Feng Jiyun, Hu Xijun, Yue Po Lock
Department of Chemical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Environ Sci Technol. 2004 Nov 1;38(21):5773-8. doi: 10.1021/es049811j.
Four heterogeneous catalysts containing Fe including a bentonite-clay-based Fe nanocomposite (Fe-B), hematite (alpha-Fe2O3), amorphous FeOOH, and calcined FeOOH (denoted as FeOOH-M) were employed for the photo-Fenton discoloration and mineralization of 0.2 mM Orange II in the presence of 10 mM H2O2 and 8 W UVC at two different initial solution pH values (3.0 and 6.6). It was found that, at an initial solution pH of 3.0, their photocatalytic activities follow the order Fe-B > FeOOH, FeOOH-M > alpha-Fe2O3. When the Fe-B nanocomposite, FeOOH, and FeOOH-M were used as heterogeneous catalysts, both heterogeneous and homogeneous photo-Fenton reactions were responsible for the discoloration and mineralization of 0.2 mM Orange II because homogeneous photo-Fenton reaction occurred due to the presence of Fe ions leached from the catalysts. At an initial solution pH of 6.6, their photocatalytic activities still follow the order Fe-B > FeOOH, FeOOH-M >> alpha-Fe2O3. However, only heterogeneous photo-Fenton reaction accounted for the discoloration and mineralization of 0.2 mM Orange II because Fe leaching from the catalysts was significantly depressed. In the case of alpha-Fe2O3 as a catalyst, whether at an initial solution pH of 3.0 or 6.6, only heterogeneous photo-Fenton reaction happened for the discoloration and mineralization of 0.2 mM Orange II because Fe leaching from the catalyst is negligible. The apparent discoloration kinetics of Orange II with the four catalysts at two different initial solution pH values was also investigated.
采用了四种含铁的非均相催化剂，包括膨润土 - 粘土基铁纳米复合材料（Fe - B）、赤铁矿（α - Fe₂O₃）、无定形FeOOH和煅烧FeOOH（记为FeOOH - M），在10 mM H₂O₂和8 W UVC存在的条件下，于两个不同的初始溶液pH值（3.0和6.6）下对0.2 mM橙黄II进行光芬顿褪色和矿化反应。结果发现，在初始溶液pH为3.0时，它们的光催化活性顺序为Fe - B > FeOOH、FeOOH - M > α - Fe₂O₃。当使用Fe - B纳米复合材料、FeOOH和FeOOH - M作为非均相催化剂时，非均相和均相光芬顿反应都对0.2 mM橙黄II的褪色和矿化起作用，因为催化剂中浸出的铁离子引发了均相光芬顿反应。在初始溶液pH为6.6时，它们的光催化活性仍然遵循Fe - B > FeOOH、FeOOH - M >> α - Fe₂O₃的顺序。然而，由于催化剂中铁的浸出显著降低，只有非均相光芬顿反应导致了0.2 mM橙黄II的褪色和矿化。以α - Fe₂O₃作为催化剂时，无论初始溶液pH是3.0还是6.6，对于0.2 mM橙黄II的褪色和矿化仅发生非均相光芬顿反应，因为催化剂中铁的浸出可忽略不计。还研究了在两个不同初始溶液pH值下，四种催化剂对橙黄II的表观褪色动力学。
