Al2O3催化臭氧化去除水中有机物的研发进展

综述了Al2O3应用于非均相催化臭氧化体系的研究进展,对比了催化体系和单独臭氧体系对水中有机物的去除效果,从催化剂对有机物的吸附、溶液的pH值影响、溶液中存在的无机离子和臭氧的分解机理方面,探讨了影响Al2O3催化臭氧化体系催化效果的主要因素,分析了目前研究中存在的问题,展望了Al2O3催化剂在水处理方面的应用前景。     

Effect of magnetic catalysts on the kinetic behaviour of Reactive Black 5 decomposition by an O3/H2O2 process

BACKGROUND: Particles are often too small to be separated from a reaction system and recycled, especially in waste‐water treatment via a catalytic ozonation process. Therefore, the objective of this study was to prepare a magnetic catalyst (SiO₂/Fe₃O₄) that can be recycled by using an external magnetic field. The characteristics of the magnetic catalyst and kinetics of decomposition of Reactive Black 5 (RB5) using a magnetic catalyst/H₂O₂/O₃ have been investigated. Magnetic catalysts (SiO₂/Fe₃O₄) were characterized by X‐ray diffraction (XRD), vibrating sample magnetometry (VSM) and Fourier transform infrared (FTIR) spectroscopy. RESULTS: In the case of the decomposition of RB5 by the SiO₂/Fe₃O₄/H₂O₂/O₃ process, the contribution of the destruction by the indirect oxidation of OH· caused by the chain reaction of H₂O, OH^?, and H₂O₂ was found to be larger than that of the direct attack of O₃. The kinetic behaviour of the reacting species during the decomposition of RB5 by catalytic ozonation could be well modelled under various experimental conditions. CONCLUSIONS: The paramagnetic behaviour of the prepared SiO₂/Fe₃O₄ led to the formation of the magnetic catalyst SiO₂/Fe₃O₄, which could be separated more easily by the application of a magnetic field. More than 90% of the magnetic catalyst was recovered and easily redispersed in a solution for reuse by mixing with a flat‐bladed turbine. Copyright © 2010 Society of Chemical Industry     

过渡金属单原子催化剂活化H2O2/PMS/PDS降解有机污染物的研究进展

单原子催化剂（SACs）是一种将金属以原子态负载于载体上的新型材料,具有原子利用率高、催化活性强和易回收等优点,使其在催化降解有机污染物方面备受关注。本文介绍了SACs的催化影响因素,总结了SACs催化降解有机污染物在环境领域中的应用。此外,着重综述了不同过渡金属（Fe、Co、Mn、Cu等）单原子催化剂在基于双氧水或过硫酸盐的高级氧化技术中的催化机理,单原子金属（M）一般与N键合形成活性位点M—N _x,活化氧化剂生成自由基或单线态氧,高效降解有机污染物。最后,提出未来SACs在催化降解有机污染物的研究方向是合成金属负载量高、稳定性高、pH适用范围更广的SACs,以及根据SACs的结构-性能关系和催化机理,对目标污染物设计特定催化剂。     

O_3/H_2O_2高级氧化技术处理对硝基苯酚废水的研究

实验采用O3/H2O2联合高级氧化技术处理对硝基苯酚的生产废水。结果显示在实验条件下,该技术对此种废水具有显著的处理效果。废水中的TOC去除率在90%以上,pH 7左右,出水达到国家一级排放标准,整套工艺具有良好的经济效益。     

Kinetics,degradation pathway and reaction mechanism of advanced oxidation of 4‐nitrophenol in water by a UV/H2O2 process

Photooxidation of 4‐nitrophenol (4‐NP) in water by the UV/H₂O₂ advanced oxidation process was carried out in order to investigate the kinetics and pathway of 4‐NP degradation. The experimental results showed that the photodegradation of 4‐NP accorded well with pseudo‐first order kinetics. The effects of different parameters, such as H₂O₂ dosage, pH value and various anion scavengers on the degradation of 4‐NP have been investigated in detail. It was found that acidic conditions are more favorable to the degradation of 4‐NP but many anions, such as HCO₃^?, NO₃^? and Cl^?, slow down the photooxidation rate of 4‐NP. Hydroquinone, 1,2,4‐trihdroxybenzene, 4‐nitropyrogallol, and 4‐nitrocatechol were tentatively identified as the intermediates of 4‐NP degradation by GC/MS after samples were derivatized by N,O‐bis(trimethylsilyl)‐trifluoroacetamide (BSTFA). A degradation pathway was proposed to account for the observed intermediates produced during 4‐NP degradation by the UV/H₂O₂ process. Copyright © 2003 Society of Chemical Industry     

