Remediation with surfactant foam of PCP-contaminated soil

An investigation was made into evaluating the capability of surfactants in the form of foam for removing the contaminant pentachlorophenol (PCP), a highly toxic, wood preservative, from soil. Several surfactants were investigated for their ability to make foam. Two of them, Triton X-100 and JBR425 (a rhamnolipid biosurfactant), generated foam with higher quality (99%) and higher stability than other surfactants. Triton X-100 and JBR425 were then used to investigate the removal efficiency in soils contaminated with pentachlorophenol (PCP). Triton X-100 showed better results in terms of final removal efficiency. Triton X-100 (1%) removed 85% and 84% of PCP from fine sand soil and sandy-silt, respectively, contaminated with 1000 mg/kg PCP. These values were 60% and 61% for JBR425 (1%). Of this, 66% and 57% of the PCP was removed by volatilization by Triton X-100 and 36% and 44% by JBR425. Further experiments with Triton X-100 indicated that 1% Triton X-100 removed more than 0.5% and that PCP removal was approximately the same for 1% Triton X-100 for a higher contaminant level (3000 mg/kg) but more pore volumes of foam were required for fine sand (23 pore volumes compared to 12). For the sandy-silt soil, PCP removal was higher for the higher contaminant level, 84% compared to 76%. More pore volumes were required (35 compared to 21). Comparison of liquid and foam injection of 1% Triton X-100 indicated that the foam removed more than twice as much PCP in all cases than the liquid surfactant solution. The results of this study on a sandy and sandy-silt media, thus, found that the foam can be used as a fluid to enhance soil remediation under low pressures compared to other fluids such as liquid surfactant solutions.