Efficient, low overhead means to scrub acid gases without water loss? [closed]








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This question is pretty much what it says on the tin: what would be an efficient (low pressure drop, reasonable energy consumption), low overhead (simple, lightweight) means to scrub acid gases from a feedstock stream without water loss (and ideally, with water capture)? 


Say, the stream is primarily $\ce{CO2}$, a few percent nitrogen, 80kPa / 25°C; the $\ce{H2O}$ partial pressure is ~5 Pa (~20ppm); and there's a variety of acid gases in the dozens to hundreds of ppm range, and you'd like to scrub at least 90% of the $\ce{H2O}$ and acid gases, preferably more. Obviously if you were to just, say, run it through a packed bed with water you're just going to humidify the gas stream in the process of scrubbing, because the vapour pressure of water is three orders of magnitude higher than the $\ce{H2O}$ partial pressure already in the stream. Obviously if the gas stream were compressed to several hundred atm or more then you could do that, but such levels of compression would neither be efficient nor low overhead. You could likewise freeze out $\ce{CO2}$ to increase the partial pressures of everything else, and even distill the remaining gases - but these are anything but efficient, low-overhead solutions. I thought about the use of dilute sulfuric acid as the scrubbing medium to drop the vapour pressure, but the vapour pressure drop isn't nearly enough until high molarity, which would be relatively useless for scrubbing. 


I'm sure there's a "right" solution for such a case, but I'm not sure what it is. Adsorption into a solid chemical bed, with subsequent regeneration (and if so, what sort of chemical)? Multistage, with say acid gas scrubbing first, then water scrubbing (and if so, what method for the latter to get down to under a few pascals partial pressure)? Selective membranes - say, to exclude $\ce{CO2}$, with a partial vacuum drawn on the other side? Some sort of ion pump? 


