油污土壤中柴油去除的影响因素

Factors affecting diesel oil removal from oil-contaminated soil

以柴油为污染物,通过一维砂柱实验模拟油污土壤中柴油去除过程,从油水界面张力(IFT)角度分析溶液pH、淋滤速度和表面活性物质对除油效果的影响。结果表明,延长油水接触时间、升高或降低蒸馏水pH值均使油水界面张力下降,低淋滤速度下单位孔隙体积水中石油浓度较大,而水溶液pH的变化对除油效果影响不明显。十二烷基硫酸钠(SDS)和乙醇使油水界面张力显著下降,因此表面活性物质的除油效率明显高于蒸馏水,乙醇溶液的除油效率随着体积浓度的增加而升高。从石油释放动力学方程计算的柴油累积释放量看,50%乙醇除油效率最高,8 mmol/L SDS溶液次之,在淋洗初期柴油去除效果最为明显,而在中期和后期除油率增加幅度逐渐减小。

Oil release process was measured in one-dimensional synthetic glass column, and diesel oil was the pollutant. The effects of pH, leaching velocity and surface active substances on oil removal rate were ana- lyzed from the standpoint of oil-water interracial tension （IFT）. The results show that IFT decreases to some ex- tent with extending oil-water contact time, rising or lowering the pH value of distilled water. The oil contamina- tion of effluent is higher under low leaching velocity. But changing the solution pH causes little effect on oil re- moval rate. The IFT decreases drastically with the use of SDS or ethanol in water. The oil removal rate is signifi- cantly higher with surface active substances than with distilled water, and which increases with the increment of ethanol volume concentration. First-order kinetic equation can describe the relationship between oil concentration of effluent and the pore volume number. The cumulative released oil can be calculated by first-order kinetic e- quation. According to the cumulative released oil, the oil removal rate of 50% ethanol is the highest, and the 8 mmol/L SDS solution takes the second place. The oil removal rate is remarkable at the initial leaching stage, but the increasing rate of it declines gradually at the mid and late stage.