Magnetic Fe(2)MO(4) (M:Fe, Mn) activated carbons: fabrication, characterization and heterogeneous Fenton oxidation of methyl orange

We present a simple and efficient method for the fabrication of magnetic Fe(2)MO(4) (M:Fe and Mn) activated carbons (Fe(2)MO(4)/AC-H, M:Fe and Mn) by impregnating the activated carbon with simultaneous magnetic precursor and carbon modifying agent followed by calcination. The obtained samples were characterized by nitrogen adsorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), and the catalytic activity in heterogeneous Fenton oxidation of methyl orange (MO) was evaluated. The resulting Fe(2)MnO(4)/AC-H showed higher catalytic activity in the methyl orange oxidation than Fe(3)O(4)/AC-H. The effect of operational parameters (pH, catalyst loading H(2)O(2) dosage and initial MO concentration) on degradation performance of the oxidation process was investigated. Stability and reusability of selected catalyst were also tested.     

Decolourization and mineralization of commercial reactive dyes by using homogeneous and heterogeneous Fenton and UV/Fenton processes

The oxidative decolourization and mineralization of three reactive dyes in separately prepared aqueous solutions C.I. Reactive Yellow 3 (RY3), C.I. Reactive Blue 2 (RB2) and C.I. Reactive Violet 2 (RV2) by using homogeneous and heterogeneous Fenton and UV/Fenton processes have been investigated. The effects of H(2)O(2), Fe(2+) and Fe(0) concentrations, Fe(2+)/H(2)O(2) and Fe(0)/H(2)O(2) molar ratios at pH 3 and T=23+/-1 degrees C have been studied. Optimal operational conditions for the efficient degradation of all three dye solutions (100 mg L(-1)) were found to be Fe(2+)/H(2)O(2)=0.5mM/20mM and Fe(0)/H(2)O(2)=2mM/1mM. The experimental results showed that the homogeneous Fenton process employing UV irradiation was the most effective. By using this process, the high levels of mineralization (78-84%) and decolourization (95-100%) were achieved. Pseudo-first-order degradation rate constants were obtained from the batch experimental data.     

Degradation of 2,4-dichlorophenol in aqueous solution by a hybrid oxidation process

A hybrid photoelectroreaction system has been developed in this study, which consists of three functional electrodes: a TiO2/Ti sheet as the anode, a steel (Fe) sheet as another anode in parallel and a piece of graphite felt (GF) as the cathode. While an electrical current is applied between the Fe anode and GF cathode and UV light is irradiated on the surface of TiO2/Ti anode, both of E-Fenton reaction and photoelectrocatalytic (PEC) reaction are involved simultaneously. The integration of E-Fenton and PEC reactions was evaluated in terms of 2,4-dichlorophenol (2,4-DCP) degradation in aqueous solution. In the meantime, the current distribution between two anodes and pH influence on the 2,4-DCP degradation were studied and optimized. Experimental results confirmed that 2,4-DCP in aqueous solution was successfully degraded by 93% and mineralized by 78% within 60 min in such a hybrid oxidation process. When a current intensity of 3.2 mA was applied, the current efficiency for H2O2 generation on the GF cathode was determined to be 61%. Furthermore, the experiments demonstrated that combination of E-Fenton reaction with photocatalytic reaction let the process be less pH sensitive and would be more favorable to water and wastewater treatment in practice.     

