Zschimmer & Schwarz
CLEANING
SPECIALITIES
SURFACTANTS &
SURFACTANT CLASSES
Water – an important and extraordinary liquid
Why are falling water droplets
spherical?
Answer:
Water minimizes the contact with air.
Spheres have the smallest surface of all
geometrical forms.
Surfactants 2
Water also tries to minimize the contact with some hard surfaces…
Water droplets on a feather Water droplets on a window
Surfactants 3
Water molecules have special bonds…
Surfactants 4
Water molecules in detail
Water molecules in liquid state Water molecule
Surfactants 5
The attraction between water molecules is strong enough to carry
objects!
Water strider „walking“ on water Leaves floating on water
Surfactants 6
Surface Tension
The special bonds between water molecules (Hydrogen bonds) lead to a high surface
tension.
Surface tension =
Energy needed to increase a liquid surface in mN / m
Surface tension of water: About 70 mN / m
Measurement methods: Ring method, Wilhelmy plate method, etc.
Surfactants 7
Water is not always compatible with other liquids…
Thin oil layer on a water surface Oil poured in a glass with water
Surfactants 8
Interfacial Tension
Interfacial tension: Energy to increase the interface
between two liquids in mN / m
Rule of thumb: The more hydrophobic a substance,
the higher the interfacial tension with water:
Octanol / water: 8 mN / m
Vegetable oils / water: 30 mN / m
Octane / water: 51 mN / m
Surfactants 9
Partial Summary
Water alone does not
- Wet all surfaces
- Mix with oil / oily dirt
But: these parameters are important for cleaning applications!
Luckily, water can be “manipulated“, e. g. by surfactants!
Surfactants 10
What is a surfactant?
Surfactant = SURFace ACTive AgeNT
Molecules consist of two parts:
HYDROPHILIC (“water-loving“) linked to
HYDROPHOBIC (“water-hating“)
Schematic picture:
Surfactants 11
A surfactant in water…
… will orientate like this:
The consequence:
The surface tension
is lowered.
Surfactants 12
Surface tension of water
The surface tension of water is influenced by adding other substances.
Surfactants lower it most efficiently:
- Water alone: 70 mN/m
- 20 % Ethanol 40 mN/m
- 0.01 % Surfactant 30 mN/m
The reason: surfactants assemble as monolayer at the surface.
Surfactants 13
Increasing surfactant concentration
„Concentration“ at surface ↑
Concentration in solution ↑
Exceeding maximum
surfactant solubility
Micelle
Important: With exceeding critical micelle concentration (CMC) the surfactant
monomer concentration is constant
Cleaning Specialities 14
Surfactants and surface tension
Surface tension σ
σ
[mN / m]
CMC
Surfactant concentration c 2
70
CMC: Critical micelle concentration
30
Analogue:
ln (c 2 /M) Interfacial tension oil / water is lowered
to values about 5 mN / m
Cleaning Specialities 15
Surfactants and surface tension
Key message:
Surfactants must not be too well soluble in water!
Otherwise they will not
- Go quickly to surfaces or interfaces
- Assemble mainly at surfaces or interfaces
- Form micelles at low concentrations
Surfactants 16
Micelles
Spherical micelle:
Most simple shape
For sodium dodecyl sulfate (SDS):
About 80 surfactant molecules
aggregate
Surfactants 17
Lyotropic liquid crystals
Surfactants 18
The micellar structure influences the viscosity
Surfactants 19
Surfactants can create foam…
Surfactants 20
Surfactants can be low-foaming…
Surfactants 21
Surfactants can solubilize…
Surfactants 22
Surfactants can emulsify…
Surfactants 23
Surfactants can demulsify…
Surfactants 24
Surfactants can disperse / create suspensions…
Surfactants 25
Surfactants can make surfaces water-repellent…
Surfactants 26
Surfactants can wet surfaces…
Surfactants 27
Surfactants can clean!
