Kinetic aspects of dye-transfer inhibition by catalytic oxidation

Dye-transfer inhibition (DTI) during laundering can be achieved by catalytic bleaching of the migrating dyes in the wash-liquor. The rate of the bleaching reaction should be significantly higher than the rate of dye adsorption onto the acceptor fabric. Further, the stability of the catalyst should be high enough in order to bleach dye which is slowly released from colored fabrics during the entire wash-cycle. The performance of three manganese-salen (Mn-salen) complexes as DTI catalysts is discussed in terms of their activity and their stability. It is shown that a very high activity is compatible with a high stability, leading to excellent DTI effects. For less stable catalysts, the performance can be markedly improved by optimizing the catalyst and peroxide concentrations or by formulation in a polymer matrix.