文摘
Studies of pollution due to hexavalent chromium areimportant because it represents a risk to human healthand the environment. Hexavalent chromium is a toxicsubstance and has been found to be carcinogenic. Fortunately,its reduced form, Cr(III), is much less toxic. This paperdiscusses the remediation Cr(VI) by its reduction in aqueousmedia by polypyrrole (PPy)-coated reticulated vitreouscarbon substrates (RVC). The study is focused on the effectof PPy-film electropolymerization conditions and itsefficiency toward the reduction of toxic chromate. Wehave studied parameters such as the influence of thepolymerization electrolyte, the scan rate, the potential limits,and the polymerization cycles concerning the reductioncapability of the film. Key results obtained in the presentstudy show that in the presence of different anions duringformation of the PPy film, the efficiency of chromatereduction depends on the nature of the anion. We foundthat the films prepared and treated in the presence of KIperformed much better and lasted much longer than thoseprepared in the presence of KF. Films synthesized atlower scan rates, and higher positive potential limits showedhigher chromate reduction efficiencies. Some of ourresults show reduction of ca. 100% of Cr(VI) from a 10mg/L solution, even after using the film in 20 contacts withthe chromium solution, with films synthesized in KBr andKI electrolytes, at a scan rate of 20 mV/s, between -0.3 and0.9 V and 40 polymerization cycles. Our study shows thatremediation of Cr(VI) by reduction with PPy-coated substratescould be developed into an effective method toward thesolution of this problem.
