Earth is flooded with plastics and the need for sustainable recycling strategies for polymers has become increasingly urgent. Enzyme‐based hydrolysis of post‐consumer plastic is an emerging strategy for closed‐loop recycling of polyethylene terephthalate (PET). The polyester hydrolase PHL7, isolated from a compost metagenome, completely hydrolyzes amorphous PET films, releasing 91 mg of terephthalic acid per hour and mg of enzyme. Vertical scanning interferometry shows degradation rates of the PET film of 6.8 μm h−1. Structural analysis indicates the importance of leucine at position 210 for the extraordinarily high PET‐hydrolyzing activity of PHL7. Within 24 h, 0.6 mgenzyme gPET−1 completely degrades post‐consumer thermoform PET packaging in an aqueous buffer at 70 °C without any energy‐intensive pretreatments. Terephthalic acid recovered from the enzymatic hydrolysate is then used to synthesize virgin PET, demonstrating the potential of polyester hydrolases as catalysts in sustainable PET recycling processes with a low carbon footprint.
Many areas of science and industry require a fundamental understanding of crystal dissolution. Examples are diverse and include chemical weathering, pharmaceutical delivery, and the response of marine carbonates to CO2 increases. Understanding these processes ultimately demands knowledge of reaction dynamics. Techniques allowing high-resolution observations of dissolving crystals have greatly improved our understanding of reaction kinetics at a variety of scales. Atomic force microscopy and vertical scanning interferometry can reveal reaction mechanisms and permit tests of working hypotheses. However, understanding the substantial complexity and heterogeneous distribution of surface reactivity cannot be made by simple observation alone but requires advances in fundamental theory. Model simulations of molecular-scale processes provide the critical link between nanoscale surface observations of crystal dissolution and the phenomenological result at scales of environmental importance.