Tribo-electrification of pharmaceutical powder blends

Abstract

It is well known in industrial applications involving powders and granular materials that the presence of electrostatic charges influences drastically the material flowing properties. The triboelectric charges are produced during flow at the contacts between the grains and at the contacts between the grains and the container. 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. In the present study, the ability of a set of excipients and active pharmaceutical ingredients (APIs) to produce electrostatic charges during flow in contact with different materials is analyzed with a recently developed instrument called GranuCharge. While different excipients have almost the same triboelectric behavior and a low chargability, APIs show complex triboelectric properties. Some APIs charge a lot while other APIs charge less. Afterward, the electrostatic behavior of API/ excipient blends is considered. We show that the net charge of the blend is a complex function of the relative quantity of API in the mixture. Moreover, both the quantity and the sign of the charge are found to depend on the material in contact with the powder during the flow.

Loss-in-weight feeding, powder flow and electrostatic evaluation for direct compression hydroxypropyl methylcellulose (HPMC) to support continuous manufacturing

“…The equipment consists of a 700 mm long, 47 mm diameter V-shaped tube made of 316 L stainless steel where the powders acquire a charge when flowing through the tube. The V-tube geometry combines the different mechanisms leading to tribo-electrification: (i) friction between the grains, (ii) friction between the grains and the wall, and (iii) impact of the grains on the wall at the connection between the two tubes where the powder changes direction (Rescaglio et al, 2019). Approximately 50 ml of the powder was weighed in a glass beaker and grounded to dissipate any charge.…”

“…Particle triboelectric charging (electrostatics) is a physical effect frequently ignored but can occur with pharmaceutical powders and APIs (Rescaglio et al, 2019;Š upuk et al, 2012;Wong et al, 2015). Factors which influence powder charging can be: type of surface material, contact area, surface roughness, surface cleanliness, chemical structure, absorbed moisture, particle size distribution, shape, roughness, crystallinity and surface area.…”

“…Factors which influence powder charging can be: type of surface material, contact area, surface roughness, surface cleanliness, chemical structure, absorbed moisture, particle size distribution, shape, roughness, crystallinity and surface area. Even environmental conditions such as contact time, temperature, and relative humidity can influence triboelectric charging (Mukherjee et al, 2016;Naik et al, 2016b;Rescaglio et al, 2019;Wong et al, 2015). Whenever particles are in contact amongst themselves or processing equipment, there is potential for charging to occur.…”

Applications of Artificial Intelligence and Machine Learning Algorithms to Crystallization

“…115 The optimal formulation estimate that complies with a set of requirements of other selected properties and save excipients can be obtained using numerous ML techniques, as comprehensibly reviewed recently by Gao et al 114 and Yang et al 262 Powder flow behavior, for example, is a key factor to assess the potential for the manufacturability of oral solid dosage forms in drug development (e.g., tablet), 263 which is attractive due to its fewer unit operations involved in the production and its convenience for the patient. 264 Flowability is a problematic property to measure and predict, especially in the context of small particle sizes and uncontrolled shape distributions, 263 electrostatic forces, 265 and varying surface properties. 266 Predicting powder flow behavior opens possibilities to fine-tune the crystallization process with reduced risks in the feasibility of downstream processing and easier scale-up.…”

Analysis of static electricity generation and elimination in the process of food powder screw feeding

“…Choi et al (2017) found that when the moisture content of the drug powder is lower than 5 wt%, the charge‐to‐mass ratio of the powder begins to increase. Rescaglio et al (2019) study proved that the net charge of the drug mixture is a complex function of the relative amount of active pharmaceutical ingredient in the mixture, and the number and sign of the drug powder charge depend on the material in contact with the powder. Woodhead and Armour‐Chélu (2003) studied the charging characteristics of alumina particles in pipeline transportation and found that a decrease in temperature and an increase in relative humidity usually lead to a decrease in the charge level.…”