Synthesis and performance evaluation of biodiesel from waste cooking oil using copper doped zinc oxide nanocatalysts

Abstract

Biodiesel occupies a unique position in the area of renewable energy. Biodiesel serves as an alternate fuel to diesel due to the increasing demand, high cost of diesel and also to tackle energy crisis. In this study, biodiesel is prepared from Waste Cooking Oil (WCO) using Copper doped Zinc Oxide (CZO) nanocatalysts. Characterisation of synthesized copper doped zinc oxide nanocatalysts are done by X-Ray Diffraction (XRD) and High-Resolution newlineTransmission Electron Microscope (HRTEM). In this work, Response Surface Methodology (RSM) based on Central Composite Rotatable Design (CCRD) is used to design experiments, find the optimum reaction conditions and study the effect of process parameters such as catalyst loading, copper loading, reaction temperature, reaction time and oil/methanol molar ratio on biodiesel yield. The regression equation for the RSM model is generated using the experimental results (32 experiments). A maximum yield of 96.3% is obtained at optimum conditions of copper loading to zinc oxide at 9.7%, catalyst loading at 2%, temperature at 70oC, and oil to methanol ratio maintained at 5 for 48.5 minutes. Hence, it is established that nanocatalysts exhibited good catalytic activities on biodiesel production from waste cooking oil. Ultrasonication type transesterification is also carried out to enhance the transesterification process and is found to be better than the conventional method. Properties of biodiesel produced are compared with the American Society for Testing and Materials (ASTM) D6751 standard and found to be matched. The cost of biodiesel per litre works out to be 68 rupees INR, which is equal to the cost of diesel. The environmental impacts of using waste cooking oil for biodiesel production are investigated by Life Cycle Assessment (LCA) methodology. newline newline