AUTHOR=Landauer Johann , Tauwald Sandra Melina , Foerst Petra 

TITLE=A Simple μ-PTV Setup to Estimate Single-Particle Charge of Triboelectrically Charged Particles

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 7 - 2019

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00323

DOI=10.3389/fchem.2019.00323

ISSN=2296-2646

ABSTRACT=Triboelectric separation is a useful phenomenon that can be used to separate fine powders. To design technical devices or evaluate the potential of powders to be triboelectrically separated, knowledge about the charge distribution on a single-particle level has to be obtained. To measure the single-particle charge distribution in an application-oriented way, a simple $\mu$-PTV system was developed. The designed setup consists of a dispersing and charging unit using a Venturi nozzle and a tube, respectively, followed by a separation chamber. In the separation chamber, a homogenous electrical field leads to a deflection of the according their individual charge. The path lines of the particles are captured on single frames using microscope optics and a high-speed camera with a defined exposure time. The particles are illuminated using a laser beam combined with a cylindrical lens. The captured pictures enable simultaneous measurement of positively and negatively charged particles. Initial experiments were carried out using starches of different botanical origins and protein powder. Single-component experiments with starch powders show completely different charge distributions for positively and negatively charged particles, whereas protein powder shows bipolar charging. Different starch-protein mixtures each show similar patterns for positive and negative charge distributions.