电解法研究DF988膜对钠离子的水传递数
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摘要
离子膜电解过程中,水分子伴随阳离子通过离子膜而发生移动的现象称为水的电渗透或水传递.简要介绍了国产DF988离子交换膜的结构.通过傅立叶红外光谱(ATR-FTIR)对DF988膜表面进行分析,表明其一侧为磺酸层另一侧为羧酸层即阻挡层.采用自制的电解测试装置对DF988膜的水传递进行了较为系统的实验研究,测定了不同条件下的水传递数和氢氧化钠中氯化钠含量,包括阳极液浓度、阴极液浓度、电流密度和温度等条件.结果表明,电解液浓度对水传递数有明显的影响,水传递数随盐水浓度的降低有明显的增大;而电流密度和温度等则对氢氧化钠中含氯化钠的量影响明显.
In the process of ion-exchange membrane electrolysis,ions passing through an ion exchange membrane are accompanied by a solvation shell of water molecules,which is known as the electro-osmotic water flux or water transfer phenomenon.The structure of domestic DF988 ion-exchange membrane was introduced briefly.The attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectra revealed that DF988 membrane do contain a sulfonic polymer layer and a carboxylic layer,the barrier layer.Research on water transfer phenomenon is conducive to understand the transference performance of DF988 membrane.The water transfer was investigated systematically using self-made electrolysis equipment.The water transfer number(tw) and the sodium chloride content in NaOH were determined under different conditions,including anolyte concentration,catholyte concentration,current density and temperature.The results show that water transfer number was remarkably affected by the concentration of the electrolytes.The decreasing of anolyte concentration can increase the water transfer number.While the current density and temperature have an obvious influence on the sodium chloride content in NaOH.
In the process of ion-exchange membrane electrolysis,ions passing through an ion exchange membrane are accompanied by a solvation shell of water molecules,which is known as the electro-osmotic water flux or water transfer phenomenon.The structure of domestic DF988 ion-exchange membrane was introduced briefly.The attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectra revealed that DF988 membrane do contain a sulfonic polymer layer and a carboxylic layer,the barrier layer.Research on water transfer phenomenon is conducive to understand the transference performance of DF988 membrane.The water transfer was investigated systematically using self-made electrolysis equipment.The water transfer number(tw) and the sodium chloride content in NaOH were determined under different conditions,including anolyte concentration,catholyte concentration,current density and temperature.The results show that water transfer number was remarkably affected by the concentration of the electrolytes.The decreasing of anolyte concentration can increase the water transfer number.While the current density and temperature have an obvious influence on the sodium chloride content in NaOH.
引文
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[2]王伟红,邢家悟.离子膜交换膜技术在氯碱行业应用与发展[J].膜科学与技术,2002,22(6):54-58.
[3]张永明.全氟离子交换膜的研究和应用[J].膜科学与技术,2008,28(3):1-4.
[4]高自宏,王学军,张恒,等.氯碱用国产离子膜研发及应用[J].氯碱工业,2010,46(10):11-16.
[5]张永明,李虹,张恒.含氟功能膜材料[M].北京:化学工业出版社,2008:372.
[6]程鹏里.隔膜电解法测定离子水化数[J].物理化学学报,1985,1(6):579-585.
[7]Heitner W C.Recent advances in perfluorinated iono-mer membranes:Structure,properties and applications[J].J Membr Sci,1996,120:1-33.
[8]Kenneth A M,Robert B M.State of understanding ofNafion[J].Chem Rev,2004,104:4535-4585.