Optimization of Facile Synthesized ZnO/CuO Nanophotocatalyst for Organic Dye Degradation by Visible Light Irradiation Using Response Surface Methodology

Abstract

In this study, we aimed to observe how different operating parameters influenced the photocatalytic degradation of rhodamine B (RhB, cationic dye) and bromophenol Blue (BPB, anionic dye) over ZnO/CuO under visible light irradiation. This further corroborated the optimization study employing the response surface methodology (RSM) based on central composite design (CCD). The synthesis of the ZnO/CuO nanocomposite was carried out using the co-precipitation method. The synthesized samples were characterized via the XRD, FT-IR, FE-SEM, Raman, and BET techniques. The characterization revealed that the nanostructured ZnO/CuO formulation showed the highest surface area (83.13 m2·g−1). Its surface area was much higher than that of pure ZnO and CuO, thereby inheriting the highest photocatalytic activity. To substantiate this photocatalytic action, the investigative analysis was carried out at room temperature, associating first-order kinetics at a rate constant of 0.0464 min−1 for BPB and 0.07091 min−1 for RhB. We examined and assessed the binary interactions of the catalyst dosage, concentration of dye, and irradiation time. The suggested equation, with a high regression R2 value of 0.99701 for BPB and 0.9977 for RhB, accurately matched the experimental results. Through ANOVA we found that the most relevant individual parameter was the irradiation time, followed by catalyst dose and dye concentration. In a validation experiment, RSM based on CCD was found to be suitable for the optimization of the photocatalytic degradation of BPB and RhB over ZnO/CuO photocatalysts, with 98% degradation efficiency.