ORCID Profile
0000-0002-3770-3223
Current Organisation
Universidad de Antioquia
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Publisher: Walter de Gruyter GmbH
Date: 09-2015
Abstract: A dynamic one-dimensional model accounting for pectin generation from protopectin in the solid matrix of mango peels and its degradation in both interstitial and extra-particle (i.e. reactor-filling) acid solution is proposed. The model assumes that pectin diffusive transport occurs in the interstitial fluid while eventual diffusive, thermal and pH influences in the solid phase were lumped into the kinetic coefficient of protopectin-pectin conversion. First-order kinetic was assumed to pectin degradation. Differential equations were numerically solved by adapting an in-house simulator of bioprocesses via the lattice Boltzmann method (LBM). As part of the LBM method, particle distribution functions were assigned to the pectin concentration in interstitial and reactor-filling fluid as well as assigned to the protopectin concentration in the solid phase. Equilibrium distribution functions were adopted by considering stationary solid phase, diffusive transport in interstitial fluid, and no spatial dependence in the reactor-filling fluid. Model parameters were assessed by comparing numerically simulated extraction yield curves with existing experimental data of pectin extraction using a batch reactor under either conventional or microwave heating. While the expected behavior of extraction yield curves was fairly reproduced in LBM simulations, discrepancies with respect to the experimental data can be assigned to assumptions in this preliminary model (e.g. first-order degradation kinetic and/or lumping effects into the protopectin-to-pectin kinetic). Prospective influence of slab thickness on extraction yields was also examined in LBM simulations.
Publisher: American Chemical Society (ACS)
Date: 05-02-2020
Publisher: Springer Science and Business Media LLC
Date: 19-03-2015
DOI: 10.1007/S00894-015-2593-5
Abstract: Diethyl carbonate (DEC) is an oxygenated fuel additive. During its synthesis through a promising green process, a DEC-water azeotrope is formed, which decreases DEC production efficiency in the gas phase. Molecular information about this system is scarce but could be of benefit in understanding (and potentially improving) the synthetic process. Therefore, we report a detailed computational study of the conformers of DEC, and their microsolvation with up to four water molecules, with the goal of understanding the observed 1:3 DEC:H2O molar ratio. The most stable DEC conformers (with mutual energy differences < 1.5 kcal mol(-1)) contribute to the energetic and structural properties of the complexes. An exhaustive stochastic exploration of each potential energy surface of DEC-(H2O)n, (where n = 1, 2, 3, 4) heteroclusters discovered 3, 8, 7, and 4 heterodimers, heterotrimers, heterotetramers, and heteropentamers, respectively, at the MP2/6-311++G(d,p) level of theory. DEC conformers and energies of the most stable structures at each heterocluster size were refined using CCSD(T)/6-311++G(d,p). Energy decomposition, electron density topology, and cooperative effects analyses were carried out to determine the relationship between the geometrical features of the heteroclusters and the non-covalent interaction types responsible for their stabilization. Our findings show that electrostatic and exchange energies are responsible for heterocluster stabilization, and also suggest a mutual weakening among hydrogen bonds when more than three water molecules are present. All described results are complementary and suggest a structural and energetic explanation at the molecular level for the experimental molar ratio of 1:3 (DEC:H2O) for the DEC-water azeotrope.
Publisher: American Chemical Society (ACS)
Date: 09-12-2021
No related grants have been discovered for Aída Luz Villa.