scholarly journals Electrochemical Oxidation of Ethinylestradiol on a Commercial Ti/Ru0.3 Ti0.7O2 DSA Electrode

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Karla M. Vieira ◽  
Clésia C. Nascentes ◽  
Artur J. Motheo ◽  
Rodinei Augusti
Keyword(s):  
Reaction Time ◽  
Electrochemical Oxidation ◽  
Degradation Products ◽  
Electrochemical Treatment ◽  
Flow Cell ◽  
Constant Current ◽  
Direct Infusion ◽  
Degradation Rates ◽  
Dsa Electrode ◽  
Methanolic Medium

The electrochemical oxidation of the hormone ethinylestradiol in an aqueous-methanolic medium by the application of a constant current of 40 mA cm−2 in a flow cell with a commercial Ti/Ru0.3 Ti0.7O2 electrode was evaluated. The effect caused by the use of NaCl as a support electrolyte was also investigated. Hence, HPLC-UV analyses revealed that ethinylestradiol was almost totally consumed after a 60 min reaction time in the presence of NaCl. Conversely, much lower degradation rates were obtained when NaCl was not employed. Moreover, direct infusion ESI-MS and GC-MS analysis revealed that apparently no degradation products had been formed under these conditions. Hence, this study clearly demonstrated that such electrochemical treatment can be efficiently used to promote the complete degradation (and probably mineralization) of the hormone ethinylestradiol.

Electrochemical Oxidation of Perfluorooctanesulfonate by Magnéli Phase Ti4O7 Electrode in the Presence of Trichloroethylene

2020 ◽  
Vol 1 (4) ◽  
Author(s):  
Peizeng Yang ◽  
Yaye Wang ◽  
Junhe Lu ◽  
Viktor Tishchenko ◽  
Qingguo Huang ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Current Density ◽  
First Order ◽  
Degradation Rates ◽  
Oxidation Technology ◽  
Magnéli Phase ◽  
Polyfluoroalkyl Substances ◽  
Titanium Suboxide ◽  
Gas Tight ◽  
Magneli Phase

This study examined the degradation of perfluorooctanesulfonate (PFOS) in electrochemical oxidation (EO) processes in the presence of trichloroethylene (TCE). The EO experiment was performed in a gas-tight reactor using Magnéli phase titanium suboxide (Ti4O7) as the anode. The experimental data demonstrated that 75% of PFOS (2 μM) was degraded at 10 mA/cm2 current density in 30 min without TCE present in the solution, while the presence of 76 μM TCE apparently inhibited the degradation of PFOS, reducing its removal down to 53%. Defluorination ratio suggested that PFOS was significantly mineralized upon EO treatment, and it appeared to be not influenced by the presence of TCE. The respective pseudo-first order rate constants (kobs) of PFOS removal were 0.0471 and 0.0254 min-1 in the absence and presence of TCE. The degradation rates of both PFOS and TCE increased with current density rising from 2.5 to 20 mA/cm2. In the presence of TCE, chloride, chlorate, and perchlorate were formed that accounted for 79.7 %, 5.53%, and 1.51% of the total chlorine at 60 min. This work illustrates the promise of the Magnéli phase Ti4O7 electrode based electrochemical oxidation technology for degrading per- and polyfluoroalkyl substances (PFASs) and co-contaminants in groundwaters.

scholarly journals Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one : emerging munitions compounds

2021 ◽  
Author(s):  
Julie Becher ◽  
Samuel Beal ◽  
Susan Taylor ◽  
Katerina Dontsova ◽  
Dean Wilcox
Keyword(s):  
Aqueous Solutions ◽  
Degradation Products ◽  
Pure Water ◽  
Transformation Products ◽  
Water Soluble ◽  
Uv Exposure ◽  
Degradation Pathways ◽  
Solution Ph ◽  
Photo Degradation ◽  
Degradation Rates

Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. We irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10% degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were >80% for all three wavelengths. NTO degradation was greatest at 300 nm with 3% remaining after 32 h, followed by 254 nm (7% remaining) and 350 nm (20% remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48% by 32 h. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH.

scholarly journals Elucidation and Characterization of New Chlorinated By-Products after Electrochemical Degradation of Hydrochlorothiazide Using Graphite–Poly Vinyl Chloride Electrode

