Simultaneous separation and biocatalytic conversion of formaldehyde to methanol in enzymatic membrane reactor

Combination of the reaction simultaneously with separation inside a single process unit or commonly known as reactive separation technology is widely studied nowadays as it would give mutual benefits for both enzymatic catalysis and membrane separation process. Alcohol dehydrogenase (ADH) at 0.10 g/L (dissolved in 0.10 M Tris-HCl buffer) was immobilized on commercially available PES and PVDF membrane at pH 7 and TMP 2 bar by reverse filtration method. Then the immobilized enzyme was subjected to the biocatalytic conversion of formaldehyde to methanol. The immobilization process successfully immobilized 87.67% and 70.94% of ADH enzyme in/on the PVDF and PES membrane, respectively. The subsequent reaction was able to convert formaldehyde to methanol as high as 90% conversion and a high biocatalytic productivity of 460 mu mol CH3OH/mg(enzyme)center dot h for PVDF membranes. Enzyme relative activity could be retained for at least seven consecutive cycles. This study suggested that immobilization of ADH on the polymer membrane can increase enzyme loading and also retain its activity for a simultaneous conversion and separation of formaldehyde to methanol.