Experimental density and volumetric properties of DESs based on tetrabutylammonium bromide and used for effective extraction of naphthol green B and malachite green

BACKGROUND To improve the quality of wastewater and thereby to meet the standards as per environmental production agency in US and UK. In the present work, Malachite green (MG) and Naphthol Green B (NGB) has been taken as model dyes in wastewater. Solvent extraction process was carried out using deep eutectic solvents (DESs) as an alternative solvent for organic and ionic liquids. RESULTS The possible molecular interaction between DESs and selective dyes in water were analyzed and discussed in details using volumetric properties including excess molar volume VmE, partial molar volume Vi¯, excess partial molar volume V¯iE, apparent molar volume V∅i, isobaric thermal expansion (α) and excess isobaric thermal expansion (αE). Further, the extraction of selective dyes was conducted and characterized in terms of extraction efficiency (η), effect of temperature on extraction efficiency, effect of shaking time on extraction efficiency, effect of concentration on extraction efficiency, effect of HBD on extraction efficiency, distribution coefficient (D). Finally, the thermodynamic extraction feasibility was analysed by means of Gibbs free energy ΔGT0, change in enthalpy ΔHT0, and change in entropy ΔST0. CONCLUSION There is possible molecular interaction between hydrophilic DESs and NGB/MG in water at molecular level. 96% of extraction efficiency was obtained for NGB using hydrophobic DESs like {[TBAB][DA]} and {[TBAB][OA]} whereas {[TBAB][DA]} and {[TBAB][OA]} gave above 72% removal efficiency of MG. Finally the thermodynamic feasibility of extraction process was analyzed and discussed. © 2023 Society of Chemical Industry (SCI).