Home Cosmetic Science Talk Formulating General Off Topic Why is CMC separating from this liquid laundry detergent?

  • Why is CMC separating from this liquid laundry detergent?

    Posted by Abdullah on December 4, 2022 at 7:21 am

    This is my laundry detergent formula 

    SLS in powder form 7.5% active 
    Lauryl glucoside 2.5% active 
    STPP 5% 
    CMC 0.5% 
    pH 10-11

    But it always separates in one day.
    I did knockout test and it was CMC being separated.

    I did add CMC as first ingredient in hot water and as last ingredient but it separated in both methods.

    I was using homogenizer when mixing so no fisheyes.

    My question is

    What can be the problem here and how should i add CMC to this liquid laundry detergent to prevent separation?

    Abdullah replied 1 year, 6 months ago 5 Members · 18 Replies
  • 18 Replies
  • ariepfadli

    Member
    December 4, 2022 at 4:26 pm

    Actually with surfactant quite high, you can add small amount CAPB and adjust viscosity with sodium chlorideor sodium sulphate and you can eliminate CMC and get desired viscosity.

  • Abdullah

    Member
    December 5, 2022 at 12:56 am

    @ariepfadli i was adding CMC for it’s anti redeposition purpose, not viscosity increasing.
    Viscosity is ok. 

  • ketchito

    Member
    December 5, 2022 at 12:00 pm

    @Abdullah That’s too much precipitate to be the CMC. Maybe you’re salting out your surfactants. Could you try reducing the STPP? 

  • chemicalmatt

    Member
    December 5, 2022 at 2:49 pm

    @Abdullah, I agree with @ketchito here. Might be the STPP working against the glucoside? CMC is pretty robust otherwise, even at that pH.

  • Abdullah

    Member
    December 6, 2022 at 6:35 am

    ketchito said:

    @Abdullah That’s too much precipitate to be the CMC. Maybe you’re salting out your surfactants. Could you try reducing the STPP? 

    What is “salting out” of surfactant? 

    What percentage of STPP do you suggest?

  • Abdullah

    Member
    December 6, 2022 at 6:40 am

    @Abdullah, I agree with @ketchito here. Might be the STPP working against the glucoside? CMC is pretty robust otherwise, even at that pH.

    After your comment i made another sample and used CAPB instead of lauryl glucoside. It separated again after a few hours. 
    Any other suggestion?

    This is photo 

  • ketchito

    Member
    December 6, 2022 at 9:52 pm

    @Abdullah Could you try one without STPP?

  • RobboAU

    Member
    December 7, 2022 at 2:32 am
    Abdullah said:

    ketchito said:

    @Abdullah That’s too much precipitate to be the CMC. Maybe you’re salting out your surfactants. Could you try reducing the STPP? 

    What is “salting out” of surfactant? 

    What percentage of STPP do you suggest?

    Salting out is the practice of reducing the solubility in water of a compound by increasing the ionic strength, i.e. adding more Na+ ions.

    My suspicion is that 5% STPP is a lot of Na+, the back of my napkin says it’s equivalent to 4% NaCl.

    With 7.5% active SLS, 4% equivalent of NaCl is going to push a lot of that SLS back into the associated state.

    Like Ketchito said, try without the STPP.

  • Abdullah

    Member
    December 7, 2022 at 4:31 am

    @ketchito @RobboAU thanks 

    I have made a sample without STTP but with 2% EDTA and it also separated. 

    The only stable sample is the one without CMC, even with all those STPP.

    Can it be that there are different types of CMC and each one need different method to incorporate them? 

    I just add CMC to water and mix with high shear mixer. The same as i do for xanthan gum. Is my method correct? 

  • ketchito

    Member
    December 7, 2022 at 11:10 am

    @Abdullah Can you try one sample without STPP nor EDTA? Just add your surfactants and CMC. If that one doesn’t separate, then your CMC doesn’t toletare that much electrolyte…but if that one also separates, then maybe the way you’re adding your CMC needs to be changed.

