Membrane fouling is a critical issue during the membrane filtration process. Photocatalytic membranes have been developed to address the membrane fouling issue, although current approaches are mostly based on irradiation under the UV light. In this study, we report the preparation of a photocatalytic membrane with self-cleaning property under visible light irradiation. A 3-(3,4-dihydroxyphenyl)lalanine (LDOPA) layer was first attached onto the surface of polysulfone (PSF) hollow fiber membrane (HFM) via self-polymerization with an immersion time of 6 h/12 h/18 h/24 h. Then, N–TiO₂–NH₂ (NTN) was introduced to the LDOPA layer via chemical bonding. The NTiO₂ NPs were able to degrade humic acid (HA) under visible light irradiation. Various methods were applied to characterize the photocatalyst and membrane, including thermal gravimetric analysis, scanning electron microscopy, and cyclic filtration tests of deionized water and HA solution. The normalized water flux of PSF 18LDOPA-NTN HFM was 22% higher than that of PSF HFM under visible light condition or 25% higher under the UV irradiation, measured in filtration tests lasting 6 days. In comparison with the pristine PSF HFMs under visible light irradiation, the self-cleaning performance of the modified PSF HFMs was significantly improved due to the photocatalytic property of N–TiO₂ (12%, 25%, and 30% enhancements of normalized flux by 6LDOPA-NTN HFM, 18LDOPA-NTN HFM, and 24LDOPA-NTN HFM, respectively) as indicated by the experimental results of the two-day filtration.

中文翻译：

---

具有自清洁和防污性能的光催化聚砜中空纤维膜用于水处理

膜结垢是膜过滤过程中的关键问题。已经开发出光催化膜来解决膜结垢问题，尽管当前的方法主要基于紫外线照射。在这项研究中，我们报告了在可见光照射下具有自清洁性能的光催化膜的制备。首先通过自聚合将3（3,4-二羟基苯基）丙氨酸（LDOPA）层附着到聚砜（PSF）中空纤维膜（HFM）的表面上，浸入时间为6 h / 12 h / 18 h / 24小时 然后，通过化学键合将N–TiO ₂ –NH ₂（NTN）引入LDOPA层。NTiO ₂NP能够在可见光照射下降解腐殖酸（HA）。应用了各种方法来表征光催化剂和膜，包括热重分析，扫描电子显微镜以及去离子水和HA溶液的循环过滤测试。在持续6天的过滤测试中，PSF 18LDOPA-NTN HFM的归一化水通量在可见光条件下比PSF HFM高22％，在紫外线照射下则高25％。与原始PSF HFMs在可见光照射下相比，由于N-TiO ₂的光催化性能，改性后的PSF HFMs的自清洁性能得到了显着改善。 两天过滤的实验结果表明（6LDOPA-NTN HFM，18LDOPA-NTN HFM和24LDOPA-NTN HFM分别将归一化通量提高了12％，25％和30％）。