Nonionic
surfactants are surface active agents which do not dissociate
into ions in aqueous solutions, unlike anionic surfactants which
have a
negative charge and cationic surfactants which have a positive charge
in aqueous solution. Nonionic surfactants
are more widely used as detergents than ionic surfactants because anionic surfactants are insoluble in
many hard water and cationic surfactants are considered to be poor cleaners. In
addition to detergency, nonionic surfactants show excellent solvency, low foam properties
and chemical stability. It is thought that nonionic
surfactants are mild on the skin even at high
loadings and long-term exposure. The hydrophilic group of
nonionic surfactants is a polymerized alkene oxide (water soluble
polyether with 10 to 100 units
length typically). They are prepared by polymerization of ethylene oxide, propylene oxide, and butylene oxide in the
same molecule. Depending
on the ratio and order of oxide addition, together with the number of carbon atoms
which vary the chemical and physical properties, nonionic
surfactant is used as a wetting agent, a detergent, or an emulsifier.
HLB (Hydrophilic-Lipophilic Balance)
values for proper applications.
<10 :
Lipid soluble (or water-insoluble) >10 : Water Soluble 4-8 :
Antifoaming 7-11 : Water-in-oil emulsion 12-16 : Oil-in-water
emulsion 11-14 : Good Wetting 12-15 : Good detergency 16-20 :
Stabilizing
Nonionic
surfactants include alcohol ethoxylates, alkylphenol
ethoxylates, phenol
ethoxylates, amide ethoxylates, glyceride
ethoxylates
(soya
bean oil and caster oil ethoxylates), fatty
acid ethoxylates, and
fatty amine ethoxylates. Another commercially significant nonionic surfactants are the alkyl glycosides
in which the hydrophilic groups are sugars (polysaccharides).
Alcohol ethoxylates, clear to yellowish liquid to waxy solids depending on
alkyl chain length and the number of ethoxy groups, are non ionic surfactants
which contain both hydrophobic tail portion (alcohol part) and hydrophilic
polar head groups (ethoxy chain part), and are thus tend to dissolve in both
aqueous and oil phase and to reduce the surface tension of liquids. Ethylene
oxide (also called epoxyethane and oxirane) is the simplest cyclic ether or
epoxide, with the formula C2H4O; reactive material which is added to the base of
alcohols (or amines) to form ethoxylated surfactants. The Hydrophilic-Lipophilic Balance (HLB) of
EO surfactant is related to the hydrophilic portion of the molecule. More
hydrophilic groups enable more solubility in water as more hydrogen
bondings exist. They are non-ionic in solution which has no electrical charge, which
means well-work in hard water at low temperatures as well as stability in acid
and alkali solution and compatibility with other surfactants. Generally,
surfactant's name are formed by adding the mole number of ethylene oxide. There
is a wide HLB range depend their molar ratios between nonylphenol and E.O. The common mole ratio forms for
detergency are NPE 9 - 12, where the number indicates
ethoxylate chain length.
The lower number mole ratio products are used as wetting agent whereas the higher moles ratio products are emulsifiers
and solubilizer. Nonylphenol ethoxylates features excelent emulsifying and
high detergency
properties.
End
applications include;
Detergents
and Industrial Cleaners, Dispersants, Stabilizers, Sanitizers, Defoaming
Agents. Agrochemical Emulsifiers, Metal Working, Textile
Processing, Paper De-inking, Drilling Products Intermediate
Anionic Surfactants Synthesis, Dust Control, Adhesive, Plastic Industry, Lube Oil,
Cosmetic and Pharmaceuticals.
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