Article
Synthesis and characterization of acrylamide/acrylic acid hydrogels crosslinked using a novel diacrylate of glycerol to produce multistructured materials
Fecha
2014Autor
Zago, E.
Botton, V.
Alberton, D.
Cordova, J.
Yamamoto, C.I.
Cocco, L.C.
Mitchell, D.A.
Krieger, N.
Institución
Resumen
We grew Rhizopus microsporus CPQBA 312-07 DRM in solid-state fermentation on a 1:1 mixture, by mass, of sugarcane bagasse and sunflower seed meal, to produce a fermented solid containing lipases (tricaprylin-hydrolyzing activity of 91 U g-1) and then used this fermented solid to catalyze the ethanolysis of corn oil. A 23 factorial design was used to optimize the reaction using n-heptane as the solvent. The best conversion was 91% at 48 h, obtained at 44°C, with a molar ratio of ethanol/oil of 3:1 and the addition of 1.32 g of fermented solids/15 mL of reaction medium. Using these optimized conditions, we studied the effect of increasing the concentration of the reactants in the medium and even the use of a solvent-free system. In these systems, conversions were quite poor when the ethanol was added in a single aliquot at the start of the reaction. However, when the ethanol was added stepwise, with three equal aliquots added at 0, 24, and 48 h, promising conversions were obtained, including an ester yield of 51% at 72 h in the solvent-free medium. An improved fermented solid (tricaprylin-hydrolyzing activity of 183 U g-1) was then used to improve the production of ethylic esters in solvent-free medium, with an ester yield of 68% being obtained at 72 h. These results are promising and justify further optimization studies. " 2014 American Chemical Society.",,,,,,"10.1021/ef501081d",,,"http://hdl.handle.net/20.500.12104/44940","http://www.scopus.com/inward/record.url?eid=2-s2.0-84906495852&partnerID=40&md5=da1936254875733dffd04b493fda8941 http://dx.doi.org/10.1021/ef501081d",,,,,,"8",,"Energy and Fuels",,"5197 5203",,"28",,"Scopus WOS ChemAbsS",,,,,,,,,,,,"Synthesis of ethylic esters for biodiesel purposes using lipases naturally immobilized in a fermented solid produced using rhizopus microsporus",,"Article"
"46749","123456789/35008",,,,,,"2002",,,,,,,,"10.1021/es022245c",,"0013-936X","http://hdl.handle.net/20.500.12104/44970","http://dx.doi.org/10.1021/es022245c",,,,"American Chemical Society",,"7",,"Environmental science & technology",,"131A 131A",,"36",,"ChemAbsS",,,,,,,,,,,,"News Briefs: Citizens from across the globe believe that environmental quality has deteriorated over the past 10 years,",,"Journal Article"
"46699","123456789/35008",,"Lopez-Ureta, L.C., Instituto Tecnologico Superior de Zapopan, Zapopan, Mexico; Orozco-Guareño, E., Department of Chemistry, University of Guadalajara, Guadalajara, Mexico; Cruz-Barba, L.E., Department of Chemical Engineering, University of Guadalajara, Guadalajara, Mexico; Gonzalez-Alvarez, A., Department of Chemical Engineering, University of Guadalajara, Guadalajara, Mexico; Bautista-Rico, F., Department of Engineering, Centro de Enseñanza Tecnica Industrial, Tonala, Mexico",,"Lopez-Ureta, L.C. Orozco-Guareno, E. Cruz-Barba, L.E. Gonzalez-Alvarez, A. Bautista-Rico, F.",,"2008",,"In this work we propose a new crosslinking agent and the method to use it for the synthesis of acrylate based hydrogels. The use of this diacrylate of glycerol, synthesized in our laboratory, allows the generation of materials with well defined micro-structures in the dry state, unique meso- and macro-structures during swelling, and enhanced mechanical properties and swelling capacity in water. These properties depend on the crosslinking agent concentration, as well as synthesis thermal history. Poly(acrylamide-co-acrylic acid) hydrogels are commonly crosslinked with N,N?-methylenebisacrylamide or N-isopropylacrylamide. Here we obtain and use a new crosslinking agent, obtained from the reaction between glycerol and acrylic acid to produce a Diacrylate of glycerol (DAG). Two synthesis methods at equivalent molar ratio of acrylamide/acrylic acid (AM/AA) were analyzed. The mechanical properties, the swelling capacity, and the morphology at microscale of these hydrogels showed a well defined transition at a critical concentration of crosslinking agent. DAG induces the generation of hydrogels with hierarchichal structure. The micro-structure surface morphology was investigated by scanning electron microscopy, the meso-structure by polarized light microscopy and the macro-structure by CCD imaging. The hydrogels with hierarchical structures showed improved mechanical properties when compared with structureless hydrogels. Control of the microstructure allows the generation of materials for different applications, i.e. templates or smart materials that interact with electromagnetic radiation. " 2008 Wiley Periodicals, Inc.