离子印迹复合吸附材料对目标离子识别性吸附的协同效应研究

Firstly, the lead, zinc, arsenic, cadmium and other heavy metal hydration ion radius, heat of hydration, hydration free energy and electricity negative in wastewater are investigated. Then, diatom silica with a large amount of surface hydroxyl, hydrogen and free water, and chitosan with free aminogroup are combined to form composite functioned monomer by hudrothermal bulk polymerization. Thirdly, taking As5+ as template ion, composite material is formed from As5+ and ethylene glycol dimethacrylate by cross-linking. Finally, the adsorbent with capacity of As5+ recognition is made fter As5+ eluting by dilute hydrochloric acid. According to experiments in various conditions, i. e., different adsorbent dosage, different solution pH, different initial concentration, different adsorption equilibrium time, diatoms with different heavy metals solid / liquid interfacial adsorption mechanism and sorbent conversion cycle stability are analysized. The complex stability constant, ion-exchange, coordination and co-precipitation and other complex adsorption law are explained. The solid / liquid interface adsorption model is established. The relationship of modifier complex interface and diatoms is revealed. The coordination mechanism of diatom surface potential and heavy metal ion charge is clarified. The microscopic mechanism is analyzed and the dynamic model of modified diatoms adsorbing of heavy metal ions is built by controlling the pH of the medium, ζ potential and hydration free energy. These works can offer important scientific basis for assembling the special sorbent with good recognition adsorption ability for different heavy metal ions in wastewater.

首先研究废水中目标离子水合离子半径、水化热、水合自由能及电负性等；然后采用水热本体聚合法，利用硅藻表面的大量硅羟基、氢键和自由水，以及壳聚糖具有游离氨基(-NH2)羟基(-0H)的碱性特点，形成复合功能单体；再以As5+为模板离子，与乙二醇二甲基丙烯酸酯交联形成复合材料；最后通过稀盐酸将模板离子洗脱，制备对As5+具识别性的吸附剂。在改变吸附剂用量、溶液初始浓度、pH、吸附平衡时间等试验条件情况下，研究吸附剂对目标离子固/液界面吸附转换机制及吸附剂循环稳定性；解析络合稳定常数、离子交换性、配位络合和共沉淀等多种吸附规律，建立固/液界面吸附模型；揭示吸附剂复合界面关系，阐明吸附剂表面电性与目标离子的协同机制。通过控制介质pH值、ζ电位，水合自由能等，分析吸附剂吸附目标离子的微观机理，建立吸附剂识别性吸附目标离子的动力（等温吸附）模型，从而为组装具良好识别性吸附废水中不同重金属离子的吸附剂提供科学依据。

砷是环境污染物中毒性最强且需优先控制的元素之一，水体砷污染治理备受关注。本项目采用表面离子印迹技术，以硅藻和壳聚糖复配体为功能单体，As(V)为模板离子，γ-缩水甘油醚氧丙基三甲氧基硅烷（DGTMS）为交联剂，制备了As(V)离子印迹聚合物（As-IIP）。以单因素控制变量法，确定了As-IIP最佳的制备条件。通过SEM、XRD、FT-IR、XPS等表征手段解析了As-IIP的印迹机制和吸附机制。采用静态吸附实验考察了As-IIP的吸附特性。实验研究表明，对初始浓度为2mg/L的As(V)溶液最佳吸附条件为：pH为5，投加量为4g/L，反应温度为25℃，反应时间为10h。在最佳吸附条件下As-IIP对As(V)的去除率达到93.99%，吸附后砷浓度满足《污水综合排放标准》（GB8978-1996）中关于总砷排放标准（<0.5mg/L）的要求。吸附实验数据更加符合Langmuir模型和准二级动力学模型，吸附过程可自发进行，吸附反应为放热反应。As-IIP材料的选择性、再生性较好。在分别与7种离子的二元共存体系中，As-IIP对As(V)的相对选择性系数均在2.32以上。材料循环利用5次后，吸附量为最初除砷量的97.69%。研究表明As-IIP对As(V)具有较好的吸附性能，并具有很好的选择性和复用性，本研究对水体砷污染治理和回收具有重要意义。