I am working with a company to help improve their reaction process where they use SDA 2B Alcohol (Karl Fischer titration has it at 99.66% EtOH, 0.3375% toluene). Specifically, I am attempting to determine what theoretical %wt or %vol of water is pulled from atmospheric air into pure ethanol given an infinite amount of time? Does it ever reach an equilibrium state and, if so, what is it?
My gut guess is ~95.5%wt EtOH/4.5%wt H2O, the azeotropic concentration.
Assume constant relative humidity and room temperature. The ethanol is stored in a closed tote (~220 gallons). Initially, the tote is full of as-shipped ethanol (negligible air volume). However, half the ethanol is removed as part of a batch run. So, really, what I'm trying to get at is what happens to the leftover ethanol that is now sitting in a closed tote with ambient conditions.
Please let me know if additional details will help answer the question. Thanks!