Degradation of cyanobacteria toxin by advanced oxidation processes

Advanced oxidation processes (AOPs) using O(3), H(2)O(2), O(3)/H(2)O(2), O(3)/Fe(II), and Fenton treatment were investigated for the degradation of aqueous solutions of cyanobacteria. The effects of concentration of reactants, temperature, and pH on toxins degradation were monitored and the reaction kinetics was assessed. O(3) alone or combined with either H(2)O(2) or Fe(II) were efficient treatment for toxins elimination. A higher toxin oxidation tendency was observed with Fenton reaction; total toxins degradation (MC-LR and MC-RR) was achieved in only 60s. The ozonation treatment was successfully described by second-order kinetics model, with a first-order with respect to the concentration of either ozone or toxin. At 20 degrees C, with initial concentration of MC-LR of 1mg/L, the overall second-order reaction rate constant ranged from 6.79 x 10(4) to 3.49 x 10(3)M(-1)s(-1) as the solution pH increased from 2 to 11. The reaction kinetics of the other AOPs (O(3)/H(2)O(2), O(3)/Fe(II), and Fenton), were fitted to pseudo first-order kinetics. A rapid reaction was observed to took place at higher initial concentrations of O(3), H(2)O(2) and Fe(II), and higher temperatures. At pH 3, initial concentration of toxin of 1mg/L, the pseudo first-order rate constant, achieved by Fenton process, was in order of 8.76+/-0.7s(-1).     

Green synthesis of uniform magnetite (Fe3O4) nanoparticles and micron cubes

Single-crystalline Fe3O4 microcubes were obtained through a green hydrothermal procedure using Fe3+, Fe2+ and H2O2 as starting materials. The structures and morphologies of the as-prepared samples were characterized in detail by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) respectively. Magnetite (Fe3O4) cubes averaging 3 microm in diameter were synthesized by H2O2 oxidation of Fe3+ and Fe2+ under neutral conditions. The contrastive experiments were designed to elucidate the effects of Fe3+, Fe2+ and H2O2 on the morphology of the final products. Irregular and ellipsoidal Fe2O3 structures were obtained by H2O2 oxidation of Fe3+ and Fe2+ respectively. Meanwhile, Fe3O4 nanotubes and nanoparticles were obtained when H2O2 was replaced by NH4HCO3 and urea respectively. The results show that H2O2, Fe3+ and Fe2+ in the reactive system play critical roles in obtaining micrometric cube-like Fe3O4. While, other nanometric Fe2O3 and Fe3O4 particles with tube-like and other morphologies could also be developed by controlling the reaction parameters.     

The decolorization and mineralization of acid orange 6 azo dye in aqueous solution by advanced oxidation processes: a comparative study

The comparison of different advanced oxidation processes (AOPs), i.e. ultraviolet (UV)/TiO(2), O(3), O(3)/UV, O(3)/UV/TiO(2), Fenton and electrocoagulation (EC), is of interest to determine the best removal performance for the destruction of the target compound in an Acid Orange 6 (AO6) solution, exploring the most efficient experimental conditions as well; on the other hand, the results may provide baseline information of the combination of different AOPs in treating industrial wastewater. The following conclusions can be drawn: (1) in the effects of individual and combined ozonation and photocatalytic UV irradiation, both O(3)/UV and O(3)/UV/TiO(2) processes exhibit remarkable TOC removal capability that can achieve a 65% removal efficiency at pH 7 and O(3) dose=45mg/L; (2) the optimum pH and ratio of [H(2)O(2)]/[Fe(2+)] found for the Fenton process, are pH 4 and [H(2)O(2)]/[Fe(2+)]=6.58. The optimum [H(2)O(2)] and [Fe(2+)] under the same HF value are 58.82 and 8.93mM, respectively; (3) the optimum applied voltage found in the EC experiment is 80V, and the initial pH will affect the AO6 and TOC removal rates in that acidic conditions may be favorable for a higher removal rate; (4) the AO6 decolorization rate ranking was obtained in the order of O(3)相似文献   

