Investigation the effect of super hydrophobic titania nanoparticles on the mass transfer performance of single drop liquid-liquid extraction process

Hydrophobic titania nanoparticles were synthesized by a novel in situ sol-gel method and applied in a single drop liquid-liquid extraction column to enhance the overall dispersed-phase mass transfer coefficient (Kod). The chemical system of toluene, acetic acid and water was used, and the direction of solute (acetic acid) mass transfer was from dispersed phase, including: toluene and acetic acid to the continuous phase of water. For such system, much of the mass transfer resistance exists in the dispersed phase, which is nonpolar organic liquid. Hence, modified titania nanoparticles (MTNP's), prepared by sol-gel route, in five different concentrations of 0.001-0.005 wt.% were added in the dispersed phase. Also, the impact of MTNP's at the different solute concentrations and nozzles was investigated. Results indicated an anomalous enhancement in the overall dispersed-phase mass transfer coefficient at 0.002 wt.% of MTNP's. A maximum enhancement of 70% in the overall mass transfer coefficient was found in droplets formed from a nozzle of 2.5 mm inner diameter, containing 3 wt.% of solute. Eventually, based on the theoretical model of Newman, a semi-empirical model was presented, that is capable to predict the overall dispersed-phase mass transfer coefficient of nanofluids with an average absolute relative error of 8.6%.