RESUMO
In this study, we report the production of a free-standing film of non-modified cellulose impregnated with 12â¯wt.% of MnO2 nanoparticles with less than 100â¯nm in size. The method here described can be applied to the immobilization of different types of nanoparticles. The film was prepared by dissolving microcrystalline cellulose in an ionic liquid followed by its regeneration by adding water to the former solution. Then, the wet film was impregnated with the nanoparticles by dipping it in a MnO2 dispersion. Electron microscopy images revealed manganese dioxide nanoparticles distributed not only at the film surface but also in its interior. The cellulose film impregnated with MnO2 nanoparticles was capable of efficiently discolouring an Indigo Carmine dye solution in 25â¯min upon ambient light. The film was easily removed from the dye solution and repeatedly reused for at least 10 times without losing its discolouring efficiency.
RESUMO
In this work, waste expanded polystyrene (WEPS) was irradiated with gamma rays, ranging doses from 100 kGy to 1,000 kGy. After irradiation, the WEPS had decrease on its glass transition temperature (Tg), as consequence of the scissions of its polymer chains. Then, the irradiated WEPS was sulfonated, and its degree of sulfonation (DS) was measured. The highest DS value, 46.6%, was obtained for an irradiation dose of 200 kGy. The sulfonated and irradiated polystyrene (denominated as iS-WEPS), was used as a support of iron oxide nanoparticles. Such composite system was denominated (FeO-NPs + iS-WEPS). The results show nanoparticle sizes of 31.5 nm containing 21.97% iron oxide. The composites followed a pseudo-second order model, with a maximum adsorption capacity of 20 mg/g, and an equilibrium time of 30 min, according to the Langmuir model. Moreover, the optimal conditions followed by the Fenton process were: pH = 3.2, H2O2 concentration = 0.32 mM/L, composite concentration (FeO-NPs + iS-WEPS) = 2 g/L, and a reaction time 20 min. Finally, 99% removal of indigo carmine dye was achieved, and a reduction of 83% of COD in textile wastewater.