Degradation mechanism of Methyl Orange by electrochemical process on RuOx–PdO/Ti electrode

2011 ◽  
Vol 63 (7) ◽  
pp. 1539-1545 ◽  
Author(s):  
Lin Du ◽  
Jin Wu ◽  
Song Qin ◽  
Changwei Hu
Keyword(s):  
Methyl Orange ◽  
Degradation Mechanism ◽  
Reaction System ◽  
Oxygen Demand ◽  
Electrochemical Process ◽  
Gas Chromatography Mass Spectrometry ◽  
Low Molecular Weight ◽  
Electrochemical Degradation ◽  
Derivatives Of ◽  
Present Reaction System

The electrochemical degradation of Methyl Orange in 0.1 M NaCl solution over RuOx–PdO/Ti anode was investigated. Chemical oxygen demand (COD), ion chromatography (IC), Fourier Transform Infrared Spectroscopy (FTIR) and Gas chromatography-mass spectrometry (GC-MS) were employed to detect the intermediates formed during the electrochemical degradation. In the present reaction system, Methyl Orange could be effectively degraded. After 1 h treatment, the discoloration could reach 97.9% with COD removal of 57.6%. The results indicated that in the presence of chloride, the electrolysis was able to oxidise the dye with partial mineralisation of carbon, nitrogen and sulfur into CO2, NO3− and SO42−, respectively. After 8 h electrolysis, 62% of sulfur contained in Methyl Orange was transformed to SO42−, and 17.6% of nitrogen changed to NO3−. The intermediates during electroprocess were detected to be low molecular weight compounds, chlorinated compounds, derivatives of benzene and long chain alkanes. Based on these data, a possible degradation mechanism of Methyl Orange was proposed.

scholarly journals Study on Electrochemical Degradation of Nicosulfuron by IrO2-Based DSA Electrodes: Performance, Kinetics, and Degradation Mechanism

2019 ◽  
Vol 16 (3) ◽  
pp. 343 ◽  
Author(s):  
Rui Zhao ◽  
Xuan Zhang ◽  
Fanli Chen ◽  
Xiaobing Man ◽  
Wenqiang Jiang
Keyword(s):  
High Performance ◽  
Degradation Mechanism ◽  
Electrochemical Process ◽  
Electrode Spacing ◽  
Human Beings ◽  
Electrochemical Degradation ◽  
Dimensionally Stable Anodes ◽  
Liquid Chromatograph ◽  
Crack Network ◽  
Electrolysis Condition

The widely used sulfonylurea herbicides have caused negative effects on the environment and human beings. Electrochemical degradation has attracted much attention in the treatment of refractory organic compounds due to its advantage of producing no secondary pollution. Three kinds of IrO2-based dimensionally stable anodes (DSAs) were used to degrade nicosulfuron by a batch electrochemical process. The results showed that a well-distributed crack network was formed on the Ti/Ta2O5-IrO2 electrode and Ti/Ta2O5-SnO2-IrO2 electrode due to the different coefficients of thermal expansion between the Ti substrate and oxide coatings. The oxygen evolution potential (OEP) increased according to the order of Ti/RuO2-IrO2 < Ti/Ta2O5-SnO2-IrO2 < Ti/Ta2O5-IrO2. Among the three electrodes, the Ti/Ta2O5-IrO2 electrode showed the highest efficiency and was chosen as the experimental electrode. Single factor experiments were carried out to obtain the optimum electrolysis condition, shown as follows: currency intensity 0.8 A; electrode spacing 3 cm, electrolyte pH 3. Under the optimum conditions, the degradation of nicosulfuron followed first-order kinetics and was mainly due to indirect electrochemical oxidation. It was a typical diffusion-controlled electrochemical process. On the basis of the intermediate identified by high performance liquid chromatograph-mass spectrometry (HPLC-MS), two possible degradation routes were proposed.

scholarly journals Effect of Temperature on the Chemical Composition and Physicochemical Properties of Diester Aviation Lubrication Oil

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Ting Yao ◽  
Na Zhang ◽  
Jianqiang Hu ◽  
Xiaoxiao Liao ◽  
Yongli Shen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Degradation Mechanism ◽  
Oxidation Stability ◽  
Lubricating Oil ◽  
Effect Of Temperature ◽  
Gas Chromatography Mass Spectrometry ◽  
Low Molecular Weight ◽  
Chemical Compositions ◽  
Main Process

