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.