Preparation, Characterization Of BiPO₄and Photocatalytic Degradation For Organic Contaminants

Nanocrystal BiPO4-S1, BiPO4-S3and BiPO4-H were prepared through solvothermal method and hydrothermal method, respectively. The XRD applied to analyse the phase of samples resulted the synthesized BiPO4were all monoclinic phase with high purity and crystallinity. The SEM and TEM showed that the BiPCO>4samples were nanorods with uniform size which was about500nm in length and100nm in diameter. The EDS was used to test the elements composition of BiPCO>4samples which showed only Bi, P and O were detected from the samples. The XPS result indicated that the proportion of Bi:P:O of the samples proximately was1:1:4. Moreover, according to the UV-vis diffuse reflectance absorption spectra of BiPO4-S1, BiPO4-S3and BiPO4-H, the band gaps were theoretically calculated to be4.500eV,4.476eV and4.443eV, respectively.In attempt to investigate the photocatalytic activity of prepared BiPO>4under UV-light irradiation, dyes methylene blue (MB) and rhodamine B (RhB), and paranitrophenol (p-NP) were selected as probes to be photocatalytically degraded. Experimental results showed that, the dye MB could effectively be photocatalytically degraded by BiPO4-S1and the optimal dosage was1.2g/L. When the initial concentration of MB solution was10.0mg/L, the removal rate could achieve94.48%in120min. When the reaction carried out for160min, the MB solution became colourless and the removal rate reached to100%. At the same time, the BiPO4-S3was a good catalyst to photocatalytically degrade RhB under UV-light irradation. While the initial concentration of RhB was5.0mg/L, the colour of RhB solution became transparent from red after180min irradiation. Compared with BiPO4-S3, BiPO4-H showed much higher photocatalytic activity for degrading RhB. The RhB solution became colourless in120min and the removal rate reached to100%. Paranitrophenol (p-NP) could be strongly photodegraded by BiPO4-H. After the reaction carried out for270min,p-NP was wholly removed.In addition, the effect of initial concentration of organic contaminants upon the photocatalytic activity of the catalysts was also studied. With the increase of initial concentration of organic contaminants, the photocatalytic activity of BiPO4decrease. Through kinetics fitting, the reactions of BiPO>4photocatalytically degrade organic compounds were in line with first-order kinetic model. Furthermore, BiPO4showed higher photocatalytic activity than that of spectrograde TiPO>2, while the photocatalytic activity of B1PO4was equivalent to that of TiO2-P25. The experiment results indicated that BiPO>4could be effectively reused and had excellent reuse value.