类芬顿反应降解除草剂研究进展

除草剂在农业生产上的广泛应用给生态环境带来了危害。近年来,如何攻破低成本、高效、温和且二次污染少的除草剂降解关键技术,成为业界的关注热点。综述了2015—2019年期间,利用类芬顿反应降解多种除草剂(包括草甘膦、敌草隆和莠去津等)的研究进展。这些方法包括芬顿法与生物氧化结合、电芬顿法等去除水体中除草剂的机理及关键技术。分析了这些方法应用存在的二次污染、技术难度与成本等问题。并概述了利用自然界存在的类芬顿反应降解土壤除草剂的可行性与可能机制。最后,对降低除草剂降解产物二次污染的有效方法,以及土壤中除草剂降解新动向进行了展望。     

磁性树脂催化H_2O_2降解盐酸黄连素制药废水的研究

通过化学合成法制备出磁性大孔树脂类Fenton催化剂,研究其催化降解盐酸黄连素制药废水的效能,同时考察了pH值、H_2O_2投加量、催化剂投加量及废水初始浓度对其降解效能和反应速率的影响。结果表明:在盐酸黄连素的初始质量浓度为800 mg/L、催化剂投加量为15 g/L、H_2O_2投加量为297 mmol/L、pH值为4、室温(25.0±0.5)℃的条件下,盐酸黄连素的降解率为84.4%,达到最高。研究表明,该非均相类Fenton反应体系对pH值的使用范围广,且催化剂易于分离,反应数次后依然具有较高的催化活性,重复利用率高。     

Study on decolorization of Rhodamine B by raw coal fly ash catalyzed Fenton-like process under microwave irradiation

Coal fly ash (CFA) catalyzed Fenton-like process was studied under microwave (MW) irradiation for the decolorization of Rhodamine B (RhB) wastewater. The physical-chemical properties of CFA were characterized, including the specific surface area, micromorphology, chemical and crystal components, and the distribution and chemical valence of metallic elements. The metallic oxidants in the CFA indicate CFA can work as Fenton-like catalyst and MW-absorbent simultaneously. The results reveal OH is more significant in the decolorization of RhB than HO₂ and O₂^?. The generation of more OH in the MW-Fenton-like process (293–326 K) than that in the conventional heated Fenton-like process (326 K) reflects the function of hot spot effect and possible non-thermal effect of MW. Under the optimum condition ([H₂O₂] 2 mmol L^?1, [CFA] 15 g L^?1, pH 3, P_MW 0.1 kW), the decolorization rate reaches 91.6% after 20 min. The intrinsic kinetic model of RhB decolorization is $-\frac{\mathrm{d}{C}_{\mathrm{R}\mathrm{h}\mathrm{B}}}{\mathit{dt}}={1.76\times 10}^{-4}·C_{\mathrm{R}\mathrm{h}\mathrm{B}}·C_{{\mathrm{H}}_2{\mathrm{O}}_2}^{1.89}·C_{\mathrm{C}\mathrm{F}\mathrm{A}}^{1.97}-\mathrm{d}{\mathrm{C}}_{\mathrm{R}\mathrm{h}\mathrm{o}\mathrm{d}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{B}}/\mathrm{d}\mathrm{t}=1.76\times {10}^{-4}·{\mathrm{C}}_{\mathrm{R}\mathrm{h}\mathrm{o}\mathrm{d}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{B}}·{\mathrm{C}}_{{\mathrm{H}}_2{\mathrm{O}}_2}^{1.89}·{\mathrm{C}}_{\mathrm{c}\mathrm{o}\mathrm{a}\mathrm{l}\mathrm{f}\mathrm{l}\mathrm{y}\mathrm{a}\mathrm{s}\mathrm{h}}^{1.97}$. The loss of catalytic metallic elements causes the decline of catalytic capacity of CFA. The energy consumption (4313.3 kW·h kg^?1 RhB) is a limitation for the MW-Fenton-like process, which can be overcame by the safe application of nuclear energy. The intermediates and the path of RhB decolorization were detected and proposed, respectively.     

