Valorization of citrus waste using reactive distillation for sustainable biodiesel production

Abstract

Except for orange juice, the remainder is major waste created during orange processing. Indeed, this residue is an issue in the citrus business since its chemical makeup is more complex than other agro-industrial wastes like peels and seeds. Orange peels conceal within them valuable resources in the form of wax and aromatic oil, comprising a mixture of hydrocarbons and other chemical compounds. While in India, orange peels are typically perceived as domestic waste or consigned to landfills, they possess a rich history of traditional applications in medicine and insect repellent. This study aims to produce biodiesel from orange peel oil via trans-eterification process in reactive distillation transforming waste into wealth. Experimental outcomes demonstrate that revamping the reboiler duty and reflux ratio within specified ranges achieves the highest purity level of 96 %, corresponding to a reboiler duty of 6824.28 BTU/hr and a reflux ratio of 4.

Reactive distillation being highly complex and non linear in nature, a time varying control study is must. In view of this, dynamic simulations is performed that reveal at methanol flow rate of 0.07 liters per minute, a reboiler duty of 6810 BTU/hr can be retained corresponding to highest purity level. Characterization of the B20 biodiesel from orange oil (comprising 20.00 % biodiesel and 80.00 % diesel) showcases its suitability, with a basic pH of 7.6, a density of 872 kg/m³, a viscosity of 2 cSt, and a flash point of 180 °C.

Economic Analysis is another important aspect of any research. Comparison between the two production processes were made in terms of the economic indicators such as Return-On-Investment (ROI) and payback period. The simulation results show that the reactive distillation catalyzed is more economically advantageous than the conventional process for biodiesel synthesis due to a much higher ROI, and lower payback period.