摘要:
使用正硅酸乙酯(TEOS)作为硅源,采用溶胶-凝胶法在钛白粉表面包覆致密SiO2膜层,对包膜过程的主要影响因素进行研究。用SiO2沉积量和酸溶率综合评价包覆效果,确定了最佳包覆条件。使用胺类分散剂,采用并流加料方式,打浆浓度为200 g/L,温度为60℃,催化剂氨水添加量为4%,水醇比为1:6.9时,达到最佳包覆效果。对比研究发现TEOS比硅酸钠包膜产物显示出更低的酸溶率和光催化活性,表明TEOS包覆的SiO2膜层具有更高的致密度,包膜产物耐候性更高。红外光谱和扫描电镜表征确定了SiO2膜层以化学键合的方式包覆于TiO2表面。使用电导率测定方法分析了包膜过程的机理。
Abstract:
Dense SiO2 film was coated on TiO2 pigment by sol-gel method using ethyl orthosilicate(TEOS) as silica source.The effects of main factors on the coating process were studied.Through evaluating the coating results by SiO2 deposition quantity and acid solubility,the optimum parameters were determined.The most excellent coating effect can be obtained with amines as dispersant,parallel flow feeding mode,200 g/L of TiO2 concentration,60℃ of temperature,4% of ammonia amount added as catalyst and 1:6.9 of volume ratio of water to alcohol.Compared with the product coated by sodium silicate,the product coated with TEOS shows lower acid solubility and photocatalytic activity,indicating more compact film and better weatherability for the product coated with TEOS.SiO2 layer is proved to be coated on TiO2 particles via chemical bonding by fourier transformation infrared spectrum(FT-IR) and scanning electron microscopy(SEM) characterizations.Finally,the mechanism for coating process was analyzed based on the results of conductivity tests.
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