Effect of Gas Sparging on the Mass Transfer Rate at the Surface of a Cylinder

摘要

The rate of dissolution of copper in potassium dichromate solutions as oxidizing agent using gas (N_2) stirring as a means for enhancing the rate of mass transfer and reaction between a copper cylinder surface and the aqueous phase (K_2Cr_2O_7 + H_2SO_4 solutions) was studied. Variables studied were: N_2 flow rate, sulphuric acid concentration in the aqueous phase, height of copper cylinder and the temperature. The investigation revealed that the mass transfer coefficient increased with nitrogen flow rate, while the effect of copper cylinder height on mass transfer coefficient was negligible. The mass transfer coefficient was found to increase with temperature and the activation energy was found to be 18.3 kj/mol denoting a diffusion controlled process. Mass transfer data were correlated by the equation: J = 0.172 (Fr. Re)~(-0.31) with an average deviation of ±5%. The results were interpreted in the light of the theory of mass transfer and the behavior of gas bubbles in gas-liquid dispersions.