Degradation of azo dye C.I. Acid Red 18 in aqueous solution by ozone-electrolysis process

In this paper, the degradation of azo dye C.I. Acid Red 18 (AR18) with initial concentration of 100 mg L⁻¹ in aqueous solution by ozone-electrolysis process (OEP) as hybrid method of advance oxidation process was investigated. All experiments were performed in a 450 mL mixed semi-batch reactor to obtain the optimal conditions. The effects of NaCl concentration as supporting electrolyte, current density and initial pH on the removal efficiency of AR18 solution were investigated. The efficiency of color and TOC removal were compared as functional of degradation and decolorization of AR18. The results of UV/vis spectra showed that the AR18 structures were destroyed under ozone-electrolysis reaction. This investigation revealed ozone-electrolysis presents good efficiency for both solution decolorization and total organic carbon (TOC) removal. Results of experiments indicated that ozone-electrolysis process has a synergistic effect on decolorization rate of AR18.     

Mineralization of an azo dye Acid Red 14 by photoelectro-Fenton process using an activated carbon fiber cathode

The mineralization of an azo dye Acid Red 14 (AR14) by the photoelectro-Fenton (PEF) process was studied in an undivided electrochemical reactor with a RuO₂/Ti anode and an activated carbon fiber (ACF) cathode able to electrochemically generate H₂O₂. Anodic oxidation and UV irradiation of AR14 were also examined as comparative experiments. Results indicate that the electro-Fenton process yielded about 60–70% mineralization of AR14, while the photoelectro-Fenton could mineralize AR14 more effectively (more than 94% total organic carbon (TOC) removal) even at low current densities assisted with UV irradiation after 6 h electrolysis. The mineralization current efficiency (MCE) of the PEF process increased with the increasing AR14 concentrations. In addition, the initial solution pH ranging from 1.49 to 6.72 had little influence on the TOC removal probably due to the formation of organic carboxylic acids which balanced the pH increase caused by the cathodic generation of hydrogen gas. The ACF cathode showed a long-term stability during multiple experimental runs for degradation of AR14, indicating its good potential for practical application in treating refractory organic pollutants in aqueous solutions.     

Optimisation of electrochemical decolourisation process of an azo dye,Methyl Orange

The decolourisation of an azo dye, Methyl Orange, by an electrochemical technology was studied in a reaction cell with a working volume of 1 dm³, using graphite for both electrodes (anode and cathode). No decolourisation was detected in the treatment of pure solutions of Methyl Orange, but significant decolourisation was observed in the presence of NaCl, the influence of which was established. The extent of decolourisation, treatment time, and electrical consumption largely depended on the applied potential difference; the optimum value being around 5V. To achieve effective decolourisation, the NaCl concentration should be increased as the concentration of azo dye increases. Thus, almost complete decolourisation was achieved in 60 min for an effluent containing 40 kg m^?3 NaCl and 90 g m^?3 of dye. Increasing temperature (from 20 to 40°C) did not improve the efficiency of electrochemical oxidation. Copyright © 2004 Society of Chemical Industry     

Anodic oxidation of azo dye C.I. Acid Red 73 by the yttrium-doped Ti/SnO2-Sb electrodes

This work was conducted to study the ability of anodic oxidation of azo dye C.I. Acid Red 73 (AR73) using the yttrium-doped Ti/SnO₂-Sb electrodes. The effects of Sb doping level, yttrium doping level, thermal decomposition temperature and cycle times of dip-coating thermal decomposition on the properties of the electrodes were investigated. The results showed that the excellent electrochemical activity of Ti/SnO₂-Sb-Y electrode can be achieved at a 7∶1 molar ratio of Sn∶Sb and thermal decomposition temperature of 550°C. Moreover when the cycle times of dip-coating and thermal decomposition were up to 10 times, the performance of the electrode tends to be stable. The Ti/SnO₂-Sb electrodes doped with yttrium (0.5 mol-%) showed the most excellent electrochemical activity. In addition, the influences of operating variables, including current density, initial pH, dye concentration and support electrolyte, on the colour removal, chemical oxygen demand (COD) removal and current efficiency were also investigated. Our results confirmed that the current efficiency increased with the concentrations of dye and sodium chloride. Moreover, increasing the current density and the initial pH would reduce the current efficiency.     

