膜科学与技术

炭膜表面疏水改性及老化性能研究

作者：周晓东，李琳，王同华

单位：大连理工大学化工学院精细化工国家重点实验室炭材料研究室膜科学与技术研究开发中心，大连 116024

关键词：溶胶凝胶；疏水炭膜；正硅酸乙酯（TEOS）；甲基三乙氧基硅烷（MTES）；气体分离

出版年,卷(期):页码： 2014,34(4):12-19

摘要：

采用溶胶凝胶法，以正硅酸乙酯（TEOS）和甲基三乙氧基硅烷（MTES）为混合硅源，合成疏水硅溶胶，将其浸渍涂覆在卷式炭膜上，经干燥、热处理制备了具有高疏水性能的疏水炭膜。考察了硅溶胶制备工艺和膜热处理工艺对所制备炭膜疏水性能的影响。采用水接触角测试仪、TG、 FTIR、AFM、SEM和TEM等测试手段，对疏水炭膜的表面结构和疏水性能进行了表征。结果表明，通过硅溶胶表面改性，在炭膜表面引入了甲基化的二氧化硅的表面结构，提高了其疏水性能。硅溶胶的制备工艺对所制备疏水炭膜的表面化学结构、形貌及粗糙度都有较大的影响。其中硅溶胶合成反应温度对提高膜表面疏水性能的影响最为显著；膜表面甲基基团含量对改善炭膜表面的疏水性能起到决定性作用。通过控制硅溶胶合成和膜的热处理工艺可以有效地调控疏水炭膜的表面疏水性能；在最佳条件下制备的疏水炭膜，其表面粗糙度为34.263nm；水接触角达到138°左右，表现出良好的疏水性能。在最佳工艺条件下制备疏水炭膜，并对其气体渗透性能和老化性能进行测试，气体渗透性能测试结果表明炭膜表面疏水层的引入对原始炭膜的气体渗透性能影响较小，其中O2渗透通量降低了13%，O2/N2选择性提高了18%，老化实验结果表明疏水改性炭膜具有良好的耐老化性能，其在相对湿度为60%条件下放置30天后，O2渗透通量下降了34.7%，而原始炭膜O2渗透通量下降量超过90%，可以发现尽管疏水炭膜较原始炭膜通量有所下降，但是总体看来疏水改性有效地改善了炭膜的老化问题，延长了炭膜的使用寿命。

The hydrophobic carbon membranes were prepared by coating the methylated silica sol, which was prepared by sol-gel method using the tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as silica sources, on the carbon membrane and calcinating at 400-600℃ in the N2 atmosphere. The effects of silica sol preparation and membrane calcination condition on the hydrophobicity of carbon membranes were investigated. The surface structure and morphology of the hydrophobic carbon membrane were characterized by TG, FTIR, AFM, SEM and TEM. The results show that the hydrophobicity of carbon membranes is greatly improved by introducing the methylated silica structure onto the carbon membrane via silica sol. The preparation conditions of silica sol, especially the reaction temperature, have great influence on the surface chemical structure, morphology and roughness of hydrophobic carbon membrane. The contents of Methyl group on the membrane surface play a decisive role in the improvement of hydrophobic properties of carbon membranes. The hydrophobicity of carbon membranes can effectively tuned by controlling the preparation condition of silica sol and membrane calcination condition. The hydrophobic carbon membrane prepared under the optimum conditions exhibits an excellent hydrophobicity. Its surface roughness is 34.263nm and water contact angle is 138°. Aging experiment results show that hydrophobic modification greatly reduces water activity on the surface of the carbon membrane, improves the aging problem of carbon membrane and prolonges the service life of the carbon membrane. O2 permeation flux of hydrophobic carbon membrane can still keep around 65% of the original flux after 30 days under the condition of 60% relative humidity, while O2 permeation flux of original carbon membrane dropped to 10% of the original flux under the same condition.

周晓东(1988-)，男，安徽芜湖人，硕士生，从事炭膜材料的研究

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