Abstract: The forward initial extraction rate of gallium(Ⅲ) with HDEHP has been measured by means of growing drop method at 298±1 K.The experimental results indicate that the rate-determining step of the extraction process is controlled by interfacial reactions Ga³⁺+A_i^-=GaA_i²⁺ GaA_i²⁺+A_i^-=GaA_2i⁺ The addition of anionic surfactant(SDS,ABS) has no effect on the distribution ratio,but decreases the forward initial rate of extraction.Firstly,it is caused by the competitive adsorption of HDEHP,SDS and ABS on the interface.Secondly,surfactants bring about close molecular arrangement in the interfacial membrane and the thickening of membrane,producing greater mass transport resistance than in the absence of surfactants.

Key words: HDEHP, extraction kinetics, gallium, interface