Diffusion controlled relaxation time and acceleration of velocity of sol-gel transformation for cross-linked metal alginate ionotropic gel comlexes

The rate of gel-growth for spherical ionotropic metal alginate gel droplets has been studied. Experimental observations have shown that the relaxation time of the metal alginate ionotropic gel complexes of the droplet shapes decreased in the order Hg > Cd > Sn > Pb-alginates, whereas the velocity of sinking under gravitational acceleration decreases in the same order. The factors which affect the relaxation time and velocity of acceleration, such as the concentration and viscosity of the alginate sol, the nature and radius of the metal ion as well as the density and pH of the electrolyte solution have been examined. The activation energies indicated that the stability of these metal alginate gel complexes follows the order Hg > Cd > Pb ~ Sn alginates. A mechanism consistent with the experimental results has been discussed.