Effects of pH and dissolved oxygen on Cr(VI) removal in Fe(0)/H2O systems

The effects of pH and dissolved oxygen (DO) on aqueous Cr(VI) removal by micro-scale zero-valent iron (Fe(0)/H(2)O system) were investigated. Batch experiments were conducted at pH 4.0, 5.0 and 6.0 under oxic and anoxic conditions. Column experiments were performed at pH 5.0 and 7.5 under oxic condition. Spectroscopic analyses were applied to explain the mechanism of Cr(VI) removal using X-ray absorption near-edge structure (XANES), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Results showed that the kinetics of Cr(VI) removal were fastest at pH 5 under both oxic and anoxic conditions. As a rule, Cr(VI) removal were faster under oxic conditions than under anoxic conditions. Column experiments showed that Cr(VI) removal was about 1.7-fold higher at pH 5 than at pH 7.5. XANES (X-ray absorption near edge structures) results showed that Fe(0) reduced Cr(VI) to Cr(III) under both oxic and anoxic conditions. X-ray diffraction patterns of the Cr(VI)-Fe(0) reaction products suggested partial formation of chromite (FeCr(2)O(4)) at pH 5 and 6 under oxic conditions. However, nano-sized clusters of Cr(III)/Fe(III) hydroxide/oxyhydroxide were formed on the surface of Fe(0) under anoxic conditions. These results indicate that the presence of oxygen in solution plays an important role in control of the kinetic of Cr(VI) removal and in development of various Cr(VI) reduction products.     

TiO2-Cu2O复合膜的制备及其可见光催化降解染料性能研究

采用电化学方法制备了TiO2-Cu2O纳米复合材料,并用喷涂法在玻璃表面制成TiO2-Cu2O复合膜.通过X射线衍射(XRD)、扫描电镜(SEM)等手段对TiO2-Cu2O复合材料进行了表征,用正交设计法研究了TiO2-Cu2O复合膜与Fe2 EDTA构成的Fenton试剂在可见光照射下催化降解亚甲基兰的性能,并用实验证实了H2O2存在.结果显示,TiO2-Cu2O复合膜光催化降解性能明显优于TiO2膜和Cu2O膜.与传统Fenton试剂相比,TiO2-Cu2O复合膜与Fe2 EDTA构成的Fenton试剂体系有效作用时间更长,并可重复使用.     

Synthesis of Fe(2)O(3)/TiO(2) nanorod-nanotube arrays by filling TiO(2) nanotubes with Fe

Synthesis of hematite (α-Fe(2)O(3)) nanostructures on a titania (TiO(2)) nanotubular template is carried out using a pulsed electrodeposition technique. The TiO(2) nanotubes are prepared by the sonoelectrochemical anodization method and are filled with iron (Fe) by pulsed electrodeposition. The Fe/TiO(2) composite is then annealed in an O(2) atmosphere to convert it to Fe(2)O(3)/TiO(2) nanorod-nanotube arrays. The length of the Fe(2)O(3) inside the TiO(2) nanotubes can be tuned from 50 to 550?nm by changing the deposition time. The composite material is characterized by scanning electron microscopy, transmission electron microscopy and diffuse reflectance ultraviolet-visible studies to confirm the formation of one-dimensional Fe(2)O(3)/TiO(2) nanorod-nanotube arrays. The present approach can be used for designing variable one-dimensional metal oxide heterostructures.     

Photo degradation of methyl orange an azo dye by advanced Fenton process using zero valent metallic iron: influence of various reaction parameters and its degradation mechanism

