摘要
以激光动态光散射法考察了气相SiO2在不同pH值的H2SO4和NaOH介质中的分散平均水化粒径与表面Zeta电位及二者间的关系。Zeta电位数据表明,气相SiO2在水中分散的表面硅羟基的等电点(IEP)和滴定终点(TE)的pH值分别为pH(IEP)=2.09和pH(TE)=7.47,利用滴定终点pH(TE)给出了一种简单的气相SiO2表面Si-OH浓度的测定方法。分散相粒径数据显示,在等电点和滴定终点之间,气相SiO2在水中的分散粒子的粒径能够稳定在230 nm附近;在H2SO4介质中,当pH<pH(IEP)时,随着H2SO4浓度的增大,体系中的分散粒子发生聚结而使表观粒径增大;在NaOH介质中,当pH>pH(TE)时,随着NaOH浓度的增大,分散相的表观水化粒径降低,表明NaOH的加入有利于气相SiO2的分散。
The effect of pH on the particle distribution and zeta potential of the fumed silica（SiO2） suspended in H2SO4 or NaOH aqueous solution and their relationship were investigated with laser dynamic light scattering（DSL）.The experiment showed that the isoelectric point（IEP） and titration end（TE） of silanol were at pH（IEP）=2.09 and pH（TE）=7.47,respectively,and a simple method was given for the determination of Si-OH concentration on SiO2 particle surface based on pH（TE）.The dispersed phase particle size measurement showed that between IEP and TE,the hydration radius of SiO2 was stabilized near 230 nm;in H2SO4 medium,when pHpH（IEP）,the apparent hydration radius of SiO2 increased with the increased H2SO4 concentration due to the coalescence of dispersed SiO2 aggregates;in NaOH medium,when pHpH（TE）,the SiO2 aggregates decomposed and the apparent size of the dispersed phase decreased with increasing the NaOH concentration,which showed that NaOH can promote the dispersion stability of fumed silica in aqueous.
出处
《应用化学》
CAS
CSCD
北大核心
2011年第12期1448-1452,共5页
Chinese Journal of Applied Chemistry
基金
福州大学科技发展基金(2008-XQ-09)
福州大学人才基金(XRC-0820)
福州大学博士后科研启动基金资助项目
