1,721,020 research outputs found
The use of essential oils in chitosan or cellulose‐based materials for the production of active food packaging solutions: a review
Full text linkIn recent decades, interest in sustainable food packaging systems with additional functionality, able to increase the shelf life of products, has grown steadily. Following this trend, the present review analyzes the state of the art of this active renewable packaging. The focus is on antimicrobial systems containing nanocellulose and chitosan, as support for the incorporation of essential oils. These are the most sustainable and readily available options to produce completely natural active packaging materials. After a brief overview of the different active packaging technologies, the main features of nanocellulose, chitosan, and of the different essential oils used in the field of active packaging are introduced and described. The latest findings about the nanocellulose- and chitosan-based active packaging are then presented. The antimicrobial effectiveness of the different solutions is discussed, focusing on their effect on other material properties. The effect of the different inclusion strategies is also reviewed considering both in vivo and in vitro studies, in an attempt to understand more promising solutions and possible pathways for further development. In general, essential oils are very successful in exerting antimicrobial effects against the most diffused gram-positive and gram-negative bacteria, and affecting other material properties (tensile strength, water vapor transmission rate) positively. Due to the wide variety of biopolymer matrices and essential oils available, it is difficult to create general guidelines for the development of active packaging systems. However, more attention should be dedicated to sensory analysis, release kinetics, and synergetic action of different essential oils to optimize the active packaging on different food products
Effect of Nano Fibrillated Cellulose on Facilitated Transport Membranes for CO2 separation
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Models for Facilitated Transport Membranes: A Review
Full text linkFacilitated transport membranes are particularly promising in different separations, as they are potentially able to overcome the trade-off behavior usually encountered in solution-diffusion membranes. The reaction activated transport is a process in which several mechanisms take place simultaneously, and requires a rigorous theoretical analysis, which unfortunately is often neglected in current studies more focused on material development. In this work, we selected and reviewed the main mathematical models introduced to describe mobile and fixed facilitated transport systems in steady state conditions, in order to provide the reader with an overview of the existing mathematical tools. An analytical solution to the mass transport problem cannot be achieved, even when considering simple reaction schemes such as that between oxygen (solute) and hemoglobin (carrier) ( A + C ⇄ A C ), that was thoroughly studied by the first works dealing with this type of biological facilitated transport. Therefore, modeling studies provided approximate analytical solutions and comparison against experimental observations and exact numerical calculations. The derivation, the main assumptions, and approximations of such modeling approaches is briefly presented to assess their applicability, precision, and flexibility in describing and understanding mobile and fixed site carriers facilitated transport membranes. The goal is to establish which mathematical tools are more suitable to support and guide the development and design of new facilitated transport systems and materials. Among the models presented, in particular, those from Teramoto and from Morales-Cabrera et al. seem the more flexible and general ones for the mobile carrier case, while the formalization made by Noble and coauthors appears the most complete in the case of fixed site carrier membranes
Modelling water sorption in Facilitated Transport Membranes with PC-SAFT Equation of State: the case of Polyvinyl amine
Full text linkFacilitated transport membranes have great potential for carbon dioxide removal. By coupling the solution diffusion mechanism and the facilitation effect of the chemical reaction, CO2 transport in such systems is substantially higher compared to other gases, like nitrogen and methane. The presence of water is needed in the membrane to activate the reaction mechanism, and affects the sorption and diffusion of all the gases in the membrane. The present work focuses on the modelling of water sorption in purified Lupamin® (polyvinylamine (PVAm)), with the PC-SAFT Equation of State (EoS) (Gross and Sadowski, 2001). The work is aimed at finding the best parameters and association schemes to model the water sorption in PVAm with the PC-SAFT model, in order to use it to model more complex situations such as the multicomponent sorption in the system
CO2 sorption modelling in humidified Polyvinyl amine (PVAm) with PC-SAFT
Full text linkCarbon dioxide emissions represent one of the main environmental issue of our time. The greenhouse gases atmospheric loading, due to anthropogenic activities, are causing a continue rise of global temperature. In the field of CO2 capture from gas streams, membrane technologies are promising alternative to the more common operations. Among these, Facilitated Transport Membranes show high performances in terms of CO2 permeabilities and selectivities even at low pressures by coupling a simple solution diffusion transport mechanism and a reversible chemical reaction with a carrier agent. Polyvinyl amine (PVAm) binds one primary amino group for each monomer along the chain, showing high hydrophilicity and affinity to CO2. In this work we use the PC-SAFT [1] Equation of State to model the H2O uptake and the solubility of CO2 in the ternary system of PVAm / H2O / CO2
Effect of humidity and nanocellulose content on Polyvinylamine-nanocellulose hybrid membranes for CO2capture
No full textIn order to address the need for more efficient technologies for carbon capture applications, a novel type of nanocellulose based hybrid membrane has been successfully prepared by blending the commercial Polyvinylamine solution Lupamin® 9095 (BASF) with Nano Fibrillated Cellulose (NFC) to improve its mechanical and separation capabilities. Self-standing films with different nanocellulose loading (from 30 to 70 wt%) have been prepared and characterized at 35 °C through water vapor sorption experiments and humid gas permeation tests. As expected, membrane permeability consistently increased with increasing water vapor and a higher presence of Lupamin in the film resulted in an increment of both gas permeability and selectivity. In particular blends with a NFC content of 70 wt% Lupamin reached an ideal selectivity of 135 for the separation of CO2/CH4and 218 for CO2/N2, at 60 RH%, while the maximum permeability in the order of 187 Barrer was instead reached at 80% RH. Water vapor solubility was also measured and modeled through Park Model to correlate the gas separation properties with the effective content of water present in the membrane matrix. As expected, a higher content of the hydrophilic polymer resulted in a larger water uptake, which at medium to high humidity appeared to trigger a water clustering phenomenon in the matrix. This fact was accompanied by a substantial relaxation of the polymer network, causing a marked reduction of selectivity, which dropped, at the highest RH investigated, to values in the order of 30 and 80 towards CH4and N2respectively. Despite this loss in performance, most materials tested still showed very interesting properties, well above Robeson's 2008 Upper Bound, making them an interesting alternative for traditional gas separation processes
Graphene/Graphene Oxide stabilized polyvinylamine nanocomposite membranes for CO2 separation
No full textThermodynamics characterization of CO2 sorption in polymers for CO2 transport applications
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