生物表面活性剂对河道底泥重金属的淋洗效果比较

Comparison of biosurfactants for heavy metals washing from river sediment

为了比较生物表面活性剂性质、活性剂浓度和淋洗时间等对河道底泥中重金属淋洗效果的影响。研究中选取了3种不同的生物活性剂即茶皂素、皂角苷和槐糖脂。研究结果表明:活性剂不同,淋洗效果不同;生物活性剂的胶束形成性质会影响淋洗效果;在3种活性剂中,临界胶束浓度低的槐糖脂淋洗效果最好;此外,活性剂浓度为8%时,淋洗效果已达到最佳。淋洗时间对淋洗效果的研究则证明:茶皂素、皂角苷和槐糖脂对重金属淋洗动力学过程可以用Elovich方程进行描述,淋洗过程为非均相扩散过程。研究中还对淋洗前后重金属形态进行了分析,淋洗可以有效去除底泥中弱结合态(离子交换态和碳酸盐结合态)重金属,使得强结合态的重金属所占比例增加,从而降低重金属的生物有效性。

In order to investigate the effects of biosurfactant properties,concentration and time on the removal of heavy metals from river sediment,three different bio-active agents,tea saponin,saponin and sophorolipid were selected for the study. Results indicate that washing efficiency varied among these biosurfactants. Critical micelle concentration（ CMC） of biosurfactant had a significant effect on washing efficiency. Biosurfactant with the lowest CMC,i. e. sophorolipid,manifested the highest washing efficiency.In addition,washing efficiency reached its optimum at a concentration of 8%. Study on washing time to leaching effect showed that Elovich equation describe well the kinetics of washing by tea saponin,saponins and sophorolipid which means that heavy metal washing involved multi-phase diffusion. Forms of heavy metal before and after washing were also analyzed. Biosurfactant washing was effective in removing weakly-bound（ ion exchangeable and carbonated-bound） heavy metal thus increased the proportion of strongly-bound ones and reduced the bioavailability of heavy metals.