Advanced Fenton process (AFP) using zero valent metallic iron (ZVMI) is studied as a potential technique to degrade the azo dye in the aqueous medium. The influence of various reaction parameters like effect of iron dosage, concentration of H(2)O(2)/ammonium per sulfate (APS), initial dye concentration, effect of pH and the influence of radical scavenger are studied and optimum conditions are reported. The degradation rate decreased at higher iron dosages and also at higher oxidant concentrations due to the surface precipitation which deactivates the iron surface. The rate constant for the processes Fe(0)/UV and Fe(0)/APS/UV is twice compared to their respective Fe(0)/dark and Fe(0)/APS/dark processes. The rate constant for Fe(0)/H(2)O(2)/UV process is four times higher than Fe(0)/H(2)O(2)/dark process. The increase in the efficiency of Fe(0)/UV process is attributed to the cleavage of stable iron complexes which produces Fe(2+) ions that participates in cyclic Fenton mechanism for the generation of hydroxyl radicals. The increase in the efficiency of Fe(0)/APS/UV or H(2)O(2) compared to dark process is due to continuous generation of hydroxyl radicals and also due to the frequent photo reduction of Fe(3+) ions to Fe(2+) ions. Though H(2)O(2) is a better oxidant than APS in all respects, but it is more susceptible to deactivation by hydroxyl radical scavengers. The decrease in the rate constant in the presence of hydroxyl radical scavenger is more for H(2)O(2) than APS. Iron powder retains its recycling efficiency better in the presence of H(2)O(2) than APS. The decrease in the degradation rate in the presence of APS as an oxidant is due to the fact that generation of free radicals on iron surface is slower compared to H(2)O(2). Also, the excess acidity provided by APS retards the degradation rate as excess H(+) ions acts as hydroxyl radical scavenger. The degradation of Methyl Orange (MO) using Fe(0) is an acid driven process shows higher efficiency at pH 3. The efficiency of various processes for the de colorization of MO dye is of the following order: Fe(0)/H(2)O(2)/UV>Fe(0)/H(2)O(2)/dark>Fe(0)/APS/UV>Fe(0)/UV>Fe(0)/APS/dark>H(2)O(2)/UV approximately Fe(0)/dark>APS/UV. Dye resisted to degradation in the presence of oxidizing agent in dark. The degradation process was followed by UV-vis and GC-MS spectroscopic techniques. Based on the intermediates obtained probable degradation mechanism has been proposed. The result suggests that complete degradation of the dye was achieved in the presence of oxidizing agent when the system was amended with iron powder under UV light illumination. The concentration of Fe(2+) ions leached at the end of the optimized degradation experiment is found to be 2.78 x 10(-3)M. With optimization, the degradation using Fe(0) can be effective way to treat azo dyes in aqueous solution.     

Photocatalytic reduction of Cr(VI) on the new hetero-system CuAl2O4/TiO2

A magnetic adsorbent, amine-functionalized silica magnetite (NH(2)/SiO(2)/Fe(3)O(4)), has been synthesized to behave as an anionic or cationic adsorbent by adjusting the pH value of the aqueous solution to make amino groups protonic or neutral. NH(2)/SiO(2)/Fe(3)O(4) were used to adsorb copper ions (metal cation) and Reactive Black 5 (RB5, anionic dye) in an aqueous solution in a batch system, and the maximum adsorption were found to occur at pH 5.5 and 3.0, respectively. The adsorption equilibrium data were all fitted the Langmuir isotherm equation reasonably well, with a maximum adsorption capacity of 10.41 mg g(-1) for copper ions and of 217 m g g(-1) for RB5. A pseudo-second-order model also could best describe the adsorption kinetics, and the derived activation energy for copper ions and RB5 were 26.92 kJ mol(-1) and 12.06 kJ mol(-1), respectively. The optimum conditions to desorb cationic and anionic adsorbates from NH(2)/SiO(2)/Fe(3)O(4) were provided by a solution with 0.1M HNO(3) for copper ions and with 0.05 M NaOH for RB5.     

Photo-assisted Fenton type processes for the degradation of phenol: a kinetic study

In this study the application of advanced oxidation processes (AOPs), dark Fenton and photo-assisted Fenton type processes; Fe(2+)/H(2)O(2), Fe(3+)/H(2)O(2), Fe(0)/H(2)O(2), UV/Fe(2+)/H(2)O(2), UV/Fe(3+)/H(2)O(2) and UV/Fe(0)/H(2)O(2), for degradation of phenol as a model organic pollutant in the wastewater was investigated. A detail kinetic modeling which describes the degradation of phenol was performed. Mathematical models which predict phenol decomposition and formation of primary oxidation by-products: catechol, hydroquinone and benzoquinone, by applied processes were developed. The study also consist the modeling of mineralization kinetic of the phenol solution by applied AOPs. This part, besides well known reactions of Fenton and photo-Fenton chemistry, involves additional reactions which describe removal of iron from catalytic cycle through formation of ferric complexes and its regeneration induced by UV radiation. Phenol decomposition kinetic was monitored by HPLC analysis and total organic carbon content measurements (TOC). Complete phenol removal was obtained by all applied processes. Residual TOC by applied Fenton type processes ranged between 60.2 and 44.7%, while the efficiency of those processes was significantly enhanced in the presence of UV light, where residual TOC ranged between 15.2 and 2.4%.     

