Synthesis and application of magnetic graphene nanocomposite for removal sodium dodecyl benzenesulfonate (SDBS) from aqueous solutions

Surfactants are one of the most important pollutants of surface water and underground water resources, and create potential health risks for humans and environment. The purpose of present study was to synthesize the MGNCs to be used for the removal of sodium dodecyl benzenesulfonate (SDBS) from aqueous solutions. First, graphene was synthesized through pyrolysis of orange peel as carbon precursor and KOH as an activating agent. The magnetic adsorbent nanocomposite was prepared through the solvothermal method using ferric chloride hexahydrate. The absorbent characteristics were analyzed using Fourier transformed infrared (FT-IR), vibrating sample magnetometer (VSM), Atomic force microscope (AFM), scanning electron microscopy (SEM) and Raman spectrometer techniques. The effects of the adsorbent amount, pH, the initial concentration of SDBS, and contact time were investigated for removal of SDBS. The adsorption isotherms were interpreted using Langmuir and Freundlich models and the kinetic data of adsorption process was also evaluated using pseudo-first-order and pseudo-second-order kinetic models. Based on the findings of the study, the absorbent dose of 20 mg, pH 3 and the contact time of 60 min were found to be the optimal conditions for the removal of SDBS. The equilibrium isotherm data fitted well with the Langmuir model (R2 = 0.9989) and the pseudo-second-order kinetic model was found to explain the adsorption kinetics more effectively (R2 = 0.9992). The maximum adsorption capacity of SDBS onto magnetic graphene nanocomposite was attained to be about 276 mg/g. Desorption experiments of ethanol and methanol from MGNCs were performed. The percentage adsorption recoveries of ethanol and methanol were 74 and 76%, respectively. The results showed that the as-synthesized MGNCs has an efficient and cheap adsorbent for removal of SDBS because of its high adsorption capability, high porosity, and large surface area and has the advantage of easy and rapid separation from the aqueous solution via external magnetic field.