Rate of cadmium ions removal from dilute solutions by cementation on zinc using a rotating fixed bed reactor

The present study is concerned with the removal of Cd (II) ions from wastewater by cementation on zinc Raschig rings placed in a rotating basket reactor. The influence of several parameters on the rate of cementation such as initial concentration of cadmium ions, temperature, basket rotation speeds and diameter of zinc rashing rings have been investigated. The rate of cementation was found to increase with increasing bed rotational speed and temperature. On the other hand the rate decreases with increasing the initial cadmium ions concentration in solution and the diameter of zinc Raschig rings. The activation energy was found to be 3.99 kCal/mol. The present reactor proved to be an efficient reactor for cementation reactions in view of its high area per unit volume and its high rate of mass transfer. Rates of cementation which can be expressed in terms of the rate mass transfer were correlated to the controlling parameters by the dimensionless equation Sh = 0.046 Re 0.45 Sc 0.33 esent mass transfer data was found to agree with the surface renewal theory.