Fe3O4纳米粒子修饰碳纳米管的制备及其磁学性能（英文）

通过FeCl2.4H2O和FeCl3.6H2O混合共沉淀,合成平均粒径为6 nm和10 nm的Fe3O4纳米粒子。然后将两种Fe3O4纳米粒子分别与经HNO3氧化处理的多壁碳纳米管(MWCNTs)置于乙醇水溶液(水和乙醇的体积比为1∶1)中,在超声波作用下制备Fe3O4/MWCNT复合材料。用高分辨透射电子显微镜、X-射线光电子能谱、振动样品磁强计、X射线衍射仪、热重分析仪对所制备的Fe3O4/MWCNT复合材料进行表征。结果表明:由6 nm和10 nm Fe3O4纳米粒子所制备的Fe3O4/MWCNT复合材料中,Fe3O4的质量分数分别为26.65%和29.3%,相应的磁饱和强度分别为16.5 emug-1和7.5 emug-1。     

Effects of reaction conditions on nuclear laundry water treatment in Fenton process

This study presents the efficiency of Fenton process in the degradation of organic compounds of nuclear laundry water. The influence of Fe(2+) and hydrogen peroxide ratio, hydrogen peroxide dose, pH and treatment time were investigated. The degradation of non-ionic surfactant and other organic compounds was analysed as COD, TOC and molecular weight distribution (MWD). The most cost-effective degradation conditions were at H(2)O(2)/Fe(2+) stoichiometric molar ratio of 2 with 5 min mixing and H(2)O(2) dose of 1000 mg l(-1). With the initial pH of 6, the reductions of COD and TOC were 85% and 69%, respectively. However, the removal of the organic compounds was mainly carried out by Fenton-based Fe(3+) coagulation rather than Fenton oxidation. Fenton process proved to be much more efficient than previously performed ozone-based oxidation processes.     

Ni_(0.5)Zn_(0.5)Fe_2O_4铁氧体的制备及其电磁损耗性能

以Zn(NO3)2.6H2O、Ni(NO3)2.6H2O和Fe(NO3)3.9H2O及柠檬酸为原料,采用溶胶-凝胶法制备前驱体,在1 200℃下煅烧3 h合成ZnFe2O4和Ni0.5Zn0.5Fe2O4铁氧体粉体。利用差热分析、X射线衍射、扫描电镜、透射电镜和红外光谱等测试手段对产物进行分析和表征。结果表明:ZnFe2O4和Ni0.5Zn0.5Fe2O4属于立方晶系尖晶石结构,结晶完整,晶粒大小在100 nm左右。在0.2~1.8 GHz的频率下对产品进行了电磁损耗性能测试,发现Ni0.5Zn0.5Fe2O4具有较好的电磁损耗特性。     

Heterostructured bismuth molybdate composite: preparation and improved photocatalytic activity under visible-light irradiation

A heterostructured photocatalyst containing the same Bi, Mo, and O elements (Bi(3.64)Mo(0.36)O(6.55)/Bi(2)MoO(6)) was realized by a facile hydrothermal method. The heterostructured composite was characterized by powder X-ray diffraction, selected-area electron diffraction, scanning electron microscopy, and high-resolution electron microscopy. The Bi(3.64)Mo(0.36)O(6.55)/Bi(2)MoO(6) composite exhibited notable enhanced photocatalytic activity compared to Bi(2)MoO(6) or Bi(3.64)Mo(0.36)O(6.55) in the photocatalytic degradation of rhodamine B and phenol under visible-light irradiation. More interestingly, it is found that the heterostructured composite could mineralize organic substances into CO(2) efficiently. This study offered a clue for the design of an efficient photocatalyst in the application of environmental treatment.     

