The Preparation And Selective Photocatalysis Properties Of Molecular Imprinted TiO₂

Now, environmental problem has got more and more attention, and TiO2photocatalyst is popular for its unique advantage, it can degrade organic and inorganic pollutants completely without secondary pollution. Now, the TiO2materials mainly exists in the form of powder and thin film, this article focuses on composing and studying TiO2thin film.Because of the process of TiO2degrade pollutant is consisted of a series of free radical reactions, so TiO2show no selectivity. This article use a new method to compose TiO2, which combined molecular imprinting technology, make the synthesized TiO2thin film can degrade salicylic acid in solution selectively. For increasing the selectivity, we added Ti(NH4)2F6in raw materials, synthesized TiO2/SiO2composite films. In order to make the TiO2has the best catalytic activity, these films were calcined in400℃to let TiO2obtain anatase phase. In order to compare, we didn’t only synthesize molecular imprinted TiO2/SA and TiO2/SiO2/SA thin films, but also synthesized pure TiO2and TiO2/SiO2thin films.We do XRD, SEM, IR and TG analysis on these films. XRD show that TiO2in all films ate in anatase phase, IR and TG indicate that TiO2/SiO2/SA film act with salicylic acid in the synthesis process. For the calcined films, we use TG test the force between film and target molecules, the result show that TiO2/SiO2/SA film have the biggest react force toward salicylic acid. In the experiments of photodagradation of salicylic acid solution over films, TiO2/SiO2/SA film shows the better degradation ability than other three kinds of films. To test the selectivity ability toward target molecule, we have chosen five materials that is similar to the structure of salicylic acid, such as phenol、 p-hydroxybenzoic acid、p-Toluic acid、4-Methyl salicylate and hydroxyphenylacetic acid. Let the films degrade these substances in solution respectively in single system, by the compare of the rate constant k value, we find that TiO2/SiO2/SA film show the best selectivity toward target molecule, and though the data summarized the influence factors of molecular recognition function. At last we synthesized TiO2powder. TiO2/SA powder、TiO2/SiO2powder and TiO2/SiO2/SA powder in the same way, by the DCV test, we found that TiO2/SiO2/SA powder have the largest combination capacity of salicylic acid. In the photodegradation test, TiO2/SiO2/SA film show the best degrade effect and good selectivity. What’s more these powder can use more longer UV light ant the light use efficiency higher than thin film.