Comparative Experimental Study of Natural, Non-Toxic Solvents for Sustainable Gallic Acid Separation

Abstract

Gallic acid, a polyphenolic compound with strong antioxidant activity, exhibits notable anti-inflammatory, anticancer, antibacterial and antioxidant properties, making it valuable across the food, packaging, cosmetics and pharmaceutical industries. For its commercial utilization, efficient and sustainable extraction from natural sources is essential. This study investigates the feasibility of liquid–liquid extraction (LLE) for the separation of gallic acid from aqueous solutions using natural solvents. Four vegetable oils - mustard, sesame, sunflower and soybean oil - were evaluated as extractants at various gallic acid concentrations. Equilibrium data collected at 298.15 ± 1 K were used to calculate distribution coefficients (KD) and extraction efficiencies (%E). The results revealed the following average trends in KD and %E: soybean oil (0.4019, 28.69%) > sunflower oil (0.3372, 25.23%) > sesame oil (0.2982, 22.99%) > mustard oil (0.2676, 21.15%), respectively. The highest efficiency was achieved with soybean oil at 0.05 mol·L-1 gallic acid, yielding 30.40% separation. Multiple separation units in series may be applied to achieve even higher separations. These findings highlight the potential of natural solvents for environmentally safe gallic acid separation.