表面活性剂改性沸石去除地下水中痕量类固醇雌激素的吸附机理研究

The Zeolite modified by quaternary ammonium cationic surfactant is an excellent adsorbent for the removal of hydrophobic organics in water, and is very impressively applied for the repair applications in the actual site of hydrophobic organic pollution because of its advantage such as good water transmissibility, formidable flushing resistance, no secondary pollution, etc. However, the study of the relationship between the molecular layer structure formed on the surface of natural zeolite and quaternary ammonium cationic surfactant with different carbon chain length and concentration are still not systematic. Moreover, the adsorption study of steroid estrogens removal by quaternary ammonium cationic surfactant modified zeolite has less been reported. The project of this study is to consummate the relationship between the molecular layer structure formed on the surface of natural zeolite and quaternary ammonium cationic surfactant with different carbon chain length and concentration; Figure out the adsorption behavior of alone and co-exist steroid estrogens removal by modified Zeolite and the parameters of the best modified zeolite adsorbent preparation condition; Reveal the adsorption mechanism of alone and co-exist steroid estrogens removal by the best modified zeolite adsorbent and provide the theoretical basis for remediation of actual site trace steroid estrogens contaminated groundwater.

季铵盐阳离子表面活性剂改性沸石能够有效吸附水体中疏水性有机物，且因其具有导水性能好、耐冲洗性能强、无二次污染等优点，适合广泛应用于疏水性有机物污染的水体处理。然而，对于不同碳链长度、不同浓度的季铵盐阳离子表面活性剂在天然沸石表面形成不同分子层结构的关系研究尚不够系统，同时季铵盐阳离子表面活性剂改性沸石对水体中类固醇雌激素的吸附研究仍鲜见报道。本项目拟完善不同碳链长度、不同浓度的季铵盐阳离子表面活性剂在天然沸石表面形成不同分子层结构的关系条件；明确改性沸石对各类固醇雌激素单独存在以及共同存在时的吸附行为及最佳改性沸石吸附剂的制备条件参数；揭示最佳改性沸石对各类固醇雌激素单独存在以及共同存在时的吸附机理，为实际场地痕量类固醇雌激素污染地下水的修复提供理论基础。

本项目通过季铵盐阳离子表面活性剂对沸石进行改性，将其亲水性转变为部分亲水部分疏水，提高了对水中雌激素的吸附性能。利用三种阳离子表面活性剂，制备了不同有机改性沸石，应用FTIR、BET 和SEM等对有机改性沸石进行表征，证明了改性剂的负载且并未对沸石结构造成破坏。通过单因素静态吸附实验系统考察了原沸石和有机沸石吸附雌激素的效能和主要影响因素，包括初始浓度，温度，离子强度，pH等。研究发现低的初始浓度，低温，离子强度为零以及5-7范围的pH有利于吸附的进行。通过吸附等温线、动力学、热力学等研究探讨了改性沸石吸附雌激素的特性，发现改性沸石对雌激素的吸附符合Langmuir吸附模型和拟二级动力学模型，是一种自发放热反应。综上为揭示改性沸石吸附雌激素的吸附机理提供重要的科学理论依据。