The mechanism and application of the electro‐Fenton process for azo dye Acid Red 14 degradation using an activated carbon fibre felt cathode

BACKGROUND: The discharge of azo dyes into the environment poses concerns due to their limited biodegradability. The electro‐Fenton process (EF) is a good method to effectively degrade these dyes. The aim of this work was to study the mechanism and the feasibility of the EF reaction using an activated carbon fibre (ACF) cathode. In this study, two methods were used to measure the reactive species generated in anodic oxidation (AO), anodic oxidation with electrogenerated H₂O₂ (AO‐H₂O₂) and the EF process. Acid Red 14 (AR14) was chosen as a model pollutant. The effects of the operational parameters, pH and initial concentrations were investigated. A short‐term biodegradability test was also carried out to evaluate the EF process from a biological point of view. RESULTS: After 2 h EF reaction 118.7 µmol L^?1?OH were produced, which was much higher than that of the AO‐H₂O₂ (63.2 µmol L^?1) process. H₂O₂ is largely generated and Fe³⁺ efficiently reduced on the high surface area of the ACF cathode. The EF process provides more effective degradation of AR14 than the conventional Fenton process, and its current efficiency is significantly affected by the initial pH and the initial AR14 concentration. Following EF treatment, the biodegradability of AR14 is significantly increased. CONCLUSION: The higher formation of ^?OH in the EF process suggests it is an effective method for pollutant removal. This process also leads to increased biodegradability, which is expected to facilitate subsequent biological treatment. Copyright © 2010 Society of Chemical Industry     

Degradation of pararosaniline (C.I. Basic Red 9 monohydrochloride) dye by ozonation and sonolysis

Pararosaniline (C.I. Basic Red 9) is an important dye used in biological and chemical assays, suspected of being carcinogenic. Thus, the environmental and occupational issues related to it are very important. This study aims at investigating the chemical oxidation of pararosaniline dye by ozonation and sonolytic processes. Experimental results indicate that ozonation of pararosaniline solution is more efficient than ultrasonic irradiation alone or in combination with O₃. The detoxification was assessed by determining acute toxicity and mutagenicity of the ozonized dye solutions. Even for short-term ozonation (15 min) any mutagenic effect was verified although longer treatment periods (120 min) are necessary to obtain high toxicity removal. The results obtained indicate that ozonation is a powerful tool for the treatment of the pararosaniline wastes, even when compared to other advanced oxidation processes as photocatalytic and hydrogen peroxide dye degradation. The kinetics of different pararosaniline degradation techniques are also discussed such an understanding is necessary for the design and application of pararosaniline treatment processes.     

分子识别作用下光催化降解偶氮染料酸性红B

以250 W金属卤化物灯(λ365 nm)为光源,二氧化钛为催化剂,研究了经分子识别作用后的酸性红B光催化降解行为,考察了影响光催化降解的条件因素。研究结果表明:对于20 mg/L的酸性红B,经β-环糊精分子识别后酸性红B的光催化降解效率可以提高24%;β-环糊精浓度、pH值和TiO2剂量对酸性红B的光催化降解速率有明显的影响。分子识别作用下酸性红B光催化降解的增强效应主要源于β-环糊精能有效促进酸性红B在TiO2表面的吸附。     

Degradation of azo dye by an electroenzymatic method using horseradish peroxidase immobilized on porous support

An electroenzymatic process is an interesting approach that combines enzyme catalysis and electrode reactions. Degradation of orange II by an electroenzymatic method using horseradish peroxidase (HRP) bound on inexpensive and stable inorganic beads was studied in a continuous electrochemical reactor with in situ generation of hydrogen peroxide. HRP was immobilized on Celite®R-646 as a porous support with 2% aqueous glutaraldehyde (GA), while the protein and activity yield were 3.6 mg protein and 5,280 U per g Celite, respectively. Based on a parametric study, the operating conditions were chosen, and over 90% of the degradation efficiency of orange II was maintained during continuous operation for 36 hr. From the results of GC/MS analysis, degradation products were identified and a possible breakdown pathway of orange II was also proposed. This study shows the feasibility of an electroenzymatic process to degrade azo dye compounds in wastewater.     

