Biodiesel Production from Waste Cooking Oil Via Homogeneous Transesterification: A Comparative Study

Abstract

Using edible oil for the production of biodiesel is widely accepted, but there has always been a debate on food versus fuel concept. Biodiesel produced from waste cooking oil (WCO) constitutes a viable approach to lowering the dependency on edible oils, decreasing the production cost, and reducing environmental effect. The disposal of WCO presents an environmental challenge due to its adverse impacts on the ecosystem. In this study, the WCO was collected from the mess canteen in NIT Rourkela campus, filtered multiple times to remove the residuals, and heated to remove moisture content. The FFA value of the waste cooking oil was found to be 4.52%, which required a two-step process for the production of biodiesel. An acid-catalyzed "pre-treatment" (esterification) was used to lower the FFA value of WCO below 2% using H2SO4 (1 wt.%) at 60 °C for 1 hour with 6:1 (methanol;oil). Homogeneous base transesterification was performed to convert the esterified oil into fatty acids methyl esters (FAME). The process parameters were kept at 1 wt.% (KOH, NaOH and KOH+NaOH) catalyst loading; 6:1 (methanol;oil); 60°C for 1 hour at around 500 rpm. The yield was found to be 90.3% (using KOH), 86.4% (using NaOH) and 82.6% (using KOH+NaOH). FTIR, NMR and GCMS analysis were carried out for the successful conversion of WCO to FAME. The biodiesel samples' physicochemical properties met ASTM and EN standards. The future work of this study is to use heterogeneous catalyst derived from the waste biomass sources for the production of biodiesel from WCO.