Effects of temperature, pH, and ionic strength on the Henry's law constant of triethylamine

Abstract

The Henry's law constants (KH) of triethylamine (TEA) in pure water and in 1-octanol were measured for the temperatures pertinent to the lower troposphere (278-298K) using a bubble column system coupled to a Fourier transform infrared spectrometer. The KH values of TEA in water and 1-octanol at 298K are 5.75±0.86molL-1atm-1 and 115.62±5.78molL-1atm-1. The KH values display strong dependence on temperature, pH, and ionic strength. The characteristic times for TEA to establish an equilibrium between gas and droplet with a size of 5.6μm are ∼33s (298K, pH=5.6); ∼8.9×102s (278K, pH=5.6); ∼1.3×103s (298K, pH=4.0); and 3.6×104s (278K, pH=4.0). The evaluation of TEA partitioning between gas phase and condensed phase implies that TEA predominantly resides in rainwater, and TEA loss to organic aerosol is negligible. Key Points Henry's law constants of amines depend on temperature, pH, and ionic strength Characteristic time for gas-droplet equilibrium depends on temperature and pH Amines predominantly reside in rainwater, and loss to organics is negligible