| Summary: | Titanium dioxide (TiO<sub>2</sub>) has been widely applied as a photocatalyst for wastewater treatment due to its high photocatalytic activity and it can remove various harmful organic pollutants effectively. Under heated system, however, TiO<sub>2</sub> is prone to agglomeration that decrease its abilities as a photocatalyst. In order to overcome the agglomeration and increase its thermal resistance, addition of silica (SiO<sub>2</sub>) as supporting material is proposed in this research. Silica or silicon dioxide can be extracted from natural resources such as beach sand. Here, we report the application of a composite photocatalyst of TiO<sub>2</sub>/SiO<sub>2</sub> to remove phenolic compounds in wastewater. The photocatalyst was synthesized by adding SiO<sub>2</sub> from beach sand onto TiO<sub>2</sub> through impregnation methods. The results of the X-ray diffraction (XRD) showed that TiO<sub>2</sub> was present in the anatase phase. The highest crystallinity was obtained by TiO<sub>2</sub>/SiO<sub>2</sub> ratios of 7:1. SEM results showed that the shape of the particles was spherical. Further characterizations were conducted using Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, and a particle size analyzer (PSA). By using the optimized condition, 96.05% phenol was degraded by the synthesized photocatalyst of TiO<sub>2</sub>/SiO<sub>2</sub>, under UV irradiation for 120 min. The efficiency of the TiO<sub>2</sub>/SiO<sub>2</sub> is 3.5 times better than commercial TiO<sub>2</sub> P25 for the Langmuir–Hinshelwood first-order kinetic model.
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