Liquid vs powder detergent (chemistry)

[NeoPTLD]

I used to think if sugar is powdered detergent, then syrup is liquid detergent, but after checking out the MSDS for both, there's a vast difference in ingredients.

Liquid Tide:
http://www.pg.com/content/pdf/..._Tide_Detergent_1X.pdf

It contains ethanol, sodium borate and ethanolamine as reportable hazardous ingridients and rest are non-hazardous.

The pH of 10% solution is 8.1-8.6

Tide Ultra powder:
http://www.pg.com/content/pdf/..._Laundry_Detergent.pdf

Tide Ultra powder contains a significant amount of sodium carbonate and zeolite, ingredients not found in the liquid form and it's 1% solution is 10 to over 100 times more alkaline than a 10% solution of liquid Tide at pH of 10-11 (pH is logarithmic) and a high reserve alkalinity


So do these differences affect washing performance or damage to fabric/environment?

 

[gururu2]

the liquid form is likely gentler on fabrics due to its closer to neutral pH. the listed additives, ethanol, borate, and ethanolamine are probably surfactants that both reduce the sudsy character of the concentrated solution and/or provide a better matrix to ensure homogeneity of the mixture). the powered form is probably easier to manufacture and transport since it would be lighter and boxes are cheaper. the high alkalinity likely serves to help dissolve the active compounds quickly (as you note it is shown as not completely soluble at lower temperatures). the higher alkalinity may or may not serve to provide a more thorough cleaning. an ideal from would be easy to transport and very soluble with the same potency.

i favor the powdered forms for no good reason :/

 

[CycloWizard]

It would depend on how concentrated they are in the final solution (i.e. after you add the water to the washer). There's no real point in doing a 1:1 comparison because I'd bet that you never add as much of the powder as you would of the liquid. If you dilute the solid a little more, that difference of 2-3 pH that you cited would disappear.

The different ingredients probably don't change performance all that much. Ethanol and ethanolamine are solvents included in the liquid form because it's a liquid at room temperature, so they can't be included in the solid form. Sodium borate is just a run-of-the-mill detergent compound, so I'm sure the solid form has something coparable. Sodium carbonate is just baking soda, does a little cleaning and deodorizing, as well as adjusting the pH. Zeolite is a solid metallic compound with very high surface area that is often used for catalysts. Interesting that it's in there - must be to help whatever detergent is included in bonding to soil and stains.

 

[NeoPTLD]

Sodium carbonate isn't baking soda. Na2CO3 = sodium carbonate, a strong base, NaHCO3 = baking soda, weak base.

 

[PolymerTim]

Looks like sodium carbonate is also known as washing soda and primarily softens the water so that magnesium and calcium ions don't compete with the detergent, but is also a degreaser and controls pH.

Wikipedia has an article on detergent components that may give you a little info. For instance it mentions that the zeolite is used as an ion exchange agent, but I'm not sure which ions they are trying to exchange and why.

As for the differences between the two, I can only speak generally, but formulation can be an amazingly complicated process when trying to determine the best properties of any formulation including cost. It is not uncommon that changing one requirement significantly changes the entire formulations optimum mix. You might guess that changing the requirement of solid to liquid significantly changes the formulation, even if the end result might be a very similar cleaning power.

 

[CycloWizard]

Originally posted by: NeoPTLD
Sodium carbonate isn't baking soda. Na2CO3 = sodium carbonate, a strong base, NaHCO3 = baking soda, weak base.

Oops, bicarbonate is baking soda. I've only slept about 20 hours in the last 8 days, so the brain is failing. The thesis gets turned in tomorrow, then I should be able to catch up on some z's. 😛