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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, N2 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 (qemax) 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 (ΔG0), entropy change (ΔS0) and enthalpy change (ΔH0) 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.

In this paper, we report graphene oxide (GO) supported Platinum(Pt)-Cobalt(Co) nanomaterials produced by a simple hydrothermal method after a series of water-ethanol treatments. To understand the change in chemical states, surface and crystal structure of the obtained Pt-Co@GO nanomaterials, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) analyses were used. Pt-Co@GO nanomaterials exhibit a high adsorption effect in the methylene blue (MB) removal from the aqueous medium. The parameters including ultrasonic irradiation method contact time (1–90 min), initial dye concentration, temperature (293–323 K) and pH (4–10) were investigated for removal MB using Pt-Co@GO nano-adsorbent. The kinetic studies show that the MB adsorption processes can be described by pseudo-first-order, the pseudo-second-order model, and intraparticle diffusion. Thermodynamic activation functions including enthalpy change (?H0), Gibbs free energy change (?G0), and entropy change (?S0) were determined. The maximum adsorption capacity of the synthesized Pt-Co@GO nano-adsorbent reaches 273.6 mg/g under the condition that the pH 10, 318 K and the initial dye concentration is 3.0 × 10-5 M. It is understood from the obtained data, Pt-Co@GO nano-adsorbent has demonstrated to be an effective nano-adsorbent for removing MB under several parameters in aqueous solution by ultrasonic process systems. © 2018, Dumlupinar Üniversitesi: 2014-05, The authors would like to thank to Dumlupinar University ( 2014-05 ) and Igdir University for funding.