Silica Aerogel Composite Bismuth Tungstate Photocatalyst

At present, due to the increasingly serious energy shortage and environmental pollution problems of the rapid development of industry, clean energy and demand to the efficient use of solar energy clean technology is getting more and more urgent, and the photocatalytic technology for its environmental protection and energy saving, mild reaction conditions and no two pollution has showed good application prospect, in many photocatalytic the material, Bi₂WO₆ is currently the research more, a catalyst of visible light photocatalytic activity of light is also good.

Bi₂WO₆ is a typical semiconductor material. By light irradiation, electrons undergo photoexcited transitions and leave corresponding holes to form electron-hole pairs. These photogenerated electron hole pairs have strong redox ability. They are easy to redox reaction with organic compounds and polymers, and their response to visible light is good due to their narrow band gap. However, this also increases the recombination probability of the photogenerated electron hole, reduces the efficiency of the light quantum, and affects the photocatalytic performance of Bi₂WO₆. Therefore, it is necessary to study the Bi₂WO₆ photocatalyst with high activity, high stability and good recycling performance.

After many scholars' research, bismuth tungstate has already had ten kinds of compound schemes. Some scholars proposed a silica aerogel compound bismuth tungstate photocatalyst scheme, supported silica as carrier and enhanced bismuth tungstate, so as to improve its catalytic activity.

With the two step acid-base catalysis by 20mL tetraethoxysilane (TEOS), 20mL (ETOH), ethanol 8mL water, two 7mL N-N dimethylformamide (DMF), finally adding 10 L of concentrated hydrochloric acid as catalyst, DMF as drying control chemical additive (DCCA), is used to form a three-dimensional network of gel regulation the. The gelatinization temperature is 60 degrees. The gelation process is carried out in the oil bath environment. The stirring method is selected as magnetic stirring. The stirring speed is 500 revolutions / minutes, the stirring time is 1.5h, and the pH value of gelation is 6. In the process of gelation, the alkali regulator is used as ammonia. Add 180mg or bismuth tungstate before the gel, continue stirring for a period of time, wait for gel, gel, add aging solution, aging solution is ethanol, aging time is 2 times, and use n-hexane for one time. They were dried at atmospheric pressure for 2 days at the normal temperature, and then dried in the oven at 60 degrees. They were dried 8h at 80 degrees, dried at 4h, and dried 2H at 100 degrees Celsius. Silica aerogel composite bismuth tungstate photocatalyst was obtained.

The silica aerogel composite tungstic acid cerium photocatalyst can effectively treat the herbicide 2,4‐D, or phenol, methylene blue, rhodamine B, methyl orange, heavy metal ion chromium, lead and mercury ions and other polluted wastewaters, has a very important environmental significance.

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