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a b s t r ac tThis work is an experimental study on the extraction of Cr(VI) ions from aqueous acidic solutions using a flat sheet supported liquid membrane. Sunflower oil used as alternative solvent due to the stricter environmental regulations. Aliquat 336 and NaOH solution were employed as carrier and stripping agent. A hydrophobic microporous polytetrafluoroethylene (PTFE) support was impregnated with liquid membrane consist of solvent and carrier. The Cr(VI) pass through the supported liquid membrane from aqueous feed phase to the stripping phase by means of diffusion. Hydrochloric acid (HCl) was used to regulate the feed phase pH. The efficiency of the extraction was optimized as a function of the various parameters: Feed pH, stripping phase (NaOH) concentration, feed concentration, and carrier concentration. The maximum separation of Cr(VI) was about 95.2% in 10 h. Also, the results of experiments were compared with other organic solvents such as kerosene, n-octanol, dodecane, and tetrahydrofurane (THF) to evaluate the efficiency of sunflower oil. Results indicated that Cr(VI) extraction is on average about 0.5%-55% higher with sunflower oil. The optimum conditions were achieved as: pH = 2, NaOH = 0.1 M, feed concentration = 25 ppm, and Aliquat 336 = 35% v/v. The results indicate that the Cr(VI) ions can be efficiently transported through the SLM by using Aliquat 336 dissolved in sunflower oil as a green solvent.