چكيده به لاتين
The aim of this dissertation was to prepare TiO2-based nanostructures using cellulose nanofibers (as template), and then to prepare the nanocomposite using polyaniline conductive polymer for use in water-based (acrylic) photocatalytic pseudo-paint to remove volatile organic pollutants from the gaseous environment under visible light. In order to control the hydrolysis reaction in the sol-gel process and as a result, optimal nucleation and growth of nanoparticles on the template, the Stober method was used, so that the amount of water in the reaction medium was reuced as minimum as possible, the nanocellulose template was used in the form of alcogel and the nanostructure was controlled by changing synthesis parameters. The effect of sol-gel parameters: amount of precursor (0.6, 0.8 and 1 ml), reaction time (2, 3, 6 and 12 hours), presence and absence of ultrasonic waves and volume percentage of ammonia (0.2, 0.25, 0.3, 0.4, 0.5 and 0.6 vol.%) were evaluated. The microstructure study of prepared nanoparticles using FESEM images showed the formation of nanowhiskers, nanofibers and intertwined nanofibers. The nanowhiskers were about 30-50 nm thick and 250-300 nm long. Due to increasing the porosity and the specific surface area from 52.308 m2g-1 for pure TiO2 to 86.367 m2g-1 related to TiO2-alcogel, improving the adsorption capacity of pollutants increased the photocatalytic degradation efficiency. Also, the band gap energy of these nanostructures was 2.95 and 2.72 eV, respectively, thus the degradation efficiency of benzene in the gas phase using paint film containing 5 wt.% of these two, after 48 hours of exposure to UV light was 4.8% and 14.6%, respectively. The sample containing pure TiO2 exposed to visible light did not show any activity even after 48 hours, while in the case of TiO2-alcogel it was 7.9%. Polyaniline conductive polymer (PAni) was layered on the synthesized nanofibers by oxidation polymerization. The combination of PAni and TiO2 enhanced the photocatalytic activity by helping to form electron-holes and preventing their recombination. The photocatalytic degradation efficiency of benzene in the presence of pseudo-paint containing PAni/TiO2-alcogel was 48% after 48 hours of exposure to UV light and about 21.6% in visible light. XRD, FTIR, TGA, BET, Raman, SEM, FESEM, EDX, UV-Vis DRS, TEM and XPS analyzes were used to characterize the samples and UV-Vis and GC spectroscopy were used to investigate the photocatalytic degradation.
