If I add concentrated linear alkyl benzene sulfonic acid (thick, dark brown liquid) to a Sodium hydroxide solution
it takes days to react.
It forms an insoluble white powder that doesn't seem to dissolve, or takes several days to do so.
Then I tried dissolving sulfonic acid in 3X it's volume of water (it remains a bit thick, it doesn't become really water thin after diluting), then add it to Sodium hydroxide
it reacts and becomes a light yellow liquid in about 1 day.
How much to dilute the sulfonic acid?
Should I add the dilute sulfonic acid to the Sodium hydroxide solution, or viceversa for large scale convenience and reduced tank time?
Readymade Sodium sulfonate is unavailable here, BTW.
Comments
The neutralization with NaOh i prefer to diluate NaOh in water then i will add it to sulfonic acid that for me make operation easier.
good luck friend.
it ain't supposed to be there
Linear Sulfonic acid shouldn't precipitate out of solution (and ain't a white powder AFAIK)
Sodium sulfonate. While the powder can be white, it should be soluble, and make a pale yellow solution.
The only thing I can think of, is that Sodium hydroxide has some Sodium carbonate in it, but it still should react to make Sodium sulfonate,
and no CO2 like bubbles are seen either.
At first I thought sulfonic acid was reverting EDTA Na-4 to EDTA free acid, but then I just reacted water + NaOH with sulfonic acid (nothing else added), and the white precipitate remains
The mistery remains.
shouldn't happen at all.
Wait, are you mixing pure LAS with pure NaOH?.
Then will use the Sodium sulfonate for several products, like dishwash and laundry detergent liquid.
distilled or deminaralized water 50% vol
Sodium hydroxide flakes 1.31% or 2.31% wt
I wait for the NaOH flakes to fully dissolve, before adding the sulfonic acid. IDK if this makes any difference.
Linear alkylbenzene sulfonic acid 10% vol
Then I get the dreaded white powder
The above formula doesn't add up to 100% as some ingredients will be added later, but I can't get past the neutralization stage unless I predilute sulfonic acid:
Phase A
water 10% vol
NaOH 1.31% wt (or 2.31% if additional acids like citric acid (to get Sodium citrate builder), or oleic acid (for laundry detergent suds control) will be added later)
Phase B
water 40% vol
Linear alkylbenzene sulfonic acid 10% vol
even the sulfonic acid takes a couple days to fully dissolve (it forms a brown gunk) and you can't stir it much as bubbles appear.
Finally add phase B to A
I prefer to handle the sulfonic acid larger volume solution, instead of NaOH smaller volume but more dangerous to handle.
Prediluting LABSA still made a milky white solution, albeit now it seems fully dissolved, unlike the previous white powder precipitate.
Phase A
distilled or demineralized water 10 % vol
NaOH 2.31% wt
Phase B
water 40% vol
LABSA 10% vol
Allow for each phase to be fully dissolved
Then pour phase B to A.
Maybe LABSA decomposes when touching large amounts of concentrated Sodium hydroxide?
Next time I'll try slowly pouring phase A to B, pouring it real slow, while allowing ample time for it to react, and get fully dissolved.
Sometimes I got the white powder precipitate, sometimes it didn't and worked perfectly with the same batch,
but my experimentation notes only mention 'Phase A+B' and I don't quite remember how the phases were added together.
This time I prediluted LABSA (makes a thick, pale brown liquid)
Then poured NaOH little by little, like 1/10th of the total NaOH amount at a time.
At first, LABSA form a white swirl, which seems to dissapear after stirring.
But in the last NaOH additions, it formed the dreaded milky white solution
so it seems that excess NaOH degrades LABSA.
I found some literature that says that sulfonic acids may react with excess NaOH may create Sodium phenoxide, but high temperature was supposed to be required.
http://staff.um.edu.mt/ratk1/BenzeneSulphonicAcids.htm
https://chemistry.tutorvista.com/organic-chemistry/benzenesulfonic-acid.html
@Fekher
The 2.31% NaOH was used because it will neutralize some other acids in the formula too (citric and oleic acids)
Next time I'll add LABSA the last thing, as to avoid excess NaOH.
