Membrane distillation (MD) is an emerging technology for brine concentration, but plagued by scaling/fouling/wetting in realistic applications. There has been tremendous progress in the mitigation of scaling via chemical modification to reduce the surface energy and hydraulic operation to change flow state in feed channel. But there still lacks an undisputed cognition yet which approach outperforms the others. To address this issue, this study comprehensively investigates the impact of state-of-the-art technologies on scaling mitigation based on a surface corrugated hydrophobic PVDF membrane with high flux and potential for mass production. The technology selected include CF4 plasma modification, pulse flow, and negative feed pressure from both thermodynamic and hydraulic perspectives. CF4 plasma modification resulted in a low surface energy superhydrophobic surface, but the scaling resistance of the membranes was not significantly improved. Pulse flow effectively mitigated scaling, yet the intrusion of calcium sulfate into the membrane matrix still occurred. Negative pressure at the feed channel created a stable air layer, leading to excellent stable vapor flux and distillation conductivity. The results indicated that the hydraulic operation using negative pressure at feed was an efficient approach for scaling mitigation. This study further elucidated the mechanism underlying the scaling resistance of superhydrophobic membranes and underscored the importance of hydraulic factors in enhancing the scaling resistance in MD.

中文翻译：

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增强波纹聚偏二氟乙烯疏水膜在膜蒸馏中的抗结垢性：CF4 等离子体修饰、脉冲流和负压的影响


膜蒸馏 （MD） 是一种新兴的盐水浓缩技术，但在实际应用中受到结垢/结垢/润湿的困扰。在通过化学改性降低表面能和水力操作来改变进料通道中的流动状态来减轻结垢方面取得了巨大进展。但仍然缺乏无可争议的认知，但哪种方法比其他方法更胜一筹。为了解决这个问题，本研究全面调查了最先进的技术对基于具有高通量和大规模生产潜力的表面波纹疏水 PVDF 膜的阻垢缓解的影响。选择的技术包括 CF4 等离子体改性、脉冲流和热力学和水力角度的负进料压力。CF4 等离子体改性导致低表面能超疏水表面，但膜的抗垢性没有显着提高。脉冲流有效减轻了结垢，但硫酸钙侵入膜基质的情况仍然存在。进料通道的负压创造了稳定的空气层，从而获得了出色的稳定蒸汽通量和蒸馏电导率。结果表明，在进料时使用负压的液压操作是缓解结垢的有效方法。本研究进一步阐明了超疏水膜抗垢性的潜在机制，并强调了水力因素在增强 MD 抗垢性中的重要性。