纳米Fe2O3粒子修饰/填充碳纳米管的可控制备

为研究碳纳米管填充和负载的可控制备,通过沉积负载方法和湿化学填充法制备了不同负载率和填充率的碳纳米管,采用红外光谱仪、X射线衍射仪、高分辨透射电子显微镜和热重分析仪进行了结构表征分析.研究结果表明,负载率和填充率与C和Fe的比例有关.当C与Fe的质量比为4∶1或8∶1时,负载率分别为28.52%或16.17%,填充率分别为11.32%或9.43%.     

介孔氧化镍微球的水热-热分解法制备及其在血红蛋白直接电化学检测中的应用

以聚乙二醇-6000为模板剂,Ni(NO3)2.6H2O为镍源,通过微波水热法合成了Ni(OH)2前驱体微球,再采用热分解法最终获得介孔氧化镍微球,并对样品XRD、SEM、TEM和N2吸-脱附等结构表征。利用涂布法以离子液体为粘合剂,制备了固定血红蛋白(Hb)的复合工作电极,并对吸附于膜内的Hb电化学行为进行了研究。结果表明采用水热-热分解法可以获得直径为2.0μm颗粒堆积介孔氧化镍微球,该氧化镍微球具有高的比表面积(234m2/g)和窄的孔径分布(3.25nm)。循环伏安实验表明,在pH值=7.0的磷酸缓冲溶液中,Hb表现出一对峰型良好的准可逆氧化还原峰,为Hb Fe(Ⅲ)/Fe(Ⅱ)电对的特征峰,对其直接电化学行为进行了研究,求出电位为-0.278V(vs Ag/AgCl),电子转移数为1.104,电荷传递系数为0.476,表观异相电子转移速率常数为0.775s-1。     

Fe(III)/rGO/Bi2MoO6复合光催化剂制备及光催化芬顿协同降解苯酚

光催化-芬顿技术耦合可高效降解有机污染物。本研究采用溶剂热法制备了Fe(III)掺杂rGO/Bi₂MoO₆复合催化剂(Fe(III)/rGO/Bi₂MoO₆), 通过外加H₂O₂构建了光催化-芬顿协同体系, 可见光照射3 h后对苯酚的降解率(82%)远高于单独光催化(18%)或芬顿反应(48%), 进一步优化条件对苯酚可实现完全降解。这主要是通过Fe得失电子实现价态的转变, 并以此作为桥梁实现光催化-芬顿的协同作用。同时石墨烯的优异导电性能不仅克服了光催化中光生电子空穴难以分离的问题, 而且促进了Fe³⁺/Fe²⁺的循环反应, 促使芬顿反应产生更多的羟基自由基(?OH), 进一步提高了苯酚的降解效率。实验考察了Fe(III)含量、催化剂投加量、H₂O₂含量以及pH等因素对协同降解效果的影响。淬灭实验证明?OH是协同降解体系中最主要的活性物种, ?O₂^-和h⁺对降解活性也会产生一定的影响, 结合实验结果提出了Fe(III)/rGO/Bi₂MoO₆光催化-芬顿协同降解苯酚的机理。     

Oxidative degradation of diethyl phthalate by photochemically-enhanced Fenton reaction

A kinetic investigation into the photo-degradation of aqueous diethyl phthalate by Fenton reagent was conducted in this study. The obtained results showed the enhancement of diethyl phthalate (DEP) decomposition by UV irradiation with the Fenton reaction. It was found that H2O2 concentration, Fe2+ concentration, and aqueous pH value were the three main factors that could significantly influence the degradation rates of DEP. The highest degradation percentage (75.8%) of DEP was observed within 120 min at pH 3 in the UV/H2O2/Fe2+ system, with original H2O2 and Fe2+ concentrations of 5.00 x 10(-4) and 1.67 x 10(-4)mol L(-1), respectively. The present study provides an effective approach to the treatment of wastewater containing DEP.