Voltammetric Investigations of the Reduction of Direct Orange-31 a Bisazo Dye

摘要

The electrochemical reduction of bisazo dye Direct Orange-31 has been studied at Pyrolytic graphite electrode (PGE) in the pH range 2.0-10.3. Two well-defined 4e~-, 4H~+ pH dependent reduction peaks (Ⅰc & Ⅱc) have been observed in linear and cyclic sweep voltamme- try. It has been observed that reduction of azo groups in the dye does not stop at hydrazo stage but further reduction leads to the cleavage of -NH-NH- linkage to give amino compounds as the fi- nal products. At pH 3.0 and 7.0, 4-aminosalicylic acid and 3,3'-di- methylbenzidine have been characterized as the major products of reduction. A tentative mechanism for the reduction has also been suggested.