INTRODUCTION.Chromium is used in a variety of applications including electroplating,dye production,tannery,water-cooling and others.As the toxicity of hexavalent chromium as a carcinogenic agent was proven,its effluents concentration is controlled and the limit levels are very low(the Brazilian legislation limits Cr(VI)discharge in 0.1 mgL~(-1)).The reduction of Cr(VI)to its trivalent state makes it less toxic and easily adsorbed or precipitated.Thus,the reduction of Cr(Vl)to Cr(III)serves to immobilize it [1].In this paper a process using the conducting polymer polyaniline(Pani)to reduce the hexavalent chromium was studied.Two possible processes were tested:the process under open circuit conditions and the process operating under cathodic protection of the film.The polymer degradation and the Cr(VI)reduction rate were evaluated in both cases.
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