Process Optimization of Biodiesel Production Using Waste Snail Shell as a Highly Active Nanocatalyst

In this work, we reported the transesterification of soybean oil (SO) to biodiesel using a basic CaO nanocatalyst produced by sequential calcination, hydration, and dehydration of waste snail shells. Response-surface methodology (RSM) and a central composite design (CCD) were used to predict several optimization parameters. 1H-NMR confirmed that 98.5% of the SO was transformed into methyl ester biodiesel. Under the optimal reaction parameters of catalyst loading of 6 wt. %, methanol to oil molar ratio of 8 : 1, reaction duration of 3 h, and temperature of 70 degrees C, an excellent biodiesel yield of 96.1% was obtained. The transesterification of SO to biodiesel displayed a significantly low activation energy (30.45 kJ mol-1), whereas, the turnover frequency of the transesterification reaction was found to be 0.0063 mol g-1 h-1. The catalyst showed excellent stability and was consecutively used for six cycles without a significant decline in catalytic activity. Based on life cycle cost analysis (LCCA), the estimated cost for producing 1 kg of biodiesel in this study comes out to be just $0.935, signifying its strong potential for widespread commercial use.

Automated summary

In this study, a basic CaO nanocatalyst derived from waste snail shells was used for the transesterification of soybean oil to biodiesel. Under optimized reaction conditions, a high biodiesel yield of 96.1% was achieved, with low activation energy and excellent catalytic stability. Life cycle cost analysis showed that the cost of producing biodiesel using this method is very low, indicating its strong potential for commercialization.