Bismuth Tungstate / Polyaniline Composite Photocatalyst

Some new non TiO2 photocatalysts have been developed, such as perovskite type, vanadium subgroup complex oxide and bismuth series photocatalyst, since TiO₂ has been found to be able to degrade water and degrade organic pollutants under ultraviolet radiation. The research of new photocatalytic Bi₂WO₆ has been developed in recent ten years. Only the pure phase Bi₂WO₆ has low quantum efficiency, and its low utilization rate of visible light (about 400nm), which limits its application in photocatalysis.

Bismuth tungstate is a kind of easy to be compatible photocatalyst. It is easy to improve the performance of compound modification. There are many methods of modification of bismuth tungstate. Researchers have proposed a preparation method provides a simple process and excellent product performance of the bismuth tungstate / polyaniline composite photocatalyst. This composite photocatalyst is said to have worked wonders for wastewater treatment of methylene blue.

1.The preparation process of bismuth tungstate / polyaniline composite photocatalyst: Na₂WO₄ solution was added to the Bi(NO₃)₃ solution, at room temperature in the fully mixed reaction; under the stirring condition, adding NaOH solution to the mixed liquid in regulating pH, and then transferred to the reactor, the product obtained after the reaction was washed with distilled water and ethanol, dried at 60 ℃ to obtain bismuth tungstate powder;

2.The bismuth tungstate and polyaniline were compounded: 0.009g polyaniline (PANI) was added to 20mL NMP (N- methyl pyrrolidone) (PANI, 0.45g/L), ultrasonic 30min was used to disperse it evenly. Then, according to the different mass ratio of PANI/Bi₂WO₆, the Bi₂WO₆ powder was dispersed in the 0.45g/L polyaniline organic solution, ultrasonic about 30min, then stirred 6h, washing centrifugation and drying, the final product of bismuth tungstate and polyaniline powder was obtained.

0.02 g of bismuth tungstate / polyaniline powder was dissolved in 20 mL of 10 mg / L methylene blue solution and irradiated for 2h under a light source of λ = 365 nm. The supernatant after centrifugation was tested with a UV-visible spectrometer. When the wavelength range is 200nm-800nm, PANI / Bi₂WO₆ mass ratio is 1%, prepared bismuth tungstate / polyaniline heterojunction photocatalyst has the highest photo-degradation rate of methylene blue to 82.5%.

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