Superhydrophobic modification of TiO2 nanocomposite PVDF membranes for applications in membrane distillation
Superhydrophobic modification of TiO2 nanocomposite PVDF membranes for applications in membrane distillation
复制标题
DOI：
10.1016/j.memsci.2012.06.004
复制
发表时间：
2012-10-01
影响因子：
9.5
通讯作者：
Chen, Vicki
中科院分区：
文献类型：
--
作者：
Razmjou, Amir;Arifin, Ellen;Chen, Vicki
通过低温水热法在PVDF微孔膜上沉积纳米TiO 2粒子，形成具有多级粗糙度的分级结构，制备了适用于膜蒸馏的超疏水膜。然后使用低表面能材料H，1H，2 H，2 H-全氟十二烷基三氯硅烷对TiO 2涂覆的膜进行氟硅烷化。采用毛细管流孔法、TEM、SEM、XPS、KI测试、液体入口压力（LEP）测量和接触角测量等技术，研究了表面改性对膜表面化学、结构和性能的影响。以氯化钠和腐殖酸溶液为模型物料，考察了改性膜和未改性膜在直接接触膜蒸馏（DCMD）过程中的抗污染性能。结果表明，改性是机械和热稳定性和光活性。液体进入压力（LEP）和水接触角分别从120 kPa和125度增加到190 kPa和166度。二氧化钛纳米复合PVDF膜的氟硅烷化没有损害的平均孔径。还表明，TiO 2涂层不仅有助于设计分级结构，而且还为水解的硅烷偶联剂提供位点（OH官能团）以锚定形成坚固的均匀防水膜。过滤结果还表明，改性膜的纯水通量低于原始膜，特别是在较高的温度下。然而，氯化钠DCMD测试表明，原始膜的渗透电导率急剧增加，而改性膜在实验期间没有改变。一个20小时的污垢DCMD实验与腐殖酸并没有显示出减少通量的处女和改性膜。然而，观察到通量的大幅减少与添加到溶液中的3.775 mM CaCl 2由于形成复合物与腐殖酸和随之而来的颗粒凝聚和沉淀在膜表面上。虽然原始膜和改性膜表现出类似的污染行为，改性膜相比，原始膜的通量恢复显着更高。(c)2012爱思唯尔有限公司版权所有。
Superhydrophobic membrane for the application in membrane distillation was generated by creating a hierarchical structure with multilevel roughness via depositing TiO2 nanoparticles on microporous PVDF membranes by means of a low temperature hydrothermal (LTH) process. The TiO2 coated membranes were then fluorosilanized using a low surface energy material H, 1H, 2H, 2H-perfluorododecyltrichlorosilane. A variety of techniques such as capillary flow porometry, TEM, SEM, XPS, KI test, liquid entry pressure (LEP) measurement and contact angle goniometry were applied to explore the effects of surface modification on the surface chemistry, structure and performance of the membranes. The anti-fouling performance of virgin and modified membranes were examined in a direct contact membrane distillation (DCMD) process using sodium chloride and humic acid solution as a model feed. Results showed that the modification was mechanically and thermally robust and photoactive. The liquid entry pressure (LEP) and water contact angle were increased from 120 kPa and 125 degrees to 190 kPa and 166 degrees, respectively. The fluorosilanization of TiO2 nanocomposite PVDF membranes did not compromise the mean pore size. It was also appeared that the TiO2 coating not only contributes in engineering the hierarchical structure but also provides sites (OH functional groups) for the hydrolyzed silane coupling agent to be anchored forming a robust uniform water repellent film. The filtration results also showed that the pure water flux of the modified membrane was lower than that of the virgin membrane particularly at higher temperatures. However, the sodium chloride DCMD test showed that the permeate conductivity of the virgin membrane was increased sharply whereas it was not changed for the modified membrane over the period of the experiment. A 20 h fouling DCMD experiment with humic acid did not show a reduction in flux for virgin and modified membranes. However, a substantial reduction in flux was observed with the addition of 3.775 mM CaCl2 into the solution due to the formation of complexes with humic acid and consequent particles coagulation and precipitation on the membrane surface. Although both virgin and modified membranes showed similar fouling behaviors, a significantly higher flux recovery was found for modified membrane compared to the virgin membrane. (c) 2012 Elsevier B.V. All rights reserved.