EQUILIBRIUM AND KINETIC-STUDIES OF COPPER-ION UPTAKE BY CALCIUM ALGINATE

Equilibrium and kinetic experiments of copper ion uptake by calcium al ginate beads were carried out under different values of pH, ionic stre ngth, initial concentration of copper ion, and amount of calcium algin ate. The removal efficiency increases with increasing pH and decreasin g ionic strength and initial concentration. The removal of copper occu rs rapidly in the first hour, followed by a slow process that takes ab out 15 h. The copper ion uptake becomes faster with increasing pH and decreasing initial copper concentration and ionic strength. Mass trans port of copper ions plays an important role in the kinetics of uptake. Equilibrium experiments show that surface complex formation is the ma jor mechanism for copper ion uptake. Modeling of equilibrium and kinet ics was also conducted based on a surface complexation approach. Model ing results showed that the two-pK Basic Stern model can successfully describe the effect of pH on equilibrium uptake. A diffusion-controlle d model can also predict the effect of pH on the kinetics.