Nepal J Biotechnol. 2020 Dec; 8 (3): 87-94 DOI: https://doi.org/10.3126/njb.v8i3.33661 Research article ©NJB, BSN 87 Biofuel Production from Waste Cooking Oils and its Physicochemical Properties in Comparison to Petrodiesel Ganesh Lamichhane 1,2 , Sujan Khadka 3 , Sanjib Adhikari 3 , Niranjan Koirala 4,5 , Dhruba Prasad Poudyal 1 1 Department of Chemistry, Birendra Multiple Campus, Tribhuvan University, Bharatpur Chitwan, 44200, Nepal 2 Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, 44613, Nepal 3 Department of Microbiology, Birendra Multiple Campus, Tribhuvan University, Bharatpur Chitwan, 44200, Nepal 4 Department of Environment and Energy Research, Dr. Koirala Research Institute for Biotechnology and Biodiversity, Kathmandu, 44613, Nepal. 5 Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, 999078, China Article history:- Received: 15 Aug 2020; Revised: 11 Dec 2020; Accepted: 19 Dec 2020; Published online: 30 Dec 2020 Abstract Haphazard mining and consumption of fossil fuels have reduced petroleum reserves causing fossil fuel depletion and environmental degradation; thus, reflecting the need for the cheaper, renewable and eco-friendly alternative source of petroleum to meet the fuel demand. A million liters of edible oil used for cooking foods and date expired oils from oil manufacturers are discarded into sewage. This study primarily intends to study the feasibility of biodiesel production using such waste oils. In this work, biodiesel was prepared from waste cooking oils by a process called transesterification with NaOH as a catalyst. Our results showed that methyl ester (biodiesel) (92.67±0.90%), soap materials (1.33±0.224%), and glycerol (6±0.68%) were obtained after the transesterification of waste cooking oil. The physicochemical properties of biodiesel such as density, viscosity, volatility, surface tension, and flashpoint were analyzed, which were found to be 0.862±0.006 g/cm 3 , 2.23 ±0.021 cP, 0.327×10 -3 ±4.5×10 -6 g/s, 32.03±0.138 dyne/cm, 169.67±0.810°C, respectively. These properties were compared with that of commercial diesel as well as with the values specified by the American Society for Testing and Materials (ASTM) D6751. The density and the surface tension of the biodiesel were found similar to that of petrodiesel but its volatility was 3 times lower. Fourier-transform infrared spectroscopy (FTIR) spectra of the biodiesel showed methyl ester functional group at 1436 cm -1 . Based on the cost of the materials used for production, the cost of biodiesel was estimated to be about 81 Nepalese rupees (0.67 USD) per liter. The properties of biodiesel also met the standard values of ASTM D6751. These findings indicate that waste oil is one of the feasible biodiesel sources and it can be used as a suitable alternative to petrodiesel. Keywords: Waste cooking oils; Transesterification; FTIR spectra; Methyl ester; Biodiesel Corresponding author, email: dhruba.degree@gmail.com Introduction A sharp population increase and the lifestyle changes in the world today have gradually increased the enormous demand for fuel [1]. Alternative sources of petroleum fuel are a serious topic of discussion since petroleum fuel has an ever-increasing price, non-renewable nature, and exerts a negative effect on the global climate [2]. Several sources of alternative energy (solar, wind, hydropower, geothermal, biogas, biodiesels, etc.) have been identified and are being used. Among them, biodiesel is of special interest due to its ubiquitous demand, cheaper price, and eco-friendly properties [3]. Biodiesel, a sulfur-free, oxygenated, renewable, non-toxic, and eco-friendly biodegradable oil, is chemically alkyl esters of long-chain fatty acids derived from renewable sources, such as vegetable oil, animal fat, and is used or waste cooking oil [4, 5]. Attempts to obtain biodiesel from waste cooking oil have been done from antiquity [6], and even today, plethora of researches are going in the same direction for identifying and synthesizing biofuel of higher efficiency and feasibility [6, 7, 8, 9, 10]. In early 1853, scientists E. Duffy and J. Patrick conducted the first transesterification process to synthesize biofuel from waste cooking oils [11]. In 1900, Rudolf Diesel, an inventor of a diesel engine, demonstrated the engine powered by peanut oil as biofuel at the world fair in Paris, France [6]. These discoveries have motivated the scientific communities to accomplish the search for alternatives to drastically vanishing petroleum products. Inspired by this, waste oil has already been re-used by other industries such as animal feed and cosmetics [8], but the quantity is still being wasted [12] and the production sites are very small in number. Synthesizing biodiesel from waste cooking oil is the forthcoming means of preserving energy and meeting our requirements without depending on anyone [13]. Nepal Journal of Biotechnology Publisher: Biotechnology Society of Nepal ISSN (Online): 2467-9313 Journal Homepage: www.nepjol.info/index.php/njb ISSN (Print): 2091-1130