A novel CaO-based catalyst obtained from silver croaker (Plagioscion squamosissimus) stone for biodiesel synthesis: Waste valorization and process optimization

A new catalyst was synthesized from the South American Silver Croaker's stone - the Silver Croaker is a fish widely consumed in Brazil and the stone is a residue from the fish's head. The stone and the biobased catalyst obtained from it were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray fluorescence, thermogravimetric analysis, surface area, and soluble alkalinity. It was confirmed that the stone is composed of aragonite (calcium carbonate) and the catalyst obtained by calcination of calcium oxide (CaO). The catalytic activity was evaluated by transesterification reactions. The process was optimized by surface response methodology based on Box e Behnken design. Methanol:oil molar ratio of 11.8, 5.33 wt% of catalyst, 175 min of reaction time, and 67.85 degrees C were identified as optimal conditions, reaching conversions close to 99% and ester content of 97.4%. The catalyst derived from silver croaker stone was reused 5 times while maintaining its high performance. Thus, a new application was given to this little-known waste, showing its potential as a catalyst in the synthesis of biodiesel. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The new catalyst synthesized from the South American Silver Croaker's stone showed high performance in esterification reactions and could be reused multiple times, demonstrating its potential application in biodiesel synthesis. These findings highlight the promising prospects of utilizing waste materials for catalytic purposes.