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.

通过共沉淀法制备的铁钛复合催化剂，在黑光灯辐照条件下用于偶氮染料酸性红8的非均相光芬顿（photo-Fenton）降解性能评价。针对钛含量各异（0 < Ti/Fe < 0.6）的催化剂样品，分别采用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（specific surface area）测试以及X射线光电子能谱法（X-ray photoelectron spectroscopy）进行了表征分析。钛含量最低的催化剂样品主要物相为赤铁矿（hematite），而高钛含量样品的主要物相则为钛磁赤铁矿（titanomaghemite）。无钛催化剂展现出最高的染料降解效率，这是由于铁溶出引发了均相反应。添加钛后反应转为非均相过程，当Ti/Fe比值为0.40时降解效率达到峰值：在pH 5.6、过氧化氢（H₂O₂）投加浓度为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，该性能至少为低钛含量催化剂的三倍。实验结果表明，钛能够稳定催化剂结构，并提升其在光芬顿过程中的非均相催化活性。