Removal of 4-nitrophenol using high performance magnetic graphene oxide nanocomposite: synthesis, characterization

Magnetic graphene oxide (MGO) as a carbon based material was synthesized through a co-precipitation method and characterized via FTIR, XRD, SEM and BET analysis to obtain an economically recoverable adsorbent in order to 4-nitrophenol (4-Np) removal. The performance of the process was investigated as a function of operating conditions including temperature, solution pH, mixing time and 4-Np initial concentration. The experiments represented that synthesized MGO has an excellent adsorption capacity for removal of 4-Np which has a cost effective recovery ability. The results showed that the time to reach an equilibrium system was obtained at 70 min. Langmuir isotherm model and for kinetic, pseudo second order were best fitted with experimental data. The thermodynamic parameters showed that the adsorption process was physical and spontaneous. The adsorption mechanism was discussed and the pi-pi stacking and electrostatic interactions were supposed as the main mechanisms of adsorption of 4-Np on adsorbent. Finally, response surface methodology (RSM) as a statistical investigation was used to optimize adsorption factors to obtain maximum adsorption capacity and investigate the interactive effect of parameters using box-behnken design (BBD). Optimum conditions obtained by response surface method for temperature, initial concentration, pH, time and maximum adsorption capacity were calculated 25 degrees C, 320 ppm, 3.95, 120 min and 486.6 mg g(- 1), respectively.