Enhanced fluidization of nanosized TiO₂ by a microjet and vibration assisted (MVA) method

A microjet and vibration assisted (MVA) fluidized bed was developed to enhance the fluidization quality of nanosized TiO₂ particles. Two commercially available TiO₂ nanopowders, P25 and P90, were tested. Fluidization quality was assessed by determining the non-dimensional bed height as well as the non-dimensional pressure drop. Smooth fluidization of the TiO₂ nanopowders was observed in the MVA system. The non-dimensional bed height for the nanosized TiO₂ in the MVA system optimized at about 5 and 7 for P25 and P90 TiO₂, respectively, at a resonance frequency of 50 Hz. The non-dimensional pressure drop was also determined and showed that the MVA system exhibited a lower minimum fluidization velocity for both of the TiO₂ types as compared to fluidization that employed only vibration assistance. Additional experiments were conducted with the MVA to characterize the synergistic effects of vibrational intensity and gas velocity on the P25 and P90 fluidized bed heights. Mathematical relationships were developed to correlate vibrational intensity, gas velocity, and fluidized bed height in the MVA. To test the mathematical model, 18 additional experimental points were gathered for both P25 and P90 under varying conditions. The actual and model-predicted non-dimensional bed heights were found to correlate well, with less than 14% error between values. The non-dimensional bed height in the MVA system is comparable to previously published P25 TiO₂ microjet assisted (MA) fluidization employed with the addition of an alcohol that was used to minimize electrostatic attraction within the system. However, the MVA system achieved similar results without the addition of a chemical, thereby expanding the potential chemical reaction engineering and environmental remediation opportunities for fluidized nanoparticle systems. Fluidized bed stability was greatly improved when the dual effects of vibration and microjet assistance were used.