Uranium removal onto chitosan: Competition with organic substances

Organic materials and especially humic substances are often present in natural waters. The influence of organic compounds on uranium removal onto chitosan is studied. The pH of the media is fixed at 6. In operating conditions, uranium major species present in solution are: (UO2)(3)(OH)(5)(+) and (UO2)(4)(OH)(7)(+). Capacity of fixation is found to be 450 mg g(-1), considering precipitation phenomena. Experimental results show that chitosan offers a selective adsorption depending on the different organics used: the adsorption capacity is maximum with benzaldehyde, average with humic acids, limited with phenol and insignificant with benzoic acid. Phenol does not affect the fixation capacity of uranium significantly whereas benzoic add and benzaldehyde have an average effect upon it and humic acids decrease it to 200 mg g(-1) and less as the concentration of the acid increases.