类Fenton试剂深度处理糖蜜酒精废水

采用单因素试验方法,研究了类Fenton试剂对糖蜜酒精废水深度处理的效果。研究结果表明,类Fenton试剂深度处理糖蜜酒精废水的最佳工艺参数为初始pH=6.0,FeCl3·6H2O的最佳投加量为1000g/m3、3%H2O2的最佳投加量6.7L/m3、慢速搅拌时间为5min。在此条件下,色度和COD的去除率分别为90.35%和77.28%。     

Fe3+、Co2+、Ni2+、Cu2+参与UV/类Fenton反应动力学研究

以活性艳红X-3B为研究对象,用4种3d轨道过渡金属离子协同UV作催化剂,以H2O2为氧化剂,探讨不同pH值、不同催化剂和氧化剂投入量对色度、COD去除效果的影响;通过改变温度研究4种过渡金属离子进行催化反应的活化能。结果表明,4种过渡金属离子都能发生类Fenton反应,且对活性艳红X-3B的降解速率模型符合二级反应速率模型,通过对反应速率、体系活化能和指前因子的量化研究,得知催化能力的大小顺序为Fe^3＋〉Cu^2＋〉Ni^2＋〉Co^2＋;受温度影响的大小程度排序为：Ni^2＋〉Co^2＋〉Cu^2＋〉Fe^3＋。     

Azo-dye Orange II degradation by heterogeneous Fenton-like reaction using carbon-Fe catalysts

In this work, the degradation and mineralization of the non-biodegradable azo dye Orange II (OII) was studied, making use of a heterogeneous Fenton-like oxidation process. For that, hydrogen peroxide activation was achieved by means of two different carbon-based catalysts, which have been impregnated with 7 wt% of iron. The carbon supports employed are quite different, one of them being an activated carbon prepared from agricultural by-products (olive stone), while the other one is a carbon aerogel, prepared by carbonization of an organic resorcinol–formaldehyde polymer. The solids have been characterized using several techniques, namely N₂ and CO₂ adsorption at −196 and 0 °C, respectively, mercury porosimetry, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Then, the catalyst's performance in the Fenton-like oxidation of OII was compared, and the effects of the most relevant operating conditions (pH, catalyst concentration, H₂O₂ concentration and temperature) analyzed for the most promising one (the carbon aerogel based catalyst). In this catalyst, characterization data point for a very good iron dispersion on the carbon surface. This sample showed very good catalytic performances, with mineralization degrees as high as 90%. However, iron leaching from the support is also considerable leading to a progressive deactivation in consecutive reaction cycles.     

钼酸铁在邻苯二甲酸氧化降解中的催化性能研究

研究了钼酸铁作为类Fenton试剂对邻苯二甲酸的催化氧化性能。考察了催化剂用量、H2O2浓度和反应温度对邻苯二甲酸去除率的影响。结果表明,当催化剂用量为1000 mg/L,H2O2浓度为4.995 mg/L,反应温度40℃时,反应90 min后,邻苯二甲酸的去除率可达92.36%。     

非均相类Fenton催化剂脱汞的实验与机理

采用共沉淀法分别制备Ti、Co、Cu掺杂Fe₃O₄的非均相类Fenton催化剂,在小型实验台架上进行非均相类Fenton反应脱汞的实验研究。利用X射线衍射(XRD)、扫描电子显微镜(SEM)对催化剂的晶体结构和形貌进行了表征。实验考察了掺杂前Fe₃O₄和掺杂后Fe_2.59Ti_0.41O₄、Fe_2.52Co_0.48O₄、Fe_2.44Cu_0.56O₄催化剂的类Fenton脱汞性能,并通过电子顺磁共振技术(EPR)分析了非均相类Fenton脱汞的机理。结果表明:Ti、Cu掺杂后的催化剂具有较高的催化活性, 的强氧化作用是类Fenton脱汞的主要原因。     

Self-propelling nanomotor made from halloysite and catalysis in Fenton-like reaction

A new class of catalytically self-propelled nanomotors were fabricated by modifying natural clay tubes, halloysite, with randomly distributed particles of MnO₂ and Fe₃O₄. The prepared MnO₂–Fe₃O₄/HNTs composites were validated to be efficient Fenton catalysts in the degradation of rhodamine B (RhB). Compared to the previous preparation of rolled-up microtubes or other template-assisted syntheses, this strategy has its merits in utilizing clay minerals of abundance, cheap-price, and no complex instruments needed. The nanomotors were able to be prepared on a large scale. The MnO₂–Fe₃O₄/HNTs motors displayed powerful autonomous movement, and a high velocity of up to 380 µm s⁻¹ was achieved in 5.0 wt. % H₂O₂ solution. For Fenton catalysis of RhB, the removal ratio of 94% dye molecules was obtained within 30 min, which was triply higher than other samples of the nonpropelling sample Fe₃O₄/HNTs. The autonomous movement provided adsorptive bubble separation, and the adsorption capacity was greatly enhanced by halloysite. These synergistic effects boosted the removal efficiency of dye molecules. The presence of magnetic MnO₂–Fe₃O₄ made these motors move directionally in external magnetic fields and provided a facile recovery for collecting heterogeneous catalysts.