Studies on extraction of gallium (III) from chloride solution using Cyphos IL 104 and its removal from photodiodes and red mud

An efficient solvent extraction process was developed for extraction of gallium (III) from acidic chloride medium using the ionic liquid Cyphos IL 104 diluted with toluene. The kinetics of gallium extraction was very fast. The extraction percent of gallium was found to increase with increase in hydrochloric acid concentration in the feed and 99.8% extraction of gallium was achieved with 3 M HCl. The stoichiometry of the formation of gallium-Cyphos IL 104 complex was found to be 1:1 and the corresponding extracted species was proposed as [R3R′PGaCl4]. Presence of sodium chloride increased the percentage extraction of gallium. The thermodynamic parameters calculated from the temperature variation study suggested the process was spontaneous and endothermic. Loading capacity of the ionic liquid was executed and the stripping study of the loaded organic phase was investigated using four stripping agents namely HCl, H2SO4, NH3 and HNO3 each having concentrations of 0.5 mol/L. It was found that HCl performance was poor and the rest three could recover > 90% gallium from the loaded organic phase. Binary separation studies were carried out using commonly associated metal ions with gallium (Al (III)/Zn (II)/Fe (III)/Cu (II)/Ni (II)) and the process was extended to study the recovery of gallium from leach liquors of photodiodes and red mud sample.