Desorptive behavior of chlorophenols in contaminated soils

A study was conducted to assess the desorptive behavior of chlorophenols in contaminated soils. Two soils spiked with three types of chlorophenols, i.e., 2,6-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP), respectively, were examined. The effects of pH, methanol, surfactants, and soil properties were investigated. Amount of three chlorophenols desorbed from soils increased with increasing pH. Deprotonated chlorophenols were more mobile than their conjugate acids. When methanol was added to the soil-water system, the amount of chlorophenols desorbed increased. The desorption of PCP was enhanced in the presence of anionic surfactant, SDS. However, when non-ionic surfactant, TX-100, was present, the desorption of PCP decreased. The effects of pH and surfactants on desorptive behavior of chlorophenols were most significant on PCP. Generally, the amount of chlorophenol adsorption deceased in the order PCP > TCP > DCP. Hydrophobic interaction was found to be the major driving force of adsorption reactions. It was therefore proposed that hydrophobicity of chlorophenols is an important factor controlling their desorptive behavior.