Realization for rapid extraction of citric acid from aqueous solutions using deep eutectic solvents

Citric acid is highlighted as a valuable chemical in the pharmaceutical and food industries. We present an extraction technique using hydrophobic deep eutectic solvents (HDES), which has emerged as an efficient and sustainable alternative solvent for the purification and recovery of this important compound from the production environment. HDES systems were formed by combining DL-Menthol as the hydrogen bond donor (HBD) and Tributyl Phosphate (TBP) as the hydrogen bond acceptor (HBA). HDES exhibited excellent performance as a hydrophobic medium for both physical and reactive extraction of citric acid. To demonstrate the effect of HDES composition over-extraction ability, HDESs with various DL-Menthol mole fractions (Xm) were prepared and tested. TOA molar concentration, initial citric acid concentration (CA0), and effect of temperature were also investigated as other effective parameters. The optimized HDES demonstrated remarkable extraction efficiency (E%) of over 90% using tri-n-octylamine (TOA) as the extractant, while offering rapid extraction rates within minutes. Our findings highlight the promising potential of these environmentally conscious HDES for sustainable chemical separation processes.