Mixed first and zero order kinetics in the electrooxidation of sulfamethoxazole at a boron-doped diamond (BDD) anode

Li, Shuhuan; Bejan, Dorin; McDowell, M. Steven; Bunce, Nigel J.

doi:10.1007/s10800-007-9413-2

Cited by 55 publications

(29 citation statements)

References 39 publications

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“…The complication of the observed kinetics for loss of S 2-is explained by the competition between 2-electron oxidation of sulfide and 6-electron oxidation of elemental sulfur. Otherwise, we would have expected a monotonic trend from current control at low conversion towards diffusion control as the concentration of S 2-falls [21].…”

Section: Electrolyses In the Absence Of Naphthenic Acidsmentioning

confidence: 94%

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Electrochemical oxidation of sulfide ion at a Ti/IrO2–Ta2O5 anode in the presence and absence of naphthenic acids

2009

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Electrochemical oxidation of sulfide ion at a Ti/ IrO 2 -Ta 2 O 5 anode followed partial order kinetics (between current and mass transport control) in the absence and presence of chloride ion and of naphthenic acids, at sulfide concentrations typical of sour brines. The desired outcome was to promote the 2-electron oxidation of sulfide to elemental sulfide rather than the 8-electron oxidation to sulfate. Although elemental sulfur accumulated to some extent at low conversion of sulfide, sulfate ion became the principal product as the reaction progressed. At high conversion, the overall current efficiencies were typically higher than 50%, with material balance about 90%. However, this anode material was gradually poisoned by sulfide in long term use.

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Section: Electrolyses In the Absence Of Naphthenic Acidsmentioning

confidence: 94%

“…We examined kinetic models based on both current control (rate independent of the concentration of sulfide) and diffusion control (rate first order in sulfide). A partial order model [21]-rate proportional to [SH -] n (0 \ n \ 1)-gave the best fit to the data: Eq. 1 and its integrated form Eq.…”

Section: Electrolyses In the Absence Of Naphthenic Acidsmentioning

confidence: 99%

Electrochemical oxidation of sulfide ion at a Ti/IrO2–Ta2O5 anode in the presence and absence of naphthenic acids

2009

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“…To find the equations that best fit the experimental data, the model of partial order was used, 31 where the reaction rate is made proportional to [S , i is the current intensity in A, t is the time in h, and n and m are partial reaction orders. Since in each test both the current intensity and the n value remained constants throughout the electrolysis, equations 20 and 21 can take The analysis of [S 2-] 1-n versus time, at constant current density, were carried out by varying n in steps of 0.01, until the best correlation factor was obtained for each applied current density.…”

Section: 27mentioning

confidence: 99%

Anodic Oxidation of Sulfide to Sulfate: Effect of the Current Density on the Process Kinetics

Caliari¹,

Ciríaco²,

Lopes³

2016

Journal of the Brazilian Chemical Society

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The kinetics of the conversion of sulfide to sulfate by electro-oxidation, using a boron-doped diamond (BDD) electrode was studied. Different applied current densities were tested, from 10 to 60 mA cm -2 . The results showed that the electrochemical conversion of sulfide to sulfate occurs in steps, via intermediate production of other sulfur species. The oxidation rate of the sulfide ion is dependent on its concentration and current density. The reaction order varies with the current intensity, being 2 for the lower applied current intensity and high S 2-concentration, which is compatible with a mechanism involving two S 2-ions to give S 2 2-. For higher current densities, where current control is less important, reaction order varies from 0.15 to 0.44 for the current densities of 20 and 60 mA cm -2 , respectively. For the formation of SO 4 2-from S 2-electro-oxidation, the reaction orders with respect to sulfide concentration and current intensity are 0 and 1, respectively.

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“…Anodic oxidation needs an active anode, such as a boron-doped diamond (BDD) anode. The anodic oxidation of SMX at the BDD anode has been investigated by several authors [28,29]. The most common of the indirect electrooxidation methods is electro-Fenton (EF), which is based on the continuous supply of H 2 O 2 generated from two electron reduction of oxygen on the catalytic cathode, such as carbon felt [30,31], O 2 -PTFE cathode [32][33][34][35][36][37] and activated carbon fiber (ACF) [38,39] to a contaminated acid solution containing Fe 2+ or Fe 3+ as catalyst.…”

Section: Introductionmentioning

confidence: 99%

Mineralization of antibiotic sulfamethoxazole by photoelectro-Fenton treatment using activated carbon fiber cathode and under UVA irradiation

Wang

Estrada

2011

Applied Catalysis B: Environmental

139

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a b s t r a c tThe mineralization of antibiotic sulfamethoxazole (SMX) of concentrations up to 300 mg L −1 was examined by photoelectro-Fenton (PEF) using an activated carbon fiber (ACF) cathode with UVA (365 nm) irradiation. Comparative mineralization has been studied by different methods: RuO 2 /Ti anodic oxidation (AO), AO in the presence of electrogenerated H 2 O 2 (AO-H 2 O 2 ), AO-H 2 O 2 in the presence of UVA (AO-H 2 O 2 -UVA), and both the electro-Fenton (EF) and PEF processes. PEF treatment at a low applied current of 0.36 A yields a faster and more complete depollution with 80% of the TOC removed after 6 h of electrolysis. The higher oxidative ability of the PEF process can be attributed to the additional hydroxyl radicals (• OH) produced by the photo-Fenton reaction. The 63% mineralization in the case of EF treatment was due to the formation of short intermediates, such as carboxylic acids, which were difficult to oxidise with• OH. In the AO-H 2 O 2 -UVA process, about 36% of the TOC was removed after 6 h electrolysis, while 28% of the TOC was removed in the AO-H 2 O 2 process. SMX is only slightly mineralized by the AO process, with only 25% of the TOC removed. HPLC-MS analysis allowed for up to six aromatic reaction products to be identified during the SMX degradation in the PEF process, mainly formed from the hydroxylation of the aromatic ring or/and isoxazole ring, accompanied by the substitution of the amine group (on aromatic cycle) or methyl group (on isoxazole ring) by• OH. The carboxylic acids generated, including oxalic, maleic, oxamic, formic and acetic acids, were detected by ion-exclusion chromatography. The initial organic nitrogen was mainly converted into NH 4 + along with a very small proportion of NO 3 − ion. Considering all the oxidation intermediates and end products for SMX degradation in the PEF process, a general mineralization mechanism by• OH and UVA was proposed.

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Mixed first and zero order kinetics in the electrooxidation of sulfamethoxazole at a boron-doped diamond (BDD) anode

Cited by 55 publications

References 39 publications

Electrochemical oxidation of sulfide ion at a Ti/IrO2–Ta2O5 anode in the presence and absence of naphthenic acids

Electrochemical oxidation of sulfide ion at a Ti/IrO2–Ta2O5 anode in the presence and absence of naphthenic acids

Anodic Oxidation of Sulfide to Sulfate: Effect of the Current Density on the Process Kinetics

Mineralization of antibiotic sulfamethoxazole by photoelectro-Fenton treatment using activated carbon fiber cathode and under UVA irradiation

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