孔径分布和溶液浓度对碳气凝胶电极电吸附除盐性能的影响分析

The influence of pore size distribution of carbon aerogel electrodes and solution concentration on electrosorption desalination

在不同进水浓度下,采用两种比表面积相似但是孔径分布不同的碳气凝胶作为电极进行了一系列电吸附除盐平衡试验.结果表明,随着溶液浓度的变化,不同的孔径分布对碳气凝胶除盐效果影响不一样.其机理为双电层的存在,使得碳气凝胶空隙内的双电层扩散层相互叠加;同时,根据德拜定律,碳气凝胶空隙内的双电层扩散层在不同浓度溶液中厚度不同,从而使得双电层扩散层相互叠加的情况也随浓度变化而变化.这两种作用共同导致了实验结果.当溶液浓度为0.01 mo.lL-1时,选择主要孔径不小于20nm的碳气凝胶电极;当溶液浓度为0.1 mo.lL-1时,应选用主要孔径不小于10nm的材料;当溶液浓度为几mo.lL-1时,则分散层几乎消失,孔径大小对电吸附性能影响几乎不考虑.

This paper introduced a series of eleetrosorption equilibrium experiments to remove ions from aqueous solution of different concentrations, using two kinds of carbon aerogels as the electrodes which possess similar surface areas and different pore size distributions. The results show that the influence of pore size distribution on desalination varies in different solution concentrations. The reason lies in the combination of two mechanisms ： the diffuse layers of electric double layers in pores of carbon aerogels overlap each other, and, according to the Debye-Huckel theory, the length of diffuse layers varies with the solution concentration. To improve the ions removal, the aerogel carbon of the main pore size no less than 20 nm can be the best choice when the solution concentration is 0.01mol. L^ - 1 , and we should chose the aerogel carbon of the main pore size no less than 10 nm if the solution concentration is about 0. 1mol·L^-1 The pore size distribution has little effects on the desalination, when the solution concentration increases to several mol·L^-1 .