Effect of humic acid on sorption of technetium by alumina

► Tc sorption on alumina has been studied under aerobic as well anaerobic condition over pH 3-10. ► Effect of humic acid on sorption of Tc by alumina has been investigated. ► Linear additive modeling and surface complexation modeling were carried out to delineate the role of humic acid in Tc(IV) sorption in ternary system of Tc(IV)-humic acid-alumina. ► Sorption of humic acid onto alumina and strong complexation of Tc(IV) with humic acid were found to govern the sorption of Tc(IV) in the ternary system.