铝酸钠溶液的电导率与结构的关系

Relationship Between Electric Conductivity and Ion Structure of Sodium Aluminate Solution

通过测定不同浓度Na2O和苛性比(αk)的铝酸钠溶液的电导率,计算了不同Na2O浓度下铝酸根阴离子的迁移数,结合铝酸钠溶液的红外光谱表征,研究了铝酸钠溶液的电导率与结构的关系.研究结果表明,低浓度铝酸钠溶液[c(Na2O)<175g/L]中,铝酸根阴离子的迁移数约为0.6,其离子结构主要为Al(OH)4-;中等浓度溶液[c(Na2O)=175～330g/L]中,铝酸根阴离子的迁移数约为0.2,其离子结构主要为Al(OH)4-和[Al2(OH)8(H2O)2]2-;而高浓度溶液[c(Na2O)>330g/L]中,铝酸根阴离子的离子迁移数接近于0,对应的离子结构主要是Al2O(OH)62-,[Al2(OH)8(H2O)2]2-和少量Al(OH)4-.说明铝酸根离子的导电能力与结构密切相关.

A better understanding of the relationship between transference number of aluminate anions（t） and the structure of sodium aluminate solutions is of great significance for strengthening and optimizing the alumina production technologies.Combining with the characterization of FTIR analyses of the solution,the intrinsic relationship between the electric conductivity and the structure of sodium aluminate solutions was investigated by measuring the electric conductivity of the solution and calculating t in the solution of different alkali concentration and molar ratio of Na2O to Al2O3.The results show that in the solution of low concentration of c（Na2O）175 g/L,the aluminate anions dominantly exist in the form of Al（OH）-4 and t is approximately 0.6;that in the solution of medium concentration of c（Na2O） from 175 g/L to 330 g/L,the aluminate anions mainly exist in the form of Al（OH）-4 and [Al2（OH）8（H2O）2]^2-,in which t is approximately 0.2;and that in the solution of high concentration of c（Na2O）330 g/L,aluminate anions exist dominantly in the form of Al2O（OH）6^2- and [Al2（OH）8（H2O）2]^2-with a little Al（OH）4^-,where t is almost zero.This illustrates that the electric conduction ability of the aluminate anion in the sodium aluminate solution is closely related to its structure.