NaNO(2)/FeCl(3) catalyzed wet oxidation of the azo dye Acid Orange 7

A combination of ferric chloride and sodium nitrite significantly improved the wet oxidation of the azo dye Acid Orange 7 (AO7) in acid aqueous media (pH 2.6) under moderate conditions (T=150 degrees C; oxygen pressure=0.5 MPa). To evaluate the catalytic system, wet oxidation of AO7 was carried out at temperatures between 90 and 150 degrees C and oxygen pressures ranging from 0.1 to 0.5 MPa. The effect of initial solution pH from 2.6 to 11.4 and the amount of catalyst on the degradation of AO7 were also investigated. AO7 initial concentration was kept 200 mg L(-1). The degradation process was monitored by UV-visible spectroscopy, HPLC, IC (ion chromatography), GC-MS and TOC analysis. At 150 degrees C and 0.5 MPa oxygen pressure, 56% TOC was removed after 4h of treatment, while no obvious TOC removal were achieved without catalyst at the same experimental condition. The main degradation products were some small organic acids: formic acid, acetic acid, pyruvic acid, oxalic acid, succinic acid (identified and quantified by IC) and phthalic acid (identified by GC-MS).     

Treatment of phenolic wastewater by horseradish peroxidase immobilized by bioaffinity layering

Horseradish peroxidase was immobilized by bioaffinity layering and used for the treatment of wastewater containing p-chlorophenol. For this purpose, lectin Concanavalin A was bound to Sephadex beads. The glycoenzyme peroxidase was layered upon this Con A layer. Subsequently, alternate layers of the enzyme and Con A were applied. The most efficient design consisted of three layers of Con A and peroxidase each. This immobilized enzyme preparation retained 80% of the activity of the free peroxidase used for immobilization. PEG at the concentration of 0.1 mg ml(-1) was found to prevent enzyme inactivation by the products, although it increased the process time. Thus 60 U ml(-1) of enzyme completely converted the p-chlorophenol (into products) in 4 min in the absence of PEG. On the other hand, only 0.05 U ml(-1) of enzyme was required for this purpose in the presence of PEG but the process required 60 min. Peroxidase converts phenol molecules into free radicals. These free radicals then polymerize and get precipitated. As a further means of minimizing exposure of the enzyme to free radicals and enhancing the reusability, it was decided to remove the enzyme from reaction medium after 10 min. With this strategy, the bioaffinity layered peroxidase preparation could be reused five times without any loss of activity.     

Degradation of azo dye Acid Red 14 in aqueous solution by electrokinetic and electrooxidation process

A new wastewater treatment technology--electrokinetic-electrooxidation process (EK-EO process) is developed in this paper. The EK-EO process can take advantage of both electrooxidation on the anode surface and the electrokinetic process of anionic impurities under an electric field, which can enhance the TOC removal in electrolysis process. The degradation of an anionic azo dye Acid Red 14 (AR14) was experimentally investigated. It was found that under an electric field AR14 could be migrated into anode compartment and be efficiently mineralized. After 360 min electrolysis of 100 mgl(-1) AR14 solutions at 4.5 mAcm(-2), complete discoloration was observed in both cathode and anode compartment. About 60% TOC was electromigrated from cathode compartment to anode compartment, and more than 25 mgl(-1) TOC was abated in anode compartment. A possible degradation mechanism of AR14 by EK-EO process was proposed. Additionally, the effect of current density, recycling flux, and electrolyte concentration on the EK-EO degradation of AR14 was also investigated.     

