This little test is indicative only, it does not pretend to be hard science.
So the {100gr 7% acetic acid + 3gr zinc} was filtered after 22 hours, mainly just sitting (only 4 times swirling), at a lukewarm temperature so no serious heating done. The liquid was very transparent but looking very closely one could see some kind of yellow-trace yet very hardly noticeable.
Choice of base: 8mol/L lye because it would enable to add strong base to check if the precipitates really turn liquid again as suggested
here.
endlessness said:
...Another option would be to attempt using excess sodium hydroxide. The theory says that when excess sodium hydroxide is added, zinc hydroxide becomes sodium zincate, which will be soluble in the solution while THH would be insoluble and precipitate. Then one can just filter and have THH without zinc...
So we hope to acknowledge "the theory".
Ph meter was re-calibrated at 7 and 9, but seems to stall at 13.10 and goes no higher. At 8mol/L it
should say pH 14 but refuses to rise above 13-ish, it is a cheap probe so I think it's that.
Start pH is 3.13 (theoretically should be 2.85)
Lye was added 1 ml at a time, then pH measured.
Between 1 and 13 ml lye added the pH rises really slow, but starts to rise strong after that.
At 14 ml lye added, pH 5.8 , first signs of mist forms.
At 15 ml lye added, pH 7.34 , serious precipitation forms.
At 16 ml, pH 10, viscosity rises and liquid start to stick on the glass walls, see FIRST picture.
At 19 ml, pH 12.88, any further the pH meter stalls at 13.10
At 24 ml, first signs that things change, liquid start to loose viscosity.
At 37 ml, a lot of the hard ZnOH --> liquid sodium zincate, liquid became watery again, see AVI attachment.
Probably not interesting but adding more lye slowly the pH declines to just below 13, I suppose it's a side effect somehow.
To make all ZnOH "disappear", had to add 60 ml lye in total. See SECOND picture. I wonder if THH would be compromised in this much lye.
pH was brought back by adding water + HCl to around where most precipitate was seen, around just above pH 12. The supposed ZnOH filtered, dryed, see pic, weighted 335 mg. Thus not negligible IMHO.
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The OP paper precipitates the formed THH with ammonia, not lye.
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Now, a coffee
