Demonstrating photocatalytic esterification as a potential strategy to improve the properties of feedstock oil derived from dairy waste scum for biodiesel production

Abstract

The availability of quality feedstock for biodiesel production is challenging; and therefore, techniques to improve the quality of feedstock are highly desired, as they could be utilized to modify any feedstock and enhance the biodiesel production. Dairy waste scum oil (DWSO) is recently known to be a valuable feedstock for producing biodiesel. However, DWSO needs to go through an esterification process to reduce its high free fatty acid (FFA) content. To do this, herein, we have treated the DWSO using photocatalytic tin oxide (SnO2) particles under UV light irradiation and reduced the FFA content significantly compared to the conventional cumbersome acid-mediated esterification process. The synthesized catalyst is characterized for its structural, morphological, optical and surface properties using various characterization techniques. Parameters such as catalysts dosage, methanol to oil ratio, reaction time, and temperature involved in the photo-assisted esterification processes are optimized, and a mechanism for the photocatalytic esterification reaction is also proposed. Importantly, SnO2 particles also showed excellent reusability in the photo-assisted esterification process. Overall, the physiochemical and fuel properties of the photo-esterified DWSO-derived biodiesel are found to be improved compared to the biodiesel synthesized via conventional acid-esterified oil.