Degradation of C.I. Acid Red 88 aqueous solution by combination of Fenton's reagent and ultrasound irradiation

BACKGROUND: Pollution caused by industrial wastewater has become a common problem for many countries. In particular, dye pollutions from industrial effluents disturb human health and ecological equilibrium. The discharge of highly colored synthetic dye effluents is aesthetically displeasing and can damage the receiving water body by impeding penetration of light. Azo dyes can be reduced to more hazardous intermediates on anaerobic conditions. Therefore, an effective and economic treatment of effluents containing a diversity of textile dyes has become a necessity for clean production technology for textile industries. Herein we wish to report the degradation of Acid Red 88 by the combination of Fenton's reagent and ultrasound irradiation. RESULTS: The results show that the combination of ultrasonic irradiation and Fenton's reagent is effective for the degradation of Acid Red 88 aqueous solution. Furthermore, it can achieve better results than either Fenton's reagent or ultrasound alone. The optimum conditions for the degradation of Acid Red 88 aqueous solution were 1.96 mmol L^?1 H₂O₂, 0.108 mmol L^?1 Fe²⁺, pH 3.0, and ultrasonic irradiation frequency of 40 kHz. A degradation efficiency of 98.6% was achieved within 135 min. CONCLUSION: We have provided an efficient and convenient procedure for the degradation of Acid Red 88 aqueous solution. In the present procedure, the azo linkage of Acid Red 88 is broken and some carbonyl compounds are formed, but the complete mineralization of dye cannot be achieved. Copyright © 2008 Society of Chemical Industry     

Degradation of an azo dye Orange II using a gas phase dielectric barrier discharge reactor submerged in water

A dielectric barrier discharge (DBD) system employing wastewater as one of the electrodes was applied to the degradation of an azo dye, Orange II. The main advantage of this system is that reactive species like ozone and ultraviolet (UV) light produced by the DBD can be utilized for the treatment of wastewater. This system was able to remove the chromaticity and destroy the benzene and naphthalene rings in the dye molecule effectively. The results obtained under several conditions revealed that the UV emission from the DBD reactor could enhance the degradation of the dye, particularly in the presence of titanium oxide photocatalyst. The products resulting from the destruction of the rings in the dye molecule were found to be highly recalcitrant against further oxidation to smaller molecules. The change in the initial dye concentration showed that the reaction order was around 0.8 with respect to the dye concentration. The reduction in the concentration of total organic carbon was much more efficient with oxygen than with air.     

Optimization of an azo dye batch adsorption parameters using Box-Behnken design

Dye removal using adsorption requires a proper process parametric study to determine its optimal performance characteristics. In this study, response surface methodology was employed for the removal of methyl orange (MO) from aqueous solution using activated carbon-commercial grade (ACC) as an adsorbent. Experiments were carried out as per Box-Behnken surface statistical design with four input parameters namely adsorbent dose (w: 5-20 g/l), contact time (t: 2-6 h), temperature (T: 25-55 °C) and pH (pH: 2-8). Initial MO concentration (C_o = 100 mg/l) was taken as a fixed input parameter. Regression analysis showed good fit of the experimental data to the second-order polynomial model with coefficient of determination (R²) value of 0.9114 and Fisher F-value of 10.28. Optimization of w (15.75 g/l), t (4 h), T (40 °C) and pH (2) gave a maximum of 99.11% MO removal by ACC.     

电解法处理C.I. Reactive Red 241、C.I. Disperse Blue 56模拟染料废水的研究

以C.I.Reactive Red 241、C.I.Disperse Blue 56模拟染料废水为对象,研究了电解法处理该类染料废水的优化条件。考察了起始电压、电解时间、溶液初始p H对处理效果的影响。结果表明,在p H=7,U=14V、I=3.2A、t=30min的条件下,C.I.Reactive Red241模拟染料废水的脱色率可达到86%以上;在p H=7,U=14V、I=3.2A、t=25min的条件下,C.I.Disperse Blue 56模拟染料废水的脱色率可达到79以上%。     

Degradation of azo dye by three clean advanced oxidation processes: Wet oxidation, electrochemical oxidation and wet electrochemical oxidation—A comparative study

This work compared the degradation behaviors of an azo dye, cationic red X-GRL, by three clean advanced oxidation processes: wet oxidation (WO), electrochemical oxidation (EO) and wet electrochemical oxidation (WEO). It was found that the WO process was readily to remove color while the EO process was prone to decompose pollutants. Integrated with the advantage of two processes, the WEO process posed synergetic effects for both efficient removal of color and COD. Even at the low temperature of 120 °C, the color could be almost completely removed at 60 min, and the COD removal was about 43.2% at 120 min, which was greatly protomted from that by WO at similar conditions (about 7.8%). And it demonstrated a better performance under a reduced temperature and a wider dye concentration range, representing the most promising alternative for environmental application among the three processes. The main degradation products for three processes were detected and a simplified five-stages degradation pathway was suggested, which indicated that the WEO process mineralized much more completely than the other two processes.     

