(631c) Enzymatic Transesterification of Low-Cost Feedstock By Using Highly Porous Magnetic-Silica Aerogel Nanostructures As an Enzyme Support Materials

The growing energy demand, coupled with concerns about climate change and greenhouse gas emissions, has intensified the search for sustainable alternatives. Biodiesel, the third most consumed biofuel in the United States, is a renewable drop-in biofuel produced from edible and non-edible vegetable oils, animal fats, used cooking oils, and microalgae. However, the use of vegetable oils is becoming less favorable due to rising costs and the food-versus-fuel debate. Instead, waste cooking oils have emerged as an attractive alternative due to their lower cost compared to vegetable oils and their comparable performance in biodiesel production.

Enzyme catalysts have emerged as a superior alternative to conventional chemical catalysts due to their mild reaction conditions, reduced side reactions, high product purity, and lower environmental impact. However, the high cost and single-use nature of free enzymes remain major limitations. To address these challenges, we developed highly porous magnetic-silica aerogel nanostructures as enzyme immobilization supports, enabling enzyme reuse while enhancing catalytic efficiency. These nanostructures offer key advantages, including easy magnetic separation, a high surface area for enzyme loading, and improved enzyme stability.

In this study, highly porous magnetic-silica aerogel nanostructures were successfully synthesized and used as support materials for the immobilization of Amano Lipase from Pseudomonas fluorescens. BET analysis confirmed that the magnetic-silica aerogel nanostructures possess a highly mesoporous structure, with surface areas of 500–700 m²/g, pore diameters of 11–23 nm, and pore volumes of 2.5–4.2 cm³/g. The results demonstrated that the prepared hybrid enzyme catalysts were effective in producing biodiesel from waste oil under mild reaction conditions. The highly mesoporous magnetic-silica aerogel nanostructures enhanced the operational stability and lifetime of the enzyme and were easily separated from the reaction medium due to their magnetic properties. Additionally, a comprehensive life cycle assessment (LCA) was conducted using SimaPro to evaluate the environmental impacts associated with biodiesel production employing various highly mesoporous magnetic-silica aerogel nanostructures. The support materials were characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier-transform Infrared Spectroscopy (FTIR), Nitrogen Adsorption-Desorption Isotherm Analysis (BET and BJH methods), and Vibrating Sample Magnetometry (VSM). High-Performance Liquid Chromatography (HPLC) was used to analyze the biodiesel samples.