A practical approach to fixed-site-carrier facilitated transport modeling for the separation of propylene/propane mixtures through silver-containing polymeric membranes

In this work, a new consistent mathematical model for the description of the olefin flux through Ag+-containing polymeric dense membranes is proposed. A fixed site carrier "hopping" parameter acting as an effective permeability for this specific transport phenomenon is defined and calculated for the first time. This study reports a simple and versatile approach that can be incorporated into future models to simulate the more complex mobile/fixed hybrid mechanism acting in composite membranes. Furthermore, in order to validate the model, the proof of concept has been carried out with PVDF-HFP/AgBF4 facilitated transport membranes. The experimental analysis has been performed by the continuous flow permeation method through flat membranes containing increasing silver loads, from 17 to 38% w/w at olefin partial pressures ranging from 0.5 to 1.5 bar and temperatures of 293 and 303 K. These membranes showed a promising performance, reaching values of propylene permeability up to 1800 Barrer and very high propylene/propane selectivities. The reported model constitutes a very useful tool for process optimisation and scale-up.Financial support from the Spanish Ministry of Science under the projects CTQ2015-66078-R and CTQ2016-75158-R (MINECO, Spain-FEDER 2014–2020) is gratefully acknowledged. Raúl Zarca also thanks the Universidad de Cantabria for a postgraduate fellowship

Facilitated transport of propylene through composite polymer-ionic liquid membranes. Mass transfer analysis

Separation of light gaseous olefins from paraffin’s of the refinery process off-gasses has been traditionally performed by cryogenic distillation, which is a highly capital and energy intensive operation. This handicap creates an incentive for the investigation of alternative olefin/paraffin separation technologies. In this regard, membrane technology supposes a potential solution for process intensification. Previous works of our research group reported the use of facilitated transport composite membranes integrating the use of PVDF-HFP polymer, BMImBF4 ionic liquid and AgBF4 silver salt. In this type of membranes, the silver cations react selectively and reversibly with the olefin, allowing the separation via mobile and fixed carrier mechanisms. Ionic liquids were selected as membrane additives because in addition to their negligible vapor pressure that avoids solvent losses by evaporation, they provide stability to the metallic cation dissolved inside, and modify the structure improving the facilitated transport. This technology offers a commercial attractive separation alternative thanks to their modular form of operation, high values of selectivity and permeability and low operational costs. In the present work, propane/propylene permeation experiments involving the use ionic liquids and different membrane compositions were performed. Moreover, basing on the transport and equilibrium parameters previously obtained, a mathematical model description of the system will be proposed fitting the remaining parameters and allowing the design and optimization of the propane/propylene separation process at industrial levels.This research was supported by the Spanish Ministry under the projects CTQ2012-31639 (MINECO, SPAIN-FEDER 2007–2013) and (CTM2013-44081-R)

On the improved absorption of carbon monoxide in the ionic liquid 1-hexyl-3-methylimidazolium chlorocuprate

This study is focused on the design of a liquid phase system to be used in facilitated transport-supported ionic liquid membranes (SILMs) for the recovery of carbon monoxide from gaseous streams based on the ability of CO molecules to form "pi" complexation bounds with Cu+ ion. As liquid phase we propose the use of the ionic liquid 1-hexyl-3-methyl-imidazolium chlorocuprate prepared by the direct mixture of copper(I) chloride (CuCl) with 1-hexyl-3-methylimidazolium chloride ([hmim][Cl]). A comprehensive look at the reaction mechanism and the equilibrium parameters obtained from the experimental characterization of the physical and chemical solubility of carbon monoxide in pure [hmim][Cl], and in mixtures CuCl/[hmim][Cl] is presented. The gas equilibrium solubility experimental work was carried out in the CuCl/[hmim][Cl] molar ratio range from 0 to 0.75, temperature from 273.15 to 303.15 K and pressures up to 20 bar. The values of the Henry's law constant for the physical solubility of CO in [hmim][Cl] changed from 15.3 × 10-3 to 2.7 × 10-3 mol kg-1 bar-1 as the temperature increased from 273.15 to 293.15 K. The chemical solubility of CO in the reactive ionic liquid media increased with the increase of the concentration of CuCl, with the increase of pressure and as temperature decreases. In the operation range of variables the maximum absorption of CO was of 2.26 mol kg-1 that was reached working at 20 bar, at CuCl/[hmim][Cl] molar ratio of 0.75 and 273.15 K.Financial support from the Spanish Ministry of Education and Science under the projects: ENE2010-15585 and CTQ 2008-00690/PPQ is gratefully acknowledged. Oana C. David and Gabriel Z. also thank the Ministry of Education for a FPU and a FPI, respectively, postgraduate research grant

Generalized predictive modeling for facilitated transport membranes accounting for fixed and mobile carriers

