生物表面活性剂对河道底泥重金属的淋洗效果比较

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。

Comparison of biosurfactants for heavy metals washing from river sediment

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.