A facile hydrothermal synthesis, adsorption kinetics and isotherms to Congo Red azo-dye from aqueous solution of NiO/graphene nanosheets adsorbent

•A series of NGNS samples were synthesized by hydrothermal method.•NGNS was characterized by UV–vis, TG, XRD, Raman, HRTEM, SAED and XPS methods.•The adsorption kinetic and isotherm models of NGNS toward CR were investigated.•The adsorbent can be separated from system effectively and easily.•The prepared NGNS has potential application for the CR dye treatment.

A series of NiO/graphene nanosheets adsorbents (NGNS) were synthesized by a facile hydrothermal method, and characterized by UV–vis, XRD, TG, TEM, HRTEM, Raman, SAED and XPS methods. The NGNS was applied to deal with wastewater solution containing Congo Red (CR); and adsorption efficiency attained 99.56% at optimum condition. The adsorption kinetic and isotherm of adsorbent toward CR were investigated. The results indicated that pseudo second-order kinetic model and the equilibrium data were well fitted by Redlich–Peterson model. The adsorbent can be separated from system effectively and easily. The prepared adsorbent has potential application for the wastewater treatment containing CR azo-dye.

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