电容去离子电极的污染特性研究
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摘要
活性碳纤维(ACF)电极的电容去离子技术(CDI)对水中离子具有良好的脱除效果,且经多次吸附脱附循环后电极仍具有良好的吸附性能和再生性能。当溶液中有苯甲酸、腐植酸和铜离子存在时,电极在长期运行的过程中会受到污染,离子去除率随着循环次数的增加而逐渐降低。通过扫描电子显微镜技术(SEM)、低温氮气吸附-脱附技术、循环伏安法(CV)、交流阻抗法(EIS)对电极污染特性进行测试及表征。结果表明:电极被不同污染物污染后,其电吸附性能呈不同的下降趋势,污染电极表面出现颗粒状和片状的有机污染和无机结垢;苯甲酸污染引起孔隙堵塞导致比表面积下降10.8%,腐植酸和铜离子对比表面积影响较小;电极受苯甲酸和腐植酸污染后,因比表面积减小而引起比电容降低;电极受铜离子污染后,有效吸附点位的减少使得比电容下降;电极被污染后,其表面或孔隙内污染物阻碍电子在纤维丝间的传递,电化学性能下降。
The capacitive deionization(CDI) based on activated carbon fiber(ACF) electrodes has good removal effect on ions in water, and the electrodes still have good adsorption and regeneration performance after multiple adsorption and desorption cycles. When the benzoic acid, humic acid and the copper ions existed in the solution, the electrodes would be fouled during long-term operation, and the ion removal efficiency would decrease gradually with the increase of the number of cycles. The pollution characteristics of the electrode were tested and characterized by scanning electron microscope(SEM), nitrogen adsorption and desorption technology, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS), and the results indicated that: after being polluted by different contaminants, the electro adsorption performance of electrodes declined in different trends, and granular and flaky organic pollution and inorganic scale were found on its surface; the benzoic acid incurred the plugging of pore, which resulted in reduction of the specific surface area by 10.8%, while the humic acid and copper ions had little effect on the specific surface area; after being polluted by the benzoic acid and the humic acid, the specific capacitance of the electrodes decreased due to the decrease of the specific surface area; after being polluted by the copper ions, the specific capacitance of the electrodes decreased due to the reduction of effective adsorption points; after being polluted, electrochemical performance of electrode decreased, for the contaminants on the surface or in the pores hindered the transfer of electrons between the fibers.
The capacitive deionization(CDI) based on activated carbon fiber(ACF) electrodes has good removal effect on ions in water, and the electrodes still have good adsorption and regeneration performance after multiple adsorption and desorption cycles. When the benzoic acid, humic acid and the copper ions existed in the solution, the electrodes would be fouled during long-term operation, and the ion removal efficiency would decrease gradually with the increase of the number of cycles. The pollution characteristics of the electrode were tested and characterized by scanning electron microscope(SEM), nitrogen adsorption and desorption technology, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS), and the results indicated that: after being polluted by different contaminants, the electro adsorption performance of electrodes declined in different trends, and granular and flaky organic pollution and inorganic scale were found on its surface; the benzoic acid incurred the plugging of pore, which resulted in reduction of the specific surface area by 10.8%, while the humic acid and copper ions had little effect on the specific surface area; after being polluted by the benzoic acid and the humic acid, the specific capacitance of the electrodes decreased due to the decrease of the specific surface area; after being polluted by the copper ions, the specific capacitance of the electrodes decreased due to the reduction of effective adsorption points; after being polluted, electrochemical performance of electrode decreased, for the contaminants on the surface or in the pores hindered the transfer of electrons between the fibers.
引文
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[9] Yoram Oren.Capacitive deionization (CDI) for desalination and water treatment-past, present and future (a review)[J].Desalination, 2008, 228 (1/2/3):10-29.
[10] Mohamed Mossad, Linda Zou.Study of fouling and scaling in capacitive deionisation by using dissolved organic and inorganic salts[J].Journal of Hazardous Materials, 2013, 244/245(2):387-393.
[11] Wang Changming, Song Haiou.Parameter optimization based on capacitive deionization for highly efficient desalination of domestic wastewater biotreated effluent and the fouled electrode regeneration[J].Desalination, 2015, 365:407-415.
[12] Inyang M, Gao B, Yao Y, et al. Removal of heavy metals from aqueous solution by biochars derived from anaerobically digested biomass[J]. Bioresour Technol, 2012, 110(2):50-56.
[13] Ayranci E, Hoda N, Bayram E.Adsorption of benzoic acid onto high specific area activated carbon cloth[J].Journal of Colloid & Interface Science, 2005, 284 (1):83-88.
[14] Bayram E, Ayranci E.Electrosorption based waste water treatment system using activated carbon cloth electrode: electrosorption of benzoic acid from a flow-through electrolytic cell[J].Separation & Purification Technology, 2012, 86 (8):113-118.
[15] Momma T, Liu X, Osaka T, et al. Electrochemical modification of active carbon fiber electrode and its application to double-layer capacitor[J]. Journal of Power Sources, 1996, 60(2):249-253.
[2] 胡冰君.活性炭纤维电极电吸附除盐的研究[D].西安:西安建筑科技大学, 2013.
[3] 徐明,吕荣湖.改性粘胶基活性碳纤维电极用于NaCl溶液电吸附脱盐的研究[J]. 化工环保, 2008, 28 (5):383-387.
[4] 张玉洁.聚吡咯复合纳米材料制备及其在电容法脱盐中的应用研究[D]. 天津:天津大学, 2011.
[5] 赵研,强化电容去离子脱盐的实验与机理研究[D].沈阳:东北大学,2015.
[6] Kim J S, Rhim J W.Comparison of CDI and MCDI applied with sulfonated and aminatedpolysulfone polymers[J].Membrane Water Treatment, 2016, 7 (1):39-53.
[7] Lee J Y, Seo S J, Yun S H, et al.Preparation of ion exchanger layered electrodes for advanced membrane capacitive deionization (MCDI)[J].Water Research, 2011, 45 (17):5375-5380.
[8] Zhao R, Satpradit O, Rijnaarts H H,et al.Optimization of salt adsorption rate in membrane capacitive deionization[J].Water Research, 2013, 47 (5):1941.
[9] Yoram Oren.Capacitive deionization (CDI) for desalination and water treatment-past, present and future (a review)[J].Desalination, 2008, 228 (1/2/3):10-29.
[10] Mohamed Mossad, Linda Zou.Study of fouling and scaling in capacitive deionisation by using dissolved organic and inorganic salts[J].Journal of Hazardous Materials, 2013, 244/245(2):387-393.
[11] Wang Changming, Song Haiou.Parameter optimization based on capacitive deionization for highly efficient desalination of domestic wastewater biotreated effluent and the fouled electrode regeneration[J].Desalination, 2015, 365:407-415.
[12] Inyang M, Gao B, Yao Y, et al. Removal of heavy metals from aqueous solution by biochars derived from anaerobically digested biomass[J]. Bioresour Technol, 2012, 110(2):50-56.
[13] Ayranci E, Hoda N, Bayram E.Adsorption of benzoic acid onto high specific area activated carbon cloth[J].Journal of Colloid & Interface Science, 2005, 284 (1):83-88.
[14] Bayram E, Ayranci E.Electrosorption based waste water treatment system using activated carbon cloth electrode: electrosorption of benzoic acid from a flow-through electrolytic cell[J].Separation & Purification Technology, 2012, 86 (8):113-118.
[15] Momma T, Liu X, Osaka T, et al. Electrochemical modification of active carbon fiber electrode and its application to double-layer capacitor[J]. Journal of Power Sources, 1996, 60(2):249-253.