  • Abdullah

    Member
    December 7, 2022 at 1:38 pm

    @ketchito i will make  a sample without any builder tomorrow just to test. But without a builder how can this liquid laundry detergent work in hard water specially when primary surfactant is SLS? 

  • RobboAU

    Member
    December 7, 2022 at 11:44 pm

    Do you have a measure of your water hardness?

    The US Geological Survey defines very hard water as having a CaCO3 concentration greater than 180 mg/L. Converting to mol/L, that’s 0.018 mol/L.

    To treat that you’d need 0.018 mol/L of disodium EDTA, which is 6 g/L. That’s about 0.6% by weight.

  • Abdullah

    Member
    December 8, 2022 at 1:36 am

    @RobboAU TDS of water is at least 700 ppm. I don’t know how much CaCO3 concentration it would be approximately. 

  • RobboAU

    Member
    December 8, 2022 at 4:34 am

    700 ppm is 0.7 g/L (0.07% w/w) of total dissolved solids, some of which will be CaCO3.

    If we assume that all the TDS is metal cations that EDTA/STPP complexes with, then 2% is more than triple the amount you need. It’s also a lot of Na+ ions.

    To quote the famous cosmetic chemist, Lil Jon: that EDTA concentration needs to Get Low. (citation needed)

  • Abdullah

    Member
    December 8, 2022 at 11:15 am

    RobboAU said:

    700 ppm is 0.7 g/L (0.07% w/w) of total dissolved solids, some of which will be CaCO3.

    If we assume that all the TDS is metal cations that EDTA/STPP complexes with, then 2% is more than triple the amount you need. It’s also a lot of Na+ ions.

    To quote the famous cosmetic chemist, Lil Jon: that EDTA concentration needs to Get Low. (citation needed)

    2% EDTA/STPP is 2% when it is in Product, when it is in wash water, it gets diluted many time. 

    For example, in a wash cycle in automatic machine, i added 150g of liquid detergent, when wash water came out, it was around 17kg water.
    It means that 150g detergent has been diluted with 17kg of hard water.
    So if the detergent had 2% STPP, during washing it  has only 0.017%. is this amount enough to make that hard water soft? 

  • ketchito

    Member
    December 8, 2022 at 11:59 am

    @Abdullah Builders are not something you want or need to add in high amounts. Plus, replacing SLS by SLES reduce the sensitivity of your anionic towards water hardness. Also, creating mixed micelles with CAPB or similar reduce charge density of your anioninc, lowering its sensitivity as well.

  • RobboAU

    Member
    December 8, 2022 at 11:22 pm

    Abdullah said:

    RobboAU said:

    700 ppm is 0.7 g/L (0.07% w/w) of total dissolved solids, some of which will be CaCO3.

    If we assume that all the TDS is metal cations that EDTA/STPP complexes with, then 2% is more than triple the amount you need. It’s also a lot of Na+ ions.

    To quote the famous cosmetic chemist, Lil Jon: that EDTA concentration needs to Get Low. (citation needed)

    2% EDTA/STPP is 2% when it is in Product, when it is in wash water, it gets diluted many time. 

    For example, in a wash cycle in automatic machine, i added 150g of liquid detergent, when wash water came out, it was around 17kg water.
    It means that 150g detergent has been diluted with 17kg of hard water.
    So if the detergent had 2% STPP, during washing it  has only 0.017%. is this amount enough to make that hard water soft? 

    I didn’t realise you were adding it to soften the water in the washing machine.

    In that case I am skeptical that is practical or feasible. 17 kg of water at 700 ppm is about 12 g of dissolved solids. A 150 g dose of detergent would need  20 grams of Na2EDTA to bring that water down to “soft”, with some very big assumptions. You will not create a stable liquid detergent under those conditions.

    Ketchito has suggested the best solution - mixed micelles - to address detergent functionality in very hard water.

  • Abdullah

    Member
    December 9, 2022 at 3:50 am

    @ketchito @RobboAU thanks for the information. 

    If i use CAPB: APG 1:1 ratio as cosurfactant, what ratio of SLS: cosurfactant do you suggest in this formula to make SLS stable in hard water? 

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