Several industrial processes make use of dyes in order to impart colour into their products. These processes release large amounts of dye-containing wastewater which can be hazardous to human health and the environment. This has necessitated the development of cheap, reliable and sustainable technologies that can remediate the effluent, heterogeneous TiO₂ photocatalysis is one such technology that has proven successful. Different polymorphs of TiO₂ exist and literature suggests that the photocatalytic efficiency of various phases depends on the target pollutant. This study investigated the photocatalytic degradation of methylene blue (MB) dye using of three commercial TiO₂ powders with different crystal phases as catalysts. The materials properties for each catalyst were first determined using x-ray diffraction and microscopy. Degradation studies were then conducted on 10 ppm MB solutions using the three powders. Degussa P25 TiO₂, a mixture of anatase and rutile was the most efficient compared to the neat anatase and rutile powders, degrading 81.4% of the MB. This catalyst was chosen for optimisation studies, where 95% degradation was achieved at a 0.5 g/L catalyst loading and pH of 10. The degree of mineralisation decreased with increasing MB concentration. The effect of metal doping on the photocatalytic performance of the catalyst was also investigated. Copper doping increased degradation by 2% whilst zinc reduced it to 90%. The complete decolourisation of the MB coupled with the significant decrease in TOC upon completion of the degradation process, indicate that Degussa P25 catalysed photocatalysis is a viable pre-treatment technology in dye contaminated wastewater treatment.

为了将颜色赋予其产品，几种工业过程利用染料。这些过程释放出大量的含染料废水，可能对人体健康和环境有害。这就需要开发廉价，可靠和可持续的技术来补救废水，非均相的TiO ₂光催化就是一种成功的技术。TiO ₂存在不同的多晶型物，并且文献表明各相的光催化效率取决于目标污染物。这项研究研究了使用三种市售TiO ₂对亚甲基蓝（MB）染料的光催化降解具有不同晶相的粉末作为催化剂。首先使用X射线衍射和显微镜确定每种催化剂的材料性能。然后使用这三种粉末对10 ppm MB溶液进行降解研究。德固赛P25 TiO ₂与纯锐钛矿和金红石粉末相比，锐钛矿和金红石的混合物效率最高，降解了MB的81.4％。选择该催化剂进行优化研究，在0.5 g / L的催化剂负载量和pH值为10的条件下可实现95％的降解。矿化度随MB浓度的增加而降低。还研究了金属掺杂对催化剂光催化性能的影响。铜掺杂增加了2％的降解，而锌减少了90％。MB的完全脱色，以及降解过程完成后TOC的显着降低，表明Degussa P25催化的光催化是一种在染料污染的废水处理中可行的预处理技术。