School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
Water Res. 2017 Sep 15;121:302-310. doi: 10.1016/j.watres.2017.05.046. Epub 2017 May 22.
Removal of sulfate from water is an environmental challenge faced by many industrial sectors as most existing options are inefficient, costly or unsustainable. The situation is further complicated by the typical coexistence of other ions. In this work, the feasibility of sulfate removal from brackish water by single-pass constant-current membrane capacitive deionization (MCDI) under reverse-current desorption was investigated. Results revealed that sulfate is preferentially removed from the aqueous solution by MCDI compared to chloride. Equivalent circuits of the MCDI system during adsorption and desorption were proposed and the dynamic variation of cell voltage and charging voltage at different adsorption currents was satisfactorily elucidated. Optimization studies were conducted with attention given to discussing the effects of four operating parameters, i.e., adsorption current, pump flow rate, ending cell voltage and desorption current, on three performance indicators (i.e., water recovery, energy consumption and sorption ratio of sulfate to chloride) on the premise of maintaining the effluent sulfate concentration below the specified threshold of 300 mg L. Water recovery-energy consumption mapping and sorption ratio of sulfate to chloride-energy consumption mapping indicated that the combination of a lower adsorption current and a lower matching pump flow rate which reduced the effluent sulfate concentration to 300 mg L was more favorable in practical applications. An appropriately small ending cell voltage was advantageous while a trade-off between water recovery and energy cost was required in optimizing the desorption current.
从水中去除硫酸盐是许多工业部门面临的环境挑战，因为大多数现有方法效率低、成本高或不可持续。典型的共存离子使情况更加复杂。在这项工作中，研究了在反向解吸下通过单通恒流膜电容去离子（MCDI）从咸水中去除硫酸盐的可行性。结果表明，与氯化物相比，硫酸盐通过 MCDI 优先从水溶液中去除。提出了 MCDI 系统在吸附和解吸过程中的等效电路，并对不同吸附电流下的电池电压和充电电压的动态变化进行了令人满意的解释。进行了优化研究，并注意讨论了四个操作参数（即吸附电流、泵流量、终止电池电压和解吸电流）对三个性能指标（即水回收率、能耗和硫酸盐对氯化物的吸附比）的影响，前提是将出水硫酸盐浓度保持在 300mg/L 以下的规定阈值以下。水回收率-能耗映射和硫酸盐对氯化物的吸附比-能耗映射表明，在实际应用中，采用较低的吸附电流和较低的匹配泵流量组合，将出水硫酸盐浓度降低至 300mg/L 更有利。适当降低终止电池电压是有利的，而在优化解吸电流时需要在水回收率和能源成本之间进行权衡。
