硅溶胶硅酸钾混合物微量热法研究

Studies on the reactions in the combination of silica sol and Potassium Silicate via microcalorimetry

在25.0℃及搅拌条件下,采用等温热导微量热法研究了硅溶胶与硅酸钾的混合过程。结果表明,硅溶胶与硅酸钾混合,立刻发生了SiO2溶解和复杂的化学反应,并产生了完全不同于硅溶胶和硅酸钾的SiO2胶体粒子和化学成分以及热效应,热效应受硅溶胶所占的相对重量百分比的影响。其反应的特征是硅溶胶和硅酸钾的反应级数从低到高时刻都在快速不断交替变化;随着硅溶胶所占比例的提高,热谱曲线峰高、硅溶胶与硅酸钾的混合化学反应完全的曲线总面积(总焓变QT)和热力学焓变(ΔH)数值都表现出不断增大的趋势。

Isothermal heat conduction microcalorimetry is a novel characterization method for silica polymerization, and was adopted to investigate the polymerization processes of silica when the combination of silica sol and potassium silicate was stirred at 25.0℃. The experimental results indicated that chemical reactions occurred immediately in the mixed silica sol and potassium silicate were the dissolution and complex polymerization of silica with heat evolved, which was affected＇by the percentage by weight of silica sol in the mixture, and that colloidal silica particles and their chemical composition were created and distinct fi＇om the silica sol and potassium silicate. The silica polymerization was characterized by the reaction orders of the silica sol and potassium silicate, rapidly, instantaneously, and continued changing from low to high all the time, up and down in an alternate manner. For the mixtures from 53 to 85 wt% silica sol fraction, the peak height of power-time curve, the total enthalpy change （QT） for the mixing reaction when it has gone to completion, and the enthalpy change （AH） showed an increasing trend.