Purification of Water Contaminated with Heavy Metals by Example of Lead as a Promising Material Based on Graphene Nanostructures

This paper estimates the efficiency of using graphene nanostructures in water purification from lead(II) ions to improve the ecological situation of water bodies. The mechanisms and characteristic parameters of the adsorption process were analyzed using empirical models of isotherms at the temperatures of 298, 303, 313, and 323 K, which correspond to the following order (based on the correlation coefficient): Langmuir (0.99) > Temkin (0.97) > Dubinin-Radushkevich (0.90). The maximum adsorption capacity of the material ranged from 230 to 260 mg/g. The equilibrium was investigated at the level of thermodynamic parameter estimates, which indicated the spontaneity of the process, its endothermic nature, and structural changes in graphene modified with phenol-formaldehyde resin during the adsorption of lead(II) ions, resulting in a higher disorder of the system.