The effects of mass transfer direction and nanoparticles on static and dynamic holdup of dispersed phase in a pulsed-sieve column were studied, the objective being to assess holdup as the main determining factor in designing a liquid-liquid extraction column in the presence of nanoparticles. Hydrophobic SiO2 nanoparticles with a volume percent of 0.05 were dissolved homogenously in kerosene ultrasonically, and the mass transfer of acetic acid from the continuous phase (water) to the dispersed phase (kerosene) was investigated. The results of the experiment were compared to those obtained from other tests in the absence of nanoparticles in the dispersed phase and in the absence of both nanoparticles and mass transfer, under various pulses and flow rates. Results indicate that the presence of nanoparticles increased dynamic holdup by up to 70% while at the same time decreasing static holdup under flow rates higher than 70 cc/min and pulse strengths higher than 2.2 cm/s. In addition, static holdup increased along the column in the presence of nanoparticles and was intensified under higher pulses. Hydrodynamic parameters showed undesirable variations when compared with mass transfer from the dispersed to the continuous phase, which decreased the efficiency of the column.