AbstractThe theoretical equations which described the concentration profile of immobilized species of reactive dyes in the substrate were derived from the diffusion equation with the chemical reaction of first‐order or pseudofirst‐order. The theoretical profiles in the substrate described by the equations were discussed. The larger the diffusion coefficientDof active species and the smaller the reaction rate constantk, the deeper is the penetration of the immobilized and active species of reactive dyes into the substrate. The method of estimatingDandkfrom the diffusion profiles of both species obtained by means of the method of the cylindrical cellophane film roll was described. The diffusion coefficients of the hydrolyzed species of C.I. Reactive Orange 1 and Red 1 were nearly constant in all the pH values examined. The concentration profiles of both the species of Orange 1 at pH 8.8 were identical with the theoretical ones; while the profiles of immobilized species of Red 1 at pH 10 and of Orange 1 at pH 12 agreed with the theoretical ones and those of active species did not because of the hydrolysis. The diffusion coefficients of active species of these dyes at these pH ranges were smaller than those of the hydrolyzed spec
展开▼