Photocatalytic degradation of an azo dye using N-doped NaTaO3 synthesized by one-step hydrothermal process

N-doped NaTaO₃ compounds (NaTaO_3−xN_x) with nano-cubic morphology were successfully synthesized by one-step hydrothermal method and Methyl Orange (MO) was used as a model dye to evaluate their photocatalytic efficiency under visible-light irradiation. The as-prepared NaTaO_3−xN_x samples were characterized by various techniques, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra and GC-MS. The results indicate that NaTaO_3−xN_x displays a pure perovskite structure when the synthesis temperature is higher than 180 °C. Moreover, as observed by SEM images, the particles of resultant NaTaO_3−xN_x show cubic morphology with the edge length of 200-500 nm, which can be easily removed by filtration after photocatalytic reaction. Doping of N increases the photocatalytic activity of NaTaO₃, and NaTaO_2.953N_0.047 shows the highest visible-light photocatalytic activity for the degradation of MO. Based on the experiment results, a possible mechanism of the photocatalysis over NaTaO_3−xN_x and the photodegradation pathway of MO were proposed.     

铁屑还原及微波铁屑诱导氧化降解偶氮染料历程的研究

研究了铁屑内电解还原及微波诱导氧化降解偶氮染料的反应历程,采用胶束毛细管电泳法对跟踪了2种不同降解方法下的中间产物变化.实验结果表明,染料的偶氮键(-N=N-)易被铁屑内电解还原,反应过程中有中间产物苯胺生成.微波诱导铁屑氧化偶氮染料的反应过程中未检测到其他芳环类化合物生成,在微波辐照2 min时脱色率已达90%以上,TOC去除率也高达78%,矿化较为彻底;在微波辐照铁屑诱导氧化降解污染物的同时,也使铁屑自身得以活化再生,提高了铁屑的内电解能力.     

MIL-88B(Fe)固定辣根过氧化物酶去除双酚A

通过溶剂热合成法制备了水稳定性的铁基金属有机骨架材料MIL-88B(Fe),并将辣根过氧化酶(HRP)以共价固定法负载在MIL-88B(Fe)上得到MIL-88B(Fe)/HRP复合材料,并用于降解双酚A (BPA)。通过XRD、FTIR、SEM和TGA等手段对材料进行了表征。结果表明,HRP成功固定在MIL-88B(Fe)表面,没有改变MIL-88B(Fe)的形貌和晶体结构;在添加亲水剂聚乙二醇后,MIL-88B(Fe)/HRP可高效去除BPA,1 h内BPA去除率可达99.2%。分别考察了PEG用量、BPA初始质量浓度、固定化酶投加量等对降解效率的影响。结果表明,在PEG/BPA质量比0.4、pH = 7、25 ℃、BPA初始质量浓度20 mg·L⁻¹、固定化酶投加量为0.06 g·L⁻¹的条件下,3 h内可去除98.4%的BPA。此外,MIL-88B(Fe)/HRP复合材料具有较好的稳定性和可重复使用性,固定化HRP的贮存稳定性、热稳定性均优于游离HRP,循环使用4次后,固定化HRP的残余活性仍高于80%。以上研究结果可为新型酶固定材料的开发及其在废水处理中的应用提供参考。     

Reducing degradation of azo dye by zero-valent iron in aqueous solution

The reducing degradation kinetics of five azo dyes, Acid orange II, Acid orange IV, Acid orange GG, Acid red 3B and Orange I, by zero-valent iron powder in aqueous solution were studied. It showed that the degradation is a two-step reaction, with the first step being reversible. Solution acidity and iron surface area are the factors greatly influencing the degradation rates, and with increasing of acidity and iron surface area, the degradation rates increase.     

Impacts of horseradish peroxidase immobilization onto functionalized superparamagnetic iron oxide nanoparticles as a biocatalyst for dye degradation

Environmental Science and Pollution Research - To enhance the dye removal efficiency by natural enzyme, horseradish peroxidase (HRP) was immobilized onto amine-functionalized superparamagnetic iron...     

