The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environment Sciences and Engineering, Peking University, Beijing 100871, China.
Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400045, China.
Environ Sci Technol. 2024 Aug 20;58(33):14929-14939. doi: 10.1021/acs.est.4c05283. Epub 2024 Aug 10.
Membrane distillation (MD) has great potential in the management of hypersaline water for zero liquid discharge (ZLD) due to its high salinity tolerance. However, the membrane wetting issue significantly restricts its practical application. In this study, a composite membrane tailored for extreme concentrations and even crystallization of hypersaline water is synthesized by coating a commercial hydrophobic porous membrane with a composite film containing a dense polyamide layer, a cation exchange layer (CEL), and an anion exchange layer (AEL). When used in direct contact MD for treating a 100 g L NaCl hypersaline solution, the membrane achieves supersaturation of feed solution and a salt crystal yield of 38.0%, with the permeate concentration at <5 mg L. The composite membrane also demonstrates ultrahigh antiwetting stability in 360 h of long-term operation. Moreover, ion diffusion analysis reveals that the ultrahigh wetting resistance of the composite membrane is attributed to the bipolar AEL and CEL that eliminate ion crossover. The literature review elucidates that the composite membrane is superior to state-of-the-art membranes. This study demonstrates the great potential of the composite membrane for direct crystallization of hypersaline water, offering a promising approach to filling the gap between reverse osmosis and conventional thermal desalination processes for ZLD application.
膜蒸馏（MD）由于其高耐盐性，在处理高盐度水零液体排放（ZLD）方面具有很大的潜力。然而，膜润湿问题严重限制了其实际应用。在这项研究中，通过在商业疏水性多孔膜上涂覆包含致密聚酰胺层、阳离子交换层（CEL）和阴离子交换层（AEL）的复合膜，合成了一种专门用于处理高浓度甚至高盐度水结晶的复合膜。当用于处理 100 g L NaCl 高盐溶液的直接接触 MD 时，该膜实现了进料溶液的过饱和度和 38.0%的盐晶体产率，而渗透物浓度<5 mg L。该复合膜在长达 360 小时的长期运行中也表现出超高的抗润湿稳定性。此外，离子扩散分析表明，复合膜的超高抗湿性归因于消除离子交叉的双极 AEL 和 CEL。文献综述表明，复合膜优于最先进的膜。本研究表明，复合膜在高盐度水的直接结晶方面具有巨大的潜力，为填补反渗透和传统热脱盐工艺之间的差距，实现 ZLD 应用提供了一种有前景的方法。
