Membranas de transporte facilitado para separação de oxigênio utilizando biotransportadores

Abstract

The aim of this work was to develop chemically stable carriers exhibiting high oxygen selectivity to be used in facilitated transport membranes for air fractioning. Strategies adopted in order to increase myoglobin stability were preparation of cobalt substituted proteins (CoMbs) and construction of recombinant proteins. Mutation designed by 29F68F resulted in a resistance to oxidation 3,5 times higher than that observed for a wild type myoglobin at 37 °C. To the 29F mutant, oxidation rate was 30% lower at these conditions. CoMbs exhibited a remarkable stability, at least ten times higher than the correspondent FeMb. Liquid membranes (LM) were obtained by impregnating a nylon microporous support with a myoglobin aqueous solution. Results were very promising. A LM containing a 60 g/L aqueous solution of native myoglobin showed an O2 permeability of 1600 Barrer and all O2/N2 selectivity of 21, at 25 °C and 3 cmHg. On the other hand, membranes made of Polyvinylalcohol (PVA) constituted a good altemative to the problem of lack of operational stability exhibited by LM. Besides, immobilization of myoglobin in a polymeric matrix promoted an extra stabilization against autoxidation, giving half-life times about 3 times higher than those for myoglobin in solution. Halflife time of a 29F CoMb immobilized in a PVA membrane at 7 °C was estimated as being as high as 3 years.