The effect of temperature on adsorption of organic compounds to soils

Abstract

Column experiments were performed at 22–25°, 50°, and 92°C to study the effect of temperature on the sorption of toluene, perchloroethylene, and naphthalene to a silty gravel-till aquifer material. A one-dimensional numerical model incorporating kinetic adsorption with gamma-distributed rate constants was developed and fit to the data. As temperature was increased from 22–25° to 90°C, sorption coefficients decreased by 35, 40, and 60% for toluene, perchloroethylene, and naphthalene, respectively. The means and variances of the gamma distributions for sorption rate constants both increased as temperature increased. The increases in variance were attributed to the short contact times of the experiments and the increased sorption rates at higher temperatures. The decreases in sorption coefficients and increases in sorption rate constants as temperature is increased suggest that thermal remediation techniques such as hot-water and steam flushing may accelerate the removal of sorbed organic soil contamination.Key words: sorption, nonequilibrium, temperature dependence, thermal remediation.