A bimetallic nanocatalyst from carbonaceous waste for crystal violet degradation

• Published in: Materials chemistry and physics 2023-03, Vol.297, p.127455, Article 127455
• Main Authors: Druzian, Daniel Moro, Oviedo, Leandro Rodrigues, Wouters, Robson Dias, Loureiro, Sthéfany Nunes, Ruiz, Yolice Patricia Moreno, Galembeck, André, Pavoski, Giovani, Espinosa, Denise Crocce Romano, dos Santos, Cristiane, dos Santos, João Henrique Zimnoch, Silva, William Leonardo da
• Format: Article
• Language: English
• Subjects: Biosynthesis; Dyes; Heterogeneous photocatalysis; Metallic nanoparticles
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2023.127455

The contamination of wastewater by cationic dyes has caused considerable environmental problems, such as an imbalance in the aquatic ecosystem and a decrease in photosynthetic activity. In this context, this study aims to synthesize and characterize a bimetallic nanocatalyst (MMT@TiO2-NPs/ZnO-NPs), as well as to evaluate its photocatalytic activity in crystal violet (CV) dye degradation. The samples were characterized by X-ray diffraction (XRD), Field Emission Gun – Scanning Electron Microscope (FEG-SEM), N2 physisorption (BET/BJH methods), UV–Vis Diffuse Reflectance Spectroscopy (DRS), zeta potential (ZP), and zero charge point (pHZCP). Central composite rotational design (CCRD 2³) was used for the experimental design to obtain the ideal condition. The diffractograms showed characteristic peaks of MMT (analcime and neighborite), ZnO-NPs (zincite) and TiO2-NPs (anatase) with an average crystallite size determined in the range of 10–50 nm. The MMT@TiO2-NPs/ZnO-NPs showed a high surface area (98.8 ± 0.6 m2 g−1) with IV-type isotherm characteristic of porous materials. Moreover, a heterogeneous morphology with an average particle size of around 16 nm. ZP showed a negative charge (−3.84 ± 0.07 mV) and pHZCP ≈ 5.80, favoring interactions with the CV dye. Ideal condition was [CV] = 32.5 g L−1, [MMT@TiO2-NPs/ZnO-NPs] = 1.75 g L−1 and pH = 12, with a CV removal of 99.97% (k = 0.0789 min−1) under visible radiation. Regarding reuse, MMT@TiO2-NPs/ZnO-NPs showed great photocatalytic stability after six cycles with 90.62% for the CV degradation. Therefore, MMT@TiO2-NPs/ZnO-NPs showed great potential for use in the treatment of industrial textile effluents, helping in the waste management strategy from mid-to long-term perspectives. [Display omitted] •Doping of TiO2 and ZnO by simple impregnation method.•2D montmorillonite was used to support bimetallic nanocatalysts.•Best photodegradation conditions were studied through experimental design.•Nanocomposite showed catalytic activity of 99.97% for dye degradation.•Bimetallic nanocatalyst can be reused in multiple cycles.