Direct estimation of hexadecyltrimethylammonium-ion adsorption at liquid interfaces by a radioisotope technique. I. Specific ion effects at air-water interface

Flocculation Studied with the ESA Technique

The aim of this paper is to show that the ESA (electrokinetic sonic amplitude) technique can be used to study the flocculation between cationic polyelectrolytes and negatively charged silica particles. The ESA signal was measured when cationic polyacrylamide (CPAM) or cationic polyamine (POL) was mixed with silica particles. The dynamic mobility of the formed flocs was calculated from the corrected ESA signal. The amount of nonadsorbed polyelectrolyte was determined by viscosity. The floc sediment volume was also measured. It was found that the polyacrylamide molecule was more efficient than the polyamine molecule in neutralizing the charges on the silica particles due to the longer CPAM molecules and the larger distance between the CPAM charges which was in better accordance with the distance between the silica charges compared to POL. Copyright 1999 Academic Press.

The use of a multichannel scaling method to detect radioactive species in spread monolayers

This study describes a simple and inexpensive method for monitoring radioactive species spread as monolayers at the air/water interface. The combination of a discriminator and multichannel scalar counter with a personal computer functions to unify all measurements, to simplify the operational process and data acquisition, and to provide a real-time display of the data. Its use is demonstrated by following the hydrolysis of L-alpha-[1-14C]dioleoyl phosphatidylcholine by the enzyme, phospholipase A2, isolated from the porcine pancreas.