International Journal of Energy and Power IJEP Volume 1, Issue 1, August 2012 pp.31-36 ISSN(online): 2169-4931 ISSN(print): 2169-4915 www.ijep.org IJEP Volume 1, Issue 1 August 2012 PP. 31-36 www.ijep.org © Science and Engineering Publishing Company - 31 - Homogeneous Catalysis of High Free Fatty Acid Waste Cooking Oil to Fatty Acid Methyl Esters (Biodiesel) Fazeelat Tahira 1 ,Syed Tajammul Hussain 2 , Syed Danish Ali 2 , Zafar Iqbal 1 , Waqas Ahmad 2 1 Department of Chemistry, University of Engineering and Technology, Lahore, Pakistan 2 National Centre for Physics, Quaid-e-Azam University Campus, Islamabad, Pakistan Email: dr_tajammul@yahoo.ca (Abstract) The waste cooking oil (WCO) is a promising feed stock for the production of biodiesel. The waste cooking oil used in this study has very high acid value (>13 mg KOH/g), therefore a simple base transesterification utilized so far proved to be unsuitable; this process resulted in soap formation. In this study the production process of fatty acid methyl esters (biodiesel) from WCO involved two steps, acid catalyzed followed by base catalysis reactions. In the first step, the acid value of WCO was reduced below 1 mg KOH/g by homogeneous acid catalysis and in the second step, acid catalyzed WCO was transformed to fatty acid methyl esters (FAME) in the presence of NaOH as homogeneous base catalyst. Five different sorts of FAMEs were identified in the waste cooking oil biodiesel by GC/MS analysis. The FAMEs recognized were methyl dodecanoate (C12:0), methyl tetradecanoate (C14:0), methyl hexadecanoate (C16:0), methyl 9-octadecenoate (C18:1) and methyl octadecanoate (C18:0). Their structures were confirmed by FTIR and NMR ( 1 H and 13 C) analyses. The percentage conversion of triglyceride to corresponding methyl esters determined by 1 H NMR was 97.89%. The biodiesel prepared was investigated for the fuel properties using ASTM standards. Keywords: Waste Cooking Oil; High Acid Value; Homogenous Catalysis; Fatty Acid Methyl Esters; Fuel Properties. 1. INTRODUCTION The alternative renewable fuels have gained immense attention due to the soaring price of petroleum products and depletion of fossil fuels. As a result, there is an earnest need to explore new energy sources, which should be economically competitive, technically viable and environmental friendly. Biodiesel is receiving great interest for future utilization all over the world because it is renewable in nature, environmental friendly and biodegradable [1]. Biodiesel is superior as compared to petroleum diesel in terms of flash point, amount of ash, and sulphur plus aromatic contents. The higher flash point of biodiesel makes it quite safe for storage and transportation. It is free from sulphur and aromatic compounds while petro diesel contain up to 500ppm sulphur content and 20-40 wt% aromatic compounds [2]. Accordingly, petro diesel is a huge source of black smoke particulate along with SO 2 emission and contributes to one third of the greenhouse gas emission by transport [3]. While, biodiesel has comparatively less discharge of CO, CO 2 and smoke density as compare to petro diesel [4]. The use of vegetable oil for biodiesel production has been extensively studies in recent years [5,6]. However, the high cost of vegetable oil and limited availability of feedstock are the critical issue for their use in the production of biodiesel. The biodiesel produced from vegetable oil has cost approximately 1.5 times greater than that of petro diesel [7], so the use of vegetable oil for biodiesel production is not feasible. Waste cooking oil (WCO) is a promising feedstock for the production of biodiesel. The cost of waste cooking oil is about 2-3 times less than that of virgin vegetable oil [7]. Large amount of waste cooking oil is available throughout the world. USA is producing 1.2-3 billion gallon of WCO per year whereas in Japan it is 4-6 lakh tons per year [8]. Production of biodiesel from this large amount of WCO also eradicates the environmental problems caused by the disposal of waste oil. WCO are, therefore, economical choice for the production of biodiesel. There are several methods for the formation of biodiesel such as, blending, micro emulsification, cracking and transesterification [9]. Among these methods transesterification is the simplest and efficient one. In transesterification, the triglyceride molecules of the oil react with alcohol in the presence of catalyst to produce mono esters, called biodiesel. Generally, waste cooking oils contain a large percentage of free fatty acids (FFA) resulting in soap formation [10]. To avoid the soap formation new technologies should be employed. The pretreatment of the WCO with acid in the presence of alcohol will convert the FFA into esters as shown in Figure 1(b).