电容法脱盐用聚吡咯/碳纳米管复合电极成型工艺优化研究

As the most important and up-to date techniques for solving the deficiency of fresh water in coastal areas, desalination has been listed as the keystone supporting field and the priority development subject of "the national mid-long term program of science and technology" (2006-2020). In recent years, the capacitive deionization (CDI) technology achieves rapid progress, and has become the research focus of the field due to the advantages of low energy consumption, environmental friendly, high desalination rate and so on. Based on the previous work, the prepared polypyrrole/carbon nanotube composite is used as the electrode active component for fabricating the electrode. Effects of the different fabrication method (the squash method and the coating method) and parameters on the electrochemical properties and the desalting performance of the electrode samples are discussed and analyzed. Also, the relationship between the electrode configuration (symmetry and nonsymmetry) and the electrochemical resistance of the CDI unit is studied. The capacitance utilizing efficiency of the electrode is also calculated and compared for finding effective approaches to improve the desalting performance of the CDI unit. Further, the influence of the solution conditions on the mechanical strength and structure stability of the electrode are studied for obtaining the appropriate application conditions of conducting polymer based electrode. The implementation of this project is useful for making achievements in electrode fabrication, electrode configuration and CDI condition optimization.

海水淡化作为解决沿海地区淡水资源短缺问题的重要高新技术途径，已被列为我国"中长期科学和技术发展规划纲要"（2006-2020）的重点支持领域和优先发展课题。电容法脱盐技术是近年来最受重视的新型海水淡化技术之一，具有能耗低、环境友好和脱盐率高等优点。本项目拟在已有工作基础上，以制备的聚吡咯/碳纳米管复合纳米材料为活性组分，重点研究压片成型法和涂敷成型法制作电极的工艺参数对成型电极电化学性能和脱盐性能的影响关系，探索适用于电容法脱盐过程特点的导电聚合物基电极的较佳成型方法和工艺条件；研究电极对称和非对称配置方式对成型电极电容有效利用率及CDI单元阻抗的影响规律，探索提高CDI装置组件脱盐效能的有效途径和方法；研究溶液条件对成型电极机械强度和结构稳定性的影响规律，探索导电聚合物基电极的适宜环境条件范围。项目实施有望在新材料电极制作成型工艺、电极最佳配置方式及电容法脱盐环境条件优选等方面取得突破。

电容法脱盐 (CDI) 技术是新型海水淡化技术之一，具有能耗低、环境友好和脱盐率高等优点。项目以新型复合电极材料聚吡咯/碳纳米管 (PPy/CNT) 为研究对象，完成如下四方面研究内容，包括：复合电极压片成型技术研究，复合电极涂覆成型技术研究，复合电极配置方式优化研究和 复合电极溶液环境耐受性研究。.首先，项目以PPy/CNT为电极活性组分，聚偏氟乙烯 (PVDF) 为粘结剂，导电石墨为导电剂，针对电极压片法成型技术，重点考察了电极材料组分间配比、电极片厚度及成型压力对电极性能影响规律。表明：压片法制备PPy/CNT电极最佳工艺条件为mPPy/CNT : mPVDF : m导电石墨为9:1:2，电极厚度为0.59mm及操作压力为10MPa。此条件下电极的比电容与比吸附量分别为144.1F/g和53.6mg/g。针对PPy/CNT 电极涂敷法成型技术，考察了各组分间的配比、电极片厚度及干燥温度对电极性能影响规律。表明：涂敷法制备PPy/CNT电极最佳工艺条件为mPPy/CNT : mPVDF : m导电石墨为8:1:1，涂层厚度为0.3mm，干燥温度为40℃及干燥时间为6h。此条件下电极比电容与比吸附量分别高达180.61 F/g和93.68 mg/g，显著优于压片法制备的电极性能。.其次，分别以盐酸 (HCl) 和十二烷基苯磺酸钠 (SDBS) 为掺杂剂，采用最优涂敷工艺制备了PPy-Cl/CNT电极、PPy-DBS/CNT电极和CNT电极，考察了上述三种电极构成的七种配置方式对CDI组件电势分布、饱和吸附特性和循环脱盐稳定性影响规律，并从电极零电荷电势角度进行了机理分析。表明：当PPy-Cl/CNT电极为正极及PPy-DBS/CNT电极为负极时，正负电极的零电荷电势均位于各自电极工作区以外，两电极间的电势推动力损失为0 Vvs.SCE，组件Cell Cl-DBS 为最佳配置方式，其比吸附量最大，为92.75mg/g。.最后，在最佳电极配置方式基础上，考察了溶液酸性、碱性和温度条件对电极结构、电化学和脱盐稳定性影响规律。表明：电极环境适用范围为溶液pH6-8，溶液温度5-25℃，此条件下正负电极的比电容和比吸附量分别高于165F/g和73mg/g，且100次循环伏安扫描后和20次脱盐循环后的归一化吸附量的衰减率均小于17%。