Deionization without ion membranes

[gatewood]

I've been producing some biodregradable hydrogels for some time and, one of the requisites for their manufacturing is deionized water (really, really pure water). Quality ion exchange resins can be a bit costly, so I learned how to regenerate them, though the process can be a bit problematic as well.

So I ended up turning to trying to make my own process of deionization (or as close as I can get to it) to simplify my work. So I came with the following process:

1. Pass tap water through an HEPA and activated carbon filters, to get rid of small particles and VOC (volatile organic compounds).

2. Shake the water pretty hard, to eliminate some disolved gases.

3. Boil it a little bit, to eliminate low boiling point volatilites and the rest of the disolved gases (at the cost of losing a little bit of water).

4. Distill the water (as close to 100°C as possible), to rid it of solubles and high boiling point volatilites (maybe use a fractionating column?).

Such process, I think, should eliminate all but the most exact of azeotropes from the water. What do you guys think?

Edited November 12, 2020 by gatewood

[John Cuthber]

The use of a still to make pure water is well established.

But, if you live in a hard water area you may find it helpful to deionise the water first.

 

Also, have you considered reverse osmosis? 

The set-up costs are high but the maintenance cost is lower.

[gatewood]

10 hours ago, John Cuthber said:

The use of a still to make pure water is well established.

But, if you live in a hard water area you may find it helpful to deionise the water first.

 

Also, have you considered reverse osmosis? 

The set-up costs are high but the maintenance cost is lower.

Yes, as I said, I know how to deionize water, but I'm trying to make an alternate process (as cheap as possible, trying to make just 5-10 L on each run) to produce something similar to deionized water without the ion exchange membranes. I suppose many post-filter volatilites can be eliminated simply by letting water boil for 5 or so minutes (with no distillation apparatus).

Edited November 12, 2020 by gatewood

[John Cuthber]

Unless you are in a soft water area, you will spend a lot of time effort and money descaling the still if you don't deionise it.

[gatewood]

2 hours ago, John Cuthber said:

Unless you are in a soft water area, you will spend a lot of time effort and money descaling the still if you don't deionise it.

https://water-research.net/index.php/water-treatment/tools/hard-water-hardness

According to this source, soda ash can form insoluble precipitates with calcium and magnesium ions. Oh boy, getting pretty easy to decontaminate water.

Edited November 12, 2020 by gatewood