Efficient removal of Co(II) and Sr(II) from aqueous solution using polyvinyl alcohol/graphene oxide/MnO2 composite as a novel adsorbent.

In this study, a novel adsorbent, polyvinyl alcohol/graphene oxide/MnO2 composite was prepared, characterized and used for efficient removal of Co2+ and Sr2+ from aqueous solution. Polyvinyl alcohol (PVA) and Mn2+ played a synergistic role in the gelation of PVA/GO/Mn2+, while Mn2+ can be further converted into oxide to achieve functionalized aerogel (PVA/GO/MnO2). The spectroscopy analysis manifested that hydrogen bonds and electrostatic attraction were responsible for the formation of PVA/GO/MnO2. The functionalization of MnO2 enhanced the adsorption capacity for Co2+ (2.1 folds) and Sr2+ (1.3 folds) by PVA/GO/MnO2. The composite showed high adsorption capacity at broad pH range of 4.0-9.0. For competitive adsorption test, Ni2+/Zn2+ exerted the most interfering effect on Co2+ adsorption, while Mg2+/Ca2+ showed severe interfering effect on Sr2+ adsorption. Both electrostatic attraction and oxygen-containing groups contributed to the adsorption mechanism. This study may provide a new adsorbent for separation of Co2+ and Sr2+ from aqueous solution.