[Effect of thermal enhanced soil vapor extraction on benzene removal in different soil textures]

Experiments were carried out to investigate the effect of thermal enhanced soil vapor extraction (SVE) on benzene removal from sand, loam and clay and the mechanism. Compared to the routine control treatment, the benzene removal rates were improved by 13. 1% and 12. 3% and the remediation periods were reduced by 75% and 14%, from sand and loam respectively using thermal enhanced SVE. Thermal enhancement decreased the moisture content and increased the soil permeability of clay. On the surface of clay particles, absorption peaks of carboxyl and ethyl disappeared and the content of soil organic substances decreased significantly. Compared to the conventional SVE, the benzene removal rate was improved by 34% in clay soil treated by thermal enhanced SVE. For sand and loam, thermal enhancement could increase the removal rate by promoting the diffusion of benzene in the soil and achieve substantial removal of pollutants in a relatively short period of time. For clay, it could enhance the effect of SVE by reducing the absorption capacity between soil particle surface and contaminant and improving the performance of the gas diffusion in soil by decreasing the moisture content and increasing the soil permeability.