Home Cosmetic Science Talk Formulating LABSA Sulfonic acid to Sodium hydroxide ratio for dishwash liquid ?

  • chemist77

    Member
    August 8, 2018 at 3:41 pm

    Gunther I have always realised that it is difficult to give one specific ratio in such neutralisation. For me it varied from.0.5% upto 1% and I could never tell my customers a fixed ratio. Better go in little incremental dosages. 

  • belassi

    Member
    August 8, 2018 at 9:05 pm

    Just do a titration with an indicator eg. bromothymol blue, and use the result for the ratio needed. https://upload.wikimedia.org/wikipedia/commons/f/fb/Bromothymol_blue_colors_at_different_pH.png

  • ozgirl

    Member
    August 8, 2018 at 10:31 pm
    This info might be useful as a starting point.
    Ultimately the amount required will depend on your particular DDBSA. Don’t forget that DDBSA contains free sulfuric acid that also needs to be neutralised.
    I would recommend using 50% NaOH solution for neutralisation rather than using flakes.

  • belassi

    Member
    August 8, 2018 at 11:59 pm

    You have to titrate because for starters you don’t know how much of the NaOH has reacted with air CO2 to form sodium carbonate. Just titrate it, it’s not rocket science, why is there such reluctance to do basic chemistry? Buy a freaking burette and some indicator!

  • gunther

    Member
    August 9, 2018 at 5:41 pm

    Thank you guys
    At the end I ended up doing a titration with a pipette and pipette pump and pH paper (I don’t like dipping pH meters in strongly acid or alkaline solutions).
    It took 0.4% of 50% NaOH (equal to 0.2% solid NaOH) to reach a mildly alkaline pH.

    @Belassi thanks for the Bromothymol blue idea. Titration was slow as some solid debris (maybe solid NaOH coming out of solution) formed on contact with the acid, taking a bit to redissolve.

    @ozgirl
    May I ask why 50% NaOH is preferable to flakes?

    Neutralization Information:
    Temperature and pH must be controlled during neutralization of BIO-SOFT S-101 to prevent darkening of the product and corrosion of stainless steel equipment. The reaction temperature should not be allowed to exceed 50°C and the pH should not go below 6.5.
    https://www.stepan.com/uploadedFiles/Literature_and_Downloads/Product_Bulletins/Surfactants/BIO-SOFT®/BIOSOFTS101.pdf

    I wonder if this only applies to steel tanks?

  • chemicalmatt

    Member
    August 9, 2018 at 7:32 pm

    Funny, every high active DDBSA I ever saw was dark as espresso coffee. The pure 96% acid will darken 304SS when contacting for more than a few hours, but a quick treatment with peracetic acid solution takes care of that. In practice, you always add the alkali to water first (after determination ala Belassi or Stepan  lit) then slowly add the LABSA or DDBSA to the mixture until done. Cheapest way to make laundry detergent.  

  • ozgirl

    Member
    August 9, 2018 at 9:58 pm

    @Gunther It is easier to handle and you don’t have to ensure that it is dissolved.

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