The effects of radiofrequency electromagnetic radiation on the adhesion behavior of aqueous suspensions

The effect of radiofrequency treatment on the adhesion behavior of amidine and carboxylated polystyrene latexes was investigated. The isoelectric points pH(IEP) of copper and zinc were initially measured as 9.4 and 9.5, respectively, using a technique proposed by N. Kallay, Z. Torbic, M. Golic, and E. Matijevic [J. Phys. Chem. 95, 7028 (1991)] based on the attachment of charged colloids to metallic surfaces in an aqueous medium. Statistical analysis showed that the technique was repeatable with a coefficient of variation less than 6% and an accuracy greater than 95%. The effect of a radiofrequency signal (27 MHz) on adhesion behavior was evaluated and it was found that there was reduced attachment at pH values when the colloid and metallic surface were oppositely charged and enhanced attachment between similarly charged particles. It is proposed that this is due to a reduction in the surface potential of the charged particles due to thickening of the adsorbed layer by hydrogen and hydroxyl ions. (C) 2000 Academic Press.