聚硅酸稳定性的研究

Study on the Stability of Polysilicic Acid

聚硅酸作为一种常用的助凝剂,它的网状立体结构和较高的分子量,使其具有较强的粘结能力和吸附架桥作用。但聚硅酸在短时间内容易形成凝胶而失活,限制了它在水处理中的应用。本文以硅酸钠和硫酸为原料制备聚硅酸,研究了pH值、SiO2浓度、Na+浓度、温度对聚硅酸稳定性的影响,并且通过电子显微镜观察了聚硅酸的形貌。结果表明:降低聚硅酸的pH值、SiO2浓度、Na+浓度和保存温度均可提高聚硅酸的稳定性;聚硅酸的浓度对其形貌有较大的影响,聚硅酸的浓度越大,其聚集单元越大且枝杈越密,越容易聚集成为凝胶;形貌与文献中聚硅酸形态演变以及聚硅酸溶胶转化为凝胶的图像一致。同时,研究得出了各影响因素的适用条件,为聚硅酸的实际应用提供了一定的理论依据。

Polysilicic acid was commonly used as a coagulant,and it had a strong bonding capacity and adsorption bridging action because of its reticulate cubic structure and higher molecular weight.But polysilicic acid was easy to form gel and inactivation in a short time,which limited its application in water treatment.In this paper,polysilicic acid was prepared by sodium silicate and sulfate.The effects of various factors,such as pH value,the concentration of SiO2 and Na＋ and temperature,on the stability of polysilicic acid were studied.The image of polysilicic acid was observed by an electron microscope.The results showed that the stability of polysilicic acid was increased with reducing the pH value,the concentration of SiO2 and Na＋ and storage temperature.The influence of the concentration of SiO2 on the image of polysilicic acid were significant.With the increase of the concentration of polysilicic acid,its aggregation unit and branch was denser and easier to become gel.The images of polysilicic acid were in accordance with the pictures from literature.The applicable conditions about the impact factors were investigated.The results could provide some theoretical basis for the researches and applications of polysilicic acid.