Fabrication of alginate/humic acid/Fe-aminoclay hydrogel composed of a grafted-network for the efficient removal of strontium ions from aqueous solution

Abstract

A polymer hydrogel composed of alginate/humic acid/Fe-aminoclay was fabricated and utilized as a potential adsorbent for the removal of strontium ions (Sr2+) from aqueous solution. The effects of adsorbate concentration, reaction pH, and time on the removal efficiency of Sr2+ were investigated. The results revealed that the adsorption capacity increases as the Sr2+ concentration increased from 1 to 10 ppm, which might be due to the more available adsorption sites. An additional increase in the Sr2+ concentration had no effect. The optimal pH and reaction time for the removal of Sr2+ were identified as pH 7 and 24 h, respectively, with an adsorbent dosage of 20 mg. The adsorption isotherm was fitted to the Freundlich model with a maximum Sr2+ adsorption capacity of 45.65 mg g(-1). The kinetic study showed that the adsorption behavior followed a pseudo-second-order kinetics. The hydrogel showed good selectivity toward Sr2+ even in the presence of competitive cations having a higher concentration than Sr2+. From the above results, it is expected that this biocompatible hydrogel material can be used as an adsorbent for the removal of radioactive strontium. (C) 2018 Elsevier B.V. All rights reserved.