The UV/Fenton Degradation of Tetrabromobisphenol A Catalyzed by Nanocrystalline Chromium Substituted Magnetite
作者:Yuanhong Zhong、Xiaoliang Liang、Zisen He、Wei Tan、Hongping He、Runliang Zhu、Yin Zhong、Jianxi Zhu、Peng Yuan、Zheng Jiang
DOI:10.1166/jnn.2014.8967
日期:2014.9.1
The heterogeneous UV/Fenton degradation of tetrabromobisphenol A (TBBPA) catalyzed by nanocrystalline Fe3O4 and Fe2.04Cr0.96O4 was investigated, with focus on the influence of UV light and initial pH, degradation pathways and effect of Cr substation. The catalysts were prepared by a precipitation-oxidation method and characterized by chemical analysis, XRD, XAFS, TG-DSC, BET surface area and magnetometer. At pH 6.7 and under UV irradiation, almost complete degradation of TBBPA by Fe2.04Cr0.96O4 was accomplished within 240 min, and the leaching Fe ions were negligible. The substitution of chromium greatly increased the BET specific surface area and surface hydroxyl amount, which improved the heterogeneous UV/Fenton catalytic activity of magnetite. Moreover, Cr3+ on the octahedral sites enhanced the electron transfer process in the magnetite structure to accelerate the •OH generation. The produced •OH radicals preferentially attacked the C—Br bonds of TBBPA and then β-cleavaged the C—C bonds between benzene rings and isopropyl groups. The above results are of great significance for well understanding the effect of transition metal substitution on the UV/Fenton catalytic activity of magnetite and prospecting the application of magnetite minerals in environmental purification.
研究了纳米晶 Fe3O4 和 Fe2.04Cr0.96O4 催化四溴双酚 A(TBBPA)的紫外/芬顿异相降解,重点考察了紫外光和初始 pH 值的影响、降解途径以及铬的亚基效应。催化剂采用沉淀氧化法制备,并通过化学分析、XRD、XAFS、TG-DSC、BET 表面积和磁力计进行表征。在 pH 值为 6.7 和紫外线照射条件下,Fe2.04Cr0.96O4 在 240 分钟内几乎完全降解了 TBBPA,且浸出的铁离子可以忽略不计。铬的取代大大增加了磁铁矿的 BET 比表面积和表面羟基量,提高了磁铁矿的异相紫外/芬顿催化活性。此外,八面体位点上的 Cr3+ 增强了磁铁矿结构中的电子传递过程,加速了 -OH 的生成。生成的 -OH 自由基优先攻击 TBBPA 的 C-Br 键,然后β-裂解苯环和异丙基之间的 C-C 键。上述结果对于深入理解过渡金属取代对磁铁矿紫外/芬顿催化活性的影响,以及探索磁铁矿在环境净化中的应用具有重要意义。