Adsorption of divalent phosphate on hydrous aluminium oxide

THE adsorption of phosphate on aluminium and iron hydrous oxides is of practical importance in soils because of its influence on the availability of this nutrient to plants. One aspect of phosphate adsorption is the release of hydroxyl ions into the solution. This paper reports a quantitative relationship between divalent phosphate adsorbed on, and hydroxyl ions released from, hydrous alumina at different phosphate concentrations. From the relationship it is proposed that the phosphate ions are bonded to aluminium atoms forming both monodendate and bridged complexes.