Abstract The primary problem with membrane distillation (MD) for concentrating hypersaline wastewaters is its severe membrane scaling induced by increasing salt concentration of wastewater. Herein, we developed a superhydrophobic and welded-pore polyimide fibrous membranes (SH-welded PI FM) combined with optimizing feed/permeate flow velocity to alleviate membrane scaling and improve membrane water flux simultaneously. The experiments reveal that the SH-welded PI FM functionalized with welding pores avoids membrane pore deformation induced by increasing flow velocity and superhydrophobicity reduces the overall adhesive interaction between crystal and membrane surface to against membrane scaling. Comparative experiments and simulation results reveal that increasing flow velocity is also beneficial for vapor transmission by partially overcoming membrane temperature and concentration polarization and alleviating membrane scaling by producing asymmetrical disturbation on membrane two surfaces. However, the progressive increase will aggravate membrane scaling because of the excessive disturbance of flow velocity to fibers enlarging membrane pores. Therefore, designing welded-pore and superhydrophobic fibrous membrane combined with optimizing flow velocity is extraordinarily effective in simultaneously improving membrane water flux and mitigating membrane scaling for concentrating hypersaline wastewaters. These findings are significant to break the trade-off of membrane water flux and scaling for MD to concentrate hypersaline wastewaters for practical application in industries.

中文翻译：

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深入了解进料/渗透液流速对膜蒸馏中超疏水和焊接孔纤维膜的水通量和抗结垢性的权衡

摘要 膜蒸馏 (MD) 用于浓缩高盐度废水的主要问题是其因废水盐浓度增加而引起的严重膜结垢。在此，我们开发了一种超疏水和焊接孔聚酰亚胺纤维膜（SH 焊接 PI FM），结合优化进料/渗透液流速，以同时减轻膜结垢并提高膜水通量。实验表明，具有焊接孔功能化的 SH 焊接 PI FM 避免了由增加流速引起的膜孔变形，并且超疏水性降低了晶体和膜表面之间的整体粘合相互作用，以防止膜结垢。对比实验和模拟结果表明，增加流速也有利于蒸汽传输，部分克服膜温度和浓差极化，并通过在膜两个表面产生不对称扰动来减轻膜结垢。然而，逐渐增加会加剧膜结垢，因为流速对纤维的过度扰动会扩大膜孔。因此，结合优化流速设计焊接孔和超疏水纤维膜对于同时提高膜水通量和减轻膜结垢对于浓缩高盐度废水是非常有效的。