Green Extraction of Volatile Fatty Acids from Fermented Wastewater Using Hydrophobic Deep Eutectic Solvents

Ahmad S Darwish,Samah E E Warrag,Inas Alnashef,Tarek Lemaoui,Farah Abu Hatab,Ramis Rafay,Maha K Alseiari,Jorge Rodríguez,Nahla Alamoodi

doi:10.3390/fermentation7040226

Abstract

Volatile fatty acids (VFAs) are carboxylic acids mainly produced via the fermentation of organic waste streams. Being industrial platform chemicals, sustainable, green and economical recovery of VFAs is necessary. Herein, hydrophobic deep eutectic solvents (HDES), “a new generation of water-immiscible designer solvents”, were assessed for the recovery of VFAs via liquid–liquid extraction. The eutectic mixture of menthol-lauric acid exhibited the highest stability and hydrophobicity. The binary solubility of the pairs {VFA in water} and {VFA in HDES}—and the saturation of the HDES with water were measured. Furthermore, the influences of key parameters on the extraction efficiency were investigated. On multi-stage extraction, an efficiency of 88% was achieved in 4 stages, and the HDES was successfully regenerated using vacuum evaporation. The HDES performance was also compared to other reported relevant solvents. It was concluded that menthol-lauric acid HDES is a promising candidate for the green extraction of VFAs from fermented wastewater.

Highlights

The hydrophobic deep eutectic solvents (HDES) were stored in wellsealed glass bottles at room temperature for 1 week to assess their stability through phase
After a week of storage, the Tetraoctylammonium bromide (TOABr):OctAc of theseaaspects are important for the integrity of the deep eutectic solvents (DESs) had sincepartially minimum loss formed precipitate, while TOABr:DecAc and TOABr:LaAc andsolvent completely means minimum water contamination ascould well asbethe ability toto reuse solvent and of solidified, respectively (Figure 1)
This attributed the the limited ability the minimumacid amount the required solvent in the extraction process, if the solvent is predecanoic and of lauric acid to form hydrogen bonds with the tetraoctylammonium served during process

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Sustainability and green engineering principles have been the ground for scientific research. They are considered the main routes for a successful economy with fewer environmental penalties. The production of platform chemicals such as volatile fatty acids (VFAs) via bio-based processes is a hot topic in the area of sustainable and “green” research. VFAs are precursors for the production of a wide range of daily life needs such as bio-plastics, food, pharmaceuticals, cosmetics, textiles, and bio-energy to name a few. The development of sustainable, environmentally friendly, and economically viable bio-based processes for the production and recovery of VFAs is highly demanded

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