THE REDOX-CATALYZED REDUCTION OF DISPERSED ORGANIC-COMPOUNDS - INVESTIGATIONS ON THE ELECTROCHEMICAL REDUCTION OF INSOLUBLE ORGANIC-COMPOUNDS IN AQUEOUS SYSTEMS

The indirect reduction of insoluble dispersed organic compounds (e.g. dye systems) is described. Using cyclic voltammetry (CV), it is shown that aqueous alkaline iron-amine complexes reach cathodic current peak potentials of over -1000 mV. Therefore such complexes are very well suited to act as mediators for the reduction of the compounds investigated, such as dye pigments, with anthrachinoid, indigoid and disulphidic molecular structures, which have markedly less negative reduction potentials. The analysis of the CV experiments gives valuable information concerning the reaction rates (described by enhancement factors), the concentration behaviour and the type of mediator system. The experiments demonstrate a practical method of evaluating suitable mediator systems for the indirect electrochemical reduction of dyestuff molecules. In the technical dyeing processes using vat dyes, indigo and sulphur dyes, the reduction step is a main reaction in the application on cellulosic fibres, e.g. cotton.