Transformation of biodegradable polyesters into cyclic oligomers under continuous flow using an enzyme-packed column

The enzymatic degradation of typical chemically synthesized biodegradable plastics, such as poly(butylene adipate) and poly(epsilon-caprolactone), to a repolymerizable cyclic oligomer under continuous flow using an enzyme column was studied, directed towards green chemical recycling. It was confirmed that both polymers were quantitatively transformed into the corresponding cyclic oligomers by passage through the column packed with immobilized lipase from Candida antarctica (Novozym 435) at 40 degrees C using a toluene solution. Compared to the batch treatment in a flask, a short reaction time and a low reaction temperature occurred for complete transformations of the polyesters by continuous flow through the enzyme column. The degradation activity of the enzyme column was maintained for at least six months at 40 degrees C. Conceptual scheme of the continuous degradation equipment using the enzyme column.