Abstract

The continuous removal of copper ions from dilute feed streams by means of magnetic weak-base anion exchangers is studied experimentally and theoretically. After determining the respective equilibrium and kinetic parameters in initial batch experiments, pilot plant experiments were conducted with up to 0.4 m3/h throughput. The main parts of the pilot plant are a 0.12 m3 continuous stirred tank reactor (CSTR) for continuous copper ion removal, a settling tank in which the magnetic micro ion exchangers agglomerate and rapidly settle, and a reaction vessel for cyclic regeneration of the spent resin. With this set-up, continuous copper removal efficiencies of up to 70% could be achieved in the case of a 0.2 m³/h feed stream containing 0.145 eq/m³ copper ions.

In addition to the experimental investigations, a theoretical model was developed, which allows for the prediction of the pilot plant performance. Using a modified shell–core approach for the sorption kinetics in combination with the mass balances for a CSTR, the difference between the measured and predicted effluent concentrations was less than 10% in all cases examined. For the formulation of the model equations, two dimensionless numbers were defined for an easy identification of the bottlenecks of the process. The influences of process parameters like resin dosage, CSTR volume or resin particle diameter on the removal efficiency is discussed using these dimensionless numbers.