Production of Biodiesel by Transesterification of Pilot Plant Waste over Nickel (Ni)/Eggshell (CaO) Catalyst

The increment of pilot plant waste at UniKL MICET and eggshell waste cause disposal problems, such as the water and soil pollution, human health concerns, and disruption to aquatic ecosystems. Thus, to reduce the effect of disposal problem to the environment, pilot plant waste is converted into biodiesel, while eggshell is converted into catalyst in this study. This paper reports on the effect of catalyst preparation method and reaction temperature on biodiesel yield and quality. Transesterification process of pilot plant waste (olein and stearin) was conducted by using Ni/CaO (eggshell) catalyst from different preparation methods at different reaction temperatures (328 K, 333 K, 338 K and constant reaction time (5 hours), methanol-to-oil ratio (15:1), and weight of catalyst (8 wt%). The catalysts were synthesized via wet impregnation and sol–gel method and its physicochemical properties were subsequently characterized by TGA and FTIR analysis. Biodiesel analysis was done using GCMS and FTIR, while the physical properties (density, flash point, and kinematic viscosity) of biodiesel were measured according to ASTM D6751. Kissinger-Akahira-Sunose (KAS) kinetic model shows that the catalyst prepared by wet impregnation method has the lowest activation energy, which was 81.48 kJ mol–1. In addition, GCMS analysis shows that reaction temperature at 338 K produced the highest yield of biodiesel (88.26%). In conclusion, the best catalyst preparation method was wet impregnation method and the best reaction temperature was 338 K. In addition, the physical properties of the produced biodiesel corresponded to ASTM standard, thereby indicating high quality of biodiesel and can be used as petroleum-diesel substitute.