Catalytic Scientific Water Supply

Laboratories of various kinds use water. The regular water flowing out of the tap isn't up to standard due to contaminants. Which type of contamination matters varies very much between types of science.

Often, labs will buy an expensive machine <link> which uses many layers of filtration to sterilize (UV light) and filter (reverse osmosis) to produce water with a resistance of 18.2 M Ohms/cm. This is pretty clean water. It does retain contamination, for example, it has micromolar amounts of dissolved calcium, which is about 1000 fold too high for the sorts of experiments I occasionally attempt. So solving that problem involves boring steps with expensive chemicals. Anyhow, the water machines have other problems. The main one, is that no one ever wants to buy the replacement filters. We can do better.

So, I propose a different strategy. 1st step, regular cheap 0.22uM filter. Just to keep the larger chunks out. This feeds into step 2, a boiling vessel. Here around 50% of the water is vaporized, the rest drains away taking concentrated minerals etc. The boiling is done by one of those nifty high temperature Peltier elements at almost exactly 100 C, the vapor travels up and over a gas bridge to condense on the cold side of the same element. Here too, there should be a portion of water outflow, to ensure a constant washing but... the temperature is JUST a hair under 0 C. The rate of water outflow should be passively controlled by gas pressure from the next step, a nice safety feedback measure.

Step 3 the ice portion is scooped out by a wheely thing and delivered to a warmed electrolysis chamber, or electrolytic hydrolysis if you will. Water is split at two electrodes into two separated streams of Gas, H2 and O2. The pressure of either/both of these gasses feeds back to the water step to prevent any untoward build up of dangerous stuff.

The gas streams can then pass up and over another bridging structure, through gas-selective membranes if you're feeling fancy.

Step 4, the gas flows down past a platinum catalyst, or a fuel cell if you're feeling efficient, but that's not from grant money, so screw it. Here, the H2 and O2 recombine to form nice clean water.

Now, contamination is possible, but the contaminants would have to have similar boiling point to water, similar freezing point to water, similar gaseous electrolysis products to water and similar platinum catalysed reaction products to water. Walks/quacks like a duck... Should be cheaper than the alternative.