LAUSR

Abstract The water and soil pollution by pharmaceutical residues is considered one of the major environmental concerns. Most conventional methods adopted for the removal of pharmaceutical wastes are associated with high consumption of energy, time and use of volatile organic solvents. With the focus to propose economically viable and environmentally benign extraction systems, liquid-liquid extraction (LLE) approach was used to remove pharmaceutical pollutants. Aqueous biphasic systems (ABS) that are a category of LLE proved to be competent techniques for extraction of compounds of pharmaceutical interest. In this context, we proposed ABS based on monocationic and dicationic ionic liquids (MILs and DILs) and scrutinized for their ability to extract model non-steroidal anti-inflammatory drug i.e., diclofenac sodium. To date, active research has been carried out on ABS formed by MILs and the DILs ability to form phases remains unexplored. In this work, we synthesized imidazolium, pyrrolidinium, morpholinium and ammonium-based MILs and corresponding DILs with bromide as common anion. The ability of synthesized ILs to undergo phase separation was explored in combination with various potassium salts such as K3PO4, K2HPO4 and K2CO3 at 298.15 K and atmospheric pressure. The phase behavior of proposed ABS was analyzed with the aid of phase diagrams, binodal curves and tie-lines of selected ternary systems composed of ILs, potassium salts and water. The systematic comparison of phase formation by MILs and DILs has been carried out. Further, the extraction capability of the designed ABS was evaluated for diclofenac sodium by using UV–visible spectroscopy. The proposed MILs and DIL based ABS showed appreciable ability to undergo phase formation as well as to extract the pharmaceutical compound of interest.