Hygroscopic growth and times of phase change for aerosol mixtures of inorganic salts and organic substances

摘要

An intercomparison was made between two H-TDMA(Hygroscopicity Tandem Differential Mobility Analyser)instruments,measuring the hygroscopicity of ammonium sulphate(AS)and mixtures of AS and adipic acid(AA).The results showed good correspondence with the literature for both instruments.In order to evaluate the time necessary for deliquescence phase changes to occur,the residence time of the particles in high relative humidity was varied from one second to two minutes.It was shown that for inorganic salts the time for phase change was less then a second.However,for the mixtures studied here,residence times up to ten seconds were required.Thus it is important for H-TDMA measurements of mixtures to allow sufficient residence time at the specified humidity for the system to equilibrate.