J.A. Davis T.D. Waite T.E. Payne 1996 <div class="nova-c-card nova-c-card--spacing-m nova-c-card--elevation-none"><div class="nova-c-card__body nova-c-card__body--spacing-inherit"><div class="nova-e-text nova-e-text--size-m nova-e-text--family-sans-serif nova-e-text--spacing-auto nova-e-text--color-inherit">Uranium adsorption on ferrihydrite was studied as a function of pH in systems equilibrated with air, in the presence and absence of added phosphate and humic acid (HA). The objective was to determine the influence of PO43- and HA on uranium uptake. Below pH 7, the sorption of UO22+ typically increases with increasing pH (the 'low pH sorption edge'), with a sharp decrease in sorption above this pH value (the 'high pH edge'). The presence of ΣPO43- of 10-4 mol/L moved the low pH edge to the left by approximately 0.8 pH units. The PO43- was strongly bound by the ferrihydrite surface, and the increased uptake of U was attributed to the formation of ternary surface complexes involving both UO22+ and PO43-. The addition of HA (9 mg/L) increased U uptake at pH values below 7, with little effect at higher pH values. The positions of the pH edges were also affected by the ionic strength and total U content. These experiments show that sorption interactions involving PO43 and HA must be considered in order to model the behavior of U in natural systems, in which these components are often present.</div></div></div> application/pdf 10.1524/ract.1996.74.special-issue.239 en De Gruyter Uranium adsorption on ferrihydrite - Effects of phosphate and humic acid article