Degradation of caffeine by conductive diamond electrochemical oxidation

Indermuhle, Chloe; Vidales, María J. Martín de; Sáez, Cristina; Almanza-Robles, J.M.; Cañizares, Pablo; García-Reyes, Juan F.; Molina‐Díaz, Antonio; Comninellis, Christos; Rodrigo, Manuel A.

doi:10.1016/j.chemosphere.2013.05.047

Cited by 63 publications

(52 citation statements)

References 21 publications

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“…An increase in carbon concentration after illumination for longer time intervals (e.x. 210 min) is obviously not real but indicates that reaction intermediates are more readily oxidized by the TOC measuring device than the initial compounds, as also observed before [42].…”

Section: Optimization Of the Tnts Geometrymentioning

confidence: 56%

Photocatalytic degradation of salicylic acid and caffeine emerging contaminants using titania nanotubes

Arfanis

Adamou

Moustakas

et al. 2017

Chemical Engineering Journal

125

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Section: Optimization Of the Tnts Geometrymentioning

confidence: 56%

Photocatalytic degradation of salicylic acid and caffeine emerging contaminants using titania nanotubes

Arfanis

Adamou

Moustakas

et al. 2017

Chemical Engineering Journal

125

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“…As is known, the oxidation of organics by US or UV irradiation can be well fitted to a pseudo-first order kinetic model, where the kinetic constant depends on the energy irradiated. For electrochemical oxidation processes, the first-order model also performs well, and in this case, the kinetic constant is related to the mass transfer coefficient and to the kinetic constants of the various mediated oxidation processes that may coexist [26,39,44,45]. In In comparing results, significant differences between the kinetic constants calculated for the raw pollutant and TOC can be observed.…”

Section: Resultsmentioning

confidence: 98%

“…3 shows the changes in the intermediates (shown as chromatographic area due to the presence of unknown intermediates) observed during the degradation of SMX (part a), metoprolol (part b) and caffeine (part c) by photolysis, sonolysis and CDEO. The intermediates have been identified according to previous works of degradation of POPs by CDEO [26,39,45].…”

Section: Resultsmentioning

confidence: 99%

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Irradiation-assisted electrochemical processes for the removal of persistent organic pollutants from wastewater

et al. 2015

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This work focused on the removal of persistent organic pollutants (POPs) from wastewater using irradiation-assisted electrochemical technologies, i.e. sonoelectrolysis, photoelectrolysis and sono-photoelectrolysis. Single-irradiation processes (sonolysis and photolysis) and electrochemical oxidation using conductive diamond anodes (current density of 30 mA cm -2 ) were also evaluated for comparison. Three POPs with different molecular structures (sulfamethoxazole, metoprolol and caffeine, initial concentration of 100 mg dm -3 ) were studied to evaluate the robustness of the selected technologies and the oxidation mechanisms involved in each case. Results show that the single application of the irradiation technologies led to the removal of only a small amount of POPs and no mineralisation, with the nature of the pollutant showing a marked effect; the opposite was observed for the single application of conductive diamond electrochemical oxidation (CDEO), which is a highly robust and efficient technology for the degradation of all types of POPs. Sonoelectrolysis, photoelectrolysis and sono-photoelectrolysis processes (ultrasound conditions: 200 W, ultraviolet conditions: 254 nm, 4 W) may show synergistic, antagonistic or nil effects with respect to a single electrochemical oxidation event, depending on the nature of the treated molecule. The differences observed may be related to the different chemical nature of the organic species studied, indicating an important role of mediated oxidation processes, which may be enhanced with ultrasounds and ultraviolet radiation techniques.

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“…Initial breakdown of molecules can reduce their chromophoric characteristics while still keeping their organic nature (Indermuhle et al 2013); so, this may explain why color removal occurred faster than TOC depletion (the average ratio of k app Abs /k app TOC was close to 2).…”

Section: Organic Matter Removalmentioning

confidence: 99%

Discoloration and Organic Matter Removal from Coffee Wastewater by Electrochemical Advanced Oxidation Processes

Villanueva-Rodríguez

Bello-Mendoza

Wareham

et al. 2014

Water Air Soil Pollut

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The coffee agro-industry generates a large volume of wastewater that is notable for its high organic strength as well as its color content. Due to the seasonal nature of the harvest (3-4 months per year), this particular industrial waste needs a treatment method that is both reliable and fast (in terms of start-up time). As part of investigating a system capable of treating a coffee wastewater, this research evaluated four electrochemical advanced oxidation processes (EAOPs) using boron-doped diamond (BDD) electrodes. The processes were anodic oxidation (AO), anodic oxidation with electrogenerated H 2 O 2 (AO-H 2 O 2 ), electro-Fenton (EF), and photoelectro-Fenton (PEF). Experimental conditions were as follows: 40 mA cm −2 current density (all EAOPs), 0.3 mmol Fe 2+ L −1 (Fenton systems), 300 mL air min −1 (AO-H 2 O 2 , EF, PEF), and 500 μW cm −2 UV irradiation (photo-Fenton systems). The performance of the four EAOP treatment methods (in terms of color and organic carbon removal) was compared against two conventional chemical oxidation methods, namely, Fenton and photo-Fenton. The research indicated that the four EAOPs were better at removing color (89-93 %) and total organic carbon (TOC) (73-84 %) than the respective chemical Fenton (58 and 4.8 %) and photo-Fenton (61 and 7 %) methods. The trend in performance was as follows: AO-H 2 O 2 >AO>PEF≈EF. It appeared that the ferrous iron reagent formed a dark-colored complex with some coffee components, diminishing the effect of Fenton reactions. In addition, the dark color of the wastewater limited the effect of light in the UV-Fenton processes. Analysis showed that acceptable levels of Fe 2+ (0.3 mmol L −1 ) and energy (0.082-0.098 kWh g −1 TOC) were required by the EAOPs after 4-h treatment time. In conclusion, the use of electrochemical methods (equipped with BDD electrodes) seems a promising method for the effective treatment of coffee wastewaters.

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Degradation of caffeine by conductive diamond electrochemical oxidation

Cited by 63 publications

References 21 publications

Photocatalytic degradation of salicylic acid and caffeine emerging contaminants using titania nanotubes

Photocatalytic degradation of salicylic acid and caffeine emerging contaminants using titania nanotubes

Irradiation-assisted electrochemical processes for the removal of persistent organic pollutants from wastewater

Discoloration and Organic Matter Removal from Coffee Wastewater by Electrochemical Advanced Oxidation Processes

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