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Application of Combined Electrochemical Approaches for Removing/ Determining Cr(VI)

[ Vol. 13 , Issue. 3 ]

Author(s):

Elaine Cristina M. de Moura, Paulo R. do Vale Souza Gois, Djalma R. da Silva, Danyelle Medeiros de Araujo and Carlos A. Martinez-Huitle   Pages 202 - 209 ( 8 )

Abstract:


Background: In this work, a combined electrochemical approach has been developed for the purification and detection of chromium species in aqueous effluents. With this in mind, the technique of differential pulse voltammetry (DPV) using ultratrace graphite electrode was applied for the determination of hexavalent chromium during its elimination by an electrocoagulation (EC) process.

Methods: The application of combined electrochemical techniques (differential pulse voltammetry (DPV) using ultratrace graphite electrode) for the determination of Cr(VI) in aqueous solutions during its treatment by EC process (aluminum electrodes) by applying 5 and 10 mA cm-2, was proposed. Cr(VI) was selected as target due to its presence in several industrial effluents, drinking water and tap water as well as in textile dyes and as anti-corrosion and conversion coatings.

Results: The use of the DPV and UV-Vis for the monitoring of chromium concentration was tested during the EC process. A complete elimination of chromium in the solution was achieved by EC process. No increase on the removal efficiency of chromium was achieved, when an increase on applied current was applied. When low chromium concentrations were treated, complete removal was attained after 180 min, whereas at high concentrations, the elimination was achieved after 240 min. When chromium concentrations determined by DPV were compared with the determinations by UV-vis, some results are similar, principally at lower chromium concentrations (<2.5 mg L-1). However, higher concentrations of chromium were not determined by spectrophotometric approach, limiting the use of this method. Thus we may say that the DPV is a powerful electroanalytical method for determining hexavalent chromium in drinking water and effluents.

Conclusion: The use of graphite ultratrace electrode was optimized to be employed as analytical approach for determining Cr(VI) removal efficiency during the EC process. The proposed procedure permits the monitoring of the elimination of chromium content in solutions by complexation method, reducing cost and analysis times required in other instrumental techniques. The combination of electroanalytical detection and EC procedures can be used in pilot plant remediation process to remove Cr(VI) because of efficacy and suitable use.

Keywords:

Electroanalysis, electrocoagulation, chromium hexavalent, ultratrace electrode, environmental electrochemistry, Differential Pulse Voltammetry (DPV).

Affiliation:

Institute of Chemistry, Federal University of Rio Grande do Norte, Laboratório de Eletroquímica Ambiental e Aplicada, Campus Universitário 3000, Lagoa Nova, CEP 59072-970, Natal, RN, Federal University of Rio Grande do Norte, Institute of Chemistry, Laboratório de Eletroquímica Ambiental e Aplicada, Campus Universitário 3000, Lagoa Nova, CEP 59072-970, Natal, RN, Federal University of Rio Grande do Norte, Institute of Chemistry, Laboratório de Eletroquímica Ambiental e Aplicada, Campus Universitário 3000, Lagoa Nova, CEP 59072-970, Natal, RN, Federal University of Rio Grande do Norte, Institute of Chemistry, Laboratório de Eletroquímica Ambiental e Aplicada, Campus Universitário 3000, Lagoa Nova, CEP 59072-970, Natal, RN, Federal University of Rio Grande do Norte, Institute of Chemistry, Laboratório de Eletroquímica Ambiental e Aplicada, Campus Universitário 3000, Lagoa Nova, CEP 59072-970, Natal, RN

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