Photocatalytic Degradation of Rhodamine B

The evaluation for photoactivity was tested using 0.075 g of the catalyst (ZnO NPs) in 10 mg·L⁻¹ Rhodamine B solution (200 mL) at room temperature. The pollutant solution was prepared by stirring 0.0017 g of Rhodamine B with 200 mL of distilled water for 2 h. Before the experiment, O₂ was passed through the Rhodamine B solution for 60 min to saturate it. In order to fully examine the photocatalytic potential of the synthesized ZnO nanoparticles, the experiments were carried out under irradiation of both visible and UV light. The photoreactor used has four parallel lamps, at a distance of 10 cm over the samples [39 (link),40 ]. The lamps used were 15 W visible lamps of 900 lumens (made by Osram, OSRAM GmbH, Munich, Germany) and blacklight of 368 nm lamps of 830 lumens, made by Sylvania (Sylvania, Wilmington, NC, USA). All the tests were conducted at room temperature and pH equal to 6.4. The degradation of Rhodamine B was inspected, under each light source used. The absorbance of the samples was measured using the Hitachi U-2001 Spectrophotometer (Hitachi, Tokyo, Japan). The evaluation of the ratio of the measured A (absorption at each time) to the initial (A_initial) allowed the determination of the ratio C/C_o [39 (link)]. After a few hours upon irradiation, the degradation can be observed by watching the color progressively turning lighter, until it turns completely transparent.