Polymeric nanocomposite: Titania (TiO2)-Zirconia (ZrO2)-Polyaniline (PANI) for sustainable water pollutant removal

Binary/Ternary nanocomposites of polymers have emerged as an effective photocatalyst for environmental remediation, primarily due to their ability to suppress electron-hole recombination. The titania-zirconia (TiO2-ZrO2), a binary nanocomposite and titania-zirconia-polyaniline (TiO2-ZrO2-PANI), a ternary nanocomposite was synthesized by ultra-sonication and chemical oxidative polymerization techniques, respectively. The prepared catalysts were employed to investigates their photocatalytic efficiency against carbol fuchsin (CF) dye. Various characterization methods like UV-Vis Diffuse Reflectance Spectroscopy (UV-DRS), X-Ray Diffraction Spectroscopy (XRD), Photoluminescence Spectroscopy (PL), Energy Dispersive X-ray Spectroscopy (EDAX), Raman Spectra, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Selected Area Electron diffraction (SAED) techniques was employed to confirm the structural and optical properties of the nanocomposites. Additionally, the high resolution mass spectrometry (HR-MS) technique was utilized to study the possible fragments and degradation pattern of CB dye. The UV spectrum reveals that the TiO2-ZrO2 nanocomposites show the absorption of light in UV region whereas the TiO2-ZrO2-PANI nanocomposite shows light absorption in UV-Visible region, with band gap energy 3.43 eV for TiO2-ZrO2 nanocomposite and 2.54 eV for TiO2-ZrO2-PANI nanocomposite. The XRD analysis indicated that the average crystallite sizes of the TiO2-ZrO2 and TiO2-ZrO2-PANI nanocomposites were 13.63 and 15.73 nm respectively, revealing the orthorhombic crystalline phase. The photocatalytic performance of synthesized catalysts was assessed for a carbol fuchsin (CF) dye. Several parameters like effect of catalyst dosage, dye concentration, pH, irradiation time and kinetics of degradation reaction was investigated. Optimal conditions for CF dye degradation were identified as an 8 g/L catalyst dosage, 20 mg/L dye concentration and a pH of 7. The study shows that the CF dye degradation reaction follows pseudo-first order kinetics. Under same experimental conditions, the TiO2-ZrO2 nanocomposite degrades 60.13 % of the CF dye whereas TiO2-ZrO2-PANI nanocomposite degrades the same dye about 96.85 % of in first 10 min exposure of light. The complete degradation (almost 100 %) of the CF dye was achieved in 40 min using TiO2-ZrO2 nanocomposite while in 30 min using TiO2-ZrO2-PANI nanocomposite.