Photo-driven valorization of polylactic acid into hydrogen fuel and pyruvate using a biotic-abiotic configuration
Abstract: ** Lecture will be given in English**
Plastics are among the most widely used materials in modern society. Polylactic acid (PLA) is employed in numerous applications, and its demand is expected to markedly increase in the coming years. Mechanical and chemical recycling methods can degrade PLA; however, these are often energy-demanding and lead to polluted side streams. The insufficient natural degradability of PLA raises the need for improved upcycling, recycling, and waste disposal techniques. Biocatalysis offers a greener approach to depolymerizing PLA into lactic acid. Proteinase-K facilitates the hydrolysis of the ester bonds in the PLA chains, yielding lactic acid and soluble oligomers.
Herein, we present a holistic approach for the conversion of PLA into H2 fuel under mild conditions. For that, enzymatic biocatalytic PLA degradation was coupled with a photocatalyst to facilitate the photooxidation of lactic acid. In the developed system, proteinase-K was employed for the depolymerization of PLA into lactic acid. The latter was oxidized by CdS nanoparticles (NPs) under visible-light irradiation, yielding solely pyruvate, an essential material in the industry. The photogenerated conduction electrons at the NPs simultaneously reduced protons to generate H2 fuel. Furthermore, electrochemical route for the lactic acid oxidation using a BiVO₄/CoP photoanode under visible-light irradiation will be presented. The designed photo-electrochemical cell enables the conversion of enzymatic degraded PLA waste into electrical energy, value-added chemicals and hydrogen fuel.
