Biodiesel production via waste eggshell as a low-cost heterogeneous catalyst: Its effects on some critical fuel properties and comparison with CaO

Most of the world's energy needs are met by oil, and many countries import a large portion of their oil demand. This causes a very critical problem, such as energy dependence. On the other hand, as a result of the increase in consumption of petroleum products, they cause global climate changes that can cause harms to environment, human health and global dangerous developments due to harmful gases such as CO2, SO2 and NOx. In this sense, research and development of alternative fuels has become a very crucial issue. It is necessary that alternative fuel sources be human-oriented, renewable, feasible and easily available, with local resources for sustainable economic development and a cleaner environment. One of the alternative fuels is biodiesel. Catalysts used in transesterification are one of the most important parameters affecting the production efficiency in the production process by biodiesel transesterification. Homogenous and heterogeneous catalysts are used in biodiesel production. Although the yield in homogeneous catalysts, which are commonly used in transesterification reaction is high, many factors such as saponification, excess reagent consumption and extra separation cost negatively affect production costs. Therefore, efforts to develop high-efficiency and high re-usable heterogeneous catalysts that prevent saponification have gained a great speed and importance today. In this study, the use of cheap and domestic waste eggshell as a catalyst and its effects on product yield, density and viscosity parameters of biodiesel obtained in different methanol/oil molar ratios were investigated. During transesterification reaction, the reaction condition of 4% catalysts, 1-hour reaction time and 60 degrees C reaction conditions were kept constant. The highest yields, which was obtained with the above mentioned conditions (For firsts 1st use), was 96.81% and 95.12% for CaO and waste eggshell, respectively. The density and viscosity values of the biodiesel obtained in these conditions were determined as CaO: 888 kg/m(3), 4.946mm(2)/s, eggshell: 890 kg/m(3), 4.954mm(2)/s, respectively. The density and viscosity values of the biodiesel obtained from all operating parameters were between 860-900 kg/m(3) and 3.5-5.0mm(2)/s respectively (within the limits given in EN 14214). As a result of the use of both catalysts, biodiesel's flash point and pour point values have a certain increase in the expected partial decreases in the cetane number and thermal values have been determined. The study was detailed by means of XRD, P-XRF, SEM analysis methods. The results showed that the waste eggshell can be reused as a catalyst, it has a significant effects on the product yield and fuel properties, and the cost of biodiesel can be reduced significantly.