烃类污染土壤热强化气相抽提技术的脱附动力学

为研究烃类污染土壤热脱附净化效率的影响机制，采用热强化气相抽提技术(soil vapor extraction，SVE)处理烃类污染土壤，探讨了通气速率、抽提气中水蒸气的浓度(gas water content，GWC)、土壤含水量(soil water content，SWC)对热强化SVE处理效率的影响，并采用LDF和Freundlich动力学方程对脱附处理过程进行了拟合。结果表明：在120 ℃的条件下，以通气速率80 mL·min⁻¹、GWC 15%和SWC 10%为最优处理工艺，气体在土壤空隙中间的传质速率加快，能明显缩短热强化SVE的处理时间；通气速率从40 mL·min⁻¹提高到80 mL·min⁻¹时，处理时间从425 min缩短至350 min；GWC从0%增加到15%时，处理时间从350 min缩短至105 min；GWC从15%增加到25%时，处理时间从105 min延长到240 min；当SWC为10%时，热强化处理时间缩短至290 min；当SWC从10%增加到15%时，处理时间从290 min延长至390 min。通过分析可知，LDF方程适合简单条件下(通气速率)的拟合，当通气速率为80 mL·min⁻¹时，偏差率为4%。Freundlich方程更适合复杂(土-水-气)体系下的拟合，GWC为15%时偏差率为3.8%，SWC为5%时偏差率为2.6%。以上结果可为开展热强化SVE处理烃类污染土壤研究提供参考。

Desorption kinetics of thermal enhanced soil vapor extraction technology used in hydrocarbon contaminated soil

In order to study the mechanism of affecting the purification efficiency of thermal desorption of hydrocarbon contaminated soil, thermal enhanced soil vapor extraction (SVE) was used to treat hydrocarbon contaminated soil. The effects of ventilation rate, gas water content (GWC) of the extracted gas and soil water content (SWC) on the treatment efficiency of thermal enhanced SVE were studied, and the LDF and Freundlich kinetic equations were used to fit the desorption process. The results showed that when the treatment temperature was 120 ℃, the optimal treatment process was following: ventilation rate of 80 mL·min−1, 15% GWC in the extraction gas and 10% SWC, the mass transfer rate of gas was accelerated in soil pores, and the processing time of thermal enhanced SVE was significantly shorten. The aeration rate was reduced from 40 mL·min−1 to 80 mL·min−1, the processing time was shortened from 425 min to 350 min, and the water vapor concentration in the extracted gas increased from 0% to 15%, and the processing time was shortened from 350 min to 105 min. The GWC increased from 15% to 25% and the treatment time was prolonged from 105 min to 240 min. When the soil moisture content was 10%, the heat strengthening processing time was shortened to 290 min. When SWC changed from 10% to 15%, the treatment time was extended from 290 min to 390 min. The results showed that the LDF equation was suitable for data fitting under a simple condition system (ventilation rate). When the ventilation rate was 80 mL·min−1, the deviation rate was 4%. The Freundlich equation was more suitable for data fitting in a complex system (soil-water-gas). The deviation rates were 3.8% and 2.6% at GWC of 15% and SWC of 5%, respectively.