Typical forward osmosis (FO) membranes utilize non-woven fabrics or polymers as support layers, which cause severe internal concentration polarization (ICP) effects due to their unalterable thickness, thereby limiting the water flux. Herein, an ultrathin composite film based on carbon nanotubes (CNTs) and polyvinyl alcohol (PVA), with a thickness controlled down to 10.3 μm, is proposed as a support layer for the fabrication of FO membranes for application in polluted water treatments and desalination. Our observations reveal that incorporating PVA into the CNT film boosts mechanical strength and hydrophilicity, thereby efficiently alleviating the ICP effect during the FO process. Moreover, employing a uniform polydopamine (PDA) film as the interlayer reduces the pore size and roughness of the substrates, thus facilitating the formation of an ultrathin, continuous, and intact polyamide (PA) selective layer. With deionized water as the feed solution and a 1 M sodium chloride solution as the draw solution, the optimized membrane achieves an extremely high water flux of up to 90.86 L m⁻² h⁻¹ and a specific salt flux of 0.22 g L⁻¹. This work demonstrates an effective strategy to develop FO membranes with reduced membrane thickness while still exhibiting exceptional water flux and good mechanical properties, showcasing its potential in practical FO membrane applications.

中文翻译：

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基于碳纳米管/聚乙烯醇的超薄支撑层，用于具有出色水通量的正渗透膜


典型的正向渗透（FO）膜利用无纺布或聚合物作为支撑层，由于其不可改变的厚度而导致严重的内部浓差极化（ICP）效应，从而限制了水通量。在此，提出一种基于碳纳米管（CNT）和聚乙烯醇（PVA）的超薄复合膜，厚度控制在10.3μm，作为支撑层，用于制造用于污水处理和海水淡化的FO膜。我们的观察表明，将 PVA 纳入 CNT 薄膜可提高机械强度和亲水性，从而有效减轻 FO 过程中的 ICP 效应。此外，采用均匀的聚多巴胺（PDA）薄膜作为中间层可以减小基底的孔径和粗糙度，从而有利于形成超薄、连续且完整的聚酰胺（PA）选择性层。以去离子水为进料溶液，1 M 氯化钠溶液为驱动溶液，优化后的膜实现了高达 90.86 L m ⁻² h ⁻¹的极高水通量和 0.22 g L ⁻¹的比盐通量。这项工作展示了一种开发膜厚度减小的 FO 膜的有效策略，同时仍表现出出色的水通量和良好的机械性能，展示了其在实际 FO 膜应用中的潜力。