Characterization of TiO2 and an as-prepared TiO2/SiO2 composite and their photocatalytic performance for the reduction of low-concentration N-NO3− in water
2022
Zhong, Wanzhen | Fu, Weizhang | Sun, Shujuan | Wang, Lingsheng | Liu, Huaihao | Wang, Junzhi
Excessive N-NO₃⁻ water pollution has become a widespread and serious problem that threatens human and ecosystem health. Here, a TiO₂/SiO₂ composite photocatalyst was prepared via the sol–gel/hydrothermal method. TiO₂ and TiO₂/SiO₂ were characterized by X-ray diffraction (XRD), UV–Vis differential reflectance spectroscopy (DRS), Fourier infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Afterward, the photocatalytic performance of TiO₂ and TiO₂/SiO₂ to reduce low nitrate concentrations (30 mgN L⁻¹) under UV light was evaluated and the effects of different factors on this process were investigated, after which the reaction conditions were optimized. Removal rates of up to 99.93% were achieved at a hole scavenger (formic acid) concentration of 0.6 mL L⁻¹, a CO₂ flow rate of 0.1 m³ h⁻¹, and a TiO₂ concentration of 0.9 g L⁻¹. In contrast, TiO₂/SiO₂ at a 1.4 g L⁻¹ concentration and a TiO₂ load rate of 40% achieved a removal rate of 83.48%, but with more than 98% of nitrogen generation rate. NO₂⁻ and NH₄⁺ were the minor products, whereas N₂ was the main product.
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