| 环糊精键合Fe-TAML催化剂的制备及其活化H2O2氧化水中有机微污染物 |
| 摘要点击 1338 全文点击 385 投稿时间：2022-08-25 修订日期：2022-09-30 |
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| 中文关键词 环糊精键合Fe-TAML 催化剂 过氧化氢 有机微污染物 氧化降解 |
| 英文关键词 CD-Fe-TAML catalyst H2O2 organic micropollutants oxidation degradation |
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| 中文摘要 |
| 为了提高Fe-TAML催化剂的稳定性和催化活性，通过磺酰氯化反应、金属螯合反应和亲核取代反应等方法将Fe-TAML与环糊精（CD）以共价键形式结合，制备了单-6-氧-CD键合Fe-TAML催化剂（CD-Fe-TAML）.开展了CD-Fe-TAML的催化活性、稳定性测试及其活化H2 O2氧化降解水中抗生素和农药等34种有机微污染物研究.与Fe-TAML相比，CD-Fe-TAML在pH为7.0条件下活化H2 O2生成高价铁的速率提高49倍，对底物的催化降解速率提高25倍，且其自氧化速率降低70%.CD-Fe-TAML在pH为3.0~10.0范围内的稳定性比Fe-TAML的稳定性提高0.7~699倍，其中，在pH为3.0~7.0范围内提高33~699倍.CD-Fe-TAML的分子结构中的磺酸基官能团具有吸电子效应，能增加活性中心中Fe离子的正电荷密度，不仅加快H2 O2的过氧键裂解和高价铁物种的生成，提高Fe-TAML的催化活性，还能提高其水解稳定性.同时，分子结构中的CD基团具有"电子穿梭体"效应和包合作用，前者通过加快活性中心Fe-TAML与H2 O2之间的电子转移而促进高价铁物种的生成，提高Fe-TAML的催化活性；后者能通过对活性中心Fe-TAML的包合而抑制了其水解和自氧化反应，提高其稳定性.与Fe-TAML/H2 O2相比，在pH为5.0~7.0的范围内，CD-Fe-TAML/H2 O2对有机微污染物的降解速率提高了0.4~59倍.在pH为8.0条件下，CD-Fe-TAML/H2 O2对摩尔体积小于0.20 L ·mol-1的啶虫脒和磺胺嘧啶等9种微污染物的降解速率提高0.3~1.1倍，对摩尔体积大于0.20 L ·mol-1的微污染物的降解速率没有显著性变化.碘离子的氧化实验结果显示，水中的I-没有被CD-Fe-TAML/H2 O2体系氧化为HIO或IO-，不会进一步与DOM反应生成碘代消毒副产品（I-DBPs）.同时，CD-Fe-TAML/H2 O2对地表水水样中微污染物的降解不受DOM和无机盐离子等水体组分的干扰.所构建的CD-Fe-TAML/H2 O2体系具有比Fe-TAML/H2 O2体系更高的催化降解活性和稳定性，在水体中有机微污染物去除方面具有应用潜力. |
| 英文摘要 |
| In order to improve the stability and catalytic activity of Fe-TAML, mono-6-oxy-cyclodextrin bonded Fe-TAML catalyst (CD-Fe-TAML) was prepared by bonding Fe-TAML with cyclodextrin (CD) through chlorosulfonylation reaction, metal chelation reaction, and nucleophilic substitution reaction. The catalytic activity and stability of CD-Fe-TAML and the oxidation degradation efficiencies of 34 organic micropollutants such as antibiotics and pesticides by activation of H2O2in water were studied. Compared with that of Fe-TAML, CD-Fe-TAML at pH 7.0 had a 49-fold and 25-fold increase in the rate of activating H2O2 to produce iron (Ⅴ/Ⅳ)-oxo intermediates and the degradation rate of the substrate, respectively, and its self-oxidation rate was reduced by 70%. The stability of CD-Fe-TAML was 0.7-699 times higher than that of Fe-TAML in the pH range of 3.0-10.0. Specifically, the stability of CD-Fe-TAML was 33-699 times higher than that of Fe-TAML in the pH range of 3.0-7.0. The sulfonic acid group in the molecular structure of CD-Fe-TAML had an electrophilic effect, which could increase the positive charge density of Fe in the active center, accelerate the O-O bond cleavage of H2O2 and the generation of iron(Ⅴ/Ⅳ)-oxo intermediates, improve the catalytic activity of Fe-TAML, and also improve its hydrolysis stability. Meanwhile, the CD group in the molecular structure had the "electron shuttle" effect and inclusion effect. The former could accelerate the electron transfer between the active center Fe-TAML and H2O2 to improve the catalytic activity of Fe-TAML. The latter could inhibit the hydrolysis and self-oxidation of the active center Fe-TAML by inclusion or binding of the hydrolysis sites and oxidation sites, thus improving its stability. The degradation efficiencies of micropollutants by CD-Fe-TAML/H2O2 under weakly acidic and neutral conditions (in the pH range of 5.0-7.0) were 0.4-59 times higher than those of Fe-TAML/H2O2. The degradation efficiencies of CD-Fe-TAML/H2O2 on nine micropollutants with a molar volume less than 0.20 L·mol-1, such as acetamiprid and sulfadiazine, were 0.3-1.1 times higher than that of Fe-TAML/H2O2 at pH 8.0, and there were no significant differences between CD-Fe-TAML/H2O2 and Fe-TAML/H2O2for micropollutants with a molar volume greater than 0.20 L·mol-1. The results of iodide oxidation by CD-Fe-TAML/H2O2 showed that I- was not oxidized to produce iodo-disinfection byproducts (I-DBPs). The degradation of micropollutants by CD-Fe-TAML/H2O2 in the surface water sample was not disturbed by water components. The CD-Fe-TAML/H2O2 system has a potential application in the removal of organic micropollutants from water. |
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