H2O2与O2协同引发的TiO2/Fe3+光催化降解苯酚

以玻璃纤维为载体,将TiO2/Fe3+负载到其表面制成了空间玻璃纤维反应器。利用该反应器以高压汞灯为光源进行了光催化降解水中苯酚的试验研究,重点考察了H2O2及O2的协同作用对光催化氧化的影响。试验发现,H2O2的加入对HO.的产生有显著的引发作用,同时向溶液中充入O2可明显提高光催化效率,降低H2O2用量。试验结果表明,以UV365-250 W光源照射,在初始pH为3~5,O2通入量为1.0 L/(min.L),上升流速为0.7 m/min,H2O2浓度为0.1 mmol/L等试验条件下,初始质量浓度为30 mg/L的苯酚废水经120 min光催化反应后,其矿化率可达83%左右。     

Use of the axial dispersion model to describe the O3 and O3 /H2O2 advanced oxidation of alachlor in water

Experiments on alachlor degradation by ozonation alone and combined with hydrogen peroxide using different surface waters have been conducted in a reactor bubble column and a kinetic model of the advanced oxidation process has been proposed. Variables studied were the nature of the surface water (four surface waters were treated), pH (3.5–9.7) and hydrogen peroxide to ozone mass ratio at the column inlet (0.1–1.85 g g^?1). Data on residence time distribution, rate constants and the absorption kinetic regime were considered to prepare the kinetic model, which was also based on the axial dispersion model of non‐ideal flow. The model gives good predictions of alachlor and hydrogen peroxide conversions and the fraction of dissolved ozone (deviations were lower than ±15%) although it fails, in some cases, to yield accurate estimates of the observed experimental trends of concentrations in water at the reactor column outlet. The calculated results were close to those obtained from the more classical N well‐mixed tanks‐in‐series model (deviations with this model were lower than ±20%). It is concluded that quantitative deviations from experimental observations were likely due to the lack of rate data on ozone reactions with organic matter present in the surface waters investigated. © 2002 Society of Chemical Industry     

Comparison of a new immobilized Fe3+ catalyst with homogeneous Fe3+–H2O2 system for degradation of 2,4‐dinitrophenol

BACKGROUND: Heterogeneous Fenton catalysts have been used to treat various organic pollutants in an aqueous environment. The present study has investigated the degradation of 2,4‐dinitrophenol (2,4‐DNP), a priority pollutant generated by such industries as pharmaceuticals, pesticides, pigments and dyes. Degradation of 2,4‐DNP (100 mg L^?1) was studied using Fe³⁺ loaded on Al₂O₃ as a heterogeneous catalyst in the presence of H₂O₂, and the efficiency compared with the homogeneous Fe³⁺/H₂O₂ based Fenton‐like process. The effect of different parameters for both processes, such as catalyst loading, H₂O₂ concentration, initial solution pH, initial substrate concentration and temperature were investigated and the optimum operating conditions determined. RESULTS: Under optimal operating conditions of the homogeneous system ([Fe³⁺] 125 mg L^?1; [H₂O₂] 250 mg L^?1; pH 3; room temperature), 92.5% degradation was achieved in 35 min for an initial 2,4‐DNP concentration of 100 mg L^?1. In the case of immobilized Fe (Fe³⁺–Al₂O₃ catalyst), degradation improved to 98.7% under the condition 10 wt% [Fe³⁺–Al₂O₃] 1 g L^?1 catalyst loading; [H₂O₂] 250 mg L^?1; pH 3; at room temperature for the same duration. CONCLUSIONS: This study demonstrated the stability and reusability of the prepared heterogeneous catalyst. This process is a viable technique for treatment of aqueous solutions containing contaminants. Copyright © 2012 Society of Chemical Industry     

