This paper presents a systematic study on the photocatalytic activity of single-phase BiFeO3 (BFO) nanopowder, under the simulated solar irradiation in the presence of highly polluting textile dye (Mordant Blue 9). BFO nanopowder was synthesized by the means of the ultrasound-assisted sol-gel route. The structural and morphology analysis confirmed phase-pure crystalline BFO nanopowder with particle size of 70 nm. UV–vis spectroscopy measurements have revealed favorably high absorbance of the visible light with the calculated band-gap value of 2.21 eV. Photodegradation process as a function of different pH values of dye aqueous solution (pH = 1, 6.7 and 12) and irradiation time was investigated and the complete degradation mechanism was revealed.

Related photodegradation products were detected by high-performance liquid chromatography equipped with mass spectrometer (HPLC/MS-MS). BFO nanoparticles exhibited higher photocatalytic activity in the basic medium than in neutral and acid medium. HPLC/MS-MS analysis of the solutions at pH = 1 and pH = 6.7 showed only decolorization process, with no detectable degradation products, while at pH = 12 three different degradation products were observed, and their concentration slightly decreased with time. Reusability test, showed that BFO nanoparticles can be used in four successive photodegradation cycles, with no significant activity losses.

本文在高污染纺织品染料（媒染剂蓝9）存在下，模拟太阳光下，对单相BiFeO3（BFO）纳米粉的光催化活性进行了系统研究。通过超声辅助溶胶凝胶法合成了BFO纳米粉。结构和形态分析证实了相纯的结晶BFO纳米粉，其粒径为70 nm。紫外可见光谱测量显示可见光的吸收率很高，计算出的带隙值为2.21 eV。研究了染料水溶液（pH = 1、6.7和12）的不同pH值和辐照时间对光降解过程的影响，并揭示了完整的降解机理。

通过配备质谱仪（HPLC / MS-MS）的高效液相色谱法检测相关的光降解产物。BFO纳米颗粒在碱性介质中比在中性和酸性介质中显示出更高的光催化活性。在pH = 1和pH = 6.7的溶液中进行HPLC / MS-MS分析表明，只有脱色过程，没有可检测到的降解产物，而在pH = 12时，观察到三种不同的降解产物，其浓度随时间略有降低。可重用性测试表明，BFO纳米粒子可用于四个连续的光降解循环，而活性没有明显损失。