Sustainable recycling of animals rendering waste oil into biodiesel via lipase stabilized in ordered-structured large-pore mesoporous silica derived from rice husk

Abstract

The disposal of animal rendering waste oil presents substantial environmental challenges, highlighting the need for efficient and sustainable repurposing strategies. This study reports a pioneering enzymatic approach for converting animal rendering waste oil into biodiesel, representing the first reported application of this method. Furthermore, this is the first study to use ordered, structured large-pore mesoporous silica derived from rice husks (OLMS-RH) as an enzyme support, with a ship-in-a-bottle strategy to increase the enzyme stability, reusability, and catalytic efficiency. The immobilized lipase (LP@OLMS-RH) exhibited a 3.91-fold increase in specific activity and marked thermal and pH stability, and retained its performance for nine reaction cycles and 100 days of storage. Under optimized conditions, LP@OLMS-RH achieved a maximum biodiesel yield of 97.0 % within 7 h, significantly surpassing the 61.7 % yield obtained using free lipase. These enhancements were attributed to hyperactivation of the immobilized enzyme, improved substrate accessibility, and tailored microenvironment provided by the OLMS-RH. This study established OLMS-RH as a highly effective enzyme immobilization platform, enabling the development of a durable and reusable catalytic system for biodiesel production. This approach offers a scalable and environmentally sustainable solution to global waste management challenges by simultaneously improving enzyme performance and facilitating waste oil recycling.