非均相Fenton催化剂用于降解染料废水的实验研究进展

对非均相Fenton催化剂用于降解染料废水的研究现状作了较为详细的总结和评述,并指出了未来的发展方向。     

异相芬顿反应降解废水中有机污染物的研究进展

简述了芬顿反应的机理以及传统芬顿反应的局限性。综述了异相芬顿、光-异相芬顿和电-异相芬顿降解废水中有机污染物的最新研究进展。概述了新型芬顿催化剂在宽泛的pH范围内具有良好效果,以及重复利用率。探讨了未来芬顿反应的研究重点。     

异相芬顿反应降解废水中有机污染物的研究进展

简述了芬顿反应的机理以及传统芬顿反应的局限性。综述了异相芬顿、光-异相芬顿和电-异相芬顿降解废水中有机污染物的最新研究进展。概述了新型芬顿催化剂在宽泛的pH范围内具有良好效果,以及重复利用率。探讨了未来芬顿反应的研究重点。     

Fenton反应的应用及其影响因素的研究

Fenton试剂是亚铁离子和过氧化氢的组合,具有强氧化性,在环境污染治理方面得到了广泛的应用。本文主要研究Fenton反应在废水处理上的作用,为Fenton反应的进一步研究提供参考。     

Kinetic study of the solid-state reaction between phthalic anhydride and P-nitroaniline

The addition reaction between the compacted powders of phthalic anhydride and p-nitroaniline was studied. Both the reactants of equal particle size, were mixed in 1-to-1 molar ratio and compacted. Three particle sizes — 0.0065 cm, 0.0178 cm and 0.0376 cm and three compaction pressures — 302.0 kgf/cm², 785.0 kgf/cm² and 1208.0 kgf/cm² were used for the study. Conversions were measured at 80°, 90°, 100°, 110° and 120°C for 1/2, 1, 2, 4, 8, 12, 16, 20 and 24 hours. The reaction rate changed to a constant value, after an initial phase boundary process. The mole percentage conversions increased with decrease in particle size, increase in compaction pressure corresponding to a decrease in the initial porosity of the compact. It was also observed that the final porosity of the compact increased with increase in reaction temperature. Combination of Jander's model and parabolic rate law was used to calculate the values of the reaction rate constant equivalent. The activation energy was calculated to be 14 to 34 kilocalories per gram mole.     

非均相Fenton催化降解酚类化合物的研究进展

非均相Fenton催化法是去除水中难降解有机污染物的一种重要高级氧化技术,近些年以其效率高、污染少、材料来源广泛而受到人们更多的重视。介绍了现今主要的非均相Fenton催化降解酚类化合物的催化剂研究进展,包括零价铁、Fe3O4、Fe2O3、以碳、黏土、柱撑黏土、沸石、介孔二氧化硅等为载体的催化剂。最后提出了三个非均相Fenton反应的研究方向。     

Kinetic study of the reaction between molybdenum trioxide and gaseous carbon tetrachloride

The kinetics of the chlorination reaction of molybdenum trioxide with gaseous carbon tetrachloride has been studied at temperatures between 713 and 753 K. The effects of temperature, reaction time, residence time and gaseous reactant concentration on conversion were studied throughout the reaction. In all cases, there was an increase in conversion when the above operating variables were increased. The kinetic model proposed is consistent with and correlates the experimental data. In the range studied for the different variables, the step that controls the rate of reaction is the surface chemical reaction. Values of the rate constant and the activation energy were estimated.     

