[robron]

I am in the process of formulating a low pH detergent with high cleaning ability. the formula is as follows, water,sodium metasilicat(andro),STPP and sodium hydroxide.  once blended the formula seems to stay in solution, however the moment i try to lower my pH it starts to turn into gel at around 9.5 and then when i add my solvents and surfactants, it splits!

Does anyone have any info on how to keep metasilicat in solution around pH 8!

thanks

Rob

[AWK]

Metasilicid acid shows pKa1 about 10 and below this pH precipitation of H2SiO3 take place.

[eugenedakin]

Hello robron,

Sodium metasilicate needs to be present in excess of caustic.

You may want to try a different chemical that is stable at this pH.

Best wishes,

Eugene

[robron]

Thank you for your response! greatly appreciated!

Do you have any other ideas? I have tried Phosphates STPP and TKPP! But still no where near metasilicates performance.

Thank you once again

[eugenedakin]

Hi robron,

With all of the potential aspects of sodium metasilicate, which property do you want to substitute? If it is the caustic portion, then substitute caustic soda. If it is the abrasiveness, then add finely ground calcium carbonate.

Thanks for answering my question,

Eugene

[408]

Metasilicid acid shows pKa1 about 10 and below this pH precipitation of H2SiO3 take place.

That is not the reason for gel formation however...  protonation of metasilicate allows acid catalyzed sol-gel synthesis to occur, and gel formation is resultant from the crosslinked Si-O-Si polymer network forming.  Not from precipitation of a discreet species.

[robron]

ok so to get this right!

Any contact with any acid will result in gel formation or (SI-O-SI)! is this correct?

As the reply from eugene! as far as i know the reasons for Sodium Metasilicates are, Firstly as a high alkaline base(which i can sustitue with caustic) Cleaning aid,Emulsifier,Defloculant,Soil suspension and prevent soil deposition!

I really appreciate the advice from you all!

Thanks

[eugenedakin]

Hi robron,

In summary, yes, lowering the pH with acid will form gels.

As for the other properties, do you need to have all of these, or are some properties more important than others?

Sincerely,

Eugene