| 磁性Mn0.6Zn0.4Fe2O4@SiO2催化H2O2降解亚甲基蓝效能及机制 |
| 摘要点击 1875 全文点击 494 投稿时间：2021-08-23 修订日期：2021-09-28 |
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| 中文关键词 磁性催化剂 非均相 类Fenton 亚甲基蓝(MB) 降解 |
| 英文关键词 magnetic catalyst heterogeneous Fenton-like methylene blue (MB) degradation |
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| 中文摘要 |
| 为制备易固液分离和稳定性好的高效非均相类Fenton催化剂，利用正硅酸乙酯水解对Mn0.6Zn0.4Fe2 O4磁性纳米颗粒（SF-MNPs）进行功能化修饰，制备得到Mn0.6Zn0.4Fe2 O4@SiO2（MZF@SiO2）磁性纳米复合物催化剂，采用透射电镜、X射线光电子能谱和振动样品磁强计等对MZF@SiO2进行了表征，以难生物降解偶氮染料亚甲基蓝（MB）为目标污染物，考察了不同初始pH对MZF@SiO2催化效能的影响，在近中性条件下（pH=6.5）研究了H2 O2用量、MZF@SiO2投加量和温度等对MB去除率的影响，及MZF@SiO2的稳定性和循环使用性能，推测了催化反应机制.结果表明，无定形SiO2将SF-MNPs完全包裹，MZF@SiO2具有"核-壳"结构；磁核SF-MNPs的结晶度好，具有尖晶石结构；MZF@SiO2的饱和磁化强度为18.6 emu ·g-1，剩磁和矫顽力均较低，在水中的分散性和固液分离性能均较好.当反应时间为120 min，温度为303 K，MZF@SiO2投加量为1.0 g ·L-1，H2 O2的利用率为74.50%，MB的去除率可达94.76%，一级反应速率常数为0.0466 min-1，MZF@SiO2具有较好的稳定性和循环使用性能.该降解过程的速率控制步骤为固液界面反应，MZF@SiO2+H2 O2体系中的活化氧化物主要为·OH；包覆层SiO2能加速电子传递，与SF-MNPs存在正协同作用；SF-MNPs中存在氧空位，有利于反应过程中的电子转移.所制备的MZF@SiO2可磁分离，催化效率高，稳定性好，可重复使用，在实际印染废水处理中具有很好的应用前景. |
| 英文摘要 |
| To prepare high-efficiency heterogeneous Fenton catalysts with easy solid-liquid separation and good stability, Mn0.6Zn0.4Fe2O4 magnetic nanoparticles (SF-MNPs) were functionally modified through hydrolysis of tetraethylorthosilicate, and Mn0.6Zn0.4Fe2O4@SiO2 (MZF@SiO2) magnetic nanocomposite (MNC) catalysts were prepared. MZF@SiO2 was characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and a vibrating sample magnetometer. The effect of different initial pH on the catalytic performance of MZF@SiO2 was investigated using methylene blue (MB) refractory azo dye as the target pollutant. Under the initial near-neutral pH condition (pH=6.5), the effects of H2O2dosage, MZF@SiO2 dosage, and temperature on the removal efficiency of MB were investigated. The stability and recycling performance of MZF@SiO2 were studied, and the catalytic reaction mechanism was speculated. The results showed that SF-MNPs were completely encapsulated by amorphous SiO2, and MZF@SiO2 had a "core-shell" structure. Magnetic core SF-MNPs had good crystallinity with a spinel structure. The saturation magnetization of MZF@SiO2 was 18.6 emu·g-1, and the remanence and coercivity were low. The dispersibility and solid-liquid separation performance of MZF@SiO2 were excellent in water. Under the condition of neutral pH, the utilization rate of H2O2 was 74.50%, and the removal rate of MB reached 94.76%. When the reaction time was 120 min, the temperature was 303 K, and the dosage of MZF@SiO2 was 1.0 g·L-1. The first-order reaction rate constant was 0.0466 min-1, and MZF@SiO2 had good stability and recycling performance. The solid-liquid interface reaction was the rate control step of the process. The reactive oxygen species in the MZF@SiO2+H2O2 system were·OH radicles. The coating layer SiO2 could accelerate the electron transfer rate, and there was a positive synergistic effect between SiO2 and SF-MNPs. The existence of oxygen vacancies in SF-MNPs was also conducive to the electron transfer in the heterogeneous Fenton-like reaction. The as-prepared MZF@SiO2 MNC catalysts had a superior catalytic activity with good stability, and they had the advantages of easy magnetic separation and reusability. Thus, MZF@SiO2 MNC catalysts have a wider range of potential applications in actual printing and dyeing wastewater treatment. |
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