利用活性碳毡构建流通式电容去离子器件及其电容脱盐性能研究

采用活性碳毡(ACF)作为电吸附材料,构建流通式(Flow-through)电容去离子(CDI)装置,以模拟盐水为对象,考察了电压、通量、进水初始浓度及盐离子种类等条件对ACF电吸附容量的影响,并与平板式(Flow-by)电容去离子装置对比.结果表明,在流通式运行模式下,ACF电吸附容量随着电压、进水盐浓度的增大而增大,吸盐量最终会达到极值(最大吸附量).ACF电吸附容量会随着进水通量的增大先增大后减小.在电压1.2 V、通量0.053 m L·min~(-1)·cm~(-2)、进水初始浓度1000 mg·L~(-1)的条件下,流通式CDI中ACF对硫酸钠的电吸附容量达到7.73 mg·g~(-1),而平板式CDI中ACF电吸附容量为5.42 mg·g~(-1).此外,还考察了在不同盐离子类型条件下的流通式CDI脱盐效果,结果表明,ACF电极对阳离子电吸附强弱顺序依次为K~+Na~+Ca~(2+),对阴离子电吸附强弱顺序为Cl~-NO_3~-SO_4~(2-).流通式CDI装置在12个周期内脱盐效果并无明显衰减,表明CDI具有较好的稳定性.

Performance of flow-through mode capacitive deionization device with activated carbon felt electrode

Activated carbon felt (ACF) was selected as electro-adsorption material to fabricate a flow-through mode capacitive deionization (CDI) device for brine wastewater desalination. Electro-adsorption capacity (EAC) of ACF was investigated under different applied voltages, influx, salinity intensities and different type of salt ions. The EAC of ACF in flow-through CDI was also compared with that in a flow-by mode CDI device. The results indicate that EAC of ACF increases with the increasing applied voltage and salinity intensity, until reaching to the maximum EAC. However, it increases first and then decreases with the increasing influx. A maximum EAC of 7.73 mg·g^-1 has been obtained in a flow-through CDI, with the condition of 1.2 V applied voltage, 0.053 mL·min^-1·cm^-2 influx and 1000 mg·L^-1 influent salinity, while only 5.42 mg·g^-1 of maximum EAC can be obtained in a flow-by CDI. The EACs of ACF to different type of salt ions are in the order of K⁺ > Na⁺ > Ca²⁺ for cation and Cl^- > NO₃^- > SO₄^2- for anion. ACF-based flow-through CDI exhibits good stability and does not appear obvious decay in 12 cycles of adsorption-desorption.