Effectiveness of a coagulation step and polyester support on blend polyvinylchloride membrane formation and performance

2019 ◽  
Vol 39 (4) ◽  
pp. 351-359 ◽  
Author(s):  
Heba Abdallah ◽  
Marwa S. Shalaby ◽  
Ayman El-gendi ◽  
Ahmed M. Shaban ◽  
Bao-Ku Zhu
Keyword(s):  
Mechanical Test ◽  
Solution Concentration ◽  
Precipitation Process ◽  
Permeate Flux ◽  
Membrane Formation ◽  
Membrane Performance ◽  
Ftir Spectrophotometry ◽  
Polyester Support ◽  
And Performance

Abstract The effectiveness of woven and nonwoven polyester support and coagulation time during membrane formation on the performance and characterization of prepared membranes was studied. The blend membranes of polyvinylchloride with cellulose acetate were prepared by the immersion precipitation process. The prepared membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrophotometry and a mechanical test. Membrane performance was tested using a feed of different synthetic salt solutions. The results proved that the prepared membrane using woven support provided the highest permeate flux and good salt rejection (93.3%) for a salty solution concentration of 20,000 ppm. The stress-strain mechanical test indicated that the excellent mechanical behavior was shown for membranes prepared with a woven support, which has a strength of 12.6 N/cm2 with an elongation of 25 mm for M8. A fouling test was carried out using a mixture solution of salt and humic acid. Using the prepared membranes with woven support provided the best antifouling properties with a flux recovery of 99.2% compared with a flux recovery of 96% using the prepared membrane without support.

scholarly journals Characteristics and Performance of PTU-Cu Composite Membrane Fabricated through Simultaneous Complexation and Non-Solvent Induced Phase Separation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1743
Author(s):  
Marianito Tiangson Margarito ◽  
Arnel Bas Beltran ◽  
Aileen Huelgas-Orbecido
Keyword(s):  
Phase Separation ◽  
Color Change ◽  
Pure Water ◽  
Water Flux ◽  
Condensation Polymerization ◽  
Membrane Formation ◽  
Membrane Performance ◽  
Membrane Surfaces ◽  
Atomic Force ◽  
And Performance

This study aims to integrate copper (Cu) during membrane formation by a facile simultaneous phase separation process to alleviate biofouling and improve membrane performance. Polythiourea (PTU) polymer synthesized through condensation polymerization of 4,4-oxydianiline and p-phenylene diisothiocyanate in dimethyl sulfoxide was used in the preparation of dope solution. By incorporating different concentrations of cupric acetate in the non-solvent bath, both non-solvent induced phase separation and complexation induced phase separation occur instantaneously. Scanning electron microscopy—energy dispersive X-ray, fourier-transform infrared spectroscopy and time-of-flight secondary ion mass spectroscopy analysis accompanied by color change of the membrane surfaces—confirms the interaction of the polymer with Cu. Interaction of Cu at the interface during membrane formation results in a decrease in contact angle from 2 to 10° and a decrease in surface roughness from 30% to 52% as measured by atomic force microscope analysis. Pure water flux of PTU-Cu membrane increased by a factor of 3 to 17 relative to pristine PTU membrane. Both the pristine PTU and PTU-Cu membrane showed antibacterial characteristics against E. coli.

scholarly journals Preparation and Characterization of Asymmetric Ultrafiltration Membrane for Lysozyme Separation: Effect of Polymer Concentration

2017 ◽  
Vol 11 (1) ◽  
Author(s):  
A. Nora’aini ◽  
H. Sofiah ◽  
A. Asmadi ◽  
M. Abdul Wahab
Keyword(s):  
Phase Inversion ◽  
Protein Production ◽  
Polymer Concentration ◽  
Downstream Processing ◽  
High Yield ◽  
Membrane Performance ◽  
Phase Inversion Technique ◽  
Wet Phase Inversion ◽  
And Performance

