(267f) Influence of Triboelectric Charges on Powder Behaviour in Pharmaceutical Processes

It is well known empirically that electrostatic charges induce problems during powder processing in pharmaceutical processes. Triboelectric charges are produced during powder flow at the contacts between the grains and at the contacts between the grains and the container. The presence of electrostatic charges induces adhesion and cohesiveness leading to intermittent or blocked flow and consequently non-uniformity of dosage. This triboelectric effect is particularly problematic in the framework of continuous manufacturing. For example, material build-up on a loss-in-weight feeder barrel due to powder triboelectric charging results in strong mass flow fluctuations [1]. Moreover, active pharmaceutical ingredients (APIs) are known to be particularly efficient to produce electrostatic charges during flows [2,3].

Unfortunately, the triboelectric effect is still poorly understood, even at the fundamental level. Therefore, the approach to solve practical problems is mostly empirical. Moreover, reproducible electrostatic measurements are difficult to perform. A few years ago, a laboratory instrument (GranuCharge from GranuTools company) has been developed to measure the ability of a powder to produce electrostatic charges during a flow [3]. This instrument allows to predict potential problems induced by electrostatic charges in processes involving powders.

In this presentation, a quick review of the fundamental knowledge regarding the triboelectric effect in powders will be presented. Afterward, the effect on pharmaceutical processes will be discussed. Finally, some solutions to avoid charge build-up will be presented [4].

[1] C. Allenspach, P. Timmins, G. Lumay, J. Holman, and T. Minko, Loss-in-weight feeding, powder flow and electrostatic evaluation for direct compression hydroxypropyl methylcellulose (HPMC) to support continuous manufacturing, International Journal of Pharmaceutics 596, 120259 (2021)

[2] E. Supuk, A. Zarrebini, J. P. Reddy, H. Hughes, M. M. Leane, M. J. Tobyn, P. Timmins, and M. Ghadiri. Tribo-electrification of active pharmaceutical ingredients and excipients, Powder Technology 217, 427 (2012)

[3] A. Rescaglio, F. De Smet, L. Aerts, and G. Lumay, Tribo-electrification of pharmaceutical powder blends, Particulate Science and Technology 37, 1024-1031 (2019)

[4] G. Lumay, S. Pillitteri, M. Marck, F. Monsuur, T. Pauly, Q. Ribeyre, F. Francqui, and N. Vandewalle, Influence of mesoporous silica on powder flow and electrostatic properties on short and long term, Journal of Drug Delivery Science and Technology 53, 101192 (2019)