Response Surface Methodology with Central Composite Design (RSM-CCD) Study on Coconut Oil Transesterification using Zeolite-A as Catalyst

Biodiesel is a form of renewable energy source that is of particular importance, since it has been commercially produced and applied as a practical fuel. However, the price of biodiesel is still higher than that of petrochemical fuel, reflecting the need for optimizing the production process in order to reduce the cost. Current study was conducted to optimize the biodiesel production from coconut oil catalyzed by zeolite-A (zeo-A) produced by hydrothermal method utilizing rice husk silica (RH-SiO2) and food-grade aluminum foil (FGAF), followed by calcination of the zeolite at 550 °C for 6 h. Physical characteristics of the zeolite were obtained using different characterization techniques, including XRD, SEM, and BET. The zeolite was applied in transesterification experiments with the aid of response surface methodology based on central composite design (RSM-CCD) for evaluating the influence of catalyst load, the ratio of methanol to oil, and reaction duration on coconut oil conversion. A polynomial model with an analysis of the data variance indicates that the highest yield of biodiesel was produced from the experiment run for 1 h, loaded with 2.5% catalyst, and methanol to oil volume ratio of 5:1. Under optimum conditions, the biodiesel yield of 98% was achieved or a 2% error from the maximum yield (100%) as predicted by the model. In this respect, satisfactory optimum conditions for transesterification were successfully achieved with the aid of the RSM-CCD method applied.