Mn vanadate nanoneedles for visible light photocatalytic activity of rhodamine B

Manganese (Mn) vanadate nanoneedles have been successfully prepared by way of a simple hydrothermal process using sodium vanadate and Mn chloride as the raw materials, and sodium dodecyl sulfate (SDS) as the surfactant. The samples are characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The Mn vanadate nanoneedles are composed of orthorhombic manganese vanadium oxide (MnV₂O₅) phase, and the diameter of the tips and length is about 50 nm and 10 μm, respectively. The preparation parameters including SDS concentration, hydrothermal temperature and duration have played important roles in the formation of Mn vanadate nanoneedles. The photocatalytic activities of the Mn vanadate nanoneedles are assessed based on the degradation of rhodamine B (RB) in aqueous solution under solar-light irradiation. The roles of irradiation time, dosage of the Mn vanadate nanoneedles and initial concentration of RB solution in the photocatalytic degradation have been investigated. The RB degradation ratio reaches 97·41 wt% using 10-mg Mn vanadate nanoneedles in 10 ml, 10 mg/l RB solution under solar-light irradiation. The Mn vanadate nanoneedles exhibited a good photocatalytic performance for the degradation of organic pollutants.