Biodiesel production process catalyzed by acid-treated golden apple snail shells (Pomacea canaliculata)-derived CaO as a high-performance and green catalyst

In this study, acid-treated golden apple snail shells (Pomacea canaliculata)-derived calcium oxide (CaO_tr) were used as a high-performance catalyst for the transesterification of palm oil and waste cooking oil (WCO) because the golden apple snail shells were found in plenty in Thailand, and they were also the major pest of rice. The obtained final materials were calcined in air at 800 C for 3 h referred by TGA analysis denoting as CaO_tr catalyst. All of the catalysts were characterized and tested by using several techniques including XRD, EDX, SEM, basic strength by Hammett indicator method, total basic site by TPD-CO2, and BET specific surface area by N2 adsorption. The results indicated that the CaO_tr had a specific surface area of 7.5544 m2/g and it was higher than CaO_un approximately 2 times. The kinetics of the reaction followed pseudo-first-order with the rates constants of reaction (k) equal 1.3510-2 min-1 for the reaction which catalyzed by acid-treated golden apple snail shells-derived CaO catalyst (CaO_tr), while un-treated golden apple snail shells-derived CaO catalyst (CaO_un) gave k value of 1.1810-2 min-1, respectively. Under the optimal of reaction conditions at catalyst loading of 5 wt. %, methanol/oil molar ratio of 12:1, reaction temperature 65 C, and 5% v/v relative to the amount of methanol of THF as a co-solvent; more than 97% yield of biodiesel could be achieved in 150 min by using CaO_tr. The final part, biodiesel product obtained from palm oil and WCO catalyzed by CaO_tr catalyst has high quality and meets the specified standards of biofuels for the diesel engines both of the EN-14214 and ASTM-D6751 standard testing method. Thus, the utilization of the acid treatment method for enhancement of the catalytic activity of CaO catalyst from golden apple snail shells and the applied co-solvent method for increase the performance of biodiesel production was a process with a high potential in the biodiesel production for the community scale and industrial scale