Separation of pentanedioic acid using polar and natural extractants

Pentanedioic acid is a straight-chain dicarboxylic acid that finds widespread use in various industrial applications. It is a key polymer precursor for producing polyols, polyesters, and polyamides. Despite this, its separation from fermentation broths and wastewater from textile and food processing industries remains challenging, as these contain pentanedioic acid in low concentrations, mixed with various organic and inorganic components, including other carboxylic acids, sugars, proteins, and salts. This makes selective separation difficult. The present work investigates the experimental study on the recovery of pentanedioic acid from aqueous solutions via liquid–liquid extraction using two polar solvents (oleyl alcohol and octanol) and two natural, non-toxic solvents (sunflower oil and soyabean oil). Based on the equilibrium data at 298.15 ± 1 K, the distribution coefficient (KD) and extraction efficiency (E%), partition coefficient (P), and dimerization constant (D) were determined. The distribution coefficient and extraction efficiencies achieved were oleyl alcohol (1.71, 63.20%), octanol (1.42, 58.07%), sunflower oil (0.60, 37.86%), and soyabean oil (0.42, 29.57%) respectively at 1.133 mol L−1. Oleyl alcohol and octanol showed superior performance in terms of pentanedioic acid recovery. The results obtained were analyzed in terms of their physicochemical characteristics, including dipole moment (Dm), dielectric constant (ε), and solvent polarity parameter (ET).