The Preparation Of Bismuth-based Photocatalytic Materials And Its Photocatalytic Performance

With the rapid development of industry production in our country, the quantity of wastewater discharge has also increased at the same time. Dye wastewater is a kind of common industrial effluents. It has the characteristics of complex chemical composition, high hardness, and difficult to completely degradation, which could not achieve the desired effect using general method. In recent years, the rapid development of photocatalytic technology in the treatment of these pollutants was expected to provide an effective way to solve this problem. Among them, the degradation effect of bismuth-based photocatalyst is especially significant. Even more importantly, bismuth-based photocatalyst has a rather narrow band gap which could expand the absorption region of light and fully absorb the visible light, so the visible light photocatalytic activity of them is outstanding. A series of excellent features make bismuth-based photocatalyst become the hot spot of present research. This thesis mainly focuses on the preparation and photocatalytic performance of Bi OBr and Bi OBr/Bi OI composite photocatalyst, which is mainly divided into three aspects:(1)Bi OBr/Bi OI composite was successfully synthesized by a simple hydrothermal method using Bi(NO3)3?5H2O, KI, Na Br and PEG-400 as materials. The prepared samples were characterized by XRD, SEM, UV-Vis DRS and PL techniques. The photocatalytic activity of the samples was discussed in detail under visible light irradiation. The result shows that Bi OBr/Bi OI composite has a better photocatalytic activity than pure Bi OBr and Bi OI. After irradiation for 80 min under visible light, 95.6% of the dyestuff was degraded by the composite.(2)Flower-like Bi OBr photocatalyst was successfully synthesized by a simple hydrothermal method using Bi(NO3)3?5H2O, Na Br, PEG-400 and CTAB as materials. The prepared samples were characterized by XRD, SEM, UV-Vis DRS and PL techniques. Rhodamine B solution was used as dye pollutants to estimate the visible light catalytic activity based on the difference of adding surfactant. The result shows that the catalyst prepared by adding CTAB has a better photocatalytic activity, corresponding to 95% of Rh B photodegradation within 100 min under visible light irradiation.(3)Bi OBr photocatalyst was successfully synthesized by a simple hydrothermal method using Bi(NO3)3?5H2O and Na Br as materials. PEG-400 and CTAB were also used as templates in this system. The molar ratio of Bi and Br was designed for 3:2, 3:4, 3:6, and 3:8, respectively. The photocatalytic activity of Bi OBr which prepared in two templates with different ratio of Bi and Br was investigated in visible light, and then the effect of the initial concentration of the solution and p H in photocatalytic degradation was discussed. The prepared samples were characterized by XRD, SEM, UV-Vis DRS and PL techniques. Methyl orange solution was used as dye pollutants to estimate the visible light catalytic activity. The result shows that the sample prepared when Bi:Br=3:2, the reaction time was 16 h and the reaction temperature was 160 ℃has the best photocatalytic activity, corresponding to 99.1%(CTAB) and 98.3%(PEG-400) of MO photodegradation within 100 min under visible light irradiation.