Aqueous chemistry and interactive effects on non-ionic surfactant and pentachlorophenol sorption to soil

Non-ionic surfactant addition was investigated as a method to remediate pentachlorophenol (PCP) contaminated soil. The goal was to quantify surfactant (Tergitol NP-10 (TNP10)) and PCP sorption to soil and their interactive effects under varying pH, ionic strength, and soil conditions. Up to 16,700 mg/kg of TNP10 partitioned to soil, with increasing sorption far above the critical micelle concentration (CMC) and with greater amounts of PCP present. Approximately 40–45 times more TNP10 and 20–30 times more PCP sorbed to the finer soil with higher organic matter content. Aqueous TNP10 concentrations well above the CMC (>=5500 mg/L) were required to enhance PCP desorption from the soil. As pH increased by 0.5–0.85 units, TNP10 sorption decreased by 14–25% and PCP sorption as measured by the log of the equilibrium partition coefficient decreased by 1–1.5. A lower ionic strength of 0.03 versus 0.112 M increased PCP desorption from contaminated soil by 5–17% in the presence of TNP10. This work is relevant to designing ex situ soil washing or surfactant-aided PCP remediation.