Removal of Potential Toxic Inorganic and Organic Compounds from Contaminated Soils by Alkaline Leaching with Surfactant

Abstract

ABSTRACTThe objective of this study was to evaluate the influence of soil parameters (total inorganic and organic carbon, pH, particle size distribution, initial contaminant levels) on the performance of a leaching process to remove As, Cr, Cu, pentachlorophenol (PCP), and polychlorodibenzo-dioxins and furans (PCDD/F) from the fine fractions (< 0.250 mm) of various contaminated soils. The chemical treatment, including three leaching steps (pulp density (PD) = 10% (w.w−1), [BW] = 3% (w.w−1), [NaOH] = 0.85 M, retention time (t) = 2 h and temperature (T) = 80°C) followed by two rinsing steps (PD = 10% (w.w−1), T = 20°C, t = 15 min), was optimized in previous works. Five soil samples (S1 to S5 – from different location on the same industrial site) were used to study the effect of the initial contaminant levels. The results showed good performance of the leaching process used to simultaneously remove PCP (96–98%) and PCDD/F (57–81%). These results also highlighted that the initial concentration of PCP and PCDD/F slightly influenced the performance of the leaching process. Subsequently, this leaching process was applied to three different soils (F1 to F3). The results showed that this process was efficient in removing PCP (50–86%) and PCDD/F (41–45%) regardless of the nature of the soil studied. However, the results also showed that the organic matter content and the particle size slightly influenced the efficiency of the leaching process to remove PCP.