ADSORPTION OF NONIONIC SURFACTANTS
BY ACTIVATED CARBON AND CLAY
J. B. Carberry, Assistant Professor
Department of Civil Engineering
University of Delaware
Newark, Delaware 19711
A. T. Geyer, III, Project Environmental Engineer
David W. Taylor Naval Ship Research/Development Center
Annapolis, Maryland 21402
INTRODUCTION
Nonionic surfactants are being widely adopted over the traditional ionic surfactants
for a number of reasons:
1. Nonionic surfactants do not require the presence of undesirable phosphate builders
or caustic builders in the detergent formulation in order to achieve cleaning effectiveness.
2. Synthetic fabrics do not require harsh cleansing conditions usually imposed with
ionic surfactants.
3. Nonionic surfactants appear to stimulate fewer allergenic responses in human skin
tissues than do ionic surfactants.
4. Nonionic surfactants achieve more effective cleansing action in salt water.
Nonionic surfactants, however, suffer from an important disadvantage compared to
ionic surfactants, and that is their degree of degradability.   Preliminary work has shown
that the biodegradability of nonionic surfactants lies between that of the nonbiodegradable pre-1965 alkyl benzene sulfonates and that of the easily degradable linear akyl sulfonates which were adopted in ionic detergent formulations by 1965 [1-5].   Certainly,
nonionic surfactants are not as refractory in the natural environment as were the pre-1965
alkyl benzene sulfonates; they are not, on the other hand, as quickly degraded in biological wastewater treatments plants as are the linear alkyl sulfonates used presently in ionic
surfactant detergent formulations.
Two general classifications of nonionic surfactants originate from the method of manufacture [6]:
1. Polydisperse molecular weight compounds -those which utilize a hydrocarbon species
as a lipophilic base for the attachment of condensed ethylene oxide units.   The
molecular weight of the manufactured compound can be quite accurately controlled
so that the product, although not 100% pure, will contain a Gaussian distribution
of molecular weights.   In such a case, an average or mean molecular weight will describe the molecule accurately enough.
2. Heterodisperse molecular weight compounds-those which utilize a polyhydroxyl
alcohol (polyol), condensed into a heterogeneous ring structure, as a lipophilic phase.
Here, polymerized eithylene oxide units (or other hydrophilic species) can be attached
to any or all carbons in the condensed polyol ring.  The condensation of ethylene
oxide units on the multiple condensation sites of the heterogeneous ring results in
compounds having irregular distributions of molecular weights.
The adsorption of heterodisperse nonionic surfactants (Tweens, Spans, Myrjs and
Brijs, ICI, United States, Inc.) on clay has been reported previously [7].   The present
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