Graphene mesosponge: a novel material for the sequestration of azo dyes in water

Azo dyes are synthetic organic compounds widely used in industries such as textiles, printing, and pharmaceuticals. Due to their chemical stability and extensive usage, they are significant environmental pollutants, especially in wastewater. This study investigates the removal of azo dyes from aqueous solutions using a graphene mesoporous sponge (GMS), which is a high-surface sponge-like mesoporous structure predominantly composed of single-layer graphene walls with active sites for dye adsorption. Methylene Blue (MB) and Congo Red (CR) were used to evaluate adsorption performance in aqueous solutions simulating industrial effluents. The adsorption behavior, capacity, and kinetics were studied experimentally, showing that GMS efficiently removes both dyes. Complete decolorization occurred in 30-35 min for both dyes at an initial concentration of 1 mg L^-1. A relatively small quantity of GMS successfully removed significant amounts of dye, highlighting its potential to minimize material usage. This efficiency enhances the process's economic feasibility while contributing to environmental sustainability by reducing the carbon footprint of adsorbent synthesis and usage. These results indicate that GMS is a promising material for wastewater treatment. The experimental results are also aligned with ab-initio molecular dynamics (AIMD) calculations, and they confirm the superior performance of GMS over pristine graphene in dye adsorption.