Degradation of Acid Red 8 Dye Using Photo-Fenton Reaction Mediated by Titanium Modified Catalysts

Catalysts prepared by co-precipitation of iron and titanium were evaluated in heterogeneous photo-Fenton degradation of the azo dye Acid Red 8 under blacklight irradiation. Materials with different titanium contents (0 < Ti/Fe < 0.6) were characterized using X-ray diffractometry, scanning electron microscopy, X-ray fluorescence spectroscopy, specific surface area and X-ray photoelectron spectroscopy. Hematite was identified as main phase in materials with lowest Ti content, while titanomaghemite was predominant at high Ti content. Highest degradation was obtained using titanium free catalyst due to iron leaching, which promoted a homogeneous reaction. Addition of Ti led to a heterogeneous process with a maximum when Ti/Fe = 0.40 achieving 0.76 mol of dye mineralized per mol of soluble iron after 90 min, using 10 mmol L-1 H2O2 at pH 5.6, value at least three times higher than that observed for catalysts with lower Ti content. The results indicate that Ti stabilizes the catalyst and increases its heterogeneous activity in photo-Fenton process.

采用共沉淀法制备铁钛双金属催化剂，并于黑光灯辐照条件下，对其在偶氮染料酸性红8（Acid Red 8）的非均相光芬顿（photo-Fenton）降解过程中的催化活性进行评价。针对不同钛含量（0 < Ti/Fe < 0.6）的催化剂样品，采用X射线衍射法（X-ray diffractometry）、扫描电子显微镜（scanning electron microscopy）、X射线荧光光谱法（X-ray fluorescence spectroscopy）、比表面积分析以及X射线光电子能谱（X-ray photoelectron spectroscopy）进行了表征。赤铁矿（Hematite）为低钛含量样品的主要晶相，而钛磁赤铁矿（titanomaghemite）则在高钛含量样品中占主导地位。无钛催化剂展现出最高的降解效率，这是由于其铁溶出现象促进了均相反应的发生。引入钛元素后，反应转为非均相过程；当Ti/Fe摩尔比为0.40时降解效果达到峰值：在pH 5.6、过氧化氢（H₂O₂）浓度为10 mmol·L⁻¹的条件下反应90分钟后，每摩尔可溶性铁可矿化0.76摩尔染料，该值至少为低钛含量催化剂的3倍。实验结果表明，钛元素可稳定催化剂结构，并提升其在光芬顿反应中的非均相催化活性。