State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China.
Water Res. 2013 May 1;47(7):2523-30. doi: 10.1016/j.watres.2013.02.037. Epub 2013 Feb 27.
A capacitive deionization (CDI) cell was built with electrodes made of an inexpensive commercial activated carbon fiber (ACF), and then modified by incorporating ion-exchangers into the cell compartment. Three modified CDI designs were tested: MCDI - a CDI with electrodes covered by ion-exchange membranes (IEMs) of the same polarity, FCDI - a CDI with electrodes covered by ion-exchange felts (IEFs), and R-MCDI - an MCDI with cell chamber packed with ion-exchange resin (IER) granules. The cell was operated in the batch reactor mode with an initial salt concentration of 1000 mg/L NaCl, a typical level of domestic wastewater. The desalination tests involved investigations of two consecutive operation stages of CDIs: electrical adsorption (at an applied voltage of 1.2 V) and desorption [including short circuit (SC) desorption and discharge (DC) desorption]. The R-MCDI showed the highest electric adsorption as measured in the present study by desalination rate [670 ± 20 mg/(L h)] and salt removal efficiency (90 ± 1%) at 60 min, followed by the MCDI [440 ± 15 mg/(L h) and 60 ± 2%, respectively]. The superior desalination performance of the R-MCDI over other designs was also affirmed by its highest charge efficiency (110 ± 7%) and fastest desorption rates at both the SC [1960 ± 15 mg/(L·h)] and DC [3000 ± 20 mg/(L·h)] modes. The desalination rate and salt removal efficiency of the R-MCDI increased from ∼270 mg/(L h) and 83% to ∼650 mg/(L h) and 98% respectively when the applied voltage increased from 0.6 V to 1.4 V, while decreased slightly when lowering the salt water flow rate that fed into the cell. The packing of IER granules in the R-MCDI provided additional surface area for ions transfer; meanwhile, according to the results of electrochemical impedance spectroscopy (EIS) analysis, it substantially lower down the R-MCDI's ohmic resistance, resulting in improved desalination performance.
构建了一个由廉价商用活性炭纤维（ACF）制成的电极的电容去离子（CDI）单元，然后通过将离子交换剂纳入电池隔室来对其进行改性。测试了三种改性 CDI 设计：MCDI-电极被相同极性的离子交换膜（IEM）覆盖的 CDI、FCDI-电极被离子交换毛毡（IEF）覆盖的 CDI，以及 R-MCDI-用离子交换树脂（IER）颗粒填充电池腔室的 MCDI。该电池以批处理反应器模式运行，初始盐浓度为 1000mg/L NaCl，这是典型的生活污水水平。脱盐测试涉及 CDI 的两个连续操作阶段的研究：电吸附（施加 1.2V 的电压）和脱附[包括短路（SC）脱附和放电（DC）脱附]。在本研究中，R-MCDI 通过脱盐率[670±20mg/（L·h）]和盐去除效率（90±1%）表现出最高的电吸附，分别在 60 分钟后达到 670±20mg/（L·h）和 90±1%，其次是 MCDI[440±15mg/（L·h）和 60±2%]。R-MCDI 在 SC[1960±15mg/（L·h）]和 DC[3000±20mg/（L·h）]两种模式下均具有最高的电荷效率（110±7%）和最快的脱附速率，这也证明了其比其他设计的脱盐性能更好。当施加电压从 0.6V 增加到 1.4V 时，R-MCDI 的脱盐率和盐去除效率从约 270mg/（L·h）和 83%分别增加到约 650mg/（L·h）和 98%，而当降低进入电池的盐水流量时，其略有下降。IER 颗粒在 R-MCDI 中的填充为离子迁移提供了额外的表面积；同时，根据电化学阻抗谱（EIS）分析的结果，它大大降低了 R-MCDI 的欧姆电阻，从而提高了脱盐性能。
