kinetics, and thermodynamic studies of nickel adsorption from aqueous solutions using melamine-modified nanographene oxide

Today, one of the most important issues in water resources is pollution caused by heavy metals. nickel is widely used in various industries. nickel is one of the most important pollutants in the environment and its removal is very important. there are several methods for separating heavy metals from aqueous media. among all methods, adsorption is a low-cost and simple method for removing heavy metals at low and medium concentrations. the aim of this study is to investigate the adsorption efficiency of nickel ions from aqueous solutions using melamine modified nanographene oxide. melamine-modified nanographene oxide was investigated by fourier-transform infrared spectroscopy (ftir) tensor 27 mode. the pseudo-first-order and pseudo-second-order kinetic models were investigated. finally, thermodynamic parameters such as enthalpy and entropy change as well as gibbs free energy were calculated. in the kinetic studies, according to the linear regression coefficient of 0.3084 for the pseudo-first-order, and 0.9970 for the pseudo-second-order model, it was found that the pseudo-second-order model better describes the adsorption process of nickel by the melamine-modified nanoadsorbent. the maximum adsorption capacity and removal percentage occur at a concentration of 200 mg/l, during 150 min, which is equal to 1915.75 mg/g and 99.82%, respectively. the adsorption reaction of nickel ions on the surface of melamine-modified nanographene oxide was spontaneous and endothermic with an increasing entropy. nanographene oxide modified by melamine has a special surface and high potential and is a suitable adsorbent for removing nickel from aqueous solutions.