Preparation of chitosan gel beads by ionotropic molybdate gelation.

A new process is described for the preparation of chitosan gel beads using molybdate as the gelling agent. This new gelation technique leads to a structure different from that produced during alkaline coagulation of a chitosan solution. Instead of a morphology characterized by large open pores, gel beads produced in a molybdate solution, under optimum conditions (pH 6; molybdate concentration, 7 g x L(-1)), have a double layer structure corresponding to a very compact 100-microm thick external layer and an internal structure of small pores. Experimental conditions, especially pH and molybdate concentration, were selected to optimize molybdate content and the stability of the bead shape.