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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-58
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
08 Feb 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Experimental determination of Henry's law constants of difluoromethane (HFC-32) and the salting-out effects in aqueous salt solutions relevant to seawater
Shuzo Kutsuna National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, 305-8569, Japan
Abstract. Gas-to-water equilibrium coefficients, KeqS (in M atm−1) of difluoromethane (CH2F2), a hydrofluorocarbon refrigerant (HFC-32), in aqueous salt solutions relevant to seawater were determined over a temperature (T) range from 276 to 313 K and a salinity (S) range up to 51 ‰ by means of an inert-gas stripping method. From the van't Hoff equation, the KeqS value in water, which corresponds to the Henry's law constant (KH), at 298 K was determined to be 0.064 M atm−1. The salinity dependence of KeqS (the salting-out effect), ln(KH/KeqS), did not obey the Sechenov equation but was represented by an equation involving S and S0.5. Overall, the KeqS(T) value was expressed by ln(KeqS(T)) = −49.7122 + 77.7018 × (100/T) + 19.1379 × ln(T/100) + [−0.2261 + 0.5176 × (T/100)] × S0.5 + [0.0362 − 0.1046 × (T/100)] × S. By using this equation in a lower tropospheric semi-hemisphere (30° S–90° S) of the Advanced Global Atmospheric Gases Experiment (AGAGE) 12-box model, we estimated that 1 to 5 % of the atmospheric burden of CH2F2 resided in the ocean mixed layer and that this percentage was at least 5 % in the winter; dissolution of CH2F2 in the ocean may partially influence estimates of CH2F2 emissions from long-term observational data of atmospheric CH2F2 concentrations.

Citation: Kutsuna, S.: Experimental determination of Henry's law constants of difluoromethane (HFC-32) and the salting-out effects in aqueous salt solutions relevant to seawater, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-58, in review, 2017.
Shuzo Kutsuna
Shuzo Kutsuna
Shuzo Kutsuna

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Short summary
We experimentally determined gas-to-water equilibrium coefficients of difluoromethane, a refrigerant HFC-32, in aqueous salt solutions relevant to seawater at 3–39 °C to evaluate what portion of HFC-32 emitted into the atmosphere would be dissolved in the ocean.The portion in the ocean was estimated to be realistically limited to only about 1 % globally; however, in a lower tropospheric semi-hemisphere (30° S−90° S), the portion was estimated to be at least 5 % in winter.
We experimentally determined gas-to-water equilibrium coefficients of difluoromethane, a...
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