In this work, the grapheme oxide (GO) and GO/ZnO nanocomposite were successfully obtained from the oxidation of graphite and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). In the GO/ZnO nanocomposite, the GO sheets were coated with aggregated ZnO nanoneedles with ca. 20 nm of diameter. The obtained materials were used as heterogeneous catalysts for acetylation of Soybean Fatty Acids Methyl Esters (FAME), promoting the epoxy ring-opening using acetic anhydride. The epoxy ring was almost completely opened in the presence of GO or GO/ZnO nanocomposites, with conversion rates up to 99% and selectivity of ca. 90%, and partially opened using only ZnO. The GO/Zn and GO catalysts were reused three times with conversion rates of ca. 85 and 74%, respectively.
The modification of fatty substrates using heterogeneous catalysts have extensive industrial application and has an emphatic position in a sustainable context. Herein ruthenium, nickel, cobalt and copper-doped ruthenium, supported on hypercrosslinked polystyrene (HPS) catalysts were prepared by wet impregnation, characterized and applied on the modification of canola fatty acid methyl esters (FAME). The characterization showed a dispersive effect of doping metals over the ruthenium particles, the presence of acid sites and overall surface morphology, which allows targeting potential applications. The chosen modifications consisted of hydrogenation, hydroformylation, oxidative cleavage and deoxygenation, resulting in superb catalytic activities of over 99% conversions for hydrogenation and deoxygenation. The simplicity of the canola FAME composition allows the understanding of the catalytic processes and allows the upscale of more complex FAME matrixes. Finally, the obtained data stimulates further optimization studies for each application with a variation on the catalysts and the usage of residual fatty substrates, greatly enhancing the sustainability profile of the systems.
Costume jewelry may expose skin to toxic metals due to sweat and friction, causing intoxications. An investigation was conducted over costume jewelry rings to study its behavior and verify its safety throughout their use, regarding toxic metal contamination. Qualitative and quantitative elemental analysis of the internal and external layers of the ring samples (costume jewelry) were made through X-Ray Fluorescence Spectrometry (XRF) and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The ring samples were also immerged in a synthetic sweat solution for 30 days. The lixiviated solution and post treated surfaces were analyzed by ICP-OES and Search Electron Microscopy (SEM), respectively. Metals such as Cu, Cd, Cr and Ni were identified in the surface composition, as well in the composition of the digested samples. The synthetic sweat eroded the rings surfaces, and metals such as Cd and Mn were lixiviated by it. The results indicate the presence and lixiviation of harmful metals that may cause health and environmental problems.
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