Desorption of cobalt-laden algal biosorbent

Following an effective accumulation of cobalt by nonliving algal biomass of Ascophyllum nodosum, the desorption release of the metal from the biosorbent was examined using H(2)SO(4), HCl, NH(4)OH, KHCO(3), EDTA, KSCN, KCl, and CaCl(2) solutions. The solution of CaCl(2) (0.05M) in HCl appeared to be the best eluant capable of desorbing more than 96% of the sequestered cobalt at the optimum pH 2-3. The optimum solid-to-liquid ratio was more than 10 with the cobalt reuptake capacity of the biosorbent undiminished. The effect of temperature on the elution process and the elution rate was not significant up to 60 degrees C. The infrared (IR) spectra of the native and the eluted biomass did not show significant differences. The electron micrographs of the algal biomass taken after washing it with the CaCl(2) (0.1M) eluant solution indicated no damage to the cells and cell walls, while strong acid, alkaline, and KSCN treatment resulted in some changes in the cellular structure. The kinetics of the cobalt stripping process was quite rapid. The required contact time for the complete metal removal from the biomass was shorter than 2 h, even for the highest levels of cobalt initially deposited on the biomass.