Improving some thermodynamic consistency tests for VLE data evaluation

Thermodynamics Conference 2013 (Statistical Mechanics and Thermodynamics Group of the Royal Society of Chemistry), The University of Manchester, 3-6 September 2013.The fundamental Gibbs-Duhem equation is the most widely referenced condition for consistency of the experimental VLE data, leading to a variety of thermodynamic consistency tests (TC tests). TC tests should be applied rigorously because deviations between the test results and VLE experimental data are usually attributed to the doubtful quality of the experimental data. Nevertheless, in many instances are the rough approximations involved in the applications of such TC tests the responsible of the bad results provided by a given experimental data set. In the present paper a method is suggested to calculate the term depending on the excess enthalpy (HE) that is rarely available and impedes rigorous calculation of the area test and the point (or differential) test in isobaric conditions. A relevant example of this problem is that the NIST algorithm uses the area test with the empirical Herington equation to estimate the term depending of HE, despite having been invalidated, and the point test is exclusively applied to isothermal and not to isobaric conditions. The comparison of the method proposed in this work with the standard procedures and data theoretically calculated demonstrates its capacity and validates experimental data sets otherwise improperly questioned.Financial support by means of the projects: MINECO. MAT2011-24991 and PROMETEO/2012/015

Mapping Binary Liquid-Vapor or Liquid-Liquid-Vapor Equilibria Regions, including the Different Azeotropic Behaviours, as a Function of the NRTL Binary Parameters

13th Mediterranean Congress of Chemical Engineering (Sociedad Española de Química Industrial e Ingeniería Química, Fira Barcelona, Expoquimia), Barcelona, September 30-October 3, 2014As it is very well know, the synthesis and design of separation processes requires the use of models to represent the phase equilibrium data, which involves the previous correlation of experimental data to obtain the values of the corresponding parameters. In previous works, we have studied the capabilities and limitations of the classical GE models used in phase equilibrium data correlations, such as NRTL model, in representing the behaviour of different LV, LL and LLS equilibrium data. In the preset work, the relations between the binary parameters Aij of the NRTL model and the existence of different equilibrium regions (i.e.: LV, LL or LLV), as well as the different possible azeotropic behaviours are analyzed for different component systems. The Gibbs free enthalpy curve and the corresponding y-x and T-x,y diagrams along a matrix of Aij parameters has been studied within a range including the typical values observed in DECHEMA Chemistry Data Series

The understanding of the three-dimensional graphical behavior of the L-L-S phase equilibrium as a valuable tool to avoid spurious or incoherent experimental data

The complexity and variety of possible behaviors of the quaternary liquid-liquid, liquid-liquid-solid equilibrium at constant temperature are very high and, sometimes, are not well understood. It is not difficult to find references in literature where important misinterpretations and mistakes are committed as a consequence of applying a non-adequate experimental methodology and a lack of the spatial point of view. Thus, the objective of the present paper is to show several examples where special behaviors are selected to clarify some aspects concerning the experimental determination and graphical representation of liquid-liquid-solid equilibrium data, and emphasize the importance of the knowledge and consideration of the qualitative expected behavior of the system under study, obtained from the binaries.Universidad de Alicant

Geometrical aspects of the azeotropic liquid-liquid-vapour phase equilibria

The ternary isobaric liquid-liquid-vapour and liquid-vapour equilibrium can be very complex and may present a wide variety of three-dimensional representations, which sometimes are not very well understood. This paper presents several examples of possible complex spatial behaviours with different kind of azeotropes. These examples have been selected to clarify the expected projections deduced from the binaries and to help in the understanding of these type of equilibrium as well as in the experimental data determination and interpretation.Universidad de Alicant

Robust program for LLSE data correlation of ternary systems

The existing commercial software packages (like Dechema Data Preparation Package (DPP) and the regression utilities of Chemical Engineering simulators like Chemcad) have been widely used and their extensive capabilities are well-known. Nevertheless, and as long as LLE calculations is concerned, they have been designed for the simplest equilibrium behaviour. For example, for ternary systems it is only possible the correlation of type 1 and type 2 LLE data. None of these applications allows for the correlation of type 0 LLE, type 3 LLLE or type 4 LLSE systems. To enable a possible extension of such software, a robust calculation algorithm to compute phase equilibria among condensed phases for all these more complicated behaviours has been developed.Vicepresidency of Research (University of Alicante) and Generalitat Valenciana (GV/2007/125)

Trajectory-Based Morphological Operators: A Model for Efficient Image Processing

Mathematical morphology has been an area of intensive research over the last few years. Although many remarkable advances have been achieved throughout these years, there is still a great interest in accelerating morphological operations in order for them to be implemented in real-time systems. In this work, we present a new model for computing mathematical morphology operations, the so-called morphological trajectory model (MTM), in which a morphological filter will be divided into a sequence of basic operations. Then, a trajectory-based morphological operation (such as dilation, and erosion) is defined as the set of points resulting from the ordered application of the instant basic operations. The MTM approach allows working with different structuring elements, such as disks, and from the experiments, it can be extracted that our method is independent of the structuring element size and can be easily applied to industrial systems and high-resolution images

Correlation of three-liquid-phase equilibria involving ionic liquids

The difficulty in achieving a good thermodynamic description of phase equilibria is finding a model that can be extended to a large variety of chemical families and conditions. This problem worsens in the case of systems containing more than two phases or involving complex compounds such as ionic liquids. However, there are interesting applications that involve multiphasic systems, and the promising features of ionic liquids suggest that they will play an important role in many future processes. In this work, for the first time, the simultaneous correlation of liquid–liquid and liquid–liquid–liquid equilibrium data for ternary systems involving ionic liquids has been carried out. To that end, the phase diagram of the water + [P6 6 6 14][DCA] + hexane system has been determined at 298.15 K and 323.15 K and atmospheric pressure. The importance of this system lies in the possibility of using the surface active ionic liquid to improve surfactant enhanced oil recovery methods. With those and previous measurements, thirteen sets of equilibrium data for water + ionic liquid + oil ternary systems have been correlated. The isoactivity equilibrium condition, using the NRTL model, and some pivotal strategies are proposed to correlate these complex systems. Good agreement has been found between experimental and calculated data in all the regions (one triphasic and two biphasic) of the diagrams. The geometric aspects related to the Gibbs energy of mixing function obtained using the model, together with the minor common tangent plane equilibrium condition, are valuable tools to check the consistency of the obtained correlation results

Impact of the COVID-19 pandemic on hepatitis B and C elimination: An EASL survey

Hepatitis B virus; Hepatitis C virus; COVID-19 pandemicVirus de la hepatitis B; Virus de la hepatitis C; Pandemia de COVID-19Virus de l'hepatitis B; Virus de l'hepatitis C; Pandèmia del COVID-19Background & Aims The World Health Organization (WHO) HBV and HCV elimination targets, set in 2016 and based on projections to 2030, were unable to consider the impact of intervening factors. To evaluate the impact of the COVID-19 pandemic on viral hepatitis elimination programs, the European Association for the Study of the Liver (EASL) conducted a survey in liver centers worldwide in 2021. Methods A web-based questionnaire was distributed (May-July 2021) to all EASL members representing clinical units providing HBV and HCV hepatitis care. Results are expressed as absolute numbers and reduction rates for each care activity. Results Data were collected from 32 European and 12 non-European clinical centers. Between January 2019 (pre-pandemic) and December 2020 (during the pandemic), chronic HBV consultations decreased by 32% and 26%, new referrals by 38% and 39%, HBV testing rates by 39% and 21% (for HBsAg detection) and 30% and 22% (for HBV DNA detection), and new HBV treatments by 20% and 44% (p = 0.328) in European and non-European centers, respectively. With regard to HCV during the same time frame, the overall reductions were 39% and 50% for consultations, 49% and 49% for new referrals, 11% and 38% for HCV RNA detection, and 51% and 54% for new HCV antiviral treatments for European and non-European Centers, respectively (p = 0.071). Conclusions All steps in the viral hepatitis care cascade have been hampered by the COVID-19 pandemic, with a comparable impact across different centers. These data reaffirm the pandemic’s major effect on global viral hepatitis elimination programs and suggest that actions to achieve the WHO 2030 targets should be reconsidered and revised to account for each country's progress relative to pre-pandemic values

El dibujo como medio de expresi?n art?stica para potenciar el proceso de formaci?n de autoconcepto en ni?os de preescolar de la IE normal superior de Icononzo durante el semestre b del a?o lectivo 2017

28 p. Recurso Electr?nic

Should we trust all the published LLE correlation parameters in phase equilibria? Necessity of their assessment prior to publication

The review of a representative number of papers published in recent years that include the correlation of experimental liquid-liquid equilibrium (LLE) data has been carried out, after detecting serious inconsistencies in some of the parameters recently published. The result of this analysis shows that surprisingly many published parameters and calculated LLE data are inconsistent for different reasons, for instance: a) some parameters predict a type of system different from the experimental one, b) calculated tie-lines with the published parameters do not satisfy the Gibbs stability criteria, and c) in other cases do not even satisfy the isoactivity LLE condition. In most of these papers, the erroneous common final conclusion was a good agreement between the experimental and calculated tie-lines using these inconsistent parameters. Because these problems were not detected by the authors (when preparing the manuscript) nor by reviewers (during the review process), the necessity of a strategy for the validation of parameters (and compositions) calculated in LLE data fitting became evident. Such procedure should be applied to all LLE data correlation papers, prior to their publication in order to ascertain their consistency and quality. In this paper we suggest some possible tools that could be useful for this assessment