Biosorption of nickel(II) and copper(II) ions in batch and fixed-bed columns by free and immobilized marine algae Sargassum sp.

In this study, the brown algae harvested in the State of Pernambuco - Brazil, Sargassum species, and the commercial sodium alginate were used as free and immobilized biosorbents for the removal of nickel and copper ions in batch and continuous experiments from aqueous solutions. The alginate beads and immobilized biosorbent were produced from the ionic polymerization using the drip method in calcium chloride solution. Equilibrium data show that the calcium alginate matrix increased the maximum biosorption capacity in immobilization, and both biosorbent materials presented greater affinity and uptake capacity for copper ions than for nickel ions. The experimental results were better fitted to the Langmuir model than to the Freundlich model, obtaining favorable type isotherms. Continuous systems showed a different equilibrium condition, once the experiments carried out in fixed-bed columns presented higher biosorption capacity than those performed in batch experiments, also suggesting that the bed packed with immobilized biosorbent was not affected by the low porosity. The immobilized biosorbent also had easy packing.