Navegando por Palavras-chave "Waste recovery"

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    Highly selective acetalization of glycerol with acetone to solketal over acidic carbon-based catalysts from biodiesel waste
    (Elsevier Sci Ltd, 2016) Goncalves, Maraisa [UNIFESP]; Rodrigues, Raphael; Galhardo, Thalita S.; Carvalho, Wagner A.
    The glycerol acetalization reaction in the presence of acetone was evaluated using acidic carbon-based catalysts from biodiesel waste as catalysts. Acidic carbon-based catalysts were prepared with different glycerin: sulfuric acid mass ratios at 457 K for 24 h. The amount of acid groups as well as the acidity (mainly attributed to sulfur groups) enhance with an increase of glycerol: sulfuric acid ratio (1: 2 and 1: 3, named GC-1: 2 and GC-1: 3, respectively), reaching 0.9 mmol g(-1) for sulfur and 3.8 mmol g(-1) for total acidity. Very promising results were obtained when these carbon-based catalysts were tested as catalysts in glycerol acetalization, reaching about 80% of glycerol conversion and about 95% of solketal selectivity, this product has been applied as a fuel additive. Furthermore, the carbon-based catalysts surface groups showed high stability under the reaction conditions tested in this study. These results indicated that acidic carbon-based catalysts derived from glycerin are very attractive catalysts for glycerol acetalization. (C) 2016 Elsevier Ltd. All rights reserved.
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    Metal-sensitive and thermostable trypsin from the crevalle jack (Caranx hippos) pyloric caeca: purification and characterization
    (Biomed Central Ltd, 2013-10-10) Costa, Helane M. S.; Freitas Junior, Augusto C. V.; Amaral, Ian P. G.; Hirata, Izaura Y. [UNIFESP]; Paiva, Patricia M. G.; Carvalho, Luiz B.; Oliveira, Vitor [UNIFESP]; Bezerra, Ranilson S.; Universidade Federal de Pernambuco (UFPE); Universidade Federal de São Paulo (UNIFESP)
    Background: Over the past decades, the economic development and world population growth has led to increased for food demand. Increasing the fish production is considered one of the alternatives to meet the increased food demand, but the processing of fish leads to by-products such as skin, bones and viscera, a source of environmental contamination. Fish viscera have been reported as an important source of digestive proteases with interesting characteristics for biotechnological processes. Thus, the aim of this study was to purify and to characterize a trypsin from the processing by-products of crevalle jack (Caranx hippos) fish.Results: A 27.5 kDa trypsin with N-terminal amino acid sequence IVGGFECTPHVFAYQ was easily purified from the pyloric caeca of the crevalle jack. Its physicochemical and kinetic properties were evaluated using N-alpha-benzoyl-(DL)-arginine-p-nitroanilide (BApNA) as substrate. in addition, the effects of various metal ions and specific protease inhibitors on trypsin activity were determined. Optimum pH and temperature were 8.0 and 50 degrees C, respectively. After incubation at 50 degrees C for 30 min the enzyme lost only 20% of its activity. K-m, k(cat), and k(cat)/K-m values using BApNA as substrate were 0.689 mM, 6.9 s(-1), and 10 s(-1) mM(-1), respectively. High inhibition of trypsin activity was observed after incubation with Cd2+, Al3+, Zn2+, Cu2+, Pb2+, and Hg2+ at 1 mM, revealing high sensitivity of the enzyme to metal ions.Conclusions: Extraction of a thermostable trypsin from by-products of the fishery industry confirms the potential of these materials as an alternative source of these biomolecules. Furthermore, the results suggest that this trypsin-like enzyme presents interesting biotechnological properties for industrial applications.