C．I．酸性红361和2-氨基-N-甲基-N-环已基苯磺酰胺等的合成

该文推荐了c.I.酸性红361和2-氨基-N-甲基-N-环已基磺酰胺和其它磺酰胺基与γ-酸所衍生的红色酸性染料的合成方法.该类红色染料能在弱酸性染浴中用于羊毛、蚕丝和聚酰胺纤维的染色.色泽鲜艳、各项坚牢度佳、匀染性良好.     

Kinetic modeling of photoassisted-electrochemical process for degradation of an azo dye using boron-doped diamond anode and cathode with carbon nanotubes

To well describe the photoassisted-electrochemical process for treatment of the contaminated water, a new kinetic model was established based on the intrinsic reactions of the process. The kinetic model correlated apparent kinetic constants to operational parameters including applied current, initial dye concentration and flow rate. Degradation experiments were carried out with boron-doped diamond (BDD) anode and carbon nanotubes–polytetrafluoroethylene (CNTs–PTFE) cathode. The proposed kinetic model was validated by the experiments of C.I. Acid Blue 92 degradation in aqueous solution. The goodness of fitting (R² = 0.96) demonstrated that the new model could describe both the kinetics and the hydrodynamics of the photo-electrochemical system.     

C.I.颜料红264的合成工艺再研究

在仿制DPP颜料的过程中,发现原生产工艺并不完全适合我国的情况,为此对C.I.颜料红264的合成工艺进行了再研究.文中叙述了合成工艺再研究的关键是用丁二酸二叔戊酯代替丁二酸二异丙酯与芳香腈类化合物反应,从而使反应中裂解的醇是叔戊醇,使得叔戊醇的回收变得更加容易,省却了原工艺中回收叔戊醇所需的萃取塔和精馏塔.     

Crystal structures of C.I. Disperse Red 65 and C.I. Disperse Red 73

Single crystals of C.I. Disperse Red 65 and C.I. Disperse Red 73 were grown from ethyl acetate and acetonitrile/toluene solutions, respectively, and their crystal structures were determined using single-crystal X-ray diffraction analysis. In each dye molecule, the aminoazobenzene framework is almost planar due to intramolecular H-bonding. In the case of C.I. Disperse Red 65, intermolecular associations occur by π–π stacking and intermolecular H-bonding, resulting in a herringbone-type arrangement; for C.I. Disperse Red 73, toluene molecules stabilize the crystal structure via π–π stacking.     

Removal of aromatic amines and decolourisation of azo dye baths by electrochemical treatment

The presence of aromatic amines in effluent from dyeing processes of the textile industry is an added problem to the high coloration typical of this type of effluent. The main objective of the present work was to eliminate these two problems simultaneously by electrochemical treatment using bath solutions containing three azo dyes. For the analysis of amines, a liquid–liquid extraction method was developed as an easier and faster alternative to the method described in the standards and widely used in analytical laboratories. Four amines (aniline, o‐toluidine, 4‐chloroaniline and 4‐aminobiphenyl) were detected by GC‐MS in the residual azo dye baths. A total amine concentration of between 2.5 and 1 ppm was detected, 4‐aminobiphenyl being the main compound. Both residual colour and amines were removed by electrochemical treatment carried out at three current densities (3, 24 and 40 mA/cm²). At 24 mA/cm², more than 90% of colour removal was achieved, and the total amine concentration was reduced to below 0.15 ppm.     

偶氮染料在气-液-固循环浆态光催化反应器中的降解脱氮

偶氮染料废水是一种集中量大的重要污染物,其中的偶氮键可被环境微生物降解生成具有毒性的芳香胺类化合物。本文从光量子效率、脱氮速率、脱氮能耗等方面,对比研究了一种新设计的气-液-固循环浆态光催化反应器和环隙式光催化反应器对偶氮染料降解脱氮的性能。结果表明,由于空气的引入,使气-液-固循环浆态光催化反应器的量子收率有一定程度下降,同时造成单位数量级脱氮能耗也有一定增大,但偶氮染料脱氮速率比在环隙式反应器中的情况有大幅度提高,表明气-液-固循环浆态反应器在偶氮染料废水光催化降解脱氮方面具有较大应用前景。     

钛基二氧化铅阳极、泡沫镍阴极电化学降解偶氮类染料酸性红18的研究

以钛基二氧化铅作阳极,泡沫镍作阴极对偶氮类染料酸性红18溶液进行电解。在不添加隔膜的条件下,考察了电压、电流、电解质含量、pH值等因素对酸性红18电化学降解的影响,同时对不同降解时间后AR18的相对残余浓度与时间的相关性进行分析,结果表明,酸性红18的降解符合准1级反应动力学方程。在添加隔膜的条件下,对酸性红18在硫酸...