Composite polymeric membranes for process intensification: Enzymatic hydrolysis of oligodextrans

Enzymatic membrane reactors based on a polymeric matrix and activated carbon loaded with dextranase were synthesized to separate and purify dextrans. The steps carried out were: (1) testing the activity of the enzyme with a 40 kDa commercial dextran to obtain oligomers with low degree of polymerization, avoiding the production of monomer, (2) adsorbing the enzyme by the activated carbon considering concentration and pH as variables, as well as testing the activity of the loaded activated carbon obtained, (3) synthesizing the enzymatic membrane reactors, (4) characterizing them by SEM and IFME® software and (5) testing their performance in a flat membrane module at ultrafiltration pressures. Results show a proper activity of the enzyme and the loaded activated carbon, and optimal conditions for the adsorption of enzyme by the activated carbon were found (pH 5). Related to the enzymatic membrane reactors, the larger activated carbon–enzyme loading, the closer porous structure was obtained. Since a very specific enzyme was used, changes in the loading of the activated carbon–enzyme leads to a change on the mean value of degree of polymerization of the produced compounds, but not on the amount of a specific-in-size product obtained. By using 4 wt.% of activated carbon–enzyme loading in the preparation of the enzymatic membrane reactor it is possible to obtain, as purified reaction products, oligomers from 200 Da.