Reduction of hexavalent chromium by polypyrrole deposited on different carbon substrates

Abstract

Pollution due to toxic hexavalent chromium has reached dangerous levels in some parts of the world, especially in Third World countries. This work focuses on the reduction of Cr(vi) ions in aqueous media by polypyrrole deposits on porous, high area three-dimensional carbon electrodes. Since many properties of deposited polymers are known to depend on the method of synthesis we performed the electropolymerization of pyrrole either at varying potential scan rates or at constant potential on different high area carbon materials. The deposits thus obtained were then put in contact with acidic hexavalent chromium solutions; high reduction yields were obtained (up to 80%). In addition, the possibility of repeating this cycle was studied as well as the wear resistance of these deposits. Finally, the morphology of the deposits was monitored at different stages of the process by scanning electron microscopy.