Preparation of HPA/Bi₂WO₆ and its photocatalytic properties for denitrification

The HPA/Bi₂WO₆ was prepared with Na₂WO₄·2H₂O, Bi(NO₃)₃·5H₂O and different surfactant templates. The prepared sample was dried by the supercritical fluid drying (SCFD) method. It was characterized with XRD, FT-IR and SEM techniques and N₂ sorption experiment. Its photocatalytic properties were evaluated with denitrification of nitrogen-containing simulated oil as model reaction. It was shown that the sodium dodecyl sulfate (SDS) should be chosen as template. With this template, a highly dispersed, crystalline and active photocatalyst was obtained. This catalyst had a larger specific surface area. The SCFD method effectively decreased pore collapse and particles agglomeration degree, consequently increasing the specific surface area and improving the catalytic performance. Immobilization of H₃PW₁₂O₄₀ on Bi₂WO₆ increased the surface acid sites, and hence the photocatalytic activity. When the H₃PW₁₂O₄₀ loading was 10%, about 92.08% of nitrogen in simulated oil were removed by shining for 3 h with a xenon lamp at the m_catalysts/m_simulated oil ratio of 1:100.