title: Wet oxidation of real coke wastewater containing high thiocyanate concentration.
abstract: Coke wastewaters, in particular those with high thiocyanate concentrations, represent an important environmental problem because of their very low biodegradability. In this work, the treatment by wet oxidation of real coke wastewaters containing concentrations of thiocyanate above 17 mM has been studied in a 1-L semi-batch reactor at temperatures between 453 and 493 K, with total oxygen pressures in the range of 2.0-8.0 MPa. A positive effect of the matrix of real coke wastewater was observed, resulting in faster thiocyanate degradation than was obtained with synthetic wastewaters. Besides, the effect of oxygen concentration and temperature on thiocyanate wet oxidation was more noticeable in real effluents than in synthetic wastewaters containing only thiocyanate. It was also observed that the degree of mineralization of the matrix organic compounds was higher when the initial thiocyanate concentration increased. Taking into account the experimental data, kinetic models were obtained, and a mechanism implying free radicals was proposed for thiocyanate oxidation in the matrix considered. In all cases, sulphate, carbonates and ammonium were identified as the main reaction products of thiocyanate wet oxidation.
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Oviedo, C/Julián Clavería s/n, E-33071 Oviedo, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Oulego
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Oviedo, C/Julián Clavería s/n, E-33071 Oviedo, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Collado
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Oviedo, C/Julián Clavería s/n, E-33071 Oviedo, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Garrido
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Oviedo, C/Julián Clavería s/n, E-33071 Oviedo, Spain.
authors.forename: Adriana
authors.initials: A
authors.lastname: Laca
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Oviedo, C/Julián Clavería s/n, E-33071 Oviedo, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Rendueles
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Oviedo, C/Julián Clavería s/n, E-33071 Oviedo, Spain. Electronic address: mariodiaz@uniovi.es.
authors.forename: Mario
authors.initials: M
authors.lastname: Díaz
mesh_terms: D003077:Coke / Q000032:analysis*; D010084:Oxidation-Reduction; D013861:Thiocyanates / Q000737:chemistry*; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D014877:Water Pollution, Chemical / Q000517:prevention & control*
chemical_list: D003077:Coke; D013861:Thiocyanates; D062065:Wastewater; D014874:Water Pollutants, Chemical; C031760:thiocyanate
keywords: Kinetics; Reaction pathway; Real coke wastewater; Thiocyanate; Wet oxidation