鼠李糖脂洗脱土壤中多氯联苯影响因素的研究

Effects of rhamnolipids on desorption of polychlorinated biphenyls from contaminated soils

研究了由铜绿假单胞菌发酵产生的代表性生物表面活性剂鼠李糖脂(RL)对土壤中PCBs解吸的影响。结果表明,RL的种类与浓度、土壤污染类型、解吸时间、洗脱次数、pH以及离子强度对土壤中PCBs的洗脱有一定的影响,而温度对PCBs的洗脱影响很小。当RL浓度低于CMC时,对PCBs的洗脱没有明显的促进作用;当RL浓度高于CMC后,对PCBs的洗脱有显著的促进作用。具有较低HLB的单鼠李糖脂R2对PCBs的洗脱效果要优于二鼠李糖脂R1。人工污染土壤中PCBs的洗脱效果要高于陈化土壤。污染土壤中TOC的含量越高,PCBs的洗脱率越低。延长解吸时间和增加洗脱次数可增加土壤中PCBs的洗脱率。碱性环境(pH>7)或增加RL溶液中的离子强度均有利于土壤中PCBs的洗脱。

Rhamnolipids, as typical biosurfactants produced by Pseudomonas aeruginosa, were used to study desorption of poly-chlorinated biphenyls（PCBs） from contaminated soils. The results show that desorption of PCBs from soil depends on the type and concentration of rhamnolipids, type of soils, desorption duration, wash times, pH and ionic strength, while temperature has a little effect on the desoption. It is further found that rhamnolipids obviously enhance PCBs＇, desorption from soils when their concentrations exceed critical micelle concentrations （CMC） though they do not improve the PCBs＇ desorption when the concentrations below the CMC. Rhamnolipid R2 with lower hydrophile-lipophile balance （HLB） is more effective for PCBs＇ desorption than rhamnolipid R1. The desorption percentage of PCBs from laboratory contaminated soil is higher than that from field contaminated soil. The greater the TOC of soils, the lower the desorption precentage of PCBs. The desorption percentage of PCBs increases as the increase of desorption duration, wash times, pH （above 7）, or ionic strength.