Preparation, characterization and adsorption kinetics of methylene blue dye in reduced-graphene oxide supported nanoadsorbents

Reduced-graphene-oxide-supported Ni nanoadsorbents (Ni@rGO) were synthesized in this work to remove methylene blue (MB) dye from aqueous solutions using ultrasonic process method. These synthesized nanoadsorbents were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, N-2 sorption, and X-ray photoelectron spectroscopy (XPS) apparatus. The effect of independent parameters (initial dye concentration, H2O2 concentration, adsorbent particle concentration, initial pH, contact time, and temperature were investigated) on dye removal efficiency with Ni@rGO nanoadsorbents. The zero charge points (pHzpc) of the Ni@rGO composite particles were determined by using experimental results. The max adsorption capacity (qe(max)) of the removal of methylene blue (MB) with Ni@rGO was determined as 946.12 mg g(-1) as a result of experimental data under optimum conditions using ultrasonic process method. The experimental data obtained in the kinetic study concluded that the adsorption process was more consistent with the pseudo second-order model. Thermodynamic functions such as Gibbs free energy change (Delta G(0)), entropy change (Delta S-0) and enthalpy change (Delta H-0) values were investigated in order to get an idea about the working mechanism of MB as a result of adsorption interaction with Ni@rGO composite particles. As a result of all the data obtained Ni@rGO nanoadsorbent has proven to be an effective nanoadsorbent material to remove methylene blue from aqueous solution under different parameters in ultrasonic process systems. (C) 2020 Elsevier B.V. All rights reserved.