Fabrication of flexible EDTA-linked 3D graphene sponge for effective adsorption of copper

Heavy metal contamination in water sources poses a significant environmental and health risk, necessitating the development of efficient technologies for their removal. In this study, we have fabricated a novel, self-standing, durable, compact, and effective adsorbent by modifying a graphene sponge with N-(trimethoxysilylpropyl) ethylenediamine triacetic acid (EDTA-silane) to enhance its affinity for copper ions (Cu2+) serving as a model. The structural, crystallographic, and morphological properties of the EDTA-silane functionalized graphene sponge were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction spectroscopy, and scanning electron microscopy. Batch adsorption experiments revealed exceptional Cu2+uptake capacity, with a maximum adsorption capacity of 1058.6 ± 32.7 mg g−1for 72 h adsorption time. Kinetic studies demonstrated that the adsorption process followed a pseudo-second-order model, while isotherm analysis indicated multilayered adsorption consistent with the Freundlich model. The high adsorption capacity is attributed to the synergistic effects of the porous structure of the sponge and the strong chelation ability of EDTA groups. These results suggest that EDTA-silane modified graphene sponge is a promising and highly efficient material for copper ion removal.