硝酸对溶胶-凝胶法制备AlOOH胶粒粒度的影响

Influence of HNO_(3)on Particle Size of AlOOH Sol Prepared by Sol-Gel Method

为获得孔径可控的氧化铝滤膜,以异丙醇铝为原料,硝酸为胶溶剂,使用溶胶-凝胶法制备了AlOOH溶胶,并通过纳米粒度仪、Zeta电位等表征手段,研究了硝酸用量对AlOOH胶粒粒度及粒度分布的影响。结果表明,硝酸与异丙醇铝摩尔比R(n(HNO_(3))∶n(Al(C_(3)H_(7)O_(3))_(3)))为0.2~0.7时,随着R增大,AlOOH胶粒的平均粒径从66.69 nm(R=0.2)增大到138.80 nm(R=0.7),其粒度分布曲线的半高宽(FWHM)由144.62 nm增加到267.74 nm。AlOOH溶胶的粒度增大不是由颗粒团聚引起的,而是硝酸加入增大了异丙醇铝水解反应常数,使单位体积内能发生缩聚的中间产物增加,从而促进了AlOOH胶粒的生长。

To obtain an alumina filter membrane with a controllable pore size,AlOOH sol was prepared by the sol-gel method with aluminum isopropoxide used as the raw material and HNO_(3)as the peptizer.The influence of the amount of HNO_(3)on the particle size distribution of AlOOH colloidal particles was studied through nano-particle size analysis and Zeta potential measurement.The results show that when the ratio of HNO_(3)to aluminum isopropoxide R(n(HNO_(3))∶n(Al(C_(3)H_(7)O_(3))_(3)))is in the range of 0.2 to 0.7,the average particle size of the colloidal particles increases with the increase of R,from 66.69 nm(R=0.2)to 138.80 nm(R=0.7).The full width at half maxima(FWHM)of the particle size distribution of the colloidal particles increased from 144.62 nm to 267.74 nm.The reason for the increase of the particle size of AlOOH sol isn’t the agglomeration of particles,but the increase of the hydrolysis reaction constant of aluminum isopropoxide,which increases the total amount of the intermediate products per unit volume involved in the polycondensation reaction,thereby promoting the growth of AlOOH colloidal particles.