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I'm trying to increase the transport of electricity in the tap water I use in my dry cell electrolyser. Table salt is out, as it rusts the stainless steel electrodes and produces toxic gasses. Lye is caustic to skin and mucous membranes but the next best option as the products of the reaction seem to be harmless. Then I thought of water glass (sodium metasilicate) as a solution. It dissolves in water and acts well enough as an electrolyte but less extreme than lye and perhaps more stable. I got an appreciable increase in the production of hydrogen and oxygen in a simple test setup.

So what happens chemically when we use a solution of water and sodium metasilicate and say run 12 volts through it using stainless steel electrodes? Was I creating toxic silanes? What really happened?

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    $\begingroup$ There could be formed silicagel at the anode due local acidification. $\endgroup$
    – Poutnik
    Commented Aug 20, 2023 at 6:09

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If you're concerned about the safety of caustic $\ce{NaOH}$, sodium metasilicate itself is quite alkaline. From the SDS: "Causes severe skin burns and eye damage." (Though my experience is, it may be so viscous in solution that skin damage does not propagate deeply from brief contact.)

In addition, if you're passing DC current through it, there will be $\ce{NaOH}$ buildup at the negative electrode, anyway.

As far as silanes, no worry; electrolysis just yields $\ce{SiO3^2-}$ on the positive end, which likely would precipitate silica, eventually.

BTW, you might find this Study on the Electric Conductivity of Sodium Silicate interesting,

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    $\begingroup$ Looking back and considering your knowledge. The anode and cathode were both producing gasses. There seemed to be a fairly decent production of hydrogen gas (very vigorous bubbling, small bubble size) on one terminal, and very little oxygen production. (large bubbles, blurp... blurp...) Probably due to some oxygen being spent in the generation of silicates as you mentioned. These silicates might create a clogging problem in the device itself eventually. The production of lye seems negligable not detrimental. Not sure if this is a superior, equal or inferior electrolyte to be honest. $\endgroup$
    – Ron McDonald
    Commented Aug 20, 2023 at 7:12
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    $\begingroup$ In the beginning, the electrolysis will be all right. But, after a while, the anodic zone becomes acidic, and non-conducting silica $\ce{SiO2}$ will be precipitated around the anode. The will increase the resistance of the solution. The current will slowly decrease. $\endgroup$
    – Maurice
    Commented Aug 20, 2023 at 12:00
  • $\begingroup$ Also, the viscosity of the solution might hinder ion flow. Still, an interesting experiment. $\endgroup$
    – DrMoishe Pippik
    Commented Aug 20, 2023 at 17:37
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    $\begingroup$ 12 volts is excessive. current flow should be measured and optimized. My first thoughts are that metasilicate would increase viscosity, hinder ion flow and the increased voltage would destroy the anode. Water glass is oxidized silicia it is not oxidized by O2 $\endgroup$
    – jimchmst
    Commented Aug 20, 2023 at 21:08

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