Adsorption of heavy metals from aqueous media on graphene-based nanomaterials

The present paper considers experimental studies carried out to determine the effective kinetic parameters of the adsorption of heavy metal ions (Cu²⁺, Zn²⁺, and Cr³⁺) from aqueous solutions using graphene oxide (GO) and the composite materials on the basis thereof - polyamine cumulene/graphene (PAC/G) and polyquinone/graphene (PQ/G) - under static and ambient temperature conditions. The following results were obtained: GO - adsorption time 20 min (for all the metal ions), and adsorption capacity 60, 26, and 5.5 mg g^-1 (for Cu²⁺, Zn²⁺+, and Cr³⁺, respectively); PAC/G: adsorption time 30 min, adsorption capacity 26 mg g^-1 (for Cu²⁺); and PQ/G: adsorption time 30 min, adsorption capacity - 40 mg g^-1 (for Cu²⁺). According to the experimental data, more than 90 % of the adsorption capacity was achieved in the first 20 min of the contact between the GO and the heavy metal solutions. The equilibrium of the system was reached at the same time, regardless of the extracted component and the degree of adsorption. The PAC/G and PQ/G also exhibited high adsorption capacity values for the heavy metal ions in comparison with the conventional materials. Thus, the graphene-based nanomaterials can be successfully used for removing the heavy metal ions from aqueous media, which is very important from an environmental point of view (e.g., water treatment purposes).