摘要
电容去离子(CDI)实验中以活性炭纤维毡为电极,在间歇式反接电压脱附(CM-RVD)条件下以NaCl溶液为进水溶液连续循环100个周期。运行初期NaCl去除率逐渐上升并且在第50个周期达到峰值37.1%;随后去除率逐渐下降,在第100个运行周期时降低至7.4%。CDI的脱盐性能和运行稳定性主要取决于电极性能,脱盐率的下降主要是电极氧化所致。通过使用X射线光电子能谱(XPS)和BET分析发现,电极含氧量逐渐上升并且孔隙结构被破坏,这导致了CDI长期运行下脱盐性能恶化。在此基础上,使用了间歇式零电压脱附(CM-ZVD)和单通式反接电压脱附(SP-RVD)等提高脱盐率的方法。对于CM-ZVD,通过使装置短路进行离子脱附,在无电场的情况下,可减缓电极的氧化;对于SP-RVD,整个装置进水浓度稳定,总电荷量增多,脱盐效率提升,并且进水通道中H2O2的浓度降低,对电极氧化有轻微抑制作用。
Desalination experiments of capacitive deionization were conducted in batch mode-reversal voltage desorption(CM-RVD)using activated carbon fibers(ACFs)as electrodes during 100 continuous cycles.NaCl desorption rate slightly increased from 30 to 37.1%in the first 50 cycles and then dropped significantly to 7.4%,which was mainly attributed to electrode oxidation.It was clearly showed that CDI desalination performance and stability was mainly determined by the electrode properties.It was also found by XPS and Brunauer-Emmett-Teller(BET)that the disruption of electrode structure was aggravated indicating the serious electrode degradation,which had a negative effect on the prolonged desalination stability of CDI.Based on above analysis,suitable methods including batch mode-zero voltage desorption(CM-ZVD)and single-pass-reversal voltage desorption(SP-RVD)for enhancing desalination performance were employed.For CM-ZVD,the ion desorption was conducted by short-circuiting electrode and the electrode reaction in desorption process was prevented in the absence of electrical field.Regarding SP-RVD,H2O2 concentration in the spacer was greatly eliminated,which subtly inhibited the electrode oxidation.
作者
刘姗姗
陈琳
王成燚
LIU Shan-shan;CHEN Lin;WANG Cheng-yi(Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes,Hohai University,Nanjing 210098,China;College of Environment,Hohai University,Nanjing 210098,China)
出处
《环境科技》
2020年第2期32-37,共6页
Environmental Science and Technology
关键词
电容去离子
长期运行
脱盐稳定性
电极结构
Capacitive deionization
Long-term operation
Desalination stability
Electrode structure
