Adsorptive removal of Sr(II) from aqueous solution by polyvinyl alcohol/graphene oxide aerogel

In this study, a new adsorbent, polyvinyl alcohol (PVA) and graphene oxide (GO), was prepared, characterized and used for the removal of Sr²⁺ from aqueous solution. In PVA/GO composite, the inter-lamellar spacing of adjacent GO layers was dramatically enlarged due to the intercalation of PVA molecules, such a unique architecture significantly mitigated the aggregation of GO layers, which facilitated the accessible exposure of active sites and the mass transfer of strontium ions (Sr²⁺), thus enhancing the adsorption capacity toward Sr²⁺. The adsorption of Sr²⁺ by PVA/GO composite conformed to the pseudo second-order kinetic model (R² = 0.9994), the Langmuir model (R² = 0.9042), and the Freundlich model (R² = 0.9598). The complexation interaction between Sr²⁺ and oxygen atoms/π-electron domain of PVA/GO composite was primarily responsible for the adsorption mechanism, based on the characterization results of X-ray photoelectron spectroscopy (XPS), scanning electron microscope equipped with energy dispersion spectroscopy (SEM-EDS) and powder X-ray diffraction (PXRD).