氯氧铁非均相催化过氧化氢降解罗丹明B

传统芬顿(Fenton)法因反应pH值低、产生大量铁泥等限制其规模化应用.采用化学气相转变法制备氯氧铁(FeOCl)纳米片,选择罗丹明B为模型污染物,研究FeOCl作为类芬顿催化剂催化过氧化氢(H_2O_2)降解罗丹明B性能.通过扫描电镜(FE-SEM)和X射线衍射光谱(XRD)等表征结果显示,FeOCl晶型结构完整、呈现纳米片状,可充分暴露催化活性位点.罗丹明B降解实验结果表明,H_2O_2投量为1. 67 mmol·L~(-1)时,投加200 mg·L~(-1)FeOCl,可使得罗丹明B去除率由15. 5%提高至100%(15 min). FeOCl的催化性能随pH升高而降低,初始pH为3、5和7时,反应15 min后罗丹明B去除率分别为100%、100%和84. 0%,初始pH提升至9,去除率则显著降低至57. 6%.与传统Fenton法比较,FeOCl催化H_2O_2的pH值范围明显拓展,在弱酸性和中性条件下表现出优良的催化性能.自由基淬灭实验表明,FeOCl/H_2O_2体系催化降解罗丹明B起主要作用的是羟基自由基(·OH).电子自旋共振波谱仪测定(EPR)结果表明,单独H_2O_2体系未检测出明显的自由基信号,而投加FeOCl使得·OH信号显著增强,·OH是降解罗丹明B的主要氧化活性物种.

Catalytic Degradation of Rhodamine B by FeOCl Activated Hydrogen Peroxide

The wide application of traditional Fenton reactions was firmly restricted by the requirement for harsh acid conditions, as well as the inevitable generation of iron slurry. The FeOCl nanosheets, prepared by the chemical vapor transformation method, were used to degrade RhB via activation of H₂O₂. The FeOCl was characterized by a field emission scanning electron microscope (FE-SEM) and X-Ray Diffractometer (XRD), the results showed that FeOCl exhibited a fine crystal structure and nanosheet-like morphology, which was favorable for exposure of active sites. The results of degradation experiments showed that the RhB was totally removed within 15 min under the conditions ofH₂O₂]=1.67 mmol·L^-1 andFeOCl]=200 mg·L^-1. The initial pH plays a negative role in RhB degradation, and the initial pH increased from 3 to 7 as the RhB removal efficiency decreased from 100% to 84%. Typically, when the initial pH was 9, the RhB degradation sharply decreased to 57.6%. Compared with traditional Fenton reactions, the FeOCl/H₂O₂ system widened the pH range, which resulted in superior organics removal even under a mild-acidic to medium pH condition. The quenching experiments demonstrated that the·OH was the major reactive oxygen species. Additionally, Electron Paramagnetic Resonance (EPR) results showed that intense DMPO-HO·signals were detected in the FeOCl/H₂O₂ system, which further demonstrated the important role of·OH in RhB degradation.