天然磁铁矿/UV/S2O82-对焦化废水中不同种类有机物的去除特性

以过硫酸盐（PS）为中心建立了C（天然磁铁矿）/PS、UV/PS、C/UV/PS氧化体系,分别对焦化废水生化出水进行深度处理,采用超滤膜法和有机物树脂分离方法分别对深度处理前后废水中有机物分子量分布特性及亲疏水性有机物含量变化进行了研究。研究表明：生化出水中含有较多的难降解芳香性有机物,且以分子量（M_W）<1×10³的低分子量有机物为主,其次是M_W>100×10³和10×10³～100×10³的大分子有机物。疏水酸和疏水中性组分是废水中的主体有机物,其DOC分别占总DOC的45.88%和32.09%。C/UV/PS相对C/PS、UV/PS氧化效果更好,在原水pH,铁矿石和PS的投加量分别为3 g·L^-1和2 g·L^-1,紫外光照射功率为300 W条件下,氧化90 min时COD、UV₂₅₄、DOC和色度的去除率分别为74.9%、93.5%、84.1%和80.1%。从矿化效果来看,C/UV/PS氧化体系对M_W>10×10³的大分子有机物的去除效果显著,深度处理后M_W<1×10³的有机物分子占比增加;该体系对疏水性和弱疏水性有机物去除效果较高,深度处理后亲水性有机物占比增加。     

Advanced oxidation of raw and biotreated textile industry wastewater with O3, H2O2 /UV‐C and their sequential application

The advanced chemical oxidation of raw and biologically pretreated textile wastewater by (1) ozonation, (2) H₂O₂ /UV − C oxidation and (3) sequential application of ozonation followed by H₂O₂ /UV − C oxidation was investigated at the natural pH values (8 and 11) of the textile effluents for 1 h. Analysis of the reduction in the pollution load was followed by total environmental parameters such as TOC, COD, UV–VIS absorption kinetics and the biodegradability factor, f_B. The successive treatment combination, where a preliminary ozonation step was carried out prior to H₂O₂ /UV − C oxidation without changing the total treatment time, enhanced the COD and TOC removal efficiency of the H₂O₂ /UV − C oxidation by a factor of 13 and 4, respectively, for the raw wastewater. In the case of biotreated textile effluent, a preliminary ozonation step increased COD removal of the H₂O₂ /UV − C treatment system from 15% to 62%, and TOC removal from 0% to 34%. However, the sequential process did not appear to be more effective than applying a single ozonation step in terms of TOC abatement rates. Enhancement of the biodegradability factor (f_B) was more pronounced for the biologically pretreated wastewater with an almost two‐fold increase for the optimized Advanced Oxidation Technologies (AOTs). For H₂O₂ /UV − C oxidation of raw textile wastewater, apparent zero order COD removal rate constants (k_app), and the second order OH· formation rates (r_i) have been calculated. © 2001 Society of Chemical Industry     

O3/H2O2高级氧化法预处理酒精废水的实验研究

实验探讨了O3/H2O2高级氧化法预处理某制药酒精废水过程中H2O2投加量、pH值、反应时间、臭氧发生器氧气流量等因素对CODCr去除率的影响。实验得出的最佳反应条件是：H2O2投加量98 mmol/L,pH值11,氧气流量60 L/h,反应时间90 min,在最佳条件下反应后废水CODCr去除率46.3%,TOC去除率50.5%,B/C从0.08提高到0.32,废水可生化性明显提高,能够满足后续生化处理的需要。     

Fe/TiO_2-Al_2O_3催化H_2O_2降解亚甲基蓝废水的研究

采用浸渍-焙烧法制备了Fe/Ti O2-Al2O3、Fe/Ce O2-Al2O3复合催化剂,以H2O2作为氧化剂,对亚甲基蓝废水进行降解处理,考察了催化剂加入量、H2O2加入量、p H、温度以及初始浓度的变化等因素对处理效果的影响。结果表明:Fe/Ti O2-Al2O3的催化性能稍优于Fe/Ce O2-Al2O3,并且在p H=5,温度为65℃条件下,当催化剂加入量为0.15 g、H2O2加入量为15 m L、反应时间为60 min时降解率即可达到97%以上。     

Photodegradation of tetracyclines in aqueous solution by using UV and UV/H2O2 oxidation processes