Degradation of carbon tetrachloride in modified Fenton reaction

We showed that the dechlorination of carbon tetrachloride (CT) can be significantly enhanced at nearneutral pH by modified Fenton reaction in the presence of Fe(II) chelated by cross-linked chitosan (CS) with glutaraldehyde (GLA). CT dechlorination was verified by monitoring the release of chloride and detection of intermediates such as trichloromethane and dichloromethane in the modified Fenton system with Fe(II) chelated by cross-linked CS with GLA (Fe(II)-CS/GLA). Measured chlorine mass balance of each sample was greater than 91% of total chlorine mass corresponding to initial CT concentration throughout the reaction. Addition of hydroxyl radical scavenger (2-propanol) enhanced the CT degradation in 5 h at near-neutral pH (removal efficiency from 57.2% to 92.4%), while the addition significantly inhibited trichloroethylene (TCE) degradation at the same condition (74.7% to 19.9%). This implies that, in contrast to the dechlorination of TCE, that of CT did not follow an oxidative dechlorination pathway but a reductive dechlorination pathway in the modified Fenton system with Fe(II)-CS/GLA. Dechlorination kinetics of CT in the modified Fenton system was affected by the concentrations of H₂O₂, Fe(II), and CT. The formation of surface Fe(II)-CS/GLA complex and its valence change from Fe(II) to Fe(III) observed during the modified Fenton reaction gave a clue to identify the proposed reaction mechanism properly.     

Kinetic study and model verification of reaction between alumina and charred layer

The abnormal ablation of insulation materials caused by slag deposition in solid rocket motors has gradually attracted considerable attention from researchers. First, an alumina-charred layer system was thermogravimetrically experimented with 1700–1850 °C using ultra-high-temperature thermogravimetric equipment based on the dominant equation of an Al₂O₃–C system obtained from previous studies. The kinetic parameters of the alumina-charred layer reaction system were then determined by the isothermal kinetic mathematical treatment method. Second, an ablation model was established to verify the accuracy of the kinetic parameters. The ablation thickness calculated by the model is nearly similar to that in the experimental results, with an error of 16.01%. Results show that the kinetic parameters of the alumina-charred layer's reaction system obtained in this study are credible and can be used for predicting the insulator's ablation under deposition conditions.     

Kinetic study of the reaction between tocopheroxyl radical and unsaturated fatty acid esters in benzene

A kinetic study of the reaction between a tocopheroxyl radical and unsaturated fatty acid esters has been undertaken. The rates of allylic hydrogen abstraction from various unsaturated fatty acid esters (ethyl oleate2, ethyl linoleate3, ethyl linolenate4, and ethyl arachidonate5) by the tocopheroxyl radical (5,7-diisopropyltocopheroxyl6) in benzene have been determined spectrophotometrically. The second-order rate constants, k₃, obtained are 1.04×10⁻⁵ M⁻¹s⁻¹ for2, 1.82×10⁻² M⁻¹s⁻¹ for3, 3.84×10⁻² M⁻¹s⁻¹ for4, and 4.83×10⁻² M⁻¹s⁻¹ for5 at 25.0°C. Thus, the rate constants, k_abstr/H, given on an available hydrogen basis are k₃/4=2.60×10⁻⁶ M⁻¹s⁻¹ for2, k₃/2=9.10×10⁻³ M⁻¹s⁻¹ for3, k₃/4=9.60×10⁻³ M⁻¹s⁻¹ for4, and k₃/6=8.05×10⁻³ M⁻¹s⁻¹ for5. The k_abstr/H values obtained for the polyunsaturated fatty acid esters3,4, and5 containing H-atoms activated by two π-electron systems are similar to each other, and are about three orders of magnitude higher than that for the ethyl oleate2 containing H-atoms activated by a single π-system. From these results, it is suggested that the prooxidant effect of α-tocopherol in edible oils and fats may be induced by the above hydrogen abstraction reaction.     

Fenton试剂的反应机理及动力学研究进展

Fenton试剂是由H.J.H.Fenton在120年前首次发现的,其通过Fe~(2+)与H_2O_2反应,生产具有强氧化性的活性物种,将有机分子矿化为CO_2和H_2O,广泛应用于污水处理、地表水修复等领域,是一种具有广阔应用前景的污染物治理技术。关于其作用机理,目前尚未形成统一看法,总结了Fenton试剂在机理和动力学方面的研究成果,并对不同机理进行了评价,最后对该体系的理论研究进行了展望。     

