Improvement of fuel properties of used palm oil derived biodiesel with butyl ferulate as an additive

Context & Rationale

The global transition away from fossil fuels has intensified research into biodiesel as a renewable and cleaner-burning alternative. However, a fundamental challenge limiting the practical deployment of biodiesel ??? particularly that derived from used cooking oils ??? remains its susceptibility to oxidative degradation, which compromises fuel stability, storage life, and engine performance. The search for effective, non-toxic antioxidant additives capable of addressing this limitation has therefore emerged as a critical area of investigation. Concurrently, concerns surrounding the environmental and health implications of nanomaterial-based additives have underscored the need for biologically derived alternatives.

Scope of the Study

This study presents an integrated investigation into the preparation and performance enhancement of Used Palm Oil Methyl Ester (UPOME) ??? a biodiesel derived from waste cooking oil ??? through the application of butyl ferulate as a phenolic antioxidant additive. Butyl ferulate, a lipophilic ester of ferulic acid, was synthesised enzymatically using Rhizopus niveus lipase immobilised on cuttlebone powder ??? a bioceramic support that offers notable advantages in terms of enzyme loading capacity and thermal stability. The synthesised additive was subsequently incorporated into UPOME at varying concentrations and evaluated across multiple dimensions of fuel quality and engine performance.

Oxidative Stability & Spectroscopic Characterisation

The oxidative stability of the antioxidant-fortified biodiesel formulations was assessed through a combination of excitation???emission matrix fluorescence spectroscopy and the conventional Rancimat method. The differential behaviour of butyl ferulate and free ferulic acid under thermal oxidation conditions yielded results of considerable mechanistic interest ??? particularly with respect to hydroperoxide suppression and induction period enhancement ??? the magnitude of which warrants direct examination in the full publication.

Engine Performance & Emission Outcomes

The study extends beyond fuel chemistry to encompass a comprehensive compression ignition engine performance analysis, evaluating combustion characteristics, brake thermal efficiency, and exhaust emission profiles ??? including NOx, CO, CO₂, and unburned hydrocarbons ??? across a range of brake power conditions. The emission outcomes recorded for the optimised biodiesel blend represent a multi-pollutant reduction profile that positions butyl ferulate as a functionally significant additive for cleaner biodiesel combustion, with implications discussed in detail within the manuscript.

Keywords

Biodiesel ?? Used palm oil methyl ester (UPOME) ?? Butyl ferulate ?? Oxidative stability ?? Excitation???emission matrix ?? Emission reduction ?? Rhizopus niveus lipase ?? Cuttlebone ?? Ferulic acid ?? Compression ignition engine