Chemistry Reference
In-Depth Information
was the branched alkyl (PT) chain that hindered attack by the microorganisms.
Fatty acid sulfates, on the other hand, were found to degrade readily, and since
all naturally occurring fatty acids from which fatty alcohols are produced are
straight-chained, it seemed probable that a straight-chain alkylbenzene might
prove more easily biodegradable.
Test methods for determining degradability were developed and showed that, in
fact, linear alkylbenzene sulfonates (LABS) were significantly more biodegradable
and hence ecologically more acceptable. In most of the industrialized world, deter-
gent producers, voluntarily or by legislation, have switched from ABS to LABS as
their basic detergent building block. By the 1980s, more than 75% of synthetic
detergents were of the LABS family.
The change to LABS feedstocks gave some rather surprising results. It was
found that detergency in many heavy-duty cleaning formulations using LABS
was approximately 10% better than when ABS were used. Solutions of the neutra-
lized acid had a lower cloud point (see glossary in Section 1.8), and pastes and slur-
ries had a lower viscosity. The first two results were obviously advantageous, and a
lower viscosity in slurries had an advantage when the product was processed into
a powder. When the LABS product was to be sold as a liquid or paste detergent,
however, the lower viscosity was seen as a detriment to sales appeal and had to be
overcome.
Today, even though many of the application areas such as detergents and clean-
ing products are considered to be ''mature'' industries, the demands of ecology,
population growth, fashion, raw-materials resources, and marketing appeal have
caused the technology of surfactants and surfactant application to continue to
grow at a healthy rate overall, with the usual ups and downs that accompany
most industries.
While a large fraction of the business of surfactants is concerned with cleaning
operations of one kind or another, the demands of other technological areas have
added greatly to the enhanced role of surfactants in our modern existence. Not only
are personal care products becoming an even greater economic force in terms of
dollar value and total volume; applications as diverse as pharmaceuticals, petro-
leum recovery processes, high-tech applications, and medicine are placing more
demands on our ability to understand and manipulate interfaces through the action
of surface-active agents. As a result, more and more scientists and engineers with
little or no knowledge of surface chemistry are being called on to make use of the
unique properties of surfactants.
1.2. THE ECONOMIC IMPORTANCE OF SURFACTANTS
The applications of surfactants in science and industry are legion, ranging from pri-
mary production processes such as the recovery and purification of raw materials in
the mining and petroleum industries, to enhancing the quality of finished products
such as paints, cosmetics, pharmaceuticals, and foods. Figure 1.1 illustrates a few of
the major, high-impact areas of application for surfactants and other amphiphilic
