The extraction of gallium from chloride solutions by emulsion liquid membrane: Optimization through response surface methodology

Emulsion liquid membrane was used to extract gallium from a chloride medium. The influence of several critical parameters including, carrier concentration, surfactant concentration, the ratio of the internal phase to the membrane, agitation speed and their interactions on gallium recovery were investigated. A response surface methodology based on a Box-Behnken design was used to find out optimum conditions and determine the interaction effects of parameters. The liquid membrane including a diluent (kerosene), a surfactant (sorbitan monooleate), a carrier (tri-isobutyl phosphate), and 0.1 M sulfuric acid as the stripping solution was used. Maximum gallium recovery (94.6%) were obtained at the carrier concentration of 5.8% (v/v), the surfactant concentration of 3.2% (v/v), the ratio of the internal phase to the membrane of 1.1 and the agitation speed of 245 rpm. The gallium recovery increased with an increase in the level of the investigated parameters, and after reaching the optimum conditions, it decreased. A predictive model was proposed to predict the gallium recovery from the chloride solution by emulsion liquid membrane. The results indicated that the gallium can be effectively recovered from the chloride solution using emulsion liquid membrane with tri-butyl phosphate (TBP) as a carrier.