Enhancement of biodiesel production from waste cooking oil: ultrasonic- hydrodynamic combined cavitation system

ABSTRACT

Concerning the growing need for energy resources and reduction of fossil fuels, researchers seek for the use and development of biofuels. Among the biofuels, biodiesel has captured the attention of researchers since it deals with the oil cost and embraces environmental benefits. Aiming at continuous and optimal biodiesel production, the current study examines the effects of the residence time of hydrodynamic reactors, catalyst concentration, methanol-to-oil ratio, and ultrasound power on methyl esters yield. To optimize the transesterification reaction of the waste oil, the response surface method was used. Results of the study indicated that the increase of residence time results in an increase of the methyl esters yield, but following the time up to 90 s, the methyl esters yield decreases. The increase of catalyst by 1% leads to the increase of the methyl esters yield, and up to 1.25% the catalyst concentration, the methyl esters yield decreases by 7%. The increase of methanol-to-oil ratio up to 6:1 results in an increase of yield, and up to 8:1 methanol-to-oil ratio, the methyl esters yield follows an increasing trend with a slight slope. The optimal conditions in this study were 60 s residence time, 1% catalyst concentration, 6:1 methanol-to-oil ratio, and 250W ultrasound power, and that the methyl esters yield, as well as the consumed energy, were obtained 90.45% and 21.52 kJ, respectively. In conclusion, the suggested method is suitable for biodiesel production based on the methyl esters yield and energy consumption.

KEYWORDS:

• Hydrodynamic
• ultrasound
• biodiesel
• waste cooking oil
• response surface method

Acknowledgments

The authors are grateful to the Research Council of Shahrekord University is thankfully acknowledged for their financial support for conducting this study (grant No:96GRN1M1796). Also, the authors express their thankful regards for Tarbiat Modares University (http://www.modares.ac.ir) for financial supports given under IG/39705 grant for Renewable Energies of Modares research group.

Additional information

Funding

This work was supported by the Shahrekord University [96GRN1M1796];Tarbiat Modares University [IG/39705].

Notes on contributors

Mahrokh Farvardin

Mahrokh Farvardin is M.Sc students of agricultural mechanization engineering. She has worked on intensification and find the new resource of biodiesel production. The present research related to her thesis in M.Sc grade.

Bahram Hosseinzadeh Samani

Bahram Hosseinzadeh Samani is associate professor of mechanical engineering of biosystem in Shahrekord University, Iran. He was born in December of 1983. His research interests include biodiesel, biogas, and applied novel technology in the agricultural process.

Sajad Rostami

Sajad Rostami is associate professor of mechanical engineering of biosystem in Shahrekord University, Iran. His research interests include renewable energy and design and manufacturing of machine that related to agricultural operations.

Ahmad Abbaszadeh-Mayvan

Ahmad Abbaszadeh-Mayvan is assistance professor of Biosystems Engineering Department, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. His research interests include renewable energy and design and manufacturing of machine-related to agricultural operations.

Gholamhassan Najafi

Gholamhassan Najafi is associate professor of mechanical engineering of biosystem in Tarbiat Modares University, Iran.   His research interests are renewable energies and internal combustion engines (Scopus h-index = 30).

Ebrahim Fayyazi

Ebrahim Fayyazi is a re­searcher at the Renewable Energies Research Institute, Tarbiat Modares University (TMU-RERI), Tehran, Iran. He obtained his Ph.D. in mechanical and biosystems engineering from TMU in 2018. His main research area is biodiesel production using intensification methods.