One more other reasons to make soda as final add, you will neutralize many acids so it will be easier to add them all then neutralize them by soda.
For heating dissolving soda is very exothermic so that dissolving will abe to heat you blend.
@Chemist77 will do. I definitely need to switch suppliers to see if it gets better.
I bought LABSA from another supplier
the liquid is a bit thinner and goes into solution slightly faster (still takes hours or evernight), but the cloudiness problems remain.
I'm conducting tests, changing all the variables and taking detailed notes.
@Fekher what % of salt would you use to speed up LABSA dissolution?
for the Clarity reducing % of LABSA will increase the Clarity.
most (but maybe not all) test formulations became crystal clear light yellow
so it looks like they're too concentrated and some of it it's precipitating out of solution.
Not for nothing they advise to use Potassium hydroxide in premium, more concentrated formulations:
The potassium analogue (potassium carbonate, potassium silicate and potassium hydroxide) is used for the liquid detergents due to their higher solubility.
http://surfactantschemistry.blogspot.com/2013/07/laundry-detergents-formulation.html
Let us go to the lab and prepare a sample of the premium 3X liquid laundry detergent. First add deionized water (29.15%), followed by potassium hydroxide 45% solution (6.1%)
https://www.happi.com/contents/view_features/2012-04-02/formulating-liquid-laundry-detergents
Pretty much the problem remains.
So either LABSA must be added to NaOH or KOH real slow, over several hours.
Adding LABSA slowly over several minutes doesn't seem to work as LABSA is a thick liquid that just sits on the bottom, slow to dissolve.
or LABSA must be diluted in some water first (it remains a thick liquid after dilution) and then slowly add the hydroxide.
BTW I tried switching LABSA suppliers (one LABSA is a bit darker than the other) and the problem remains.
Only water Sodium/Potassium hydroxide and LABSA have been added at this point.
I'll try
Phase A
Water
KOH
Phase B
Water
LABSA
allow to hydrate and dilute overnight
Then slowly pour Phase B into A, real slow.
If it doesn't work, I'll try neutralizing LABSA with baking soda, to see if the highly alkaline NaOH/KOH is decomposing LABSA.
This 3X concentrated liquid laundry detergent advises to use
'First add deionized water (29.15%), followed by potassium hydroxide 45% solution (6.1%) in an appropriate beaker. Start mixing and slowly add Calsoft LAS-99 (10%) ...'
https://www.happi.com/contents/view_features/2012-04-02/formulating-liquid-laundry-detergents
Pilot Chemical' Calsoft LAS-99 seems to be 97%+ pure LABSA (DDBSA = LABSA as far as I know)
OTOH this premium dishwash formulation advises 9.60% or 19.20% DDBSA
https://www.happi.com/contents/view_/2011-03-04/formulating-manual-dishwash-detergents
The chart is too small to read but the transcript can be read here
https://www.thefreelibrary.com/Formulating+manual+dishwash+detergents:+an+optimum+hand+dishwash...-a0252100205
And that using Sodium hydroxide, it doesn't mention that Potassium hydroxide is really needed (Potassium salts are usually more soluble than Sodium ones).
15% isnt too much, i have used 18% labsa with naoh alone to get a viscosity similar to a famous brand in my country, and worked exccelent, it was clear and light yellow.
Today im ussing arround 8%, ussing sles / betaine to build viscosity.
I have found that mixing and avoiding the mixture to heat helps to get a lighter color and clearness
2. Add 90% of the calculated amount.
3. Check the pH.
4. Titrate to get the pH correct.
5. Record the figures and use that for future batches.
So 100g of ABS would need 18g of NaOH.
May I ask how you are measuring pH?
@Belassi I am using electronical pH meter with electrode.
Could you tell me what pH do You obtain? And what temperature are you geting through whole process?
@Chemist thanks, do you think that the Sodium Lauryl Benzene sulfonate (LABSA Sodium Salt) is on the bottom or on the top of this beaker?