High temperature is the main factor responsible for degrading the lubrication and antiwear properties of aero-lubricating oils. Accordingly, this study assessed the effects of thermal treatment of diester aviation lubricating oil and the associated mechanism. Fourier-transform infrared spectroscopy and gas chromatography/mass spectrometry analyses showed that low-molecular-weight compounds, such as monoesters, diesters, alcohols, and olefins, were the primary degradation products. An assessment of the degradation mechanism of bis(2-ethylhexyl)decanedioate showed that pyrolysis, resulting in the cleavage of β-C–H and C–C bonds, was the main process involved. Additional investigation using advanced polymer chromatography showed that the molecular weights of oil samples changed slightly at high temperatures, while the viscosity and viscosity-temperature index values were relatively stable. High-pressure differential scanning calorimetry established that the thermal oxidation stability of these oils decreased above 250°C. Finally, variations in the chemical compositions of the oil samples were found to be highly correlated with changes in physicochemical properties during thermal processing, with the formation of low-molecular-weight polar compounds greatly increasing the acid numbers of the oils.

Electrochemical degradation of 2,5-dichloro-1,4-phenylenediamine by anodic oxidation

2013 ◽  
Vol 67 (10) ◽  
pp. 2177-2183 ◽  
Author(s):  
Weijing Liu ◽  
Yong Chen ◽  
Hongyi Li ◽  
Qin Zhong
Keyword(s):  
Electrochemical Oxidation ◽  
Anodic Oxidation ◽  
Degradation Kinetics ◽  
Degradation Mechanism ◽  
Combustion Efficiency ◽  
Gas Chromatography Mass Spectrometry ◽  
Cyclic Voltammograms ◽  
Electrochemical Degradation ◽  
Initial Ph ◽  
Degradation Intermediates

Electrochemical degradation of 2,5-dichloro-1,4-phenylenediamine (DP) in aqueous solution by anodic oxidation was investigated. Linear sweep voltammograms and cyclic voltammograms were studied. The influence of operating parameters on electrochemical oxidation of DP was studied as a function of the current density, initial pH, and initial concentration of DP. The degradation kinetics analysis indicated that the electrochemical degradation of DP followed a first-order reaction. The degradation intermediates during electrochemical oxidation were analyzed by UV–vis spectrophotometer, ionic chromatograph (IC), and gas chromatography/mass spectrometry (GC/MS). The combustion efficiency of DP at the anode was also estimated. The electrochemical oxidation of DP resulted in the release of NH4+ and Cl−. Based on these results, a degradation mechanism for electrochemical degradation of DP by anodic oxidation was proposed.

scholarly journals Impact of Active Chlorines and •OH Radicals on Degradation of Quinoline Using the Bipolar Electro-Fenton Process

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 128
Author(s):  
Wenlong Zhang ◽  
Jun Chen ◽  
Jichao Wang ◽  
Cheng-Xing Cui ◽  
Bingxing Wang ◽  
...  
Keyword(s):  
Degradation Kinetics ◽  
Degradation Mechanism ◽  
Supporting Electrolyte ◽  
Reaction System ◽  
Oxygen Demand ◽  
Oh Radicals ◽  
Fenton Process ◽  
Reaction Conditions ◽  
Initial Ph ◽  
Kinetics Of

Quinoline is a typical nitrogenous heterocyclic compound, which is carcinogenic, teratogenic, and mutagenic to organisms, and its wastewater is difficult to biodegrade directly. The bipolar electro-Fenton process was employed to treat quinoline solution. The process/reaction conditions were optimized through the single factor experiment. The degradation kinetics of chemical oxygen demand (COD) was analyzed. To get the degradation mechanism and pathways of quinoline, the intermediate products were identified by gas chromatograph–mass spectrometer (GC–MS). By using sodium chloride as supporting electrolyte in the electro-Fenton reaction system with initial pH 3.0, conductivity 15,800 µs/cm, H2O2 concentration 71 mmol/L, current density 30.5 mA/cm2, and applied voltage 26.5 V, 75.56% of COD was decreased by indirect oxidation with electrogeneration of hydroxyl radicals (•OH) and active chloric species in 20 min. The COD decrease of quinoline solution followed the first order reaction kinetic model. The main products of quinoline degradation were 2(1H)-quinolinone, 4-chloro-2(1H)-quinolinone, 5-chloro-8-hydroxyquinoline, and 5,7-dichloro-8-hydroxyquinoline. Furthermore, two possible degradation pathways of quinoline were proposed, supported with Natural charge distribution on quinoline and intermediates calculated at the theoretical level of MN15L/6-311G(d).

