Effective diffusion coefficient of methylene blue in agar gel

RODRIGUEZ N; ZARITZKY NOEMI.

INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 1983 vol. 10 p. 363 - 376

0735-1933

The effective diffusion coefficient of dyes in polymers is generally highly dependent on the concentration of the diffused substance.This fact has been taken into account in proposing the equations of mass transfer and has made it possible to obtain experimentally the effective diffusion coefficient of methylene blue in agar gel.Densitometric techniques were used to quantify concentration profiles under nonstationary state conditions. The dependence of the diffusion coefficient on the concentration was interpreted theoretically and the comparison of experimental distributions of concentration with numerical solutions of the differential equations allowed to obtain the corresponding parameters. The influence of the dye concentration and of the temperature on thediffusion coefficient and position of the colored front was analyzed and equilibrium concentrations in the interphase have been determined by spectrophotometric techniques.The apparent activation energy for the diffusion of the dye in the gel was quantified and the results obtained were applied to the development of a time-temperature indicator integrator for frozen foods.