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Borax to alkalize a weak solution of sodium silicate and sodium bisulfate


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13 minutes ago, chenbeier said:

I would add more NaOH or Na2CO3, because the precipitation of SiO2 will be higher with adding silicate.

True, but how do you know that is a bad thing? They might want silica.
The OP has repeatedly refused to tell us what they are actually trying to do, so we can't be as helpful as we might.

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1 minute ago, rskorj said:

Thank you very much, what if I used sodium bicarbonate instead of borax?

It would probably be cheaper...
Slightly less toxic too.

If the solution started off significantly acidic, it would fizz as the carbon dioxide escaped.

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16 hours ago, John Cuthber said:

Because borates are slightly toxic.
If I remember rightly they are reproductive toxins.

Since I would be using a very small amount of borax the toxicity would not be an issue as the levels that impact as toxic are far far larger: Boric acid and sodium borates have been considered as being "toxic to reproduction and development", following results of animal studies with high doses. Experimentally, a NOAEL (no observed adverse effect level) of 17.5 mg/kg bw/day has been identified for the (male) reproductive effects of boron in a multigeneration study of rats, and a NOAEL for the developmental effects in rats was identified at 9.6 mg/kg bw/day. These values are being taken as the basis of current EU safety assessments. The present study was conducted to investigate the reproductive effects of boron exposure in workers employed in boric acid production plant in Bandirma, Turkey. In order to characterize the external and internal boron exposures, boron was determined in biological samples (blood, urine, semen), in workplace air, in food, and in water sources. Unfavorable effects of boron exposure on the reproductive toxicity indicators (concentration, motility, morphology of the sperm cells and blood levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and total testosterone) were not observed. The mean calculated daily boron exposure (DBE) of the highly exposed group was 14.45 +/- 6.57 (3.32-35.62) mg/day. These human exposures represent worst-case exposure conditions to boric acid/borates in Turkey. These exposure levels are considerably lower than exposures, which have previously led to reproductive effects in experimental animals. In conclusion, this means that dose levels of boron associated with developmental and reproductive toxic effects in animals are by far not reachable for humans under conditions of normal handling and use.
[Duydu Y et al; Arch Toxicol. 85(6):589-600 (2011)] **PEER REVIEWED** PubMed Abstract 

On 12/18/2018 at 8:55 AM, chenbeier said:

That would be better, you get only CO2, which will evaporate.

So what happened to the sodium part of Sodium Bicarb?

On 12/18/2018 at 7:57 AM, chenbeier said:

These are simple acid base reactions.

HA + BOH => AB + H2O

The stronger acid here bisulfate will push out the weak acid (Boric acid or silicon dioxide) and the salt (here sulfate) and water will be formed.

Can you explain this to me compared to the result sodium bicarbonate would yeild?

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