Wet dirt and surfaces - Emulsify fat / oil - Disperse particles
Surfactants 28
Surfactant classes
Surfactants can have different building blocks which have a huge influence on
their properties. There are four surfactant classes:
Anionic Cationic Amphoteric Nonionic
- + +/-
Difference of Surfactant Classes
Surfactants in cleaners
In general:
For most applications good “allrounders”:
anionic and nonionic surfactants -
Most important surfactant groups
Often used in combination
Difference of Surfactant Classes
Comparison
ANIONIC AND NONIONIC
SURFACTANTS
Comparison between anionic and nonionic surfactants
Sensitivity to water hardness
Difference of Surfactant Classes
Comparison between anionic and nonionic surfactants
Sensitivity to water hardness
► Nonionic surfactants: No sensitivity
► Anionic surfactants: Sensitivity
Soaps > Phosphates > Sulfates > Ether sulfates
Difference of Surfactant Classes
Soap in soft and hard water
20 g FLEROGUM K 38 E in 100 g demin. water 20 g FLEROGUM K 38 E in 100 g tap water
Difference of Surfactant Classes
Comparison between anionic and nonionic surfactants
CMC (anionics) >> CMC (nonionics)
Consequence for a given concentration:
For anionics:
more monomeric surfactant molecules
For nonionics:
more micelles
Difference of Surfactant Classes
General Functions of Monomers and Micelles in Solutions
Monomers get fast to surfaces: Micelles are aggregated monomers:
- Wet - Solubilize
- Foam
- Emulsify
To enable solubilizing: To improve wetting / foaming:
- Increase surfactant concentration - Increase surfactant concentration
until CMC is reached
Difference of Surfactant Classes
Influence on the CMC
CMC is influenced by:
- Surfactant class
(Anionic and Cationic >> Nonionic and Amphoteric)
- Hydrophilic part
(e.g. Fatty alcohol ethoxylates: more EO → higher CMC)
- Hydrophobic part
(Longer “tail” → lower CMC)
- Ionic mixtures
(e.g. Anionic / amphoteric micelles are more favourable)
Difference of Surfactant Classes
Comparison between anionic and nonionic surfactants
Temperature dependence
Nonionics:
► Properties strongly dependent on temperature
► Solubility decreases with higher temperature
Anionics:
► Properties are only slightly depending on temperature
► Solubility increases with higher temperature
Difference of Surfactant Classes
Temperature Influence on Anionic and Nonionic Surfactants
Anionic surfactants:
Crystallization Good solubility Good solubility Good solubility
(Krafft point)
Temperature
Nonionic surfactants:
Good solubility Good solubility Less solubility Not soluble
(Cloud point)
Difference of Surfactant Classes
Krafft point
SULFETAL LS-U (anionic surfactant)
Temperature
Difference of Surfactant Classes
Cloud point
Comparison:
Left beaker: 1 % SULFETAL LS-U (anionic surfactant) in demin. water
Right beaker: 1 % ZUSOLAT 1608/85 (nonionic surfactant) in demin. water
Temperature
Difference of Surfactant Classes
Comparison between anionic and nonionic surfactants
Salinity dependence (e. g. NaCl, MgSO4)
Nonionics:
► Properties not strongly dependent on salinity
► Solubility is only slightly reduced by salinity
Anionics:
► Properties are strongly depending on salinity
(e.g. some anionic surfactants can be thickened with sodium chloride)
► Solubility is strongly reduced by increasing salinity
Difference of Surfactant Classes
Thickening of 50 % ZETESOL NL-U in demin. water
50 % ZETESOL NL-U in demin. water: 1 g NaCl (sodium chloride, simple salt) is added
The mixture is low viscous and clear The salt particles are slowly dissolved
Thickening of 50 % ZETESOL NL-U in demin. water
More NaCl is added More NaCl is added
The salt particles are surrounded by highly viscous The viscosity of the whole formulation is increased,
surfactant structures it starts to “climb” up the stirrer
Thickening of 50 % ZETESOL NL-U in demin. water
More NaCl is added More NaCl is added
The viscosity is increased further, but the solubility The surfactant is no longer soluble, the formulation
of the surfactant gets limited gets turbid and low viscous
Surfactant Classes
PRODUCTS FROM
ZSCHIMMER &
SCHWARZ
Surfactant classes - Anionics
Z&S Products:
SULFETAL, ZETESOL, PHOSFETAL, TRIUMPHNETZER ZSG, SETACIN, some ZETESECO types,
FLEROGUM types
Features in cleaners depending on the product:
- Wetting
- Dispersing
- Hydrotropic power
- Emulsifying
- Degreasing
Difference of Surfactant Classes
Anionic Surfactants - Types
Alkyl carboxylates (Soaps)
ZETESECO SC
FLEROGUM
Alkyl sulfates
SULFETAL
Alkyl ether sulfates
ZETESOL
Difference of Surfactant Classes
Anionic Surfactants - Types
Alkyl benzene sulfonate
Part of some
LUMOROL
Dialkyl sulfosuccinate types
TRIUMPHNETZER ZSG
Difference of Surfactant Classes
Anionic Surfactants - Types
Alkyl phosphate
PHOSFETAL
Alkyl ether phosphate
PHOSFETAL
Difference of Surfactant Classes
Anionic Surfactants - Types
Amino acid derivatives
PROTELAN
ZETESECO HS
Difference of Surfactant Classes
Surfactant classes - Nonionics
Z&S Products:
ZUSOLAT, OXETAL, MULSIFAN, PROPETAL, ZUTELAN, some ZETESECO types
Features in cleaners depending on the product:
- Wetting
- Emulsifying
- Degreasing
- Defoaming
- Thickening
Difference of Surfactant Classes
Nonionic Surfactants - Types
Fatty alcohol ethoxylates
ZUSOLAT
OXETAL
MULSIFAN
Fatty acid ethoxylate
MULSIFAN
Fatty alcohol alkoxylates (EO + PO)
PROPETAL
Difference of Surfactant Classes
Nonionic Surfactants - Types
Fatty amide ethoxylates
OXETAL A
Alkyl glucoside
ZUTELAN GL
Difference of Surfactant Classes
Surfactant classes - Amphoterics
Z&S Products:
AMPHOTENSID
Features in cleaners depending on the product:
- Hydrotropic power
- Foaming / foam boosting
- Thickening
- Improve skin compatibility
Difference of Surfactant Classes
Amphoteric Surfactants - Types
Betaine
AMPHOTENSID AB
Amido betaine
AMPHOTENSID B
Difference of Surfactant Classes
Amphoteric Surfactants - Types
Iminodipropionates
AMPHOTENSID EH
AMPHOTENSID CCF
Amine oxide
AMPHOTENSID COX
AMPHOTENSID DMOX
Difference of Surfactant Classes
Surfactant classes - Cationics
Z&S Products:
AUTOPOON 4012, AUTOPOON 4019
Features in cleaners:
- Creating hydrophobic surfaces
Difference of Surfactant Classes
Cationic Surfactants - Types
Alkyl ester quat
Part of
AUTOPOON 4012,
AUTOPOON 4019
Difference of Surfactant Classes
Hydrophilic vs. Hydrophobic Surfaces on a Car
TRIUMPHNETZER ZSG AUTOPOON 4019
Difference of Surfactant Classes
Surfactant classes - Other cationics (not Z&S)
Cationics have a strong adsorption at surfaces:
► Laundry: Fabric softener
► Hair conditioner: Antistatic effects
► Enrichment in cell membrane
→ some cationic surfactants are used as biocides
Difference of Surfactant Classes
“Take home messages I“
Surfactants accumulate at the interface of water and hydrophobic substances
(liquids, particles, air)
Above the CMC the surfactant monomer concentration is constant
Concentrated surfactant solutions create lyotropic liquid crystals which often are
highly viscous
Surfactants make it possible to formulate long-term stable dispersions and
emulsions
Surfactants are the key ingredients for most cleaning formulations
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“Take home messages II“
Nonionics and anionics: Suitable surfactants for nearly all surfactant
applications („allrounders“)
To get an ideal solution for a „problem“: Decision anionic and/or nonionic
surfactants depends on the special application
Nonionics: Temperature-dependence, Anionics: Salinity-dependence
Amphoterics: Special surfactants for high alkaline / salt solutions
Cationic surfactants: Strong adsorption to surfaces
Difference of Surfactant Classes
Thank you for your
attention.
Any questions?
