Graphene-based nanomaterials for the removal of organic pollutants: Insights into linear versus nonlinear mathematical models

The adsorption-desorption behavior of methylene blue, acid orange 7, bisphenol A, and phenol on the synthesized graphene-based nanomaterials were studied. For this purpose, adsorption experiments were conducted in a batch setup and different parameters such as contact time, pH, adsorbent dose concentration, and initial micropollutant concentration were considered. In addition, linear and nonlinear kinetic and isotherm models were evaluated. The nonlinear pseudo-second-order models (R-2 > 0.98), Elovich kinetic models (R-2 > 0.94), and Langmuir isotherm models (R-2 > 0.98) best fitted the experimental data. Because of the high specific surface area and the type of oxygen functional groups, mechanochemically synthesized graphite oxide exhibited high adsorption capacities for methylene blue, acid orange 7, bisphenol A, and phenol, with a maximum uptake of 288, 232, 110, and 68 mg g(-1), respectively. Furthermore, the total costs of applying the mechanochemically synthesized graphite oxide were estimated in the adsorption process, revealing that these nanomaterials offer better uptake values than porous carbon.