Mixed electrolytes producing very weak electroacoustic signal

The electrokinetic potential of powders dispersed in concentrated solutions of salts can be determined by electroacoustic methods when the ESA (electrokinetic sonic amplitude) signal of electrolyte is properly corrected for. We propose an alternative solution to the problem of electroacoustic measurements at high ionic strengths; that is, the composition of mixed electrolytes with common ions can be adjusted to minimize the ESA signal of the electrolyte. The measurement of electrokinetic potential of powders dispersed in such mixed electrolytes does not require electrolyte background correction. Mixed electrolytes, which produce very weak ESA signals, were prepared from the following salts with common ions: Li+ (LiNO3 + LiCl), Na+ (NaNO3 + NaBr), K+ (KBr + KNO3), and NO-3 (LiNO3 + KNO3). Proportions of the components in these mixed electrolytes are concentration dependent. The electrokinetic potentials of alumina in these mixed electrolytes determined with and without background correction were only marginally different. © 2007 Elsevier Inc. All rights reserved.