Is Water Necessary for Contact Electrification?

Abstract

Hatte Thales Recht? Entgegen früheren Berichten kann es ohne Wasser zu einer Kontaktelektrifizierung kommen. Zugleich hilft Wasser, die entwickelten Ladungen zu stabilisieren. Wasserfreie Bedingungen wurden gewährleistet, indem alle Schritte unter Öl durchgeführt wurden.

Heterogeneity of surface potential in contact electrification under ambient conditions: A comparison of pre- and post-contact states

“…Naively, one might have expected that the glass would have uniform potential following contact, because (unlike many polymers) it is hydrophilic and likely to have adsorbed water that would allow ions to migrate. Adsorbed water from humidity plays a role in the magnitude of the contact charge density and the resistivity [31,32], but apparently it does not lead to charge uniformity. By contrast, the gold electrodes in our experiment showed little charge heterogeneity, which may be a result of the high density of conduction electrons in the bulk.…”

Principal Factors of Contact Charging of Minerals for a Successful Triboelectrostatic Separation Process – a Review

“…Charging parameters which influence the type of contact, contact stress, number of contacts, value of exchange charge: Feeding rate (throughput) [24] Material of the charger walls and its electric properties [51,58,72] Type of charger unit and its parameters (e.g. travel speed of the belt, vibration frequency of the plate charger) [29] Time between charging and separation [49,57] Separation parameters which influence the forces in the system: Type of electrode (rotating, plate [24] Magnitude of electric field and distance between the electrodes [52] Isolation/modification of electrodes [32] Actions before separation which influence the charging behavior: Storing, milling, transporting (precharging, contamination, aging) [78] Conditioning chamber (heating, drying, introduction of chemicals on the mineral surfaces) [104] Parameters which change charging behavior of particles: Humidity [29,47] Atmosphere [114] Temperature [47,48,58] Light…”

“…Long-term decay of charged insulators: A comparison of the temporal decay of contact charge on a polymer surface in humid air (relative humidity 40 % r.H.) and in water-free environment (in paraffin oil) [114] showed that the decay kinetics is of first-order, and that the corresponding charge decay rates vary with environmental conditions (10 -3 s -1 and 10 -2 s -1 in air and oil, respectively). This suggests that the charge decay is associated with a different stability of the introduced charges under humid air and paraffin oil.…”

A combined experimental and numerical approach to explore tribocharging of pharmaceutical excipients in a hopper chute assembly

“…However, recent theories suggest that for some insulators, the charge carriers are ions, which exist on polymer surface due to preferential adsorption of hydroxide ions from atmosphere (McCarty and Whitesides, 2008). Thus, tribocharging can be considered as a combination of these aforementioned processes and particularly for non-electrolytes, electrons can be considered as the main charge transfer carriers (Karner and Urbanetz, 2011;Baytekin et al, 2011). Considering these factors, this paper focuses on electron exchange mechanism for tribocharging of insulators and hence estimates the work function of all surfaces.…”