Examinando por Materia "Graphite electrodes"

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    Ítem
    The Box-Benkhen experimental design for the optimization of the electrocatalytic treatment of wastewaters with high concentrations of phenol and organic matter.
    (IWA PUBLISHING, 2009-01-01) GilPavas, Edison; Betancourt, Alejandra; Angulo, Monica; Dobrosz-Gomez, Izabela; Angel Gomez-Garcia, Miguel; GilPavas, Edison; Betancourt, Alejandra; Angulo, Monica; Dobrosz-Gomez, Izabela; Angel Gomez-Garcia, Miguel; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
    In this work, the Box-Benkhen experimental Design (BBD) was applied for the optimization of the parameters of the electrocatalytic degradation of wastewaters resulting from a phenolic resins industry placed in the suburbs of Medellin (Colombia). The direct and the oxidant assisted electro-oxidation experiments were carried out in a laboratory scale batch cell reactor, with monopolar configuration, and electrodes made of graphite (anode) and titanium (cathode). A multifactorial experimental design was proposed, including the following experimental variables: initial phenol concentration, conductivity, and pH. The direct electro-oxidation process allowed to reach ca. 88% of phenol degradation, 38% of mineralization (TOC), 52% of Chemical Oxygen Demand (COD) degradation, and an increase in water biodegradability of 13%. The synergetic effect of the electro-oxidation process and the respective oxidant agent (Fenton reactant, potassium permanganate, or sodium persulfate) let to a significant increase in the rate of the degradation process. At the optimized variables values, it was possible to reach ca. 99% of phenol degradation, 80% of TOC and 88% of COD degradation. A kinetic study was accomplished, which included the identification of the intermediate compounds generated during the oxidation process.
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    Ítem
    Mineralization of cyanide originating from gold leaching effluent using electro-oxidation: multi-objective optimization and kinetic study
    (SPRINGER, 2020-01-01) Dobrosz-Gómez I.; Gómez García M.Á.; Gaviria G.H.; GilPavas E.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de Procesos
    Abstract: This study examines the electro-oxidation (EO) of cyanide originating from an industrial plant´s gold leaching effluent. Experiments were carried out in a laboratory-scale batch cell reactor. Monopolar configuration of electrodes consisting of graphite (anode) and aluminum (cathode) was employed, operating in galvanostatic mode. Response Surface Methodology (RSM), based on a Box–Behnken experimental Design (BBD), was used to optimize the EO operational conditions. Three independent process variables were considered: initial cyanide concentration ([CN-]0 = 1000–2000 mg L-1), current density (J =7–107 mA cm-2), and stirring velocity (? = 250–750 rpm). The cyanide conversion (XCN-), Chemical Oxygen Demand (COD) removal percentage (%RCOD), and specific Energy Consumption per unit mass of removed cyanide (EC) were analyzed as response variables. Multi-objective optimization let to establish the most effective EO conditions ([CN-]0 = 1000 mg L-1, J = 100 mA cm-2 and ? = 750 rpm). The experimental data (XCN-, %RCOD, and EC) were fitted to second-order polynomial models with adjusted correlation coefficients (Radj2) of ca. 98, 99 and 87%, respectively. The kinetic analysis, performed at optimal EO operational conditions, allowed determination of time required to meet Colombian permissible discharge limits. The predictive capacity of kinetic expressions was verified against experimental data obtained for gold leaching effluent. Total cyanide removal and 96% of COD reduction were obtained, requiring EC of 71.33 kWh kg-1 and 180 min. The BOD5 (biological oxygen demand)/COD ratio increased from 4.52 × 10-4 to 0.5573, confirming effluent biodegradability after EO treatment. Graphic Abstract: [Figure not available: see fulltext.]The variation of cyanide (CN-), cyanate (CNO-) and ammonium (NH4 +) ions concentrations vs. time at alkaline conditions. EO operational conditions: [CN-]0 = 1000 mg/L, J = 100 mA/cm2 , ? = 750 rpm, [NaCl] = 0.15 M and pH 11.1. © 2020, Springer Nature B.V.
  • No hay miniatura disponible
    Ítem
    Mineralization of cyanide originating from gold leaching effluent using electro-oxidation: multi-objective optimization and kinetic study
    (SPRINGER, 2020-01-01) Dobrosz-Gómez I.; Gómez García M.Á.; Gaviria G.H.; GilPavas E.; Dobrosz-Gómez I.; Gómez García M.Á.; Gaviria G.H.; GilPavas E.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
    Abstract: This study examines the electro-oxidation (EO) of cyanide originating from an industrial plant´s gold leaching effluent. Experiments were carried out in a laboratory-scale batch cell reactor. Monopolar configuration of electrodes consisting of graphite (anode) and aluminum (cathode) was employed, operating in galvanostatic mode. Response Surface Methodology (RSM), based on a Box–Behnken experimental Design (BBD), was used to optimize the EO operational conditions. Three independent process variables were considered: initial cyanide concentration ([CN-]0 = 1000–2000 mg L-1), current density (J =7–107 mA cm-2), and stirring velocity (? = 250–750 rpm). The cyanide conversion (XCN-), Chemical Oxygen Demand (COD) removal percentage (%RCOD), and specific Energy Consumption per unit mass of removed cyanide (EC) were analyzed as response variables. Multi-objective optimization let to establish the most effective EO conditions ([CN-]0 = 1000 mg L-1, J = 100 mA cm-2 and ? = 750 rpm). The experimental data (XCN-, %RCOD, and EC) were fitted to second-order polynomial models with adjusted correlation coefficients (Radj2) of ca. 98, 99 and 87%, respectively. The kinetic analysis, performed at optimal EO operational conditions, allowed determination of time required to meet Colombian permissible discharge limits. The predictive capacity of kinetic expressions was verified against experimental data obtained for gold leaching effluent. Total cyanide removal and 96% of COD reduction were obtained, requiring EC of 71.33 kWh kg-1 and 180 min. The BOD5 (biological oxygen demand)/COD ratio increased from 4.52 × 10-4 to 0.5573, confirming effluent biodegradability after EO treatment. Graphic Abstract: [Figure not available: see fulltext.]The variation of cyanide (CN-), cyanate (CNO-) and ammonium (NH4 +) ions concentrations vs. time at alkaline conditions. EO operational conditions: [CN-]0 = 1000 mg/L, J = 100 mA/cm2 , ? = 750 rpm, [NaCl] = 0.15 M and pH 11.1. © 2020, Springer Nature B.V.