硅铝包覆钛白粉水悬浮液pH值调控规律

pH control of suspensions of titania coated with silica and alumina

研究了钛白粉经过氧化硅、氧化铝包膜后的水悬浮液pH值和颗粒表面电位特性的变化。实验获得连续、均匀、致密的无机氧化物膜状包覆,膜层厚度随包覆量增加而增加。根据国家标准GB/T1706—2006中的测定方法,将包膜后钛白粉制成质量分数为10%的悬浮液,检测悬浮液pH值随包覆量的变化。结果表明:钛白粉经氧化硅和氧化铝表面包膜处理后,水悬浮液pH值偏离中性;包氧化硅后钛白粉悬浮液呈碱性,随包覆量增加,pH值增高直至pH9.7;包氧化铝后钛白粉悬浮液呈酸性,随包覆量增加,pH值降低直至pH4.4。颗粒表面包覆量对颗粒表面的ζ电位的影响与pH值相似。通过对包硅产品进行微量包铝、或对包铝产品进行微量包硅能够有效调控最终包覆产品水悬浮液的pH值。

pH control of suspensions of titania coated with silica and alumina has been investigated. The experimental results show that SiO2 and Al2O3 can form a dense film coating on the titania particle surfaces,and the film became thicker as the amount of coating material was increased. According to GB/T 1706—2006,the samples were formed into aqueous suspensions at a concentration of 10% by weight. pH measurements showed that the suspension of titania coated with SiO2 is alkaline,and the pH increases with coating amount up to pH 9.7. In contrast,the suspension of titania coated with Al2O3 is acid,and the pH decreases with coating amount down to pH 4.4. The zeta potential was also affected by the surface coating in a similar way to the pH. The pH of the suspension can be controlled effectively by a thin coating of alumina on silica-coated particles,and a thin coating of silica on alumina-coated particles.