Optimisation of accelerated biodiesel production under near infrared radiation from de-oiled mustard and sunflower cakes

ABSTRACT

An energy-efficient intensification protocol for biodiesel (fatty acid ethyl ester (FAEE)) production from the mustard de-oiled cake (MDC) and sunflower de-oiled cake (SDC) through concurrent esterification-transesterification reactions has been disclosed employing near-infrared radiation retrofitted batch reactor. The triglycerides and free fatty acids of the de-oiled cake were converted to FAEE through a one-pot synthesis in the presence of ethanol and one of the co-solvents viz. acetone, dimethyl sulfoxide (DMSO), and n-hexane. The optimal condition (75:1 (w/w) ethanol to de-oiled cake ratio, 70°C infrared radiation temperature, 2.5 wt. % H₂SO₄ catalyst concentration, and 1000 rpm stirrer speed) for maximum FAEE yield was evaluated deploying Taguchi L9 orthogonal method. Higher FAEE yield was achieved under infrared radiation for both MDC (82.4 ± 0.01%) and SDC (81.7 ± 0.02%), in comparison with the conventionally heated reactor (MDC: 56.1 ± 0.02%; SDC: 54 ± 0.02%) employing identical process condition. This enlightened the energy-efficacy of the infrared radiation in accelerating the FAEE yield within a much shorter reaction time. The FAEE composition was assessed by FTIR and GC-MS analyses. The fuel properties of the product biodiesel conformed to EN standards. Thus, a feasible and efficient protocol for the conversion of de-oiled cakes to biodiesel could be explored.

GRAPHICAL ABSTRACT

KEYWORDS:

• De-oiled cake
• co-solvent
• biodiesel
• infrared radiation
• concurrent esterification-transesterification

Acknowledgements

The financial supports of CONVER-B (DST, Government of India), DHESTBT (ST/P/S&T/4G-2/2018; Government of West Bengal, India) and RUSA 2.0 (Ref. No. R-11/481/19) Jadavpur University, India are gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Department of Science and Technology Government of West Bengal: [Grant Number ST/P/S&T/4G-2/2018]; Department of Science and Technology, Government of India; RUSA 2.0 Jadavpur University, India: [Grant Number Ref. No. R-11/481/19].