الفهرس 
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Abstract
In the present study. the rate of diffusion controllt:d corrosilln in rectangular bubble columns was studied by determining the rate of diffusion controlled dissolution of copper walls of a rectangular bubble column in acidified dichromate solution in absence and presence of ceramic suspended solids. The rate of diffusion controlled corrosion was measured by analyzing the solution with time .The effect of different variables on the rate of diffusion controlled corrosion was studied, and these variables were: physical properties of solution, superficial air velocity, height of solution in the column ,and presence of suspended solids at different concentrations and sizes.
The present study revealed that • the rate of di ffusion controlled corrosion increases with increasing superficial air velocit~ and decreases with either increasing the solution height in the column or increasing H2S04 concentration .Also it was found that the presence of suspended solids increased the mass transfer coefficient of the corrosion process by amount of 5-16 % depending on superficial gas velocity and suspended solids concentration and particle size. The rate of diffusion controlled corrosion increases as the concentration of suspended sol ids increases and as the particle size decreases.
The rate of diffusion controlled corrosion was related to the other parameters using the method of dimensional analysis and the following overall equations were obtained:
-0.220 -0.169
J = 0.232 ( Fr.Re ) . ( Lid. ) • for particle free solution
-0.214 0.186
J = C.171 ( Fr.Re ) . ( Lldp ) • in presence of suspended solids