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.
Highlights
Water pollution is one of the most important causes of environmental pollution among the various other forms of environmental degradation and it is an important climatic issue worldwide
The FESEM investigation revealed that the ZnO/CuO nanocomposite exhibited a flake-like structure
The lower recombination rate indicated by the PL intensity indicates that photogenerated electron-hole pairs undergo separation at the p–n hetero-junction
Summary
Water pollution is one of the most important causes of environmental pollution among the various other forms of environmental degradation and it is an important climatic issue worldwide. The prime objective of this work was to (a) synthesize CuO, ZnO, and their nanocomposite ZnO/CuO; (b) investigate their morphological and structural properties by employing scanning electron microscopy (SEM) and the X-ray diffraction technique (XRD); (c) compare, evaluate, and optimize their photocatalytic. The well-developed XRD peaks at 2θ = 35.63◦ and 38.88◦ correspond to (−111)/(002) and (111) planes, respectively, and validate the monoclinic crystal phase (space group:C2/c) structure of CuO nanoparticles, as reported earlier (JCPDS card #45-0937) [17]. The peaks at 430 cm−1 and 606 cm−1 were the characteristic stretching vibration of the Cu-O bond, which corresponds to the crystal structure (monoclinic) of CuO (202) and (−202) plane, respectively [21]. The optical bandgap (Eg) of the synthesized samples was determined using the Tauc plot, hν vs. (αhν), as indicated in
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