Novel CTAB functionalized graphene oxide for selenium removal: adsorption results and ANN & RSM modeling

This study explored the potential of cetyltrimethylammonium bromide functionalized graphene oxide (CTAB@GO composite) to remove selenite and selenate from wastewater, given the health hazards related to selenium. It demonstrated outstanding adsorption capacities of 140 and 468 mg/g for selenite and selenate respectively, outperforming other GO composite adsorbents. The CTAB@GO composite was synthesized through a novel method involving sonication and dropwise addition of CTAB solution to GO dispersion. The composite was characterized using X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), indicating the successful incorporation of CH₃-N⁺ groups on the surface of GO, which created an electrostatic force with the anionic SeO₃²⁻ and SeO₄²⁻ species. Both the Response Surface Methodology (RSM) and the Back Propagation Artificial Neural Network (BP-ANN) were utilized to model the removal process, with strong model fits shown by the R² values for selenite and selenate removal. The Redlich-Peterson and Avrami models were the best-fitted models for adsorption isotherm and kinetics respectively. The study concluded that the CTAB@GO composite is an effective adsorbent for treating water containing selenite and selenate species.