Production of Magnetic Photocatalyst Particles of Titanium Dioxide

为了开发二氧化钛磁性光催化剂颗粒的制备工艺，尝试了利用醇钛在乙醇溶剂中的水解反应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钛包覆磁铁矿粒子制备的影响。通过对所制备颗粒的各种表征和对RhoadmineB着色剂的紫外光分解实验，考察了所制备颗粒的热处理条件。主要结果如下：(1)通过连续加水的方法得到了均匀包覆钛的磁铁矿颗粒。(2)通过改变水和醇盐的浓度制备了锐钛矿型的钛涂层。(3)以羟丙基纤维素为分散剂，制得的包覆粒子更加均匀。(4)每1g光催化剂颗粒所需的二氧化钛包覆量大于0.7g。(5)包覆颗粒的加热温度为500℃时，罗丹明B的分解速率最快。得到的颗粒具有足够的磁性，可用于实际应用。(6)磁铁矿芯与钛包覆层之间硅层的存在显著提高了罗丹明B的分解率。(7)由于磁性光催化剂颗粒能在太阳光照射下分解罗丹明B，有望应用于自然环境中的净水工艺。

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.