Btw, I came across a note that adding K2SO4 to H2SO4 increases he boiling point from the 330C's to the 370C's. I think it was the Kjedahl method of nitrogen digestion, or some other nitrogen test. So in case you want to recover moisture from the air in a desert (from what I gather, the relative humidity in deserts is usually between 10 and 30%, corresponding to about 0.5% weight moisture in the air. So for every 199 parts of absolutely dry air mass you get 1 part of steam or water vapor mass) using sulfuric acid, adding a salt like K2SO4 to it can lower the vapor pressure even further reducing sulfuric acid loss through vaporisation. All you need is an acid resistant pond and just let the sulfuric + K2SO4 sit outside overnight, or for weeks (and even at 10% concentration sulfuric has desiccant properties, though maybe not in a desert) and let it build up moisture. Then you need an acid resistant (such as glass) distillation apparatus, with a good acid resistant reflux column to distill the water out as steam, using solar or wind origin heat, which should condense fine at room temperature to absolutely pure distilled water.
Phosphoric acid has similar properties, however, according to Wikipedia it boils at 158C and decomposes at 213 C into, I'm guessing, polyphosphoric acids and water, which should boil even higher. Pure anhydrous phos acid can be obtained by vacuum distilling 85% phos acid, so I'm guessing there might be some kind of azeotrope there. So anyway, polyphosphoric acids, or just plain phosphoric acid might have a lower vapor pressure and lower loss through evaporation, including loading with phosphate salts that might lower the vapor pressure even further.
Ideally there might be some very hydrophobic sugary-like things that are liquid with water, and hold onto it strongly, I don't know if highly polysulfonated aliphatics or aromatics are like that, or even polymeric glycols which should absolutely not evaporate, but maybe they are not hygroscopic enough. I don't know if it's possible to polysulfonate them and not char them into aromatic-like brown condensates on the way to graphitization, but anything slightly polymeric and somehow, of low viscosity, should have very low vapor pressure to where if you put it outside in a pond, you can recycle it for years and years without evaporation loss. Glycerol has a high boiling pt, but also high viscosity, and a low flash point, so it's a fire hazard, which goes equally for the other organic chemicals, so the water recovery distillation part might have issues if the hydrophobic material is not properly selected. But most hydrophobic materials are ultra-loaded on hydrogenbonding oxygen groups, which should be less combustible than straight hydrocarbons, but also amine groups, which maybe more combustible, maybe not. What else can you attach a lot of to a high(or never) boiling organic polymer, besides lots of hydroxyl, sulfonate, and amine groups? Making them into a salt might increase the boiling point even further, and hygroscopicity too, but then you're probably dealing with a crystalline solid anymore, not a liquid, so when going that approach, things that are volatile in absence of being a salt might work. Also if the stuff is not volatile at all, the distillation is pretty straightforward, other than thermal degradation over time. Sulfuric and phosphoric acids are simple compounds and don't thermally degrade from repeated distillations, but most organic materials do. So something super-thermally-stable would be necessary, maybe hexa-sulfonated hidered aromatics if they still stay liquid, or even fluorinated sulfonated things, where the fluorine increases thermal stability compared to hydrogen, but it also lessens the hydrophilicity, but maybe not too much to where it's worth including it in the moisture scrubbing liquid compound.
There are molten salts that are ionic and organic, so they might be moisture scrubbing too, but maybe too thermal degradation sensitive. Thermal degradation from repeated boilings is a very important criterion for such atmospheric scrubbing liquids.
Oh yeah I also read somewhere that calcium chloride, a highly renowned and cheap dessiccant, melts in its own crystal water near 29-32 degrees depending on purity, so to become very moisture hogging again, as in crystalline water hogging, it has to be able to undergo this "freezing", and if the desert air temperature is higher than 29-32, it's not possible for it to "freeze" back into the crystal-water state. So whatever salts are used, they should have a "melt in your own crystal water" temperature higher than the ambient temperature in deserts, which is sometimes 50C (120F.) Maybe sodium hydroxide is such a thing, but its fault is also scrubbing the CO2 from the air, and losing hygroscopicity that way. So staying in the neutral pH or acidic pH may be important, other than mildly basic amines that give up their CO2 easily, which could also be used as a byproduct, to convert into a hydrocarbon from the plentiful energy but low availability of moisture or fuel materials in the desert. Or it can be used for injecting into a greenhouse atmosphere, for better growth rates of plants in it.