Biodiesel synthesis from waste coconut scum oil utilizing SnFe2O4/cigarette butt-derived biochar as a magnetic nanocatalyst: Optimization, kinetic and thermodynamic study

Abstract

This study aims to develop a novel and efficient magnetic nanocatalyst for producing biodiesel from waste coconut scum oil (WCSO). In this regard, a retrievable and robust nanocatalyst, SnFe₂O₄/biochar derived from cigarette butts, was synthesized and applied in the transesterification of WCSO under ultrasonication. The aforementioned nanocatalyst was synthesized by sol-gel technique. Various analyses were conducted to characterize the prepared nanocatalyst. These analyses confirmed the successful decoration of biochar on SnFe₂O₄. The Surface area and pore diameter were 128.47 m²/g and 15.62 nm, respectively. Central composite design (CCD) was applied to optimize the parameters influencing biodiesel synthesis. Moreover, the highest biodiesel yield employing SnFe₂O₄/cigarette butt-derived biochar nanocatalysts was attained at 98.67 % under optimal conditions, which include a methanol/WCSO ratio of 11.81:1 mol/mol, ultrasonic time of 34.25 min, temperature of 64.05 °C, and a catalyst amount of 2.73 wt%. Besides, SnFe₂O₄/cigarette butt-derived biochar demonstrated a notable biodiesel yield (90.48 %) even after seven reuse steps, highlighting its exceptional reusability. The thermodynamic and kinetic analyses of transesterification indicate that the synthesis of biodiesel is an endothermic reaction. The SnFe₂O₄/cigarette butt-derived biochar nanocatalyst stands out as a highly promising candidate for future research due to biodiesel performance, quick reaction time, and remarkable catalyst reusability.