EFFECT OF SURFACE-ACTIVE SUBSTANCES ON THE RATE OF PRODUCTION OF COPPER-POWDER FROM COPPER-SULFATE SOLUTIONS BY CEMENTATION ON ZINC RODS INGAS SPARGED REACTORS

The effect of surface-active substances on the rate of diffusion-contr olled cementation of copper on a single vertical zinc rod from dilute copper sulphate solutions was studied, Variables investigated were: ni trogen superficial velocity, concentration and type of surface-active substance, These variables were studied for their effect on the mass t ransfer coefficient of copper cementation, The mass transfer coefficie nt was found to increase with increasing superficial gas velocity, Inc reasing surfactant concentration was found to decrease the mass transf er coefficient, It was found that surfactants decrease the mass transf er coefficient by an amount ranging from 14% to 39% depending on the s uperficial gas velocity and type of surfactant added. The ability of t he four types of surfactants to decrease the mass transfer coefficient increases in the order: CTMAB < Aspecon-1030 < SABS < NPPGE. Mass tra nsfer data were correlated by the equation: Sh = 7.25 We(0.88) Sc-0.33 for the conditions: Sc = 1430 and 4.2 < We < 43.6, when Sh is a Sherw ood number, I Ve is a Weber number and Sc is a Schmidt number. In para llel with measuring the mass transfer coefficient, gas hold-up and sol ution surface tension were also measured to assess how these parameter s are affected by the presence of surface-active substances.