Boron adsorption on the clay minerals, kaolinite and montmorillonite,
and two arid zone soils was investigated as a function of solution pH
(3-12) and presence of competing anions (nitrate, sulfate, molybdate,
and phosphate) after 2 h of reaction time, Boron adsorption on all mat
erials increased from pH 3 to 8, exhibited a peak at pH 8 to 10, and d
ecreased from pH 10 to 12. Boron adsorption was greatest using a NaNO3
background electrolyte, The competitive anion effects on B adsorption
increased in the order sulfate < molybdate < phosphate. The competiti
ve effect on B adsorption was small even for the strongly adsorbing an
ion, phosphate, Our results suggest that B-adsorbing sites are, genera
lly, specific to B and act independently of competing anions, This res
ult will simplify the description of B transport in that changes in so
lution concentration of competing anions may not have to be considered
.