| In recent years, novel semiconductor photocatalytic technology has become one of the most effective methods to develop new energy and solve problems caused by environment pollution. However, semiconductor photocatalyst are also faced with many challenges such as a lot of difficulties, high cost, less value to recycle, or secondary pollution may even caused by the inadequate recycle of catalyst in practical applications. Magnetic photocatalyst has an effective recycling by applying an external magnetic field due to its magnetism performance without changing the high photocatalytic activity. It achieves the resource utilization and environmental protection. Overall, the importance of its practical significance is abvious.Bismuth oxyhalide has high photocatalytic activity and good stability because of its unique electronic and forbidden band structure, and possesses great value of theoretical research of pollutant degradation and the practical application of water treatment. In this paper, taken manganese zinc ferrite as the magnetic substrate, and bismuth oxyhalide with high photocatalytic activity as the catalyst active component, bismuth oxyhalide/manganese zinc ferrite with magnetism was prepared, then a series of study on its photocatalytic activity were carried out.The magnetic photocatalyst Bi OCl/Mnx Zn1-xFe2O4 was achieved by impregnation calcination method. Structure and properties of the prepared magnetic photocatalyst were measured through the IR, XRD, SEM, DRS and VSM. The results showed that MnxZn1-xFe2O4 could inhibit the growth of Bi OCl along 001 crystal plane and prompted the growth of 110 crystal plane orientation. Bi OCl/MnxZn1-xFe2O4 is assembled like flower microspheres with uniform 200-500 nm nanosheets. And it not only has a response enhancement in the UV region, but also can respond to visible light, the band gap is 2.48 e V. The absorption band edge increases to 550 nm, having an obvious red shift. The Ms is 4.64 emu.g-1 and the Hc is 50.12 G, which has a good resistance to demagnetization, beneficial to the reusing of magnetic photocatalyst. Effects of mass ratio, p H value, reaction time, calcination temperature on the photocatalytic activity were analyzed by single factor experiments. The optimum technological conditions were obtained by orthogonal experiments and presented as follows. The mass ratio is 15%, the calcination temperature is 200°C, the p H is 1.5, and the reaction environment is 2h. The degradation ratio of Rh B was 99.6% in 30 minutes. After recycling 5 times under an external magnetic field, photocatalytic degradation rate still being more than 83%, showing good stability and reusability.Magnetic photocatalyst Bi OI/MnxZn1-xFe2O4 was prepared using manganese zinc ferrite as magnetic substrate. Effects of the mass ratio of manganese zinc ferrite to Bi OI, calcination temperature, alcohol and water environmen, surface dispersant types and other factors on the magnetic photocatalytic activity were analyzed by XRD, SEM, DRS methods and degradation test. The results showed that, photocatalytic degradation of Rh B reaches the highest rate of 59.2% in 4 hours as the mass ratio is 25%, and excessive or deficient MnxZn1-xFe2O4 both lead to the decrease of photocatalytic activity. Further analysis on the reason why the low mass ratio photocatalytic activity is bad was carried out. XRD investigation revealed that the main active ingredient in the magnetic photocatalyst changes at the calcination temperature of 400℃, and the photocatalytic activity significantly enhances. Through SEM, morphology of magnetic photocatalyst prepared in water environment is scattered multi-sheet structure, while prepared in alcohol water environment is hollow microspheres with uniform size nanosheets. The late has a high surface/volume ratio, thus having a higher catalytic efficiency, and the degradation rate can reach 98% in 4 hours. In addition, the photocatalytic activity of magnetic catalysts prepared in dodecyl benzene sulfonate(SDBS) as surface dispersant is better than that in polyvinylpyrrolidone(PVP). |
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