Weiling Piao, Wenjing Sun, Danyang Yu, Wanying Zhang, Huangzhao Wei, Chenglin Sun*
Catalyst. Environ Sci Pollut Res 30, 108135–108149 (2023)
https://doi.org/10.1007/s11356-023-29512-7
ABSTRACT: Iron-loaded zeolite (Fe-zeolite) has shown great potential as an efficient catalyst for degrading organic pollutants with high concentrations in the catalytic wet peroxide oxidation (CWPO) process under mild conditions. Here, 0.4 wt% Lanthanum (La) was added in the 1.0 wt% Fe-ZSM-5 by two-step impregnation method for an enhanced H2O2 utilization efficiency. For a systematical comparison, the CWPO process at 55 °C, where m-cresol with a high concentration of 1000 mg/L as a substrate, was studied over Fe-ZSM-5 and Fe-La-ZSM-5 catalysts. Compared with Fe-ZSM-5, Fe-La-ZSM-5 showed 15% higher H2O2 utilization efficiency with comparable total organic carbon (TOC) removal at around 40%, meanwhile with a 15% reduced metal leaching. Transmission electron microscopy (TEM) with elemental mapping (EDS), surface acidity analysis by Fourier transform infrared (FT-IR) and NH3-temperature programmed desorption (NH3-TPD), redox property analysis by Raman spectroscopy and H2-temperature-programmed reduction (H2-TPR) of both catalysts revealed, that the La doped Fe-ZSM-5 can provide an altered surface acidity, a more uniform and evenly dispersed surface Fe species with a promoted reducibility, which effectively promoted the accurate decomposition of H2O2 into the reactive •OH radicals, enhanced the H2O2 utilization efficiency, and increased the catalyst stability. Also, more than 90% conversion was maintained during the continuous experiment for more than 10 consecutive test days under 55 °C without pH adjustment, showing a promising possibility of the Fe-La-ZSM-5 for a practical wastewater treatment process.
摘要：铁负载分子筛（Fe-分子筛）作为一种高效催化剂，在温和条件下的催化湿式过氧化氢氧化（CWPO）过程中，对降解高浓度有机污染物展现出巨大潜力。本研究通过两步浸渍法在1.0 wt%的Fe-ZSM-5催化剂中掺入0.4 wt%的镧（La），以提升H₂O₂的利用效率。在55 °C条件下，以高浓度间甲酚（1000 mg/L）为底物，系统对比了Fe-ZSM-5和Fe-La-ZSM-5催化剂在CWPO过程中的性能。结果表明，与Fe-ZSM-5相比，Fe-La-ZSM-5在总有机碳（TOC）去除率相当（约40%）的情况下，H₂O₂利用效率提高了15%，同时金属浸出量降低了15%。通过透射电镜-元素分布图谱（TEM-EDS）、傅里叶变换红外光谱（FT-IR）、NH₃程序升温脱附（NH₃-TPD）、拉曼光谱和H₂程序升温还原（H₂-TPR）等表征手段发现，La的掺杂可调节催化剂表面酸性，促进Fe物种更均匀分散并提升其还原性，从而有效驱动H₂O₂精准分解为活性·OH自由基，显著增强H₂O₂利用效率与催化剂稳定性。在连续10天、55°C且不调节pH的实验中，该催化剂活性保持率超过90%，显示出Fe-La-ZSM-5在实际废水处理中具有良好的应用前景。