BACKGROUND: The objective of the present study was to analyse the kinetics of photodegradation of three antibiotics from the tetracycline group (tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC)), and the influence of the operational variables: (1) initial concentration; (2) initial solution pH; (3) addition of hydrogen peroxide; (4) effect of the aqueous matrix (ultrapure water (UW), surface water (SW), groundwater (GW) and waste‐water (WW) on these processes. RESULTS: The results obtained show that the photodegradation of the three tetracyclines fits first‐order kinetics. The degradation rate depends on initial concentration and pH. Low concentrations of H₂O₂ markedly increased the efficacy of TC photolysis, with a linear relationship between degradation rate and H₂O₂ concentration for concentrations of 2 × 10^?2 to 2 × 10^?1 mmol L^?1. The photodegradation rate is higher in real waters than in ultrapure water. The toxicity of oxidation by‐products formed during tetracyclines photooxidation process was determined by a bioluminescent test, showing that toxicity increases during the process. CONCLUSIONS: Oxidation of tetracyclines by UV radiation alone is slow due to the low quantum yield determined. The UV/H₂O₂ process is an interesting alternative to oxidise tetracyclines in aqueous solution, because this process decreases total organic carbon concentration and tetracyclines oxidation by‐products toxicity. Copyright © 2010 Society of Chemical Industry     

Oxidation of benzothiazole, 2‐mercaptobenzothiazole and 2‐hydroxybenzothiazole in aqueous solution by means of H2O2/UV or photoassisted Fenton systems

Oxidative treatments of benzothiazole and benzothiazole derivatives (2‐mercaptobenzothiazole, 2‐hydroxybenzothiazole) in aqueous solution have been studied by using H₂O₂/UV and iron(III) photoassisted Fenton techniques. Experimental runs have been carried out in the pH range 3.0 –8.0 by means of annular reactors and proper UV lamps. The effect of pH, the initial concentration of hydrogen peroxide, the substrate, and the iron(III) concentrations have been investigated. A suitable model has been developed and used for the best estimation of kinetic constants for HO radical attack on the target molecules with the H₂O₂/UV system. The values obtained with this model are consistent with those reported in the literature for other heterocyclic compounds. © 2001 Society of Chemical Industry     

Enhanced degradation of organic wastewater containing p-nitrophenol by a novel wet electrocatalytic oxidation process: Parameter optimization and degradation mechanism

This paper explored a novel advanced oxidation process (AOP) for wastewater treatment—wet electrocatalytic oxidation (WEO), which introduced a small current into wet air oxidation (WAO) to promote the formation of hydroxyl radical and accelerate the oxidation of organic pollutants. The results showed that this novel process could couple the advantages of both WAO and electrochemical oxidation (EO). The effects of major operational factors of WEO were studied at relatively moderate condition (T = 100–160 °C, C = 1000 mg L⁻¹, P_O2 = 4 TOD, P_N2 = 0.50 MPa, current density = 0–7.08 mA cm⁻² and pH 2.7–10.6) aiming to p-nitrophenol (PNP) degradation, TOC and COD removal. The cost-effective operational parameters were found and the current efficiencies were highly beyond 100% with the maximum value of 386%. The degradation mechanism of WEO was carefully studied based on the formation of free radical. After the detail analysis of Hammett theory and quantitative structure-activity relationships (QSAR), the reaction pathway of hydroxyl radical with PNP was analyzed with the help of Gaussian 03W and the probable degradation pathway of PNP by WEO was deduced.     

Fe2O3/改性沸石催化剂的制备及其催化臭氧氧化对氯苯酚

为了提高非均相催化臭氧氧化体系处理难降解有机废水的效率,分别以十六烷基三甲基溴化铵（CTMAB）改性的天然沸石和Fe(NO₃)₃·9H₂O溶液作为载体和活性组分前体,采用浸渍法制备Fe₂O₃/改性天然沸石催化剂（MNZ）,利用能谱仪（EDS）、扫描电镜（SEM）、傅里叶变换红外光谱仪（FTIR）、X射线衍射仪（XRD）、X射线光电子能谱仪（XPS）、N₂-吸附/脱附等方法分析催化剂的结构和组成,研究其催化臭氧氧化对氯苯酚的效果和催化机制。结果表明：Fe₂O₃/MNZ催化剂保持了天然沸石的表面结构。Fe₂O₃均匀负载在沸石表面,属于典型的分子筛结构,比表面积、孔容和孔径分别为12.776m²/g、0.042cm³/g和3.932nm。在对氯苯酚初始浓度为100mg/L、臭氧浓度为2.6mg/L、温度为25℃、pH为7.0±0.2的条件下,对氯苯酚和化学需氧量（COD）去除率分别为87.26%和48.83%。天然沸石与Fe₂O₃共同促进臭氧分解生成强氧化能力的羟基自由基（·OH）,提高了对氯苯酚的去除率,反应体系遵循羟基自由基作用机理。