Evaluation of alginate hydrogel stabilized Pickering emulsion liquid membrane for methylene blue extraction from aqueous solutions

Abstract

In this work, the potential of an alginate hydrogel stabilized Pickering emulsion liquid membrane (PELM) for methylene blue (MB) extraction from aqueous solution was investigated. The waste cooking oil (WCO) was used as a green diluent, aliquat 336 was used as a carrier, and potassium hydroxide (KOH) was used as a stripping agent to synthesize PELM. The use of WCO replaces the hazardous and ecologically harmful petroleum-based organic solvents that are frequently employed in PELM production. The MB removal was maximum at internal phase concentration 1:5, initial external feed phase concentration 5 ppm, emulsifier concentration 1% (w/w), carrier concentration 20% (w/w) and O/A ratio 1:1. The mechanism of MB extraction by PELM was elucidated. The maximum extraction efficiency was 91.58% at optimum condition. The kinetic study revealed that the MB extraction by PELM followed a zero-order reaction. Furthermore, thermodynamic analysis indicated that the extraction process was both endothermic and spontaneous in nature. Overall, the findings of this study demonstrate the potential of PELM as a promising technique for the extraction of MB from aqueous solutions using alginate hydrogel as an eco-friendly and sustainable materials.