Research on Efficient Methylene Blue Adsorbents Based on Reduced Graphene Oxide–Calcium Sodium Aluminosilicate Nanocomposites

A series of reduced graphene oxide–calcium sodium aluminosilicate (rGO-CSA) composites with various rGO/CSA weight ratios (i.e., rGO/CSA 1/2.5, 1/5, 1/10, and 1/15) were successfully synthesized via hydrothermal reaction of CSA particles and GO nanosheets. The chemical compositions and morphology of as-synthesized rGO-CSA composites were characterized by XRD, SEM, BET and FTIR. Results from SEM revealed that CSA particles were deposited on the surface of rGO nanosheets resulting in rGO-CSA nanocomposites. N2-BET results showed that rGO-CSA4 composites with an rGO/CSA loading ratio of 1/15 showed a high specific surface area of 824.7 m2/g, which is higher than that of raw rGO (370.7 m2/g) and CSA (719.8 m2/g) materials. According the BET and SEM, it can be confirmed that the combination of rGO with CSA can reduce stacking during the drying process of rGO. The as-prepared rGO-CSA nanocomposites exhibited an excellent performance in the adsorption of methylene blue (MB). The rGO-CSA3 material exhibits an MB saturation adsorption capacity of 66.3 mg/g. Since rGO is the only adsorption-active material in the rGO-CSA3 composite, the rGO (9.09 wt%) in rGO-CSA exhibited an MB saturation adsorption capacity of 729.4 mg/L after content correction, which is far greater than the value of raw rGO material. The rGO-CSA3 composites showed superior adsorption efficiency of MB, mainly due to CSA particles effectively reducing rGO nanosheets stacking during the drying process.