Methodology for studying particle-particle triboelectrification in granular materials

A critical challenge for experimental studies of triboelectric charging is to generate reproducible and unambiguous data that can be linked to theoretical concepts. We have developed a methodology to investigate the triboelectric charging of granular materials due solely to particle-particle interactions (i.e. no particle-wall interactions). The methodology is based on a particle flow apparatus that generates a fountain-like flow in which the particles contact only other particles, but no equipment surfaces. Non-contact methods of measuring charge and separating particles by charge are employed so that probe-particle charging does not occur.