Effect of surfactants on the rate of diffusion-controlled Cementation of copper from dilute solutions on a stationary zinc disc in stirred vessels
✍ Scribed by Mahmoud A. Zarraa
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 511 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0933-5137
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✦ Synopsis
Abstract
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:
Where Sh is Sherwood number, Re is Reynolds number, and Sc is Schmidt number.