PVA/nano-TiO_2杂化膜的制备与碱回收性能研究

PVA/nano-TiO_2 hybrid membranes:Preparation and application for alkali recovery

利用γ-巯丙基三乙基硅烷（γ-MPTS）对纳米氧化钛颗粒（p-TiO2）进行了表面修饰引入巯基（—SH）,采用双氧水氧化的方法制备了表面带有—SO3H的纳米氧化钛颗粒（sTiO2）.利用溶液共混的方式将s-TiO2和预交联的PVA溶液混合后涂覆成膜,制备了一系列PVA/nano-TiO2有机-无机杂化膜.对杂化膜的结构测试结果表明其具有良好的机械稳定性,热稳定性和耐碱性：拉伸强度为37.0~53.4MPa,断裂伸长率为43.2%~146.0%;65℃碱液中的溶胀度为205.4%~220.2%,质量损失为10.0%~15.9%.制备的杂化膜含水量（WR）为90.9%~105.6%,离子交换容量（IEC）为0~0.025mmol/g.利用NaOH/Na2WO4体系模拟扩散渗析回收NaOH的结果表明：25℃时OH-渗析系数为0.013~0.015m/h,分离系数为21.8~30.1.

In this research, surface of pure titanium dioxide nanoparticles （p-TiO2）was modified with 3- mercaptopropyltriethoxysilane （γ-MPTS） to introduce -SH firstly and then hydrogen peroxide （Hz O2） was used as a green oxidizing agent to introduce -SO3 H. After that a series of PVA/nano-TiO2 hybrid membranes were prepared by blending s-TiO2 and pre-crosslinked polyvinyl alcohol （PVA） solution directly. The as-prepared membrane were thermally and mechanically stable, with tensile strength of 37.0-53.4 MPa and elongation at break of 43.2%-146.0%. Swelling degree of 205.4%-220. 2% and weight loss of 10.0%-15.9% in 65 ℃ 2 mol/L NaOH solution. The membrane possessed water uptake （WR） of 90. 9%-105. 6% and ion exchange capacity （IEC） of 0-0, 025 mmol/g, respectively. The membranes were used for alkali recovery via the system of NaOH/Na2 WO4 based on diffusion dialysis successfully and results showed that dialysis coefficients of OH- （UoH） were in the range of 0. 013-0. 015 m/h, separation factors （S） were in an acceptable range of 21.8-30. 1.