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In this article, droplet size and its distribution along a pulsed liquid–liquid extraction column, is studied where SiO2 nanoparticles with concentrations of 0.01, 0.05 and 0.1 vol.% and different hydrophobicities are applied to the dispersed phase. Using ultrasonication, nanoparticles were dispersed in kerosene as the base fluid. Nanofluids' stability was ensured using a UV–vis spectrophotometer. Some 22,000 droplets were measured by photographic technique and results were compared with systems containing no‐nanoparticles (Water–Acetic acid–Kerosene). Addition of nanoparticles changed the droplet shape from ellipsoidal to spherical. Also, there was a marked influence on droplet breakage and droplet coalescence at 0.01 vol.%, and 0.05 vol.% or higher volume fractions, respectively. © 2012 Canadian Society for Chemical Engineering

This work focuses on the size-controlled preparation of Ni-B nanoparticles by chemical reduction of nickel acetate with sodium borohydride in the ternary reverse micelles of cetyl trimethyl ammonium bromide (CTAB)/n-hexanol/water. A response surface methodology (RSM) with four factors: CTAB/water (0.5-3.5 g/g); CTAB/n-hexanol (0.2-0.8 g/g); B/Ni molar ratio (1-4); and nickel salt concentration (0.075-0.525 mol/L) was used to study the mean size of nanoparticles. Based on the central composite design (CCD), a total of 32 experimental tests were performed to correlate both reagent concentrations (Ni 2þ and BH 4À ) and microemulsion compositions (surfactant/oil/water) to the size of to-be-obtained nanoparticles. The Ni-B nanoparticles were obtained with a narrow size distribution of average diameter in the range of 4.5-30.6 nm. The quadratic model developed explained adequately the non-linear nature of the modelled response (R 2 ¼ 0. 97, precision ¼ 33.19). Also the influence of effective variables on the mean size of Ni-B nanoparticles was examined simultaneously and discussed theoretically by using 3D-surface and 2D-contour plots. Finally optimization of CCD based on desirability function was performed. The optimal conditions were found to be at the surfactant/oil/water mass ratio of 34/55/11, nickel salt concentration of 0.24 mol/L, and B/Ni molar ratio of 2.23 with desirability factor of 0.98. Moreover, validation of the optimization showed that the model predictions were very close to the experimental results with slight errors (7-10 %). Finally, TEM micrographs of Ni-B nanoparticles at optimum conditions showed that by applying statistical experimental design in reverse micelle technique, not only particle size but also agglomeration could be effectively controlled.