10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

Abstract View


Dry Dispersion of Cohesive Powders for Continuous Aerosol Generation in the Sub-micron Size Range

Lekhnath Pokharel, Prashant Parajuli, Li Li, Ewe Jiun Chng, RANGANATHAN GOPALAKRISHNAN, The University of Memphis

     Abstract Number: 869
     Working Group: Instrumentation

Abstract
The dispersion of dry, cohesive micro and nano sized bulk powders has wide applications ranging from medical and environmental science to manufacturing technology. Being able to disperse the dry powder at a stable concentration over periods of time (~hr to several hours) of time is more challenging to achieve, which we attempt to address with a novel dry powder dispersion technology. A portable, cost effective and simple dry powder dispersion device for continuous aerosol production is developed and tested with commercially available powders. Various size of nominal powder sizes ranging from 5 microns, 500 nm, 100 nm and 30 nm (denoting the primary particle size) are considered in this study, to show that the process works for wide range of powder sizes with consistency as well as stability in concentration over time. The study is performed for 5 μm polyamide powder and rutile TiO2 powders of 500nm, 100nm and 30 nm mean size of primary particles. The device proved to be able to disperse all of these powders, which represent low density material to high density metal oxides, with highly stable and tunable concentration over extended periods. From aerosol measurements to obtain the size distribution of various size particles, it is seen that the the the highly agglomerated powder particles are not easy to de-agglomerate as we go to the lower sized powders because of the stronger inter-particle adhesion forces between nanoparticles compared to microparticles. The SEM images of particles in their native powder state and those collected after the dispersion showed significant difference in the agglomeration of the powder particles, which suggests partial success of the turbulent jet de-agglomeration we have employed for breaking up. We have also tried made improvements based on our findings for to increase the efficiency of dispersion, de-agglomeration and reliability of the device for its commercial use.