I've read here on stack-exchange that NaOH will react with glass through the following reaction:

4 NaOH + SiO2 ⤑ Na4SiO4 + 2 H2O

I would like to briefly heat a highly concentrated NaOH solution to 140-200C over the course of a few minutes just to pass it through a filter.

Beside safety concerns, several questions come up to my mind:

1) Do I need to worry that an NaOH solution at 140-200C could dissolve more than say max 0.5ppm Boron, Aluminium and Na4SiO4 from the glassware to my solution over the course of less than 10 minutes? or is that too short of a time to be a cause of concern?

2) Could it cause problems with my glass-joints over such a short period of time?

3) I think that cellulose doesn't chemically react with NaOH. As for the temperature, wikipedia reads "whereas starch undergoes a crystalline to amorphous transition when heated beyond 60–70 °C in water (as in cooking), cellulose requires a temperature of 320 °C and pressure of 25 MPa to become amorphous in water." In light of that and of the aforementioned reaction between NaOH and glass, am I right to assume a cellulose filter would be better than fritted glass disk or fiber glass filter and suitable for the operation or would the solution risk burning or dissolving my filter?

4) I plan on keeping my filtering apparatus around 90-110C thanks to a steam bath until right before proceeding with the filtration to minimise the incremental dissipation that will occur upon contacting the solution. Wikipedia reads "The temperature differential that borosilicate glass CAN withstand before fracturing is about 165 °C (329 °F)." From this, is it reasonable to assume my filtration apparatus made of borosilicate glass WILL take the remaining temperature difference without cracking? (there might be up to max 120C difference)

5) I have an A2B2E2K2P3 cartridge for my full face mask. Does the P3 part protect against NaOH fumes?

6) Would you have any advice with respect to this prospective operation? (other than comments such as "don't do it" or the like)

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    $\begingroup$ See also: chemistry.stackexchange.com/questions/53760/… $\endgroup$
    – Buck Thorn
    Aug 2, 2019 at 18:37
  • $\begingroup$ @BuckThorn Thanks! That's very good info with respect to the reaction rate between glass and NaOH. This reaction is much less negligible than I thought it was, especially at high temperatures. $\endgroup$
    – Hans
    Aug 3, 2019 at 1:51
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    $\begingroup$ You must be filtering under pressure if above about 145 degree C as you'll be above the boiling point. If it's brief enough, you might get away with using stainless steel filtration kit. Otherwise hastelloy /Monel but that may be cost prohibitive $\endgroup$
    – Beerhunter
    Aug 3, 2019 at 21:20
  • $\begingroup$ @Beerhunter Thanks for the info! Do you know if maybe NaOH could react with some of the chromium and iron in the steel and contaminate the solution with trace amounts thereof? Or does the alloy somehow prevent this? $\endgroup$
    – Hans
    Aug 6, 2019 at 6:13
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    $\begingroup$ @Hans I have a link for a graph that may help google.com/url?sa=t&source=web&rct=j&url=https://… You can ens up with stress cracking, implying corrosion which is usually an alteration of the metal chemistry itself I would have thought. $\endgroup$
    – Beerhunter
    Aug 10, 2019 at 19:02


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