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 540
Author(s):  
Zainab Mussa ◽  
Fouad Al-Qaim ◽  
Ali Yuzir ◽  
Hirofumi Hara ◽  
Shamila Azman ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Treatment Process ◽  
Oxidation Process ◽  
Electrochemical Treatment ◽  
Electrochemical Process ◽  
Experimental Conditions ◽  
E Coli ◽  
Flight Mass Spectrometry ◽  
Negative Ionization ◽  
By Products

This paper describes an electrochemical treatment process of hydrochlorothiazide (HDZ) under different conditions such as initial concentration, sodium chloride and applied voltage. In this present study, HDZ was treated by electrochemical oxidation process using graphite-PVC composite electrode as anode and Platinum (Pt) as cathode. All results were analyzed using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS). It was found that at high applied voltages, and high amounts of NaCl, the electrochemical treatment process was more efficient. The removal% of HDZ was 92% at 5 V after 60 min. From the obtained results, the electrochemical oxidation process of HDZ followed pseudo first order with rate constant values ranged between 0.0009 and 0.0502 min−1, depending on the experimental conditions. Energy consumption was also considered in this study, it was ranged between 0.9058 and 5.56 Wh/mg using 0.5, 0.3 and 0.1 g NaCl within interval times of (10, 20, 30, 40, 50, 60, 70, and 80 min). Five chlorinated and one non-chlorinated by-products were formed and analyzed in negative ionization (NI) mode during the electrochemical process. Due to the strong oxidizing potential of the chlorine (Cl2) and hypochlorite ion (ClO−), HDZ and its by-products were removed after 140 min. Furthermore, a novel synthesis of chlorothiaizde as one of the new by-products was reported in this present study. Toxicity was impacted by the formation of the by-products, especially at 20 min. The inhibition percentage (I%) of E. coli bacteria was decreased to be the lowest value after 140 min.

Electrochemical treatment of poly- and perfluoroalkyl substances in brines

2020 ◽  
Vol 6 (10) ◽  
pp. 2704-2712
Author(s):  
Charles E. Schaefer ◽  
Danielle Tran ◽  
Yida Fang ◽  
Youn Jeong Choi ◽  
Christopher P. Higgins ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Anodic Oxidation ◽  
Electrochemical Treatment ◽  
Perfluoroalkyl Substances ◽  
Indirect Oxidation ◽  
Bench Scale ◽  
Film Forming

Bench-scale experiments were performed to evaluate the electrochemical oxidation, via direct anodic oxidation and indirect oxidation from salt-derived species, of diluted aqueous film forming foam (AFFF) in brine solutions.

Photocatalytic degradation of azo dye in TiO2 suspended solution

2001 ◽  
Vol 43 (2) ◽  
pp. 313-320 ◽  
Author(s):  
C.-H. Hung ◽  
P.-C. Chiang ◽  
C. Yuan ◽  
C.-Y. Chou
Keyword(s):  
Reaction Time ◽  
Light Intensity ◽  
Photocatalytic Degradation ◽  
Azo Dye ◽  
Batch Reactor ◽  
Reaction Rates ◽  
Pseudo First Order Reaction ◽  
Degradation Rates ◽  
Orange G ◽  
Degradation Of Azo Dye

The photocatalysis of azo dye, Orange G, by P-25 anatase TiO2 was investigated in this research. The experiments were conducted in a batch reactor with TiO2 powder suspension. Four near-UV lamps were used as the light source. The experimental variables included solution pH level, amount of TiO2, illumination light intensity, and reaction time. A pseudo-first order reaction kinetic was proposed to simulate the photocatalytic degradation of Orange G in the batch reactor. More than 80% of 10 mg/L Orange G decomposition in 60-minute reaction time was observed in this study and fast decomposition of Orange G only occurred in the presence of both TiO2 and suitable light energy. Faster degradation of Orange G was achieved under acid conditions. The degradation rates of Orange G at pH = 3.0 were about two times faster than those at pH = 7.0. Faster degradation of azo dye was observed for greater irradiated light intensity and more TiO present during the reaction. The reaction rates were proportional to TiO2concentration and light intensity with the power order of 0.726 and 0.734, respectively.

Electrochemical treatment of mature landfill leachate using Ti/RuO2–IrO2 and Al electrode: optimization and mechanism

RSC Advances ◽  
2016 ◽  
Vol 6 (53) ◽  
pp. 47509-47519 ◽  
Author(s):  
Juan Li ◽  
Zhao-hui Yang ◽  
Hai-yin Xu ◽  
Pei-pei Song ◽  
Jing Huang ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Landfill Leachate ◽  
Electrochemical Treatment ◽  
Oxidation Technology ◽  
Mature Landfill Leachate

Today, improving the elimination of refractory pollutants in landfill leachate through electrochemical oxidation technology has attracted considerable attention.

