Removal of Copper(II) and Zinc(II) Ions in Water on a Newly Synthesized Polyhydroquinone/Graphene Nanocomposite Material: Kinetics, Thermodynamics and Mechanism

An effective polyhydroquinone/graphene nanocomposite was developed to remove Cu(II) and Zn(II) metal ions in water. The composite nanomaterial was characterized by FT-IR, SEM, TEM, XRD, Raman spectroscopy, and thermo-gravimetry. The surface of the material was heterogeneous with 10–20 nm particle size. The adsorption capacity of Cu(II) and Zn(II) metal ions were 40.9 and 24.8 μgg^−1, respectively. The sorption followed Langmuir, Freundlich, Tempkin and D−Rs models. The process of adsorption was successfully described by pseudo-second-order model, thereby indicating the chemical nature of the main adsorption mechanism. Thus, it can be argued that the adsorption proceeded in a mixed-diffusion mode, with a significant contribution of a large number of high affinity active sites located on the adsorbent surface. The uptake time was 60 and 15 minutes for Cu(II) and Zn(II) at pH 6.0; indicating fast hydro-friendly nature and making the method applicable to solve water pollution in real life problems. Therefore, the reported method may be used to remove Cu(II) and Zn(II) metal ions in any water resource.