The effect of cetyltrimethylammonium bromide (CTAB) addition on green synthesis of porous N-doped TiO2 for photoreduction of heavy metal ion Cr(vi)

Abstract

In this study, porous TiO₂ photocatalysts modified by nitrogen (NCT) were successfully synthesized using a combination of green synthesis methods by utilizing Aloe vera (L.) Burm. f. peel and hydrothermal method. In addition, TiO₂ was modified by increasing the active surface area using Cetyltrimethylammonium Bromide (CTAB). The X-ray Diffraction (XRD) results indicated that the anatase phase was formed. The result of the Diffuse Reflectance Spectroscopy UV-Vis (DRS UV-Vis) using the Tauc-plot method showed that all porous N-doped TiO₂ samples experienced a decrease in the energy gap. This indicates the successful modification of TiO₂ by nitrogen, as confirmed by the Fourier Transform Infra-Red (FTIR) result. Field Emission Scanning Electron Microscopy (FESEM) result showed that the synthesized TiO₂ had a spherical morphology of 10–30 nm diameter. The Braunauer, Emmett, and Teller (BET) result indicated that the type IV isotherm curve with a mesoporous structure was formed. The NCT0.75 sample had a surface area and pore size of 95.02 m² g⁻¹ and 8.021 nm, respectively, while the NTi0.75 sample had a surface area and pore size of 90.97 m² g⁻¹ and 5.161 nm, respectively. The photocatalytic activity of the porous N-doped TiO₂ was tested on photoreduction of metal pollutant model Cr(VI). The result demonstrated that the NCT0.75 sample had the most optimal photocatalytic activity by reducing 89.42% of Cr(VI) metal ions.