Use of a COAX-DBD Plasma Fluidized-Bed Reactor for Surface Modification of TiO2 and Potato-Starch Powders

The interest of studying the plasma treatment of small particles such as powders or granules has increased over the years. Organic-and inorganic-treated powders have several industrial applications, and their surface modification allows obtaining different desirable properties. A plasma fluidized-bed reactor was constructed and tested to assess the atmospheric plasma surface treatment of powders. Among all type of powders, there is a growing interest in studying the surface treatment of type-C and type-A powders in the Geldart scale. The surface modification of powder in this reactor is achieved when small particles are exposed to a coaxial-dielectric barrier discharge (COAX-DBD). The results include the analysis of two types of powders (organic and inorganic) treated by three atmospheric plasma sources. For the organic powder (potato starch, type A), calorimetry and rheological tests were performed to assess changes in the rheological behavior and thermal properties as a consequence of plasma exposure. For the inorganic powder (titanium dioxide, type C), changes in the settling time before and after plasma treatments were measured using a turbidimeter to detect modifications in the powder surface. The dielectric barrier plasma discharge was generated by the COAX-DBD at 12 kV(pp) and 25 kHz obtained by a radio frequency power supply. The results show that treatments with plasma reactor modified the properties in both powder types.