Reduced graphene oxide composite aerogel prepared by europium-assisting radiation reduction as a broad-spectrum adsorbent for organic pollutants

Abstract

Reduced graphene oxide (rGO) composite aerogels were synthesized by the radiation reduction of graphene oxide (GO) with the assistance of Eu³⁺, which demonstrated excellent adsorption performance for diverse organic pollutants. Eu³⁺ promoted the formation of the gel by inducing the pre-assembly of GO so that the required pH range for synthesizing the rGO aerogel by radiation reduction was broadened and the minimum absorbed dose was also reduced. At pH 2, the Eu³⁺-induced pre-assembly fabricated more mesopores and enlarged the specific surface area of the obtained hierarchically porous rGO-Eu composite aerogel, which enabled the high-capacity (81–395 g g⁻¹) and ultrafast removal of organic solvents. The different effects of organic solvents on the unique fluorescence emission of Eu(III) also allowed the in situ detection of certain organic solvents such as pyridine. At pH 6, Eu³⁺ enhanced the reduction of GO by capturing more hydrated electrons, the most reductive species produced by water radiolysis, and synergistically reduced GO. The obtained rGO-Eu composite aerogel with a high reduction degree, demonstrated outstanding adsorption capacities for various anionic organic dyes (40.5–1572.5 mg g⁻¹) owing to the strong π–π interaction and electrostatic attraction. Benefitting from high reduction, it demonstrated adsorption capacity for cationic dyes (97.3–1367.6 mg g⁻¹) comparable to other reported graphene-based aerogels. The rGO-Eu aerogel prepared by radiation reduction might be suitable as a broad-spectrum adsorbent for organic pollutants.