Effects of Degumming Waste Cooking Oil on the Physicochemical and Fuel Properties of Biodiesel

Abstract

The waste cooking oil (WCO) has been a prospective and cheap feedstock for biodiesel with no competing food uses, but impurities affects biodiesel yield and result in higher production cost. This study examined the effects of degumming WCO on the physicochemical and fuel properties of biodiesel using degummed-bleached cooking oil (DCO), and methanol in the presence of sodium hydroxide catalyst. The properties and fatty acids profile were determined using the Association of Officials of Analytical Chemists (AOAC), American Society for Test and Material (ASTM) Quality, gas chromatography mass spectroscopy (GCMS) technique while the Fourier transform infrared (FTIR) gave the foremost peak regions between 1600-3600 cm-1. The pH of degummed cooking methyl ester (DCME), degummed-bleached cooking oil (DCO) and WCO varied between 5.83 and 8.61. Density of DCME, DCO and WCO varied between 0.88 and 0.93 (g/cm3). Comparing the quality improvements between DCO and WCO, the results showed percentage increases in properties such as recovery yield (8.5%), acid value (61.5%), saponification value (10.8%), iodine value (4.9%), peroxide value (26.9%), calorific value (10.9%), specific gravity (6.3%), density (2.2%), kinematic viscosity @ 40OC (54.2%), smoke point, OC (30.9%), flash point, OC (12.1%), fire point, OC (10.8%), pour point @ 40oC (2.3%), higher heating value (0.7%), and cetane number (-29.6%). The fatty acids profile in DCO has octanoic acid (5.86%), benzoic acid (3.74%), and hexadecanoic acid (74%) was the most abundant. The biodiesel from DCO as feedstock have quality improvements over WCO, and values compared well with ASTM standard recommendations.

Keywords: biodiesel, waste cooking oil, degumming, physicochemical