摘要
为考察污染土壤淋洗修复过程中表面活性剂的动态吸附解吸过程及其对淋洗效果影响,以北京潮土为例,采用土柱淋洗实验,对4种浓度(600、1 800、3 000和4 200 mg·L^(-1))的阴离子表面活性剂十二烷基苯磺酸钠(SDBS)淋洗柴油污染土壤的过程进行模拟。结果表明,土柱淋洗过程中北京潮土对SDBS的吸附过程可分3个阶段:快吸附阶段、慢吸附阶段及动态平衡阶段。吸附动力学较好地符合颗粒内扩散方程。SDBS淋洗柴油污染潮土时,初期由于表面活性剂在土壤中的吸附未达到平衡而无法在溶液中形成胶束,导致淋洗液中柴油浓度很低。此后SDBS在土壤中的吸附逐渐达到平衡状态,溶液中SDBS的浓度超过临界胶束浓度(CMC)开始形成胶束,土壤中残留的柴油开始大量解吸。淋洗液中柴油浓度总体呈先升到峰值,而后呈锯齿状波动下降的变化规律。淋洗到400 h时,4种浓度SDBS溶液对柴油的去除率分别为1.06%、1.52%、25.55%和27.99%,柴油去除率与表面活性剂浓度呈正相关。但表面活性剂浓度过高时,会降低土柱中土壤渗透系数,导致淋洗流量显著降低,采用SDBS淋洗柴油污染潮土时,表面活性剂浓度在3 000~4 200 mg·L^(-1)较佳。
In order to study the dynamic adsorption process of surfactants and the effect of diesel removal through leaching, we simulated the diesel leaching process in Beijing Fluvo-aquic soils using four different concentrations of SDBS solution （600,1 800,3 000 and 4 200 mg ·L^-1）. The results indicated that the adsorption kinetics of SDBS on Fluvo-aquic soil could be divided into three stages;the rapid adsorption stage, the slow adsorption stage, and the fluctuated dynamic balance stage. In the presence of diesel pollutants, the adsorption kinetics of SDBS on Fluvo-aquic soil were in good agreement with the intra-particle diffusion equation. In the initial stage of leaching, the adsorption of surfactants on Fluvo-aquic soil did not reach equilibrium and micelles could not form in the solution, resulting in very low concentration of diesel in the eluent. With the increase in the concentration of SDBS in the eluent, diesel concentration in the eluent reached its peak and fluctuated substantially. After leac- hing for 400 h, the total removal rates of diesel by four different concentrations of SDBS solution were 1.30% , 1.60% , 26.90% and 29.85% , respectively. The total removal rates were positively related to surfactant con- centrations. However, the surfactant concentration should not he too high, else the flow rate of the eluent would decrease with the decrease in soil permeability. For that reason, when using SDBS solution to remediate diesel- contaminated Fluvo-aquic soils, using 3 000 to 4 200 mg·L^-1 of surfactant would be ideal.
出处
《环境工程学报》
CAS
CSCD
北大核心
2017年第7期4390-4396,共7页
Chinese Journal of Environmental Engineering
基金
国家自然科学基金资助项目(41271476)
