Due to excessive energy demand, there is depletion in fossil fuel reserves and an increase in the greenhouse effect and global warming, which have adverse impacts on the environment. Bio-butanol is one of the latest types of potential, economical biofuels, which has shown a promising future because of its superior properties. Bio-butanol can be produced via an acetone-butanol-ethanol (ABE) fermentation process using solventogenic Clostridium bacteria. However, the fermentative approach of butanol production leads to the inhibition of microbial activity (normally > 10 g.L-1), which affects its production. To extract butanol from the fermentation broth, there are various separation methods, such as gas stripping, liquid-liquid extraction, adsorption, membrane solvent extraction, and pervaporation which may overcome these problems. Ionic liquids can be used as extractants and could be a prospective solution to replace conventional volatile, toxic solvents. In this work, separation of butanol from an aqueous solution using an ionic liquid, tetradecyl(trihexyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (THTDP[TMPP]), oleyl alcohol (OA), and castor oil (CO) under ambient conditions (298 +/- 1 K) has been carried out. Experimental distribution coefficients (K-d) were observed to be in the order IL (2.15-26.07) > oleyl alcohol (1.55-4.84) > castor oil (1.49-3.84). The average maximum K-d value was obtained as 25.54 at 0.0695 mol.kg(-1) initial butanol feed concentration for THTDP[TMPP], whereas 96.23% of butanol separation was observed. The average minimal solvent-to-feed ratio was estimated as 0.0057, THTDP[TMPP] < 0.0705, OA < 0.094, CO, respectively. The average maximum diffusion coefficient values in extractant diluent blends (DBuOH-E-D) for butanol were found to be 2.931 x 10(11) m(2).s(-1) in THTDP[TMPP]-OA and 1.048 X 10(-11) m(2).s(-1) in THTDP[TMPP]-CO, respectively.