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Limiting current determination for the processes of electrochemical treatment of effluents containing toxic metals and organic pollutants

Grant number: 10/05939-5
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): July 01, 2010
Effective date (End): June 30, 2011
Field of knowledge:Engineering - Chemical Engineering
Principal Investigator:Luis Augusto Martins Ruotolo
Grantee:Guilherme Pincelli
Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Electrochemical processes applied to effluent treatment can be optimized in order to obtain maximum current efficiency and minimum energy consumption. This optimization occurs applying to the process the limiting current (IL), which is a function of electroactive species concentration and flow velocity. One of the techniques used to determine the limiting current consists in the calculation of the mass transfer coefficient (km), which can be done experimentally determining the limiting diffusion layer and the diffusion coefficient. Hence, in the first part of this project it will be determined the diffusion coefficients for the electroactive species Cl- and Cu2+ using a diffusion cell After that, the diffusion limiting layer will be determined for a filter-press electrochemical reactor using the technique of ferri/ferrocyanide redox pair. In the second part, the experimental information obtained before will be used to calculate the km as a function of flow. Using the values of km it will be further calculate the IL values as a function of the electroactive species concentration. The values of IL, as well as fractions of its value given by the ± parameter (± = I/IL) will be applied for two different electrochemical processes of interest in the field of effluent treatment: 1) degradation of organic pollutants using Ti/Ti0,7Ru0,3O2 electrode and 2) metal ions removal using reticulated vitreous carbon electrode. These processes will be evaluated in terms of their current efficiencies, space-time yields and energy consumptions. The main objective of this project is to validate the technique of limiting current determination using the diffusion cell and also determine the best value of ± that simultaneously optimize the reaction kinetics and the energy consumption.