Production of Magnetic Photocatalyst Particles of Titanium Dioxide

为开发磁性二氧化钛光催化剂颗粒的制备工艺，尝试利用钛醇盐在醇类溶剂中水解制备包覆二氧化钛的磁铁矿颗粒。研究了醇盐和水的浓度对制备钛包覆磁铁矿颗粒的影响。通过对所制备颗粒的各种表征和RhoadmineB染料的紫外光分解实验，考察了所制备颗粒的热处理条件，得到的主要结果如下：（1）通过连续加水，可以得到均匀的钛包覆磁铁矿颗粒。(2)通过改变水和醇盐的浓度，制备出了致密型钛涂层。(3)羟丙基纤维素作为分散剂的使用使得钛涂层颗粒更均匀。(4)分解罗丹明B所需的二氧化钛的涂覆量大于0.7g/1g光催化剂颗粒。(5)若丹明B的分解速度最快的包覆颗粒加热温度为500℃。所获得的颗粒具有足够的磁性以用于实际应用。(6)在磁铁矿核与钛包覆层之间存在二氧化硅层，可显著提高罗丹明B的分解速率。(7)预期所获得的磁性光催化剂颗粒可以应用于自然环境中的水净化过程，因为该颗粒可以在太阳光下分解罗丹明B。

To develop the production process of magnetic photocatalyst particles of titanium dioxide, the preparation of magnetite particles coated with titanium dioxide were attempted by using the hydrolysis of titanium alkoxide in alcohol solvent. The effect of the concentrations of alkoxide and water on the preparation of titanic coating magnetite particles was investigated. From the various characterizations of the particles prepared and the decomposition experiments of a RhoadmineB colorant by an ultraviolet irradiation, the heating treatment conditions of the particles prepared were also examined.The principle results obtained are as follows : (1) The uniform titanic coating magnetite particles were obtained by the continuos addition of water. (2) The titanic coating layer of anatase type was prepared by the variation of water and alkoxide concentrations. (3) The use of hydroxypropyl cellulose as a dipersant made more uniform titanic coating particles. (4) The coating amount of titanium dioxide required to decompose RhodamineB was greater than 0.7g per the photocatalyst particles 1g. (5) The heating temperature of the coating particles to give the fastest decomposition rate of RhodamineB was 500℃. The particles obtained had magnetism enough for practical usage. (6) The existence of silica layer between magnetite core and titanic coating layer increased remarkably the decomposition rate of RhodamineB.(7) It is expected that the magnetic photocatalyst particles obtained can be applied to a water purification process in natural environment because the particles can decompose RhodamineB under the sun's rays.