LaCoO_3钙钛矿型催化剂非均相Fenton处理兰炭废水

以苯甲醇为溶剂,采用水热法制备LaCoO_3钙钛矿型催化剂,研究LaCoO_3钙钛矿型催化剂非均相Fenton处理兰炭废水的最佳工艺条件及催化机理。结果表明,在过氧化氢用量3 m L、LaCoO_3钙钛矿型催化剂用量0.2 g、pH=4和反应温度25℃条件下,LaCoO_3钙钛矿型催化剂非均相Fenton处理兰炭废水的COD去除率达到72.7%,通过自由基捕获剂叔丁醇的加入及一级动力学模型研究非均相Fenton过程机理。     

Photocatalytic degradation of gaseous perchloroethylene in continuous flow reactors: Rate enhancement by chlorine radicals

The degradation of perchloroethylene (PCE) by UV/TiO₂ photocatalysis in gas phase was studied. The degradation efficiency has been compared in different continuous flow reactors: a photocatalytic tangential reactor (PTR) where the air flows tangentially over the catalytic medium and two photocatalytic filtering reactors (PFR) where the air flows through the porous catalytic medium. The degradation rate shows a linear dependence with the concentration of pollutants (up to 350 mg PCE/N m³) for the PTR, but the degradation was negligible for the PFR. The degradation rate was enhanced by accelerating the chlorine radicals’ formation (by adding HCl in catalytic quantity in the air flow or by PCE over-heating). In these conditions, the oxidation rate constant of PCE in the PFR was about five times higher than that in the PTR, although the mass of catalyst involved in the PFR was about 10 times lower and the contact time was about a 1000 times shorter than that of the PTR. Thus, the catalyst is globally more efficiently used in the PFR, as the mass transfer is not limiting. As a result, a degradation mechanism of PCE, involving the generation of free chlorine radicals, as the first limiting step, has been confirmed.     

Oxidative degradation of dyes and surfactant in the Fenton and photo-Fenton treatment of dyehouse effluents

The oxidative degradation of two dyes and a nonionic surfactant by iron(II) sulphate and hydrogen peroxide (Fenton's reagent) was studied, in the presence of UV irradiation (photo-Fenton process). The degradation kinetics were followed by measuring the residual total organic carbon (TOC) value as a function of time at different initial TOC concentrations and temperatures. The curves interpolating the kinetic data show that the residual TOC values attained a stable level after a given treatment time; a similar trend was observed in the treatment of some dyehouse effluent samples. Moreover, by fitting experimental data, a first-order equation was obtained that can explain the kinetic model proposed.     

Optimal synthesis of Fenton reactor networks for phenol degradation

There is an increasing need to treat effluents contaminated with phenol with advanced oxidation processes (AOPs) to minimize their impact on the environment as well as on bacteriological populations of other wastewater treatment systems. One of the most promising AOPs is the Fenton process that relies on the Fenton reaction. Nevertheless, there are no systematic studies on Fenton reactor networks. The objective of this paper is to develop a strategy for the optimal synthesis of Fenton reactor networks. The strategy is based on a superstructure optimization approach that is represented as a mixed integer non-linear programming (MINLP) model. Network superstructures with multiple Fenton reactors are optimized with the objective of minimizing the sum of capital, operation and depreciation costs of the effluent treatment system. The optimal solutions obtained provide the reactor volumes and network configuration, as well as the quantities of the reactants used in the Fenton process. Examples based on a case study show that multi-reactor networks yield decrease of up to 45% in overall costs for the treatment plant.     

Fenton反应处理三唑磷农药废水

采用Fenton氧化法降解三唑磷农药废水,考察了FeSO4·7H2O、H2O:投加量、pH和搅拌时间等关键因素对三唑磷模拟废水的COD去除率的影响,确定了反应的最佳条件,并对湖南天宇化工农药有限公司的综合废水和车间废水进行了降解实验研究.结果表明:综合废水和车间废水处理的最佳工艺条件(每500 mL废水)均是pH为4、FeSO4·7H2O 2.5 g、30%H2O2 37.5 mL、搅拌时间为90 min;处理后水质可以达到国家标准.