Synthesis and characterization of nano magnesium oxide impregnated granular activated carbon composite for H2S removal applications

Abstract In this study, a composite of nano‑magnesium oxide (MgO) and granular activated carbon (GAC) was synthesized and analyzed for its H2S adsorption capacity. The synthesis of composite involved a spray technique, which incorporates nano MgO even into micropores of GAC. The nanocomposite was characterized structurally and chemically, using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2-BET adsorption studies, ultra-violet photoelectron spectroscopy (UPS) and near edge X-ray absorption fine structure spectroscopy (NEXAFS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The composite described herein showed more than five times higher H2S adsorption capacity than the virgin GAC. The high adsorption capacity shown by the MgO-GAC composite could be attributed to the fact that the composite structure exploits both physical and chemical adsorption processes simultaneously. The physical adsorption was occured at the macro and mesoporous structure of GAC whereas as the chemical adsorption was at the nano-MgO site. The differential thermogravimetric (DTG) analysis evidenced that the main mode of chemical adsorption was the oxidation of H2S, whereas a secondary metal supported addition mechanism was also shown to exist.