Enhanced adsorption of Orange G dye using activated diatomite: a novel functionalization approach

Abstract

This research explores the effectiveness of cetyltrimethylammonium bromide (CTAB)-modified diatomite-based alkali-activated material (GP-DR@CTAB) for removing the organic contaminant Orange G (OG) from polluted water through adsorption. The samples were extensively characterized using techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD confirmed the activation of diatomite, while XPS and FTIR verified the successful incorporation of CTAB into the alkali-activated matrix. The GP-DR@CTAB exhibited a significantly higher surface area (107.13 m² g⁻¹) compared to the unmodified material (15.92 m² g⁻¹). The pseudo second order kinetic model best described the adsorption kinetics for both DR and GP-DR@CTAB, as evidenced by the highest correlation coefficients (R² = 0.9901 and 0.9993, respectively) and the close agreement between the experimental and calculated adsorption capacities. Both the Langmuir and Freundlich adsorption isotherms were tested, and the Langmuir model showed the highest correlation with the experimental data. Overall, the results confirm that GP-DR@CTAB is a highly effective and promising adsorbent for the removal of OG from water.