电容法脱盐用碳基电极材料功能化改性及对同离子效应抑制机理研究

In recent years, the capacitive deionization technology has become the research focus in the fields of seawater or brackish water desalination, water softening and industrial waste water desalting treatment due to the advantage of low energy consumption, high water conversion rate and environmental friendly and so on. Based on the problem of low current efficiency and desalination efficiency caused by the co-ion effect for the carbon-based electrode material in the capacitive deionization process, the carbon nanotube material used as the base material of the electrode is modified by sulfonating agent and amination agent to achieve the functional preparation of the carbon nanotubes material with charged selectivity. Effects of the material modification conditions are analyzed based on the electrode material surface charge, electronegativity, electrochemical properties and wettability. Also the adsorption kinetic and the inhibition mechanism of the co-ions effect of the electrode material before and after modification are explored. The influences of the modified electrode on the capacitive desalination capacity and efficiency are studied. Further, the tolerance and the stability of the modified electrode are investigated and evaluated in different solution environment and cyclic times. The implementation of this project is expected to solve the problem of the co-ion effect and lays the foundation for process intensification and practical development of the capacitive deionization technology.

电容法脱盐技术具有能耗低、产水收率高和环境友好等优势，成为近年来海水/苦咸水淡化、水体软化及工业废水脱盐处理等领域的研究热点。本项目针对碳基电极材料在电容法脱盐过程中存在的同离子效应严重影响电流效率和脱盐率的问题，以碳纳米管CNT为研究对象，采用磺化剂、胺化剂等改性处理方法，实现CNT材料具有荷电选择性的功能化制备。重点研究改性条件对电极材料表面荷电性、电负性、电化学性能和润湿性等的影响规律，探索电极材料改性前后吸附动力学规律及对同离子效应的抑制机理，研究改性电极对电容法脱盐效能的影响规律，评价和分析改性电极对溶液环境的耐受性和循环脱盐稳定性。项目实施有望解决电容法脱盐同离子效应问题，为该技术过程强化和实用化开发奠定基础。

项目针对碳基电极材料在电容法脱盐过程中存在的同离子效应严重影响电流效率和脱盐效率的问题，以碳纳米管（CNT）为研究对象，采用磺化剂、胺化剂等改性处理方法，实现CNT材料具有荷电选择性的功能化制备，并重点开展了如下四方面研究工作：. （1）阴/阳离子选择性荷电功能化CNT改性制备和参数优化。采用对氨基苯磺酸为磺化剂、3-氨基丙基三乙氧基硅烷为氨化剂，分别制备了具有阳离子选择性和阴离子选择性的荷电功能化CNT材料，即CNT-S和CNT-N。通过TEM、EELS和XPS等测试，证明改性CNT材料表面成功接枝氨基和磺酸基官能团。.（2）改性CNT电极成型及电极样件性能研究。采用涂覆法制备电极样件，测得CNT-N和CNT-S的初始接触角均显著小于CNT，表明CNT材料荷电功能化改性有利于提升材料的亲水性。CNT-N和CNT-S电极的比电容分别是CNT电极的1.9倍和1.6倍，其充电电阻均明显小于CNT电极，证明CNT材料荷电功能化改性有利于显著增强其电化学性能。.（3）改性CNT电极对同离子效应抑制机理探究。将CNT、CNT-N和CNT-S三种电极两两配对组成四种CDI单元，对不同CDI单元的电势推动力分析可知，组件Cell N-S正负电极上所施加的电势完全用于反离子的吸附，没有因同离子排斥而造成消耗，有效推动力最大。对吸附过程电荷效率量化分析表明，组件Cell C-C电荷效率为36.4%，而Cell N-S电荷效率高达90.45%，说明以CNT-N为正极、CNT-S为负极可实现对同离子效应的最大程度抑制。.（4）改性CNT电极溶液环境耐受性和循环脱盐稳定性的研究。对改性CNT电极进行100次循环CV测试可知，CNT-N和CNT-S电极的电容保持率分别为90.2%和84.6%，而CNT电极仅为61.4%，证明荷电功能化处理对增强CNT电极电化学稳定性具有显著贡献。对改性电极溶液环境耐受性分析表明，其适宜的溶液pH范围为5-9，温度区间为5-25℃。.项目成果对推动电容法脱盐技术实用化开发具有重要指导作用。本项目共发表见刊第一标注学术论文10篇，其中SCI检索论文9篇，中文核心1篇。培养博士生1名，硕士生8名。