Difference in polystyrene oxo-biodegradation behavior between copper phthalocyanine modified TiO2 and ZnO paint photocatalyst systems

Photo-catalytic and biotic degradation of polystyrene packaging film: Effect of zinc oxide photocatalyst nanoparticles and nanoclay

Synergistic effect of zinc oxide nanoparticles (ZnO-NPs) as photocatalyst and organonanoclay (ONC) as biodegradable promoter on the degradation of polystyrene (PS) film was investigated. The films were exposed to ultraviolet irradiation under ambient air at room temperature for photo-catalytic degradation and then submitted to biodegradation test in soil using respirometric procedure. Fourier-transform infrared and ultraviolet-visible spectroscopy, thermogravimetric analysis, colorimeter technique, contact angle measurement, and the carbon dioxide evolution results showed higher photo- and biodegradation efficiency of PS-ONC-ZnO nanocomposite compared to the neat PS, PS-ONC and PS-ZnO nanocomposites. Thermal stability, optical band gap, and water contact angle of photo-degraded PS-ONC-ZnO nanocomposite decreased by 11.37, 18.33 and 63.99%, respectively, while that of PS film was only 6.20, 6.44 and 5.84%, respectively. The photo-degraded PS-ONC-ZnO and PS-ZnO film indicated a biodegradation percentage value of 3.3 and 2.1%, respectively, over 16 weeks of incubation in soil. The possible degradation mechanism of nanocomposites was briefly discussed.

Facile Controlling of the Physical Properties of Zinc Oxide and Its Application to Enhanced Photocatalysis

In this study, the physical properties of ZnO were facile controlled by the synthesis method with the addition of capping and precipitation agents. As-prepared ZnO samples had different morphologies such as carnation flower-like ZnO (CF-ZnO), rose-flower-like ZnO (RF-ZnO), rod-like ZnO (R-ZnO), and nanoparticle ZnO (N-ZnO) and were characterized by SEM, XRD, N₂ adsorption/desorption isotherms, FT-IR, and DR/UV-vis. All samples had a crystallite structure of hexagonal wurtzite type. The CF-ZnO and RF-ZnO samples had the hierarchical structure like a carnation flower and a beautiful rose, respectively. R-ZnO was composed of many hexagonal rods and few spherical particles, while N-ZnO microstructures were made up of nanoparticles with approximately 20-30 nm, exhibiting the largest surface area, pore volume, and pore width among as-prepared samples, and their crystal size and bandgap energy were 17.8 nm and 3.207 eV, respectively. The catalytic performances of ZnO samples were evaluated by degradation of Tartrazine (TA) and Caffeine (CAF) under low UV irradiation (15 W). N-ZnO showed a high photocatalytic activity compared to other samples. Besides, the reaction kinetics was investigated by the first-order kinetic model, and the catalytic performance of ZnO was evaluated through several organic pollutants.