ADSORPTION OF LINEAR ALKYLBENZENE SULFONATE (LAS) ON SOILS

Experimental measurements of the adsorption of linear alkylbenzene sul fonate (LAS) on soils were made at 25 degrees C using a continuous ads orption apparatus. The adsorption of LAS on natural soils could be div ided into two stages: linear and exponentially increasing isotherms. A t low LAS concentration (<90 mu g ml(-1)), the adsorption isotherms we re linear and Kd was among 1.2 to 2.0. At high LAS levels (>90 mu g ml (-1)), cooperative adsorption was observed and the adsorption amount o f LAS increased exponentially with the increasing of LAS concentration in solution. LAS adsorption mechanisms on soil were mainly specific s ire surface interactions and hydrogen bonding; The LAS adsorption capa city of a soil significantly depended on its physical clay content. Un der real soil environments where LAS levels are rather low, the LAS ad sorption ability of a soil is very weak.