Specific sorption of antimony (III) by the hydrous oxides of Mn, Fe, and Al

The hydrous oxides of Mn, Fe, and Al avidly sorbed Sb from mu M Sb(OH) sub(3) solutions, with uptake levelling off as initial Sb concentration increased. Capacity values decreased along the sequence MnOOH > Al(OH) sub(3) > FeOOH. The amount sorbed by each substrate decreased gradually at pH values > 6. Addition of 0.4M CH sub(3)COONa to the aqueous phase (to minimise retention of weakly bound Sb) had little effect on MnOOH uptake capacity ( similar to 160 mmol kg super(-1) at pH < 7) but retention dropped rapidly at higher pH. With the other two substrates (pH 6-7) the calculated capacity values for specific Sb sorption were similar to 45 mmol kg super(-1) FeOOH and similar to 33 mmol kg super(-1) Al(OH) sub(3); about a third of the total capacity values. On these substrates specific Sb sorption tended to peak in the pH 7 to 8 region. The pH response pattern was modified using Sb tartrate sorbate solutions.