Three-dimensional barium-sulfate-impregnated reduced graphene oxide aerogel for removal of strontium from aqueous solutions

A three-dimensional barium-sulfate-impregnated reduced graphene oxide (BaSO₄-rGO) aerogel was successfully synthesized by a facile one-step hydrothermal method and was used as an adsorbent to remove strontium from aqueous solutions. The characterized elemental composition, crystal structure, and morphology of the prepared aerogel confirmed that barium sulfate particles were firmly anchored on the surface of the rGO sheets and exhibited a porous 3D structure with a high surface area of 129.37 m²/g. The mass ratio of BaSO₄ in the BaSO₄-rGO aerogel substantially affected strontium adsorption, and the optimal BaSO₄/rGO ratio was found to be 1:1. The synthesized BaSO₄-rGO aerogel not only reached adsorption equilibrium within 1 h, but also showed much higher adsorption capacity than an rGO aerogel. The experimental data were well fitted to a pseudo-second-order kinetic model and the adsorption behavior followed the Langmuir isotherm. The adsorption capacity of strontium on BaSO₄-rGO aerogels remained relatively high even under ionic competition in simulated seawater. These results showed that the BaSO₄-rGO aerogel is an efficient and promising adsorbent for the treatment of strontium in aqueous solutions.