Environmental concerns associated with petroleum resources have propelled the development of sustainable and renewable alternatives to petroleum based products. Vegetable oil is one amongst the foremost abundant bio-based feedstocks. The interest in using vegetable oils and low molecular weight alcohols by direct transesterification have shown great potential as alternatives to petroleum-based diesel, and the production of bio-based diesel continues to increase. Utilization of multi-response surface methodology (MRS) for the most effective combination effect or response from the uses of input to output variables to optimize the yield and higher heating values (HHV) of biodiesels was investigated. In this work, utilizing variety of non-edible vegetable oils like castor (Ricinus communis L), jatropha (Jatropha curcas), and neem (Azadirachta indica) seeds and several process variables or inputs, including mixing time, mixing speed, process temperature and catalyst dosage to formulate high quality renewable fuels were further explored. The outputs were yield, viscosity, higher heating value, density and turbidity. The proposed optimization scenarios for biodiesel using the statistical (MRS) models was aimed to optimize the processes to achieved high conversion and higher heating values, while reducing the reaction time, turbidity, density, and viscosity in the samples. The results showed catalyst dosage as the most important variable for all the three samples. For maximum yield of 100%, the molar ratio of 6.25, catalyst of 0.75 wt.%, reaction speed of 499.99 rpm, reaction time of 19.88 min and temperature of 24.50 oC were found as optimal conditions; while the molar ratio of 5.60, catalyst of 1.01 wt.%, the reaction speed of 499.5 rpm, reaction time of 20.00 min and temperature of 35.50 oC were optimal conditions for maximum biodiesel yield.

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

This work compares the physicochemical properties and fatty acid (FA) compositions of waste cooking oil (WCO) collected after deep frying periods from local restaurant with samples of refined cooking oil (RCO) produced after degumming, alkaline and bleaching treatments. The refined oil were initially kept/stored in the refrigerator at 4 o C and the biodiesel produced was subjected to gas chromatography mass spectroscopy (GCMS) for FA profile, and to Fourier Transform Infrared (FTIR) analyses to monitor esterification reactions. The degree of oil usage affected WCO properties and fatty acid composition. Density of refined cooking oil RCO and WCO varied between 0.90 and 0.93 (g/cm 3 ), and of refined cooking methyl ester (RCME) and waste cooking methyl ester (WCME) between 0.88 and 0.91 (g/cm 3 ). The pH of RCO and WCO varied between 7.36 and 8.61 and that of RCME and WCME between 5.11 and 5.59. The results of RCO and RCME showed corresponding improvements over the WCO and WCME in recovery yield, acid value, saponification value, iodine value, peroxide value, cetane number, kinematic viscosity, pour, smoke, flash, and fire points. Fatty acids analyses similarly showed comparable differences between the RCO and WCO with percent increase in octanoic ethyl acid (276.54%), benzoic acid, butyl ester (69.79%), hexadecanoic acid 15-methyl esters (267.33%) and reduction in 9,17-Octadecanoic acid (99.20%), and 9-octadecenoic acid(35.98%), respectively. The hexadecanoic acid, methyl ester (54.10%) was the most abundant. This result confirms the suitableness of WCO as feedstock for biodiesel.