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Effect of surfactants on the rate of diffusion‐controlled Cementation of copper from dilute solutions on a stationary zinc disc in stirred vessels
Author(s) -
Zarraa Mahmoud A.
Publication year - 1996
Publication title -
materialwissenschaft und werkstofftechnik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.285
H-Index - 38
eISSN - 1521-4052
pISSN - 0933-5137
DOI - 10.1002/mawe.19960271107
Subject(s) - copper , mass transfer , chemistry , mass transfer coefficient , impeller , cementation (geology) , pulmonary surfactant , zinc , diffusion , rotational speed , analytical chemistry (journal) , sherwood number , dissolution , reynolds number , chromatography , thermodynamics , metallurgy , materials science , turbulence , organic chemistry , biochemistry , physics , quantum mechanics , cement , nusselt number
The effect of surfactants on the rate of diffusion‐controlled cementation of copper from dilute copper sulphate solutions on a stationary zinc disc in a stirred vessel was studied. Variables investigated were rotational speed of the impeller, concentration and type of surfactants and concentration of copper sulphate solution. These variables were studied for their effect on the mass transfer coefficient of copper cementation. The mass transfer coefficient was found to increase with increasing rotational speed of the impeller and concentration of copper sulphate solution. It was found that surfactants decrease the rate of mass transfer during cementation by an amount ranging from 9.5 to 25° depending on the rotational speed of the impeller and type of surfactant added. Increasing surfactant concentration was found to decrease the mass transfer coefficient. The ability of different surfactants to decrease the mass transfer coefficient increases in the order: CTMAB < SABS < NPPGE. Mass transfer data were correlated, in absence and in presence of surfactants, by the following equations respectively:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}l} {\rm Sh = 1 .55}\,{\rm Re}^{0.68}\, {\rm Sc}^{{\rm 0 .33}} \\[6pt] {{\rm and}} \\[6pt] {{\rm Sh = 4}{\rm .1 Re}^{{\rm 0}{\rm .43}} {\rm Sc}^{{\rm 0}{\rm .33}} } \\ \end{array} $$\end{document} Where Sh is Sherwood number, Re is Reynolds number, and Sc is Schmidt number.