Application of pharmaceutical waste as a heterogeneous catalyst for transesterification of waste cooking oil: biofuel production and its modeling using predictive tools

Abstract

In this study, for the first time, pharmaceutical waste was used as a heterogeneous catalyst to produce biofuel from waste cooking oil (WCO). An efficient and low-cost heterogeneous catalyst was prepared from waste tablets of calcium carbonate (CaCO₃) and magnesium oxide (MgO). A certain amount of alumina nanoparticles (Al₂O₃) was added to the pharmaceutical waste to participate in the transesterification of the WCO, which positively affected mass yield. The mentioned catalysts were identified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), field-emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) analyses. According to the BET analysis, the specific surface of the catalysts increased. Also, the effects of various reaction parameters such as temperature, time, catalyst loading, and the oil: methanol ratio were investigated and optimized by response surface methodology (RSM). Furthermore, an adaptive neuro-fuzzy inference system (ANFIS) was coupled with a firefly optimization algorithm to predict biofuel yield. Under optimum conditions (Al₂O₃ 0.952 wt%, catalyst 4.978wt%, oil:methanol ratio 0.5 vol:vol, reaction time 120 min, and reaction temperature 69.6 °C), the mass yield of MgO and CaO catalysts was 95.6 and 90.4 wt%, respectively. The composition of biofuel was identified using gas chromatography–mass spectrometry (GC-MS).

Keywords:

• Biofuel
• waste cooking oil
• heterogeneous catalyst
• pharmaceutical waste
• ANFIS-firefly

Acknowledgements

The authors thank the authorities of the nano-laboratory of the faculty of environment for providing us with the facilities. We are also thankful to the personnel of the faculty of science at the University of Tehran for their help in GC-MS analysis. We thank the authorities of the University of Isfahan for XRD and FT-IR measurements.

Disclosure statement

No potential conflict of interest was reported by the authors.