An improved protocol for electrodialytic desalination yielding mineral-balanced potable water

作者：Thakur Amit K; Srivastava Niharika; Chakrabarty Tina; Rebary Babulal; Patidar Rajesh; Sanghavi Rahul J; Shahi Vinod K; Ghosh Pushpito K^*

来源：Desalination, 2014, 335(1): 96-101.

DOI：10.1016/j.desal.2013.12.007

• Desalination
• Useful mineral retention
• Selective electrodialysis
• Drinking water

Brackish water desalination through distillation produces essentially distilled water devoid of all minerals. In reverse osmosis (RO) all dissolved minerals get depleted but depletion of useful minerals (Mg2+, Ca2+, SO42- and CO32-/HCO3-) is even greater than of Na+ and Cl-. Conventional electrodialysis (EDconv) too fails to meet the desired objective, all constituents being depleted in similar proportions with respect to feed. Consequently, remineralisation is necessary but in many cases not implemented. We report selective electrodialysis (EDsel), for production of desalinated water containing relatively higher proportions of desirable minerals. Commercial cation- and anion exchange membranes (CEMCNS and AEM(CNS)) were coated with polyaniline (PANI), and the resultant membranes (PANI-CEMCNS, PANI-AEM(CNS)) were characterised by physico-chemical and electrochemical techniques. Due to sieving and hydrophobic effects, the PANI coating was demonstrated to improve the retention of Mg2+, Ca2+ and SO42- during desalination. Retention of mineral constituents was further enhanced with PANI modified styrene-co-divinylbenzene-polyethylene-based interpolymer cation- and anion-exchange membranes (CEMIP and AEM(IP)). The total alkalinity of the treated stream increased during EDsel, presumably due to concentration polarisation accompanied by preferential transport of H+ over OH-. The process efficiency was only marginally lower (5%) for EDsel, suggesting that this approach to desalination may be of practical importance.

• 出版日期2014-2-17
• 单位海洋化工研究院有限公司