scholarly journals Pretreatment of evaporated condensate generated during metal cutting process by Fe-C micro-electrolysis

2018 ◽  
Vol 79 (3) ◽  
pp. 580-588 ◽  
Author(s):  
Weiteng Lin ◽  
Ji Li ◽  
Xiaolei Zhang ◽  
Wenyi Dong
Keyword(s):  
Reaction Time ◽  
Organic Contaminants ◽  
Metal Cutting ◽  
Degradation Mechanism ◽  
Oxygen Demand ◽  
Cutting Process ◽  
Gas Chromatography Mass Spectrometry ◽  
Contaminant Removal ◽  
Liquid Ratio ◽  
Solid Liquid

Abstract Fe-C micro-electrolysis was employed to the pretreatment of evaporated condensate generated during metal cutting process. The effect of the reaction conditions on the contaminant removal and degradation mechanism were studied. Through single-factor experiments, the effects of solid–liquid ratio, gas–liquid ratio and reaction time on the treatment of wastewater were preliminarily determined. The optimal reaction condition obtained was: 500 g/L solid–liquid ratio, 30:1 gas–liquid ratio with 4 h reaction time. Under the optimal condition, the chemical oxygen demand (COD) removal efficiency of micro-electrolysis could reach around 25%, and the biodegradability of wastewater increased from 0.12 to 0.32. According to the analysis results of gas chromatography-mass spectrometry (GC-MS) qualitative analysis, it was observed that the most organic contaminants in the influent were degraded or converted into simple structures under Fe-C micro-electrolysis, indicates that Fe-C micro-electrolysis pretreatment could improve the biodegradability of the evaporated condensate generated during metal cutting process and achieve certain degree removal of COD.

The Preparation and Sunlight Activity of Nanocomposite Photocatalysts for Degradation of Methyl Orange Solution

2013 ◽  
Vol 750-752 ◽  
pp. 1397-1400 ◽  
Author(s):  
Li Mei Duan ◽  
Jing Hai Liu ◽  
Xiu Ting Xu ◽  
Ling Xu ◽  
Zong Rui Liu
Keyword(s):  
Methyl Orange ◽  
Synthesis Method ◽  
Reaction System ◽  
Methyl Orange Solution ◽  
Degradation Efficiency ◽  
Composite Photocatalyst ◽  
One Step ◽  
Orange Solution ◽  
Xrd And Tem ◽  
Degradation Of Methyl Orange

Applying one-step solvothermal synthesis method, different CdS/TiO2 nanocomposite materials are obtained by changing the ratio of sulfur and titanium sources. The composite structure and morphology are determined by XRD and TEM. Taking the degradation of methyl orange solution as a model reaction, the photocatalytic activity of CdS/TiO2 composite materials is investigated. The results show that the amount of CdS in composite photocatalyst has great effects on the degradation efficiency of methyl orange under the irradiation of sunlight, and the lower pH of reaction system is also needed to sustain the high degradation efficiency for methyl orange.

Electrochemical Treatment of Simulated Dye Wastewater

2012 ◽  
Vol 441 ◽  
pp. 555-558
Author(s):  
Feng Tao Chen ◽  
San Chuan Yu ◽  
Xing Qiong Mu ◽  
Shi Shen Zhang
Keyword(s):  
Current Density ◽  
Oxygen Demand ◽  
Electrochemical Treatment ◽  
Dye Wastewater ◽  
Electrolysis Time ◽  
Electrochemical Degradation ◽  
Mild Conditions ◽  
Thermal Decomposition Method ◽  
Initial Ph ◽  
Effects Of Ph

The Ti/SnO2-Sb2O3/PbO2 electrodes were prepared by thermal decomposition method and its application in the electrochemical degradation of a heteropolyaromatic dye, Methylene blue (MB), contained in simulated dye wastewater were investigated under mild conditions. The effects of pH, current density and electrolysis time on de-colorization efficiency were also studied. Chemical oxygen demand (COD) was selected as another parameter to evaluate the efficiency of this degradation method on treatment of MB wastewater. The results revealed that when initial pH was 6.0, current density was 50 mA·cm2, electrolysis time was 60 min, Na2SO4 as electrolyte and its concentration was 3.0 g·dm3, the de-colorization and COD removal efficiency can reach 89.9% and 71.7%, respectively.

