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Membrane Science

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Articles 31 - 37 of 37

Full-Text Articles in Transport Phenomena

Review Of Challenges And Advances In Modification Of Food Package Headspace Gases, Ziynet Boz, Bruce A. Welt, Jeffrey K. Brecht, William Pelletier, Eric Mclamore, Gregory A. Kiker, Jason E. Butler Apr 2018

Review Of Challenges And Advances In Modification Of Food Package Headspace Gases, Ziynet Boz, Bruce A. Welt, Jeffrey K. Brecht, William Pelletier, Eric Mclamore, Gregory A. Kiker, Jason E. Butler

Journal of Applied Packaging Research

Modified Atmosphere Packaging (MAP) has been widely used as an effective way to preserve foods. Fresh produce, meat and meat products, seafood, and dairy products can benefit from modified gaseous atmospheres, which are usually achieved by reducing oxygen and increasing carbon dioxide concentrations, within limits, defined by product tolerances. MAP of fresh produce is particularly challenging because products are living and respiring. Respiration rates depend on several factors including temperature, oxygen, and carbon dioxide concentrations. Balancing package permeation with respiration is challenging, often due to limited selection of practical packaging materials. Failing to remain within tolerance limits of products leads …

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Microbial Desalination Cells With Efficient Platinum Group Metal-Free Cathode Catalysts, Morteza Rezaei Talarposhti Nov 2017

Microbial Desalination Cells With Efficient Platinum Group Metal-Free Cathode Catalysts, Morteza Rezaei Talarposhti

Chemical and Biological Engineering ETDs

Iron-nitrogen-carbon based catalyst was used at the cathode of a microbial desalination cell (MDC) and compared with platinum (Pt) and activated carbon (AC) cathode. Fe-N-C catalyst was prepared using nicarbazin (NCB) as organic precursor by sacrificial support method (SSM). Rotating ring disk electrode (RRDE) experiments shows that Fe-NCB had higher electrocatalytic activity compared to AC and Pt. The utilization of Fe-NCB into the cathode improved substantially the performance output with initial maximum power density of 49±2 μWcm-2 in contrast to Pt and AC catalysts which have shown lower values of 34±1 μWcm-2 and 23.5±1.5 μWcm-2, respectively. …

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Pore-Confined Carriers And Biomolecules In Mesoporous Silica For Biomimetic Separation And Targeting, Shanshan Zhou Jan 2017

Pore-Confined Carriers And Biomolecules In Mesoporous Silica For Biomimetic Separation And Targeting, Shanshan Zhou

Theses and Dissertations--Chemical and Materials Engineering

Selectively permeable biological membranes composed of lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. This work imparts selective permeability to lipid-filled pores of silica thin film composite membranes using carrier molecules that reside in the lipophilic self-assemblies. The lipids confined inside the pores of silica are proven to be a more effective barrier than bilayers formed on the porous surface through vesicle fusion, which is critical for quantifying the function of an immobilized carrier. The ability of a lipophilic carrier embedded in the lipid bilayer to reversibly bind the target solute and transport it through …

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Elevated Test Pressure Significantly Reduces Dynamic Accumulation Oxygen Transmission Rate (Astm F3136) Measurement Time For Barrier Packaging Films, Bruce A. Welt Sep 2015

Elevated Test Pressure Significantly Reduces Dynamic Accumulation Oxygen Transmission Rate (Astm F3136) Measurement Time For Barrier Packaging Films, Bruce A. Welt

Journal of Applied Packaging Research

Measurement of gas transmission rates of materials is important for successful package design. The dynamic accumulation (DA) method (ASTM F3136) is becoming increasingly popular for measuring oxygen transmission rate (OTR) due to its simplicity and low cost. However, measurement time increases with barrier properties of materials, limiting measurement throughput. A dynamic accumulation measurement prototype capable of operating up to 1,000 psig was developed in order to accelerate gas transfer by boosting concentration gradients via elevated absolute pressures. Results show that measurement results were independent of test pressure while measurement times were substantially reduced. These results also suggest that gas transmission …

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Nanofiltration Membranes From Oriented Mesoporous Silica Thin Films, Mary K. Wooten Jan 2014

Nanofiltration Membranes From Oriented Mesoporous Silica Thin Films, Mary K. Wooten

Theses and Dissertations--Chemical and Materials Engineering

The synthesis of mesoporous silica thin films using surfactant templating typically leads to an inaccessible pore orientation, making these films not suitable for membrane applications. Recent advances in thin film synthesis provide for the alignment of hexagonal pores in a direction orthogonal to the surface when templated on chemically neutral surfaces. In this work, orthogonal thin film silica membranes are synthesized on alumina supports using block copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123) as the template. The orthogonal pore structure is achieved by sandwiching membranes between two chemically neutral surfaces, resulting in 90 nm thick films. Solvent flux of ethanol through …

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Transport Analysis And Model For The Performance Of An Ultrasonically Enhanced Filtration Process, Michael T. Grossner, Joanne M. Belovich, Donald L. Feke Jun 2005

Transport Analysis And Model For The Performance Of An Ultrasonically Enhanced Filtration Process, Michael T. Grossner, Joanne M. Belovich, Donald L. Feke

Chemical & Biomedical Engineering Faculty Publications

This paper presents an analysis of a filtration technique that uses ultrasound to aid the collection of small particles (tens of microns in diameter) from suspension. In this method, particles are retained within a porous mesh that is subjected to a resonant ultrasonic field, even though the pore size of the mesh is two orders of magnitude greater than the particle diameter. The role of acoustic forces in driving the retention phenomena has previously been studied on a micro-scale, which included modeling and experimental verification of particle motion and trapping near a single element of the mesh. Here, we build …

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Diffusivities Of N-Alkanes In Silicalite By Steady-State Single-Crystal Membrane Technique, Orhan Talu, Matthew S. Sun, Dhananjai B. Shah Mar 1998

Diffusivities Of N-Alkanes In Silicalite By Steady-State Single-Crystal Membrane Technique, Orhan Talu, Matthew S. Sun, Dhananjai B. Shah

Chemical & Biomedical Engineering Faculty Publications

A novel experimental technique that measures the diffusive flux through a single-crystal membrane (SCM) was developed and tested. Unlike all other macroscopic techniques that depend on a transient response, SCM is used under steady-state conditions, which results in a wide range of applicability from 10−2 to 10−11 cm2/s. Phenomenological equations for the steady-state data analysis were developed. The variation of driving force over the diffusion path is included in the model. As required by thermodynamics, the micropore concentration is given as a function of surface-excess amount adsorbed and gas density. The membrane configuration measures diffusivity in …

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