Synthesis and characterization of graphene oxide functionalized with MnFe2O4 and supported on activated carbon for glyphosate adsorption in fixed bed column

Glyphosate removal from contaminated water using a new adsorbent material was investigated. Graphene-MnFe2O4 nanocomposite supported on vegetal activated carbon (GO-MnFe2O4/VAC) was synthesized. Several characterization techniques such as transmission and scanning electron microscopy, N-2 physisorption, energy dispersive X-ray spectrometry, Fourier transformed infrared spectroscopy, X-ray diffraction and Raman spectroscopy were used to have insights to this material. Furthermore, the point of zero charge was determined. GO-MnFe2O4/VAC material was evaluated for glyphosate adsorptive removal in fixed-bed column under different operating conditions of solution concentration and feed flow rate. The results pointed out that glyphosate adsorption using GO-MnFe2O4/VAC was favored at pH values between 2.29 and 6.14. In fixed-bed column, the best results were obtained for the solutions having higher concentrations and also for higher feed flow rates. The equilibrium experimental data were fairly described by Langmuir model with maximum adsorption capacity reaching 6.778 mg g(-1). Among the mathematical models evaluated to describe the breakthrough curves, the best fit to the experimental data was obtained by model that considers the intraparticle diffusion and the internal diffusion step was considered to be the mass transfer limiting step. The present results indicated that the adsorbent material synthesized has a great capacity for adsorption and prove the potential of use of GO- MnFe2O4/VAC for glyphosate removal from contaminated water in the continuous mode of operation. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.