Inverse calculation of biochemical oxygen demand models based on time domain for the tidal Foshan River

2014 ◽  
Vol 70 (1) ◽  
pp. 15-23
Author(s):  
Li Er ◽  
Zeng Xiangying
Keyword(s):  
Time Domain ◽  
Biochemical Oxygen Demand ◽  
Dispersion Coefficient ◽  
Oxygen Demand ◽  
Tidal River ◽  
Data Sets ◽  
Longitudinal Dispersion Coefficient ◽  
Demand Models ◽  
Flow Directions ◽  
Derivatives Of

To simulate the variation of biochemical oxygen demand (BOD) in the tidal Foshan River, inverse calculations based on time domain are applied to the longitudinal dispersion coefficient (E(x)) and BOD decay rate (K(x)) in the BOD model for the tidal Foshan River. The derivatives of the inverse calculation have been respectively established on the basis of different flow directions in the tidal river. The results of this paper indicate that the calculated values of BOD based on the inverse calculation developed for the tidal Foshan River match the measured ones well. According to the calibration and verification of the inversely calculated BOD models, K(x) is more sensitive to the models than E(x) and different data sets of E(x) and K(x) hardly affect the precision of the models.

scholarly journals ACID ORANGE 52 DYE DEGRADATION BY ELECTROCATALYTIC PLUS PHOTOCATALYTIC TECHNIQUE AND INTERMEDIATES DETECTION

2018 ◽  
Vol 61 (4-5) ◽  
pp. 111
Author(s):  
Hui Zhao ◽  
Heng Zhong ◽  
Lei Sun ◽  
Alexander V. Nevsky ◽  
Dongsheng Xia
Keyword(s):  
Dye Degradation ◽  
Removal Rate ◽  
Degradation Mechanism ◽  
Oxygen Demand ◽  
Ionization Mass ◽  
Light Spectrum ◽  
Resource Saving ◽  
Acid Orange ◽  
Visible Part ◽  
Photocatalytic Processes

The degradation efficiency of Acid Orange 52 dye in an aqueous solutions using the combination of electrocatalytic and photocatalytic processes has been studied. Electrocatalytic and photocatalytic methods in practice reckon among advanced oxidation processes (AOPs). The effect of catalyst B dosage and irradiarion time on the rate of mentioned dye degradation was studied in the photocatalytic process. It was shown, that when Acid Orange 52 simulated dye wastewater was treated by electrocatalytic technique under optimal conditions with catalyst A, the decolorization treatment effect was 95 % in visible part of light spectrum (464 nm) and 38.6 % in ultraviolet part (270 nm), respectively. When the combined electrocatalytic-photocatalytic technique was processed with catalysts A and B, the color removal rate of dye could reach 99.3% (464 nm) and 91.5% (270 nm), respectively. The large amount of products of small mole weight was formed in the course of oxidation reaction. Moreover, the obtained values of chemical oxygen demand (COD) and total organic carbon (TOC) witnessed, that the combination of electrocatalytic and photocatalytic processes could significantly improve the biodegradability of dye as a whole．It was shown, that the removal rate of COD and TOC, respectively, were 54.3% and 72.8%. The reaction intermediates were determined by electrospray ionization-mass spectrometry (ESI-MS) analysis, and as a result, the probable degradation mechanism (pathway) has been proposed. The results of the work may be useful as theoretical bases for designing effective resource-saving, technically efficient and economically sound wastewater treatment systems, containing hardly biodegradable azo dyes.Forcitation:Zhao H., Zhong H., Sun L., Xia D., Nevsky A.V. Acid Orange 52 dye degradation by electrocatalytic plus photocatalytic technique and intermediates detection. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 111-118

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