Kinetic description of the enzymatic depolymerization of single-grade plastic waste and product purificaion

The depolymerization of polymers by (bio)chemical methods fundamentally aims at the desired recovery processes that have repeatedly demonstrated their efficiency through high selectivity even under explicitly mild reaction conditions. Thus, the depolymerization of single-grade plastic waste with functional backbones, precisely PET and PEF, for subsequent re-synthesis will be studied together by the PIs Hamel, von Langermann und Thiele by combining enzymatic and chemical degradation routes with focus on the integrated separation and (re-) recovery of the degradation products. Novel chemo-enzymatic depolymerization routes of PET and PEF by tailor-made enzymes (PETase, cutinase, etc.) and combining kinetics and separation processes (membranes, adsorption) should be investigated.

For a preselected enzyme/solvent system from Jan von Langermann kinetic experiments will be performed with BHET and PET (Trimer) as feeds providing a profound knowledge about the reaction network which should be used for the kinetic analysis and modelling. Operando spectroscopy is applied for mixture analysis. The methods and kinetic models derived for PET will then be applied to PEV to prove their applicability. The data for PEF will be provided by Julian Thiele. The kinetic models derived for free enzymes allow to study and to suggest new reactor concepts using immobilized enzymes to improve sustainability in the group of Jan von Langermann.

Besides the depolymerization kinetics suitable separation processes and its combination should be evaluated in order to separate resulting degradation products (PET, PEV, BHET, MHET, Terephthalic acid, etc.). Therefore, feasibility, application and limits, e.g., of membrane, adsorption and SMB separation technology, will be studied.

The PIs and scientists financed by the project bring all necessary experimental/numerical methods and experience needed for a successful investigation. Based on the existing experience in each group, a first demonstration of the design procedure integrating all mentioned aspects should be presented.