Penetrations of membrane technology in the downstream processing of protein production are now well accepted due its effectiveness and ability to generate high yield of product. This study aimed to investigate the effects of polymer concentrations on morphology and performance of ultrafiltration membranes for lysozyme separation. Three membrane solutions with different polymer concentration of Polyehtersulfone/N–Methyl pyrolidone/water with 15% w/w, 17% w/w and 19% w/w (15% [UF 15], 17% [UF 17] and 19% [UF 19]) were used to prepare asymmetric flat sheets membranes via a simple dry/wet phase inversion technique. The data obtained shows that the permeability coefficient decreased from 10.9 × 10–6 to 0.44 × 10–6m3/m2.s.bar with increasing polymer concentrations. UF 15 membrane discovers the highest flux and lysozyme transmission, consequently promoted this membrane as an optimum membrane for lysozyme separation. This study proves that the polymer concentration was greatly affected the membrane performance and structural properties consecutively, promoted an improvement of UF membrane capability for lysozyme separation.

scholarly journals Influence of Preparation Temperature on the Properties and Performance of Composite PVDF-TiO2 Membranes

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 876
Author(s):  
Duc-Trung Tran ◽  
Jean-Pierre Méricq ◽  
Julie Mendret ◽  
Stephan Brosillon ◽  
Catherine Faur
Keyword(s):  
Phase Separation ◽  
Membrane Properties ◽  
High Porosity ◽  
Permeate Flux ◽  
Preparation Temperature ◽  
Membrane Formation ◽  
Compression Behavior ◽  
Membrane Morphology ◽  
Ternary Phase Diagrams ◽  
And Performance

Composite PVDF-TiO2 membranes are studied extensively in literature as effective anti-fouling membranes with photocatalytic properties. Yet, a full understanding of how preparation parameters affect the final membrane structure, properties and performance has not been realized. In this study, PVDF-TiO2 membranes (20 wt% TiO2/PVDF) were fabricated via the non-solvent-induced phase separation (NIPS) method with an emphasis on the preparation temperature. Then, a systematic approach was employed to study the evolution of the membrane formation process and membrane properties when the preparation temperature changed, as well as to establish a link between them. Typical asymmetric membranes with a high porosity were obtained, along with a vast improvement in the permeate flux compared to the neat PVDF membranes, but a reduction in mechanical strength was also observed. Interestingly, upon the increase in preparation temperature, a significant transition in membrane morphology was observed, notably the gradual diminution of the finger-like macrovoids. Other membrane properties such as permeability, porosity, thermal and mechanical properties, and compression behavior were also influenced accordingly. Together, the establishment of the ternary phase diagrams, the study of solvent–nonsolvent exchange rate, and the direct microscopic observation of membrane formation during phase separation, helped explain such evolution in membrane properties.

Mn-Mo-O Catalysts for Methanol Oxidation. I. Preparation and Characterization of the Catalysts

1992 ◽  
Vol 57 (12) ◽  
pp. 2529-2538 ◽  
Author(s):  
Krasimir Ivanov ◽  
Penka Litcheva ◽  
Dimitar Klissurski
Keyword(s):  
Methanol Oxidation ◽  
Solution Concentration ◽  
Alkaline Media ◽  
Acidic Media ◽  
Chemical Methods ◽  
X Ray ◽  
Ph Values ◽  
Precipitate Composition

Mn-Mo-O catalysts with a different Mo/Mn ratio have been prepared by precipitation. The precipitate composition as a function of solution concentration and pH was studied by X-ray, IR, thermal and chemical methods. Formation of manganese molybdates with MnMoO4.1.5H2O, Mn3Mo3O12.2.5H2O, and Mn3Mo4O15.4H2O composition has been supposed. It is concluded that pure MnMoO4 may be obtained in both acid and alkaline media, the pH values depending on the concentration of the initial solutions. The maximum Mo/Mn ratio in the precipitates is 1.33. The formation of pure Mn3Mo4O15.4H2O is possible in weakly acidic media. This process is favoured by increasing the concentration of initial solutions.

scholarly journals Noise and Breakdown Characterization of SPAD Detectors with Time-Gated Photon-Counting Operation

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5287
Author(s):  
Hiwa Mahmoudi ◽  
Michael Hofbauer ◽  
Bernhard Goll ◽  
Horst Zimmermann
Keyword(s):  
Breakdown Voltage ◽  
Single Photon ◽  
Photon Counting ◽  
Low Noise ◽  
Dark Count ◽  
Fully Integrated ◽  
Trade Offs ◽  
And Performance ◽  
Noise Models

Being ready-to-detect over a certain portion of time makes the time-gated single-photon avalanche diode (SPAD) an attractive candidate for low-noise photon-counting applications. A careful SPAD noise and performance characterization, however, is critical to avoid time-consuming experimental optimization and redesign iterations for such applications. Here, we present an extensive empirical study of the breakdown voltage, as well as the dark-count and afterpulsing noise mechanisms for a fully integrated time-gated SPAD detector in 0.35-μm CMOS based on experimental data acquired in a dark condition. An “effective” SPAD breakdown voltage is introduced to enable efficient characterization and modeling of the dark-count and afterpulsing probabilities with respect to the excess bias voltage and the gating duration time. The presented breakdown and noise models will allow for accurate modeling and optimization of SPAD-based detector designs, where the SPAD noise can impose severe trade-offs with speed and sensitivity as is shown via an example.

scholarly journals Synthesis and Characterization of Novel Bio-Chiral Dopants Obtained from Bio-Betulin Produced by a Fermentation Process

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 785
Author(s):  
Veridiana G. Guimarães ◽  
Anastasiia Svanidze ◽  
Tianyi Guo ◽  
Pawan Nepal ◽  
Robert J. Twieg ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Natural Product ◽  
Fermentation Process ◽  
Synthesis And Characterization ◽  
Cholesteric Liquid Crystals ◽  
And Performance ◽  
Chiral Dopants

Cholesteric liquid crystals are frequently produced by the addition of chiral dopants to achiral nematic hosts. We report here the synthesis and performance of chiral dopants obtained from bio-betulin produced by a fermentation process. An important aspect of this work is to point out that the fermentation process used to obtain the starting materials is much easier and cheaper when carried out in large volumes than isolating it from the natural product. The performance of the dopants obtained from bio-betulin is indistinguishable from those obtained from commercially available synthetic betulin.

Design, Installation, and Performance Characterization of a Laboratory-Scale Solar Thermal System for Experiments in Solar Energy Utilization

2012 ◽  
Author(s):  
Stephanie Drozek ◽  
Christopher Damm ◽  
Ryan Enot ◽  
Andrew Hjortland ◽  
Brandon Jackson ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Solar Energy ◽  
Laboratory Scale ◽  
Energy Utilization ◽  
Solar Thermal ◽  
Thermal System ◽  
Performance Characterization ◽  
And Performance ◽  
Solar Thermal System

The purpose of this paper is to describe the implementation of a laboratory-scale solar thermal system for the Renewable Energy Systems Laboratory at the Milwaukee School of Engineering (MSOE). The system development began as a student senior design project where students designed and fabricated a laboratory-scale solar thermal system to complement an existing commercial solar energy system on campus. The solar thermal system is designed specifically for educating engineers. This laboratory equipment, including a solar light simulator, allows for variation of operating parameters to investigate their impact on system performance. The equipment will be utilized in two courses: Applied Thermodynamics, and Renewable Energy Utilization. During the solar thermal laboratories performed in these courses, students conduct experiments based on the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) 93-2010 standard for testing and performance characterization of solar thermal systems. Their measurements are then used to quantify energy output, efficiency and losses of the system and subsystem components.

Preparation of Carbon Nanofibers from Polyacrylonitrile Nanofibers by Electrospinning

2011 ◽  
Vol 415-417 ◽  
pp. 642-647
Author(s):  
En Zhong Li ◽  
Da Xiang Yang ◽  
Wei Ling Guo ◽  
Hai Dou Wang ◽  
Bin Shi Xu
Keyword(