低密度聚乙烯(LDPE)膜对内分泌干扰物的动态富集研究

Passive enrichment of endocrine disrupting chemicals(EDCs) by low-density polyethylene(LDPE) membrane from solutions

低密度聚乙烯膜(Low-Density Polyethylene,LDPE)在有机物原位被动采样中具有使用简便、耗用量少、成本低廉的优点,但在内分泌干扰物(Endocrine Disrupting Chemicals,EDCs)被动采集方面鲜见应用,有关其平衡分配系数(KLDPE)也不十分清楚.基于此,本文选取7种EDCs,包括双酚A(BPA)、壬基酚(4-NP)、辛基酚(4-t-OP)、雌酮(E1)、β17-雌二醇(E2)、三氯生(TCS)和三氯卡班(TCC),室内模拟LDPE原位动态富集过程,探究了环境因素(温度、pH)对LDPE富集效果的影响,并确定了不同EDCs在LDPE上的富集参数(KLDPE).研究发现,溶液温度升高可以加速LDPE膜对EDCs的吸附,在过低温度条件下(实验设置为4℃),EDCs较难达到膜-水分配平衡;溶液pH对于不同EDCs的影响不尽相同,这可能是因为不同pH条件下EDCs在溶液中形态差异明显,进而影响其在LDPE膜-水之间的分配平衡;7种EDCs的KLDPE实测值均低于各自的经验理论值,这主要由于经验理论值计算过程中未考虑达到分配平衡时有机物从LDPE膜上的解吸附过程,且只考虑了EDCs在膜-水两相之间的平衡.上述结果表明,为提高被动采样测定环境样品中EDCs的准确性,在尽量与实际条件相似的室内条件下获取KLDPE实测值是非常必要的.

The low-density polyethylene（ LDPE） membrane widely applied for passive sampling of organic pollutants in aquatic environments,mostly because of its unique advantages of less organic solvent consuming,lower cost,and easier operation comparing to traditional active sampling. However,there is little application for endocrine disrupting chemicals（ EDCs） sampling using LDPE,thus little was known about the actual coefficients of portioning between LDPE and water. Here seven kinds of EDCs,including bisphenol A（ BPA）,nonylphenol（ 4-NP）,octylphenol（ 4-t-OP）,estrone（ E1）,17 β-estradiol（ E2）,triclosan（ TCS）,and Triclocarban（ TCC）,were selected for a laboratory batch experiment using LDPE membrane under the circumstance of temperature gradient,and different pH of solutions as well. The results showed that,higher temperature could accelerate the sorption progress of EDCs to the LDPE,shortening the time for the balance between LDPE and water,while it was difficult to achieve balance（ more than 30 days） when the solution temperature was 4 ℃.The impact of solution pH is varied among these 7 EDCs,probably due to the change of chemical forms under differential pH circumstance. All the determined KLDPEare less than the corresponding theoretical value calculated by empirical formula promoted by either Hofmans or Booij,because the desorption of EDCs from the LDPE to water was neglected when calculating these value,and overestimated theKLDPE. Our results clearly revealed that,in order to precisely determine the concentration of EDCs by LDPE,it was necessary to determine the actual KLDPEas close to the actual field circumstance as possible.