Removal of methyl orange from aqueous solution by EA/Triton-X100/EG/water green nanoemulsions

Abstract

In the present study, attempts were made to develop green nanoemulsions for the removal of methyl orange (MO) from its bulk aqueous solution. Different nanoemulsions were prepared by low-energy emulsification method using ethyl acetate (EA) (oil phase), Triton-X100 (surfactant), ethylene glycol (EG) (cosurfactant), and deionized water (aqueous phase). Prepared nanoemulsions were characterized for thermodynamic stability, self-nanoemulsification efficiency, droplet size, polydispersity, viscosity, refractive index, and transmittance. Adsorption studies were carried out at different contact time (10, 15, and 20 min) by mixing small amounts of nanoemulsions with relatively large amounts of MO aqueous solution. The influence of contact time and EA concentration on droplet size, viscosity, and % MO removal was also studied. The droplet size, viscosity, and % MO removal efficiency were significantly influenced by EA concentration. Based on the lowest droplet size (18.6 nm), lowest viscosity (16.2 cp), and highest % MO removal efficiency (81.6%), the nanoemulsion G1 (containing 5% w/w of EA, 23.3% w/w of Triton-X100, 11.7% w/w of EG, and 60% w/w of water) was optimized as the best formulation for the removal of MO from aqueous solution after 20 min of contact time. These results indicated that the prepared nanoemulsions could be used as potential liquid-based adsorbents for the removal of MO from aqueous solution.