Yan Haiyang, Li Wei, Zhou Yongming, Irfan Muhammad, Wang Yaoming, Jiang Chenxiao, Xu Tongwen
CAS Key Laboratory of Soft Matter Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, School of Chemistry and Material Science, University of Science and Technology of China, Hefei 230026, China.
Hefei ChemJoy Polymer Materials, Co., Ltd., Hefei 230601, China.
Membranes (Basel). 2020 Jun 26;10(6):135. doi: 10.3390/membranes10060135.
The crystalized mixed salts from the zero liquid discharge process are a hazardous threat to the environment. In this study, we developed a novel electrodialysis (SBMED) method by assembling the monovalent selective anion-exchange membrane (MSAEM) into the bipolar membrane electrodialysis (BMED) stack. By taking the advantages of water splitting in the bipolar membrane and high perm-selectivity of MSAEM for the Cl ions against the SO ions, this combination allows the concurrent separation of Cl/SO and conversion of mixed salts into relatively high-purity monoprotic and diprotic acids. The current density has a significant impact on the acid purity. Both the monoprotic and diprotic acid purities were higher than 80% at a low current density of 10 mA/cm. The purities of the monoprotic acids decreased with an increase in the current density, indicating that the perm-selectivity of MSAEM decreases with increasing current density. An increase in the ratio of monovalent to divalent anions in the feed was beneficial to increase the purity of monoprotic acids. High-purity monoprotic acids in the range of 93.9-96.1% were obtained using this novel SBMED stack for treating simulated seawater. Therefore, it is feasible for SBMED to valorize the mixed salts into relatively high-purity monoprotic and diprotic acids in one step.
零液体排放过程中结晶的混合盐对环境构成了严重威胁。在本研究中，我们通过将单价选择性阴离子交换膜（MSAEM）组装到双极膜电渗析（BMED）堆栈中，开发了一种新型电渗析（SBMED）方法。利用双极膜中的水分解以及MSAEM对Cl离子相对于SO离子的高选择透过性，这种组合能够同时分离Cl/SO，并将混合盐转化为相对高纯度的一元酸和二元酸。电流密度对酸的纯度有显著影响。在10 mA/cm的低电流密度下，一元酸和二元酸的纯度均高于80%。随着电流密度的增加，一元酸的纯度下降，这表明MSAEM的选择透过性随电流密度的增加而降低。进料中单价阴离子与二价阴离子比例的增加有利于提高一元酸的纯度。使用这种新型SBMED堆栈处理模拟海水可获得纯度在93.9 - 96.1%范围内的高纯度一元酸。因此，SBMED一步将混合盐转化为相对高纯度的一元酸和二元酸是可行的。
