APPLICATION AND DETERMINATION OF SURFACE-ACTIVE AGENTS
PARTI: CATIONIC SURFACTANTS
Lawrence K. Wang, Associate Professor
Stevens Institute of Technology
Hoboken, New Jersey 07030
Robert G. Ross, Environmental Engineer
U.S. Army Mobility Equipment Research and Development Command
Fort Belvoir, Virginia 22060
Mu Hao Wang, Associate Professor
Department of Environmental Engineering
National Cheng Kung University
Tainan, Taiwan, China
INTRODUCTION
Application of Cationic Surfactants
The most common cationic surfactants being used in the industry are quaternary ammonium compounds.   They are being used as sanitizers in kitchens to a considerable extent.   The quaternary ammonium compounds containing iodine and bromine have been
found effective for bactericidal treatment [1-6].   More recently, a quaternary ammonium
compound containing chloride (i.e., cetyldimethylbenzyl ammonium chloride) has also
been demonstrated to be an excellent disinfectant [7-10].   Mallmann reported [11] that
they should be used in the hand washing of utensils and all washing of bottles and glasses
because they are also excellent detergents.   Quaternary ammonium compounds are not
widely used as household detergents due to their higher cost compared with that of common anionic detergents such as linear alkylate sulfonate (LAS) and alkylbenzene sulfonate
(ABS).
Cationic quaternary ammonium compounds are also frequently used as flotation agents
[12-25], primary coagulants and/or coagulant aids [26-28], softening agents, dyeing aids,
metal cleaners, corrosion inhibitors [2] and algicides.   Odorous effluents from industrial
processes and odors produced by the biodegradation of organic wastes are frequent sources
of pollution complaints.   Research by Schwartz [29] has shown that quaternary ammonium
salts seem to be doubly effective in controlling these malodors.   The cationic surfactants
react directly with the molecules of odorants, and kill the microorganisms that might cause
future odors.
Determination of Cationic Surfactants
For environmental engineering process control, the concentration of a cationic surfactant
to be used should be known, and any changes in concentration of such surfactant in each
unit process should be adequately monitored.   For the quality controls of drinking water,
plant effluents, irrigation waters and natural surface and ground waters, analysis of cationic
surfactant concentration in the water is also extremely important.   Unfortunately, the
Standard Methods for the Examination of Water and Wastewater [30] and the Environmental Protection Agency's laboratory manual [31] only provide the methods for analyzing anionic surfactants, such as LAS and ABS, in natural and treated waters.   These is no
standard method for measuring cationic surfactants so far.   Nevertheless many laboratory
techniques have been developed.   A critical review of some available techniques for the
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