Preparation Of Novel Photocatalysts And Photodegradable Plastic Films

Nowadays, the environment continues to get worse on the one hand, on the other hand, fuel energies are consumed every second while there is no substitute energy to replace to it. Photocatalysis, which has been studied extensively for more than 40 years, proceeds to be given specific focus to by scientists. It is and always was a tough task for scientists to discover or to be precise, compose a semiconductor photocatalyst which is visible light driven and of high quantum efficiency. At the same time, as one emerging way to deal with “white pollution”, solid-phase photocatalytic degradation of polymers, also requires the development of photocatalysis. In the paper, based on the relevant references, a novel Ag3PO4/Ag2CO3 composite photocatalyst and two photodegradable PVC films were successfully prepared. The main content of the thesis is as follows:In the first chapter, basic concepts of photocatalysis such as development background, principles, affecting factors and latest research progress were briefly discussed. Traditional ways to process white pollution, basic concepts of photodegradable polymers and related but latest research progress were also be included.A series of novel high-efficiency visible-light sensitive Ag3PO4/Ag2CO3 composite heterojunction photocatalysts were investigated in chapter two. And Rh B was employed as a target pollutant to explore the efficiency of liquid-phase photocatalytic degradation of organic pollutants. A facile coprecipitation process was employed to synthesize Ag3PO4/Ag2CO3 composite photocatalysts. Powder X-ray diffraction(XRD), transmission electron microscopy(TEM), UV–vis diffuse reflectance spectroscopy(UV–vis DRS) and transient photovoltage(TPV) were conducted to characterize these products and these results showed that Ag3PO4/Ag2CO3 n-p heterojunction composite photocatalysts were successfully synthesized. It was found that with the optimal content of Ag3PO4(n(P)/:n(C)=40%), the Ag3PO4/Ag2CO3 exhibited the highest photocatalytic degradation efficiency of Rh B under visible light irradiation. Besides, we also investigated the active species which played the most important role of oxidation during photocatalytic reactivity and found that 40%-Ag3PO4/Ag2CO3 photocatalyst could generate more h+ active species compared to pure Ag3PO4 and Ag2CO3, which played the most important role of photocatalytic degradation of Rh B for Ag3PO4, Ag2CO3 and Ag3PO4/Ag2CO3 composite photocatalysts. All these results indicated that Ag3PO4/Ag2CO3 photocatalytic degradation of Rh B was a photo-oxidation reaction, and Ag3PO4/Ag2CO3 composite photocatalyst was more efficient in photocatalytic degradation of Rh B or in photo-oxidation reaction compared to pure Ag3PO4, Ag2CO3 because the formation of heterojunction led to the effective separation of photoinduced electron-hole pairs and the low recombination rate of charge carriers.The influence of adding methanol on PVC films’ properties was discussed in chapter three and a PVC-Ti O2-CH3 OH composite film was successfully prepared. The results of weight loss indicated that PVC-Ti O2-CH3 OH composite film showed higher degradation behaviors, compared to pure PVC and PVC-Ti O2 film. It can be seen with naked eye that the surface of PVC-Ti O2-CH3 OH composite film was smooth and many nano-scale cavities could been seen with the help of SEM. Compared to the smooth surface in nano-scale of pure PVC, light could be reflected many times in the PVC-Ti O2-CH3 OH composite film when irradiated by UV light, which is good for the light absorption and enhancing photodegradation of PVC.The application of Proline modified Ti O2 photocatalyst to photocatalytic degradation of PVC films was investigated in the fourth chapter. Because of its special molecular structure, Proline is widely employed in the small organic molecules catalyzed reactions. In the paper, a facile method was employed to synthesize Pro modified Ti O2 photocatalyst which was then imbedded to the PVC film to prepare PVC-Ti O2-Pro Na composite film. The outcome of solid-phase photocatalytic degradation of PVC-Ti O2-Pro Na film suggested that Ti O2 was better dispersed in the Pro Na modified PVC-Ti O2 film, which is good for enhancing nanomaterials photocatalytic degradation efficiency of polymers.