Chemistry Reference
In-Depth Information
results approaching those obtained using smaller quantities of synthetic detergents.
The net result is a much higher organic load on the ecosystem—a very important
factor in terms of sewage treatment and environmental impact.
Alcohol ethoxylate (AE) surfactants, representing about 12% of consumption,
have shown better-than-average growth more recently relative to other surfactants.
They exhibit several important advantages, including good detergency at low wash-
ing temperatures, low foaming characteristics, good detergency in phosphate-free
formulations, good performance with synthetic fibers, and good performance in
low-temperature industrial processes. Because they can be made from both petro-
leum and renewable raw materials, AE surfactants have a stable position in that
respect.
Alkylphenol ethoxylate (APE) surfactants make up approximately 10% of over-
all consumption. While effective in many industrial applications, they face a num-
ber of environmental challenges that could greatly reduce their use in the future. Of
major importance are questions concerning their relatively slow rate of biodegrada-
tion and the possible toxicity of degradation intermediates, especially phenols and
other aromatic species. In the United States and western Europe, many detergent
manufacturers have voluntarily discontinued their use in household products.
The alcohol ether sulfates (AES) represent approximately 9% of industrialized
surfactant consumption. Because of their perceived ''mildness,'' they are used pri-
marily in personal care products. They have a strong position in terms of raw mate-
rials since they can be made from either petroleum or renewable (i.e., agriculturally
derived) raw materials. One possible disadvantage of AES surfactants is the possi-
ble presence of dioxane derivatives as a byproduct of the ethoxylation process.
Although modern processes have been shown to effectively eliminate the presence
of such contaminants, emotional factors and lack of good information must always
be considered, especially where consumer products are concerned.
The alcohol sulfates (AS) surfactants constitute approximately 6% of surfactant
consumption. They have the advantage of being efficiently derived from renewable
sources and can function as partial replacements for LABS in some applications.
Their current major applications are in personal care products and emulsion poly-
merization processes. Because their biodegradability is essentially the same as that
of soaps, AS surfactants seem to have a reasonably friendly reception on environ-
mental grounds.
1.5. THE ECONOMIC AND TECHNOLOGICAL FUTURE
The wide variety of lyophobic (''hydrophobic'' in aqueous systems) and lyophilic
(or ''hydrophilic'' in water) groups available as a result of advances in synthetic
technology and the development of new raw-materials resources provides an extre-
mely broad menu from which the surfactant shopper can select a material for a par-
ticular need. By carefully analyzing the overall composition and characteristics of a
given system, the investigator or formulator can choose from one of the available
classes of surfactants based on charge type (i.e., the ionic properties of the surface-