The present work expands previous modeling knowledge on facilitated transport membranes for olefin/paraffin separation. A new robust and practical mathematical model for the description of light olefin flux in composite polymer/ionic liquid/Ag+ membranes is reported. The model takes into account three different transport mechanisms, i.e., solution-diffusion, fixed-site carrier and mobile carrier transport mechanisms. Fixed-site carrier contribution that appears thanks to the bounding of silver cations with the polymer chains is described through a “hopping parameter”. Furthermore, given that the addition of an ionic liquid to the membrane composition promotes carrier mobility, the inclusion of a dedicated expression is necessary for a realistic description of mobile-carrier transport phenomena. The contribution of each mechanism in weighted based on the membrane composition. In order to check the model suitability, simulated values have been matched to experimental data obtained by continuous flow propane/propylene permeation experiments through PVDF-HFP/BMImBF4/AgBF4 composite membranes, working with 50:50 gas mixtures at different temperature and pressure. The resultant model offers good predictions for olefin flux and provides a very useful tool for process optimization and scaling-up. To our knowledge, this is the first time that mobile and fixed site carrier mechanisms performance are simultaneously modeled considering the influence of temperature, pressure and carrier loading.Financial support from projects CTQ2015-66078-R and CTQ2016-75158-R (MINECO, Spain-FEDER 2014–2020) is gratefully acknowledged. Raúl Zarca also thanks the Universidad de Cantabria for a postgraduate fellowship

Optimization of multistage olefin/paraffin membrane separation processes through rigorous modeling

In this work, we explore the capabilities of an NLP optimization model to determine the viability of facilitated transport membrane processes intended to replace traditional distillation currently employed for propane/propylene separation. An NLP optimization model for multistage membrane processes has been formulated, introducing the mathematical description of the facilitated transport mechanisms in the PVDF‐HFP/BMImBF4/AgBF4 membranes previously developed by our research group. For the first time, a simultaneous optimization of the process and the membrane material (i.e., carrier concentration) has been performed, thanks to the implementation of the governing equations for the fixed site and mobile carrier mechanisms. Once the model is solved in GAMS it returns the optimal membrane area, carrier loading and permeate pressure of each stage based on Net Present Value Cost (NPVC) minimization. Different process flow sheets were evaluated and the results show prominent reductions on NPVC for facilitated transport multistage processes when compared to distillation.Financial support from the Spanish Ministry of Science under the pro-jects CTQ2015-66078-R and CTQ2016-75158-R (MINECO, Spain-FEDER 2014–2020) is gratefully acknowledged. Raúl Zarca also thanks the Universidad de Cantabria for the postgraduate fellowship

Comprehensive study on PVDF-HFP/BMImBF4/AgBF4 membranes for propylene purification

In this work, a comprehensive analysis of PVDF-HFP/BMImBF4/AgBF4 facilitated transport membranes for olefin/paraffin separation is presented. Previous works of our research group have reported high flux and propylene selectivity under dry conditions and using synthetic gas mixtures, highlighting the promising potential of these membranes for industrial applications. This work advances in the understanding of the phenomena involved in membrane performance and moves one step forward in the knowledge of the industrial viability of this membrane system. First, the internal interactions between the silver cations and the polymer backbone, the silver salt dissociation and the silver degradation have been studied using FTIR, Raman and XPS spectroscopic techniques. Secondly, the experimental membrane performance during 110 days and working at changing relative humidity conditions in the feed gas has been assessed. Thermogravimetric techniques helped determining the water uptake capability of the facilitated transport membrane. Thirdly, real gas mixtures from a fluid catalytic cracking unit were provided by the industry and used in permeation experiments to check the membrane behavior under industrial-like conditions. The results provide experimental evidence for the previously theorized facilitated transport mechanisms and reveal a major influence of feed gas humidity on membrane performance. On the other hand, the industrial gas mixture produces no deviation from synthetic feed conditions due to trace contaminants. Finally, the carrier deactivation in long-term permeation has been quantified through a mathematical expression.Financial support from the Spanish Ministry of Science under the projects CTQ2015-66078-R and CTQ2016-75158-R (MINECO, Spain-FEDER 2014–2020) is gratefully acknowledged. Raúl Zarca also thanks the Universidad de Cantabria for the postgraduate fellowship

Optimized distillation coupled with state-of-the-art membranes for propylene purification

