Biodiesel production from waste cooking oil: a comprehensive review on the application of heterogenous catalysts

Development of sustainable energy resources is the need of present day in view of the depleting energy resources and increase in the energy demand throughout the world. On the other hand, fossil fuel combustion emits harmful pollutants like oxides of carbon, sulfur, nitrogen and particulate matters, which causes atmospheric pollution. Biodiesel as alternative fuels have various advantages over the fossil fuels such as its renewability, lesser emission of atmospheric pollutants and flexibility to produce from variety of feedstock. Waste cooking oil can be used as a potential feedstock for biodiesel production. Disposal of waste cooking oil itself an environmental challenge due to its adverse environmental impact. Transesterification is the key process for synthesis of biodiesel production with low cost and under mild reaction condition. Intensive studies have been done on optimization of transesterification for improvement of biodiesel yield and reduction of conversion cost. Heterogeneous catalyst can play crucial role in improvement of biodiesel yield as well as cost of biodiesel production due to their repetitive application. The present manuscript is an attempt to provide comprehensive review on characteristics of waste cooking oil, factors affecting the transesterification reaction and application of heterogenous catalyst in biodiesel production to achieve more sustainability in the process.