Fe/沸石对偶氮染料活性黑5的催化降解

为了对水中偶氮染料活性黑5的去除进行研究,通过沉淀法在沸石上负载Fe2O3制备出一种具有较高催化活性的催化剂,采用X-射线衍射仪（XRD）和扫描电镜（SEM）对其结构和形貌进行了表征,并利用Fe/沸石进行非均相Fenton反应处理模拟染料废水的研究,考察不同操作条件对活性黑5降解效果的影响。实验结果表明,活性黑5的脱色率随催化剂投加量的升高而升高,但是随着染料初始浓度的升高而降低。H2O2浓度和pH的升高均使得活性黑5的脱色率先升高而后降低。在最佳pH为3,最佳H2O2浓度为200 mg·L-1的条件下,活性黑5的脱色率达到最大,为95.7%。通过对催化剂Fe/沸石稳定性研究,发现经5次连续循环使用后,活性黑5脱色率仍然可保持在94%以上,说明该催化剂具有良好的循环使用性能。     

一株高效广谱染料脱色菌脱色条件的优化

以模拟酸性大红3R染料废水为对象,在单因素实验基础上,选取温度、初始染料浓度、酵母粉浓度三因素为影响因子,以染料脱色率为响应值,利用Box-Behnken设计及响应面分析法研究了各因素对一株广谱型染料脱色菌株Enterobacter cloacae strain M3脱色效果的影响及各因素间交互作用,建立了二次多项式回归方程的预测模型,确定了菌株脱色酸性大红3R废水的优化条件。结果表明：回归方程极显著,拟合性好。最优脱色条件为温度36℃,染料浓度121.12 mg/L,酵母粉浓度1.99%,在此条件下,染料脱色率可达99.21%。经实验验证,实际值与模型预测值拟合良好,偏差仅为0.79%。     

超声-Fenton高级氧化降解染料工业废水的研究

采用超声与Fenton高级氧化技术联合处理染料废水,取得了满意的效果。同时考察了初始浓度、初始pH值、超声时间、超声频率、超声功率、H2O2和FeSO4初始浓度等因素对其COD去除效果的影响,当超声波频率为45 kHz,功率为200 W,初始pH值为2.63,超声时间为150 min,H2O2浓度为60 mmol/L,FeSO4浓度为12 mmol/L时,染料废水COD去除率达到91.8%。     

催化湿式过氧化（CWPO）偶氮染料反应机理及降解历程研究

采用浸渍法制备出具有较高催化活性的催化剂CuO/γ-Al2O3,通过XRD、电镜等手段对催化剂进行了表征。降解了几种不同结构的偶氮染料,并通过改变CWPO的反应条件推断了其催化反应机理。采用紫外/可见分光光度计（UV-Vis）和傅里叶红外光谱仪（IR）等手段对染料降解过程进行跟踪和分析,对比染料处理前后紫外可见光谱与红...     

Exploration of the key functional strains from an azo dye degradation microbial community by DGGE and high-throughput sequencing technology

Environmental Science and Pollution Research - This study investigated a previously developed thermophilic microbial community with the ability to effectively degrade azo dyes. To identify the key...     

Fate and transformation of naphthylaminesulfonic azo dye Reactive Black 5 during wastewater treatment process

Certain aromatic amines generated by the decolorization of some azo dyes are not removed substantially by conventional anaerobic–aerobic biotreatment. These aromatic amines are potentially toxic and often released in the wastewater of industrial plants. In this study, the fate and transformation of the naphthylaminesulfonic azo dye Reactive Black 5 (RB5) during different phases of a sequencing batch reactor were investigated. The major products of RB5 decolorization during the anaerobic phase include 2-[(4-aminophenyl)sulfonyl]ethyl hydrogen sulfate (APSEHS) and 1-2-7-triamino-8-hydroxy-3-6-naphthalinedisulfate (TAHNDS). During the aerobic phase, APSEHS was hydrolyzed and produced 4-aminobenzenesulfonic acid, which was further degraded via dearomatization. TAHNDS was transformed rapidly via auto-oxidation into TAHNDS_DP-1 and TAHNDS_DP-2, which were not further removed by the activated sludge during the entire 30-day aerobic phase. In contrast, different behaviors of TAHNDS were observed during the anoxic phase. The transformation of TAHNDS was initiated either by deamination or desulfonation reaction. TAHNDS was then converted into 3,5-diamino-4-hydroxynaphthalene-2-sulfonic acid, which was subsequently removed via ring cleavage reaction under aerobic condition. In conclusion, complete degradation of TAHNDS by activated sludge occurs only during anoxic/aerobic processes instead of the conventional anaerobic/aerobic processes.     

MIL-88B(Fe)非均相芬顿催化降解磺胺甲恶唑

采用溶剂热法合成了铁基金属有机骨架材料MIL-88B(Fe),将其作为类芬顿催化剂用于催化降解水中磺胺甲恶唑(SMX)。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、傅立叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等对催化剂的结构和性能进行表征,并研究了H₂O₂浓度、催化剂投加量、溶液初始pH和污染物初始浓度等对SMX降解效果的影响。结果表明,在H₂O₂摩尔浓度为6.0mmol/L、催化剂投加量为0.2g/L、pH为4、SMX为5mg/L的优化反应条件下,MIL-88B(Fe)对SMX的降解率可达99%。在较宽的pH(4～6)范围内,MIL-88B(Fe)仍保持较好的催化活性,且5次循环使用后对SMX去除率仍可达95%以上。表明合成的MIL-88B(Fe)具有较高的催化活性和重复性能,是一种优良的非均相类芬顿催化剂。     

Coupled oxidation of aromatic hydrocarbons by horseradish peroxidase and hydrogen peroxide

The oxidation capability of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) coupled oxidation of aromatic hydrocarbons (o-xylene-d10 and naphthalene-d8) was investigated. Batch experiments were conducted using horseradish peroxidase prepared in potassium phosphate buffer in the presence of H2O2. The oxidation of aromatic hydrocarbon was tested as a function of HRP at a fixed concentration of H2O2, and as a function of the concentration of H2O2 at a constant HRP activity (4000 units/ml). The mass removal of o-xylene-d10 and naphthalene-ds increased with increasing HRP enzymatic activity, and up to 54% and 51% of mass removal were observed for o-xylene-d10 and naphthalene-d8, respectively. Increasing the concentration of H2O2 resulted in increased mass removal of aromatic hydrocarbons.     

Comparison of azo dye degradation efficiency using UV/single semiconductor and UV/coupled semiconductor systems

This study examined degradation of azo dyes using photocatalytic oxidation (UV/semiconductor). The model substrates employed in this work were Procion Red MX-5B and Amaranth, while the photocatalysts were TiO2, ZnO, and SnO2. UV-Vis spectrum analysis demonstrated that the band gap energies of TiO2, ZnO, and SnO2 were 3.17, 2.92, and 4.13 eV, respectively. The band gap energy of SnO2 is insufficient to initiate photocatalytic reaction after UV irradiation (365 nm). The reaction rate constants fit a first-order reaction model and the reaction rate constant of Procion Red MX-5B for TiO2+SnO2 (0.31 h-1) is larger than that of TiO2 (0.24 h-1) and SnO2 at pH 10. The difference between the conduction bands of SnO2 and TiO2 enables the former to act as a sink for the photogenerated electrons. Most of the reaction rate constants had higher values at pH 10 than pH 7, and thus the OH attack could be assumed to represent the main reaction in this investigation. The quantities of sulfate and chloride ions released are below stoichiometry during the degradation. Owing to the sulfonate groups of Amaranth exceeding Procion Red MX-5B, Amaranth had larger electrostatic attraction than Procion Red MX-5B with the surface of ZnO, and also had higher adsorption percentage than Procion Red MX-5B on the surface of ZnO. The trend of adsorption is consistent with the reaction rate constant at pH 7, namely Amaranth>Procion Red MX-5B. The sulfate dissociation rate constant of Amaranth in UV/ZnO at pH 7 (0.49 h-1) approaches the overall rate constant (0.53 h-1); therefore, the first step involved in Amaranth can be suggested to the cleavage of the bonds of the C-S in Amaranth, causing sulfate ion formation.