The growing production of polyolefins, mainly polyethylene and polypropylene, currently demands increasing outputs of polymer-grade light olefins. The most commonly adopted process for the separation of olefin/paraffin mixtures is performed by energy intensive high pressure or cryogenic distillation, which is considered the most expensive operation in the petrochemical industry. The use of membrane technology offers a compact and modular solution for capital and energy savings, thanks to process intensification. In this work, we move one step forward in the design of hybrid propane/propylene separation systems, using computer aided modeling tools to identify economically optimal combinations of distillation and state-of-the-art membranes. A model is proposed to optimize a hybrid configuration, whereby the membrane performs the bulk separation and the distillation column is intended for the final product polishing, accounting for membrane investment cost and process operating expenses. The decision variables are the membrane area and the column reflux ratio, and the model is able to calculate the optimal feed trays. The upper-bound properties of selected membranes, which define their performance and reliability criteria, have been studied, benchmarking the economic evaluation against conventional distillation in order to assess the expedience of a hybrid system implementation.Financial support from the Spanish Ministry of Science under the projects CTQ2015-66078-R and CTQ2016-75158-R (MINECO, Spain-FEDER 2014–2020) is gratefully acknowledged. Raúl Zarca also thanks the Universidad de Cantabria for a postgraduate fellowship

Clinical practice guidelines for BRCA1 and BRCA2 genetic testing

BRCA1 and BRCA2 gene pathogenic variants account for most hereditary breast cancer and are increasingly used to determine eligibility for PARP inhibitor (PARPi) therapy of BRCA-related cancer. Because issues of BRCA testing in clinical practice now overlap with both preventive and therapeutic management, updated and comprehensive practice guidelines for BRCA genotyping are needed. The integrative recommendations for BRCA testing presented here aim to (1) identify individuals who may benefit from genetic counselling and risk-reducing strategies; (2) update germline and tumour-testing indications for PARPi-approved therapies; (3) provide testing recommendations for personalised management of early and metastatic breast cancer; and (4) address the issues of rapid process and tumour analysis. An international group of experts, including geneticists, medical and surgical oncologists, pathologists, ethicists and patient representatives, was commissioned by the French Society of Predictive and Personalised Medicine (SFMPP). The group followed a methodology based on specific formal guidelines development, including (1) evaluating the likelihood of BRCAm from a combined systematic review of the literature, risk assessment models and expert quotations, and (2) therapeutic values of BRCAm status for PARPi therapy in BRCA-related cancer and for management of early and advanced breast cancer. These international guidelines may help clinicians comprehensively update and standardise BRCA testing practices

Thermodynamic and process modeling of the recovery of R410A compounds with ionic liquids

European regulations are limiting the use of hydrofluorocarbons (HFCs) as refrigerants because of their elevated global warming potentials (GWPs). Apart from their substitution by other compounds with lower environmental impact, one of the plausible approaches to meet the legal requirements is the formulation of new refrigerant blends containing a low GWP compound (e.g., hydrofluoroolefins) mixed with one HFC that provides the necessary thermodynamic characteristics to act as an effective refrigerant. Thus, the recovery and reuse of HFCs seems a promising approach to increase their lifespan and reduce their production. However, current regeneration technologies that are based on distillation are highly energy-intensive. Therefore, the development of novel separation processes to selectively separate HFCs is needed for the practical implementation of circular economy principles in the use of refrigerants. This work is a step forward on using ionic liquids (ILs) to selectively separate F-gases. The advanced molecular-based soft-SAFT equation of state (EoS) is used as a tool to assess the potential of ILs as a solvent platform for the selective separation of the compounds forming the R410A refrigerant blend: R32 and R125. Soft-SAFT is employed to model the absorption of these HFCs into different ILs with different fluorinated anions. Ternary diagrams are then predicted for the absorption of R32/R125 mixtures into selected ILs to evaluate the competitive selectivity between both compounds. Based on this study, a potential ionic liquid candidate is chosen and a process simulation is performed to estimate the approximate energy cost of the separation and recovery process.This research is supported by Project KET4F-Gas – SOE2/P1/P0823, which is cofinanced by the European Regional Development Fund within the framework of the Interreg SUDOE Program. Also, S. Asensio-Delgado would like to thank the FPU grant (18/03939) awarded by the Spanish Ministry of Education

Division of Domestic Work: Is There Adjustment Between Partners when One is Unemployed?

Coming back to the main models of division of work within the couple, the aim of this article is to analyze the possible transfers of domestic chores between partners facing an external shock. We test it by studying the allocation of domestic time on couples facing unemployment on the French time-use survey. Are domestic chores transferable between partners? Controlled for many covariates, bivariate tobit regressions on indicators of time, variety and number of activities show that domestic tasks performed by unemployed people, either men or women, increase. Despite the inertia due to couple’s specialization, the hypothesis of versatility is partially checked. “Dominantly Feminine tasks” are the more transferable tasks. Unemployment involves a new division of labor between spouses. Copyright Springer Science+Business Media, Inc. 2005division of labor, specialization, household production, unemployment, family, D13, D19, J12, J19,