Efficient removal of diuretic hydrochlorothiazide from water by electro-Fenton process using BDD anode: a kinetic and degradation pathway study

2019 ◽  
Vol 16 (8) ◽  
pp. 613 ◽  
Author(s):  
Hélène Monteil ◽  
Nihal Oturan ◽  
Yoan Péchaud ◽  
Mehmet A. Oturan
Keyword(s):  
Electrochemical Oxidation ◽  
Oxidation Reaction ◽  
Oxidation Process ◽  
Aqueous Media ◽  
Degradation Pathway ◽  
Constant Current ◽  
Gas Chromatography Mass Spectrometry ◽  
Aqueous Environment ◽  
Fenton Process ◽  
Kinetic Rate Constant

Environmental contextHydrochlorothiazide, a common diuretic pharmaceutical, occurs in environmental waters because current treatment technologies are unable to eliminate it from wastewater. To remove this environmentally hazardous chemical from water, we developed an advanced electrochemical oxidation process to efficiently degrade and mineralise the compound. Wider application of the process holds the promise of general, efficient destruction of pharmaceuticals in aqueous media. AbstractThe degradation and the mineralisation of the diuretic hydrochlorothiazide were studied by an advanced electrochemical oxidation process, ‘electro-Fenton’, which generates in situ hydroxyl radicals that are able to successfully oxidise or mineralise organic pollutants. In this study, a 0.1mM (29.8mgL−1) hydrochlorothiazide solution was completely oxidatively degraded in 15min under constant current electrolysis at 500 mA. The absolute kinetic rate constant of the oxidation reaction was also determined as (4.37±0.04)×109M−1s−1. The quasi-complete mineralisation of the solution was obtained with electrolysis for 6h under the same applied current. Several oxidation reaction intermediates were identified using gas chromatography-mass spectrometry (GC-MS). The formed carboxylic acids during the mineralisation process were also studied; oxamic, oxalic, acetic and maleic acids were identified and their concentrations were monitored throughout the electrolysis. The ions released during the treatment were also considered. Based on these data and the total organic carbon (TOC) removal results, a possible mineralisation pathway was proposed. These findings enable the conclusion that the electro-Fenton process is an efficient and environmentally-friendly method to eliminate the hazardous drug hydrochlorothiazide from an aqueous environment.

Application of the central composite design for condition optimization for semi-aerobic landfill leachate treatment using electrochemical oxidation

2010 ◽  
Vol 61 (5) ◽  
pp. 1257-1266 ◽  
Author(s):  
Soraya Mohajeri ◽  
Hamidi Abdul Aziz ◽  
Mohamed Hasnain Isa ◽  
Mohammad Ali Zahed ◽  
Mohammed J. K. Bashir ◽  
...  
Keyword(s):  
Reaction Time ◽  
Central Composite Design ◽  
Electrochemical Oxidation ◽  
Current Density ◽  
Landfill Leachate ◽  
Electrolyte Concentration ◽  
Process Conditions ◽  
Leachate Treatment ◽  
Condition Optimization ◽  
Central Composite

In the present study, Electrochemical Oxidation was used to remove COD and color from semi-aerobic landfill leachate collected from Pulau Burung Landfill Site (PBLS), Penang, Malaysia. Experiments were conducted in a batch laboratory-scale system in the presence of NaCl as electrolyte and aluminum electrodes. Central composite design (CCD) under Response surface methodology (RSM) was applied to optimize the electrochemical oxidation process conditions using chemical oxygen demand (COD) and color removals as responses, and the electrolyte concentrations, current density and reaction time as control factors. Analysis of variance (ANOVA) showed good coefficient of determination (R2) values of >0.98, thus ensuring satisfactory fitting of the second-order regression model with the experimental data. In un-optimized condition, maximum removals for COD (48.77%) and color (58.21%) were achieved at current density 80 mA/cm2, electrolyte concentration 3,000 mg/L and reaction time 240 min. While after optimization at current density 75 mA/cm2, electrolyte concentration 2,000 mg/L and reaction time 218 min a maximum of 49.33 and 59.24% removals were observed for COD and color respectively.

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