Surfactants Flashcards
What are surfactants?
Surface active agents with two distinct regions in their chemical structure (polar head and nonpolar tail)
How are surfactants generally classified?
According to its hydrophilic group
EX: anionic, cationic, zwitterionic or non-ionic
What is the most widely used surfactant class?
Anionic
What are the most common encountered anionic surfactants?
Carboxylate, sulfate, sulonate, or phosphate polar groups
Counter ions help with what?
Solubilty
Sodium and potassium counter ions are for ____ solubility
water
Calcium or magnesium counter ions are for ____ solbility
oil
In most cationic surfactants, charge is found on a _____ atom
nitrogen
Cationic surfactants function in ______ state
protanated
How does quaternary ammonium (cationic surfactant) compound work?
Retains charge over the entire pH range
How does amine compounds (cationic surfactant) work?
Charged at lower pH
What are zwitterionic compounds?
Molecules that contain both positive and negative charge upon full ionization
How is the positive charge carried in zwitterionic compounds?
Ammonium group
How is the negative charge carried in zwitterionic compounds?
Carboxylate group
If the ammonium group in zwitterionic compounds is quaternary, how will the molecule exist?
Zwitterion over a wide pH range since the quaternary ammonium group will be permanently charged
If the amine group in zwitterionic compound is NOT quaternary, how will the molecule exist
Goes from cationic to zwitterionic and finally to anionic as pH is increased
If the amine group in zwitterionic compound is NOT quaternary, the molecules goes from _____ to zwitterionic to ______ as pH is ________
Cationic
anionic
increased
At the isoelectric point (in zwitterionic compounds) both groups are fully ionized and behave like what surfactant?
Nonionic
Why are nonionic surfactants used for?
Good compatibility, stable, low toxicity
In the HLB classification system, the higher the number, the more ______ the surfactant
hydrophilic
In the HLB classification system, the ______ the number, the more hydrophilic the surfactant
higher
In the HLB classification system, what does HLB stand for?
Hydrophilic-lipophilic balance
In the HLB classification system, what is the range?
0-20
In the HLB classification system, what is range 2-3?
Antifoaming agent
In the HLB classification system, what is range 3-6?
Water in oil emulsifying agent
In the HLB classification system, what is range 7-9?
Wetting / spreading agent
In the HLB classification system, what is range 8-16?
Oil in water emulsifying agent
In the HLB classification system, what is range 13-15?
Detergent