Langmuir 2001, 17, 1315-1315 Reply to Comment by R. O’Brien on “Electroacoustic Phenomena in Concentrated Dispersions: New Theory and CVI Experiment”
We would like to explain our reasoning for including Dr. O’Brien’s name in the titles of the original theories. There are now two quite different approaches for deriving electroacoustic theory. The original and best-known approach employs the now well publicized relationship between the electroacoustic effect and electrophoretic mobility, which was suggested several years ago by Dr. O’Brien. This relationship has been the basis for much of the electroacoustic theoretical development in the past decade. This relationship is of key importance for this first approach, and that is why we decided to include the author’s name in the title of all theories derived using this approach. We are somewhat surprised that Dr. O’Brien wishes to distance himself from this important contribution, which he even patented (eq 4 in ref 1). We would also like to make clear that we do not consider theories derived using this first approach as “awful” or “bad”. Just the opposite. They are good theories, but they have limitations as all theories have. It would be rather naive to expect a theory to be valid always. We just clarified these limitations in our paper. The reader can go to the original paper2 for a detailed theoretical and experimental analysis. The second approach was used 50 years ago by Booth and Enderby. It does not require the reciprocal relationship suggested by Dr. O’Brien. We have modified this (1) O’Brien, R. W. Determination of Particle Size and Charge. U.S. Patent 5,059,909, Oct 22, 1991. (2) Dukhin, A. S.; Shilov, V. N.; Ohshima, H.; Goetz, P. J. Electroacoustic Phenomena in Concentrated Dispersions: New Theory and CVI Experiment. Langmuir 1999, 15 (20), 6692-6706.
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second approach and derived a new theory which works for very concentrated dispersions, at least as far as describing the colloid vibration current.2 We have used Dr. O’Brien’s name only in order to distinguish between these two approaches. We have no objection against removing his name from the titles of the theories that are based on the first approach. We apologize if we hurt his feelings. Perhaps instead of using names, it would be better to use the basic notions for distinguishing them. For instance, we can associate the first approach with “electrophoretic dynamic mobility” which may be abbreviated as the EDM approach. Because our approach is based on the direct calculation of the colloid vibration current, this might be abbreviated simply as the DCM approach (“direct calculation model”). Andrei Dukhin* and Philip Goetz
Dispersion Technology Inc., 3 Hillside Avenue, Mount Kisco, New York 10549 Vladimir Shilov
Institute of Biocolloid Chemistry, Academy of Sciences of the Ukraine, Kiev, Ukraine Hiroyuki Ohshima
Faculty of Pharmaceutical Sciences and Institute of Colloid and Interface Science, Science University of Tokyo, 12 Ichigaya Funagawara-machi, Shinjuku-ku, Tokyo 162-0826, Japan Received October 16, 2000 In Final Form: November 16, 2000
10.1021/la001454c CCC: $20.00 © 2001 American Chemical Society Published on Web 01/20/2001
LA001454C
