Lactic Acid exfolaint

I want to make a Lactic acid exfoliant at 5% AHA.
 I can get direct Lactic Acid and also Purac BF P/41. 

Option 1
I can use Lactic acid at 5% and then add a buffer, adjust ph to 4
Water QS
Aloe Vera 50%
Lactic Acid 5% 
Sodium Lactate (don't know how to calculate the buffer amount)
Adjust ph to 4 using NaOH 


Option 2
Water QS
Aloe Vera 50%
Purac BF P/41  5% 
Adjust ph to 4  

Questions
  1. Option 2 is easier for me as I don't need to calculate buffer. But wondering if it gives same exfoliating effect as option 1?
  2. Also wondering in Glycerin and Propylene Glycol has any place in the above formulation as Lactic acid itself is moisturising
  3. What exactly L+ lactic acid and D - Lactic  and why is Sodium Lactate is counted as lactic acid base don ph
Note:
Purac BF P/41
INCI: Potassium Lactate (and) Aqua (and) Lactic Acid Preservative-free 

Any help,
Much Appreciated,
Bindu

Comments

  • MarkBroussardMarkBroussard Member, Professional Chemist
    I really don't think you need to calculate the buffering effect.  Simply add L-Lactic Acid @ 5% and use Sodium Lactate (the sodium salt of Lactic Acid) to adjust the pH to 3.85 which is the pKa of Lactic Acid.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
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