This paper deals with the problem of chromium recovery from chrome-tanned waste and thus with reducing the environmental impact of the leather industry. Chrome-tanned waste was transformed by alkaline enzymatic hydrolysis promoted by magnesium oxide into practically chromium-free, commercially applicable collagen hydrolysate and filtration cake containing a high portion of chromium. The crude and magnesium-deprived chromium cakes were subjected to a process of thermal decomposition at 650°C under oxygen-free conditions to reduce the amount of this waste and to study the effect of magnesium removal on the resulting products. Oxygen-free conditions were applied in order to prevent the oxidation of trivalent chromium into the hazardous hexavalent form. Thermal decomposition products from both crude and magnesium-deprived chrome cakes were characterized by high chromium content over 50%, which occurred as eskolaite (CrO) and magnesiochromite (MgCrO) crystal phases, respectively. Thermal decomposition decreased the amount of chrome cake dry feed by 90%. Based on the performed experiments, a scheme for the total control of chromium in the leather industry was designed.
Two pieces of studlovite -Eocene amber from Študlov (Southeast Moravia, Czech Republic) were investigated. To arrive at a more detailed description, attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy, pyrolysis-gas chromatography/mass spectrometry, and gas chromatography-mass spectrometry were used. Both studlovite samples revealed signs of the same plant source, with higher polymerisation and a higher degree of maturation of the fossilized matter. Despite their close spectral resemblance, they differed in their detailed chemical composition, and in structure. Layering of one of the pieces studied showed how the resin was built and what impact the process had on the chemical composition of the amber. Characterization of the organic matter was completed with an analysis of trace elements in amber samples using scanning electron microscope combined with elemental distribution analysis (SEM/EDAX). The results demonstrated the paleoenvironmental conditions that occurred in the plant during resin exudation following wounding.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.