Vaporization and Conversion of Ethanolamines used in Metalworking Operations

Abstract

ObjectivesThis study examined how ethanolamines (EAs) with the same functional alcohol group (HOCH2CH2), such as mono-EA (MEA), di-EA (DEA), and tri-EA (TEA), in water-based metalworking fluids (wbMWFs) are vaporized, condensed, and transformed by heat generated during metalworking.MethodsTwo types of experimental apparatus were manufactured to achieve these objectives.ResultsVaporization tests using a water bath showed that the vaporization rate increased markedly from 0.19 mg/m2·min at 23.5℃ to 8.04 mg/m2·min at 60℃. Chamber tests with a heat bulb revealed that "spiked" MEA was fully recovered, while only 13.32% of DEA and no TEA were recovered. Interestingly, non-spiked types of EAs were detected, indicating that heat could convert EAs with more alcohol groups (TEA or DEA) into other EAs with fewer group(s) (DEA or MEA). The EA composition in fresh fluid was 4% DEA, 66% TEA, and 30% MEA, and in used fluids (n = 5) was 12.4% DEA, 68% TEA, and 23% MEA. Conversion from TEA into DEA may therefore contribute to the DEA increment. Airborne TEA was not detected in 13 samples taken from the central coolant system and near a conveyor belt where no machining work was performed. The DEA concentration was 0.45 mg/m3 in the only two samples from those locations. In contrast, airborne MEA was found in all samples (n = 53) regardless of the operation type.ConclusionMEAs easily evaporated even when MWFs were applied, cleaned, refilled, and when they were in fluid storage tanks without any metalworking being performed. The conversion of TEA to DEA and MEA was found in the machining operations.

Magneto‐hydrodynamic mixing: A new technique for preparing carbomer hydrogels

“…The former readily evaporates at temperatures exceeding 23.5 °C. 36 The latter is unstable and tautomerizes into acetaldehyde (eq. 2), 36 which is easily converted to ethanol via a radical based reaction mechanism (eq.…”

“…36 The latter is unstable and tautomerizes into acetaldehyde (eq. 2), 36 which is easily converted to ethanol via a radical based reaction mechanism (eq. 3), as previously observed for gamma radiolysis of N,N-diethylhydroxylamine.…”

Relationships among Fluid Ethanolamine Formulation, Airborne Ethanolamines, and Aerosol Levels in Machining Operations

“…MEA can vaporize into the air regardless of the machining operation type, whereas no vaporization of either DEA or TEA was detected in operations without metalworking. We have previously reported that, of all the EA, only MEA was found to evaporate even at 23.5°C, and that MEA evaporation increases along with increasing temperature, without condensation (Kim et al, 2010). These results demonstrate that airborne MEA can arise through the process of vaporization from sumps or tanks, where fluids are simply stored and circulated.…”

“…These results demonstrate that airborne MEA can arise through the process of vaporization from sumps or tanks, where fluids are simply stored and circulated. Therefore, engineers who handle fluids containing MEA in areas without metalworking operations can still be exposed to substantial levels of airborne MEA (Kim et al, 2010).…”

“…To date, there have been no studies examining how EA are generated and vaporize into the air during metalworking operations, including machining and grinding operations at the workplace field. We previously reported that in laboratory experiments MEA may vaporize even at 23.5°C, and that no other EA (i.e., DEA or TEA) vaporize at less than 60°C (Kim et al, 2010).…”