Extractive separation of salicylic acid using natural and conventional solvents

Abstract Separation of salicylic acid (SA) from aqueous streams was studied by using the conventional organic solvents and environmentally benign vegetable oils. Aqueous solutions of SA in the concentration range of the 0.008–0.016 mol/L was mixed with equal volumes of selected solvents, and extraction performance for SA was evaluated in terms of distribution coefficient ( K DSA ), extraction efficiency ( η %), partition coefficient ( P ), and dimerization constant ( D ). The obtained results demonstrate a very strong dependence of extraction behaviour on the physicochemical properties of the used solvents. The 1‐octanol shows the maximum extraction efficiency among the different solvents used, with average K DSA values of 2.488 and average η % of 71.23%, while the aromatic solvents such as benzene and toluene showed the significantly lower efficiencies due to weak solute–solvent interactions. In vegetable oils the sesame oil shown the good performance compared to the corn oil by achieving the extraction efficiency of ~35%, which is notably higher than that of aromatic solvents. This behaviour is generally attributed to presence of the functional groups capable of hydrogen bonding with SA. The overall extraction efficiency followed the order: benzene < toluene < corn oil < sesame oil