic methods are extensively reported in literature. Based on some preliminary tests (not shown), an abiotic method was found for oxidative PCP degradation in soil under unsaturated conditions and a neutral pH. Reagents used were heme (a catalyst) and peroxide (an oxidant). From two screening tests (not shown), the heme and peroxide were identified as the most important factors on PCP degradation in highly PCP-contaminated soil. The objective of this study was to determine the optimum doses of heme and peroxide for PCP degradation in soil. Using a statistical method, known as response surface methodology, a quadratic function was fit to the data and used to estimate the optimum doses of heme and peroxide at $0.035\mathrm{g}∕2\mathrm{g}$ -soil and $0.105\mathrm{g}∕2\mathrm{g}$ -soil, respectively, in treating PCP-contaminated soil. The model also was used to determine the region in which the response was within the 95% confidence region of the optimum. The lowest heme and peroxide doses required to achieve a response within the 95% confidence region of the optimum were found to be $0.017\mathrm{g}∕2\mathrm{g}$ -soil and $0.095\mathrm{g}∕2\mathrm{g}$ -soil, respectively. Based on the results of the optimization studies, kinetic studies were conducted to examine the rate and extent of PCP degradation in soil over time. The results showed that about 50% of PCP was degraded within the first $30\min$ , and up to $\sim 80\%$ of PCP was degraded within $4\mathrm{h}$ .