The measurement of the sink properties of triethanolamine (TEA) as a coating for collecting NO2 by using annular diffusion denuders

Experimental Research on NO2 Viscosity and Absorption for (1-Ethyl-3-methylimidazolium Trifluoroacetate + Triethanolamine) Binary Mixtures

The viscosity (9.34–405.92 mPa·s) and absorption capacity (0.4394–1.0562 g·g⁻¹) of (1-ethyl-3-methylidazolium trifluoroacetate + triethanolamine) binary blends atmospheric pressure in the temperature range of 303.15–343.15 K and at different mole fractions of [EMIM] [TFA] have been carried out. The molar fraction of [EMIM] [TFA] dependence of the viscosity and absorption capacity was demonstrated. The addition of a small amount of [EMIM] [TFA] into TEA led to rapidly decreased rates of binary blends’ viscosity and absorption capacity. However, the viscosity and absorption of binary blends did not decrease significantly when [EMIM] [TFA] was increased to a specific value. Compared with the molar fraction of the solution, the temperature had no obvious effect on viscosity and absorption capacity. By modeling and optimizing the ratio of viscosity and absorption capacity of ([EMIM] [TFA] + TEA), it is proven that when the mole fraction of [EMIM] [TFA] is 0.58, ([EMIM] [TFA] + TEA) has the best viscosity and absorption capacity at the same time. In addition, at 303.15 K, ([EMIM] [TFA] + TEA) was absorbed and desorbed six times, the absorption slightly decreased, and the desorption increased.

A physicochemical model of sorption processes in NO2 passive sampling with air humidity effects

Aqueous triethanolamine (TEA) solutions are widely used as sorption medium for passive sampling of ambient NO(2), with NO(2) trapped and accumulated as nitrite ion. The results of test measurements of ambient NO(2) concentrations using passive sampling method showed that the simple approach commonly used to describe passive sampling process might lead to substantial systematic errors. Presented in the article is a new physicochemical model of the process of passive sampling of gaseous NO(2), with aqueous TEA solution used as a trapping medium. The model is based on the available results of experimental studies of interaction of gaseous NO(2) with TEA/water solutions. The key principles underlying the model are: (1) when absorbed by a trapping solution, NO(2) forms nitrite ion only on the condition that TEA is hydrated; (2) coefficient of conversion of NO(2) to NO(2)(-) is equal to one when reacting with hydrated TEA; and (3) the fraction of hydrated TEA molecules depends on air humidity at the moment of measurement. Validation of the model was made using the data of the field measurements carried out in the Middle Urals in 2007-2009. The new model was used to calculate average NO(2) concentrations. Concentrations calculated agreed well with the results obtained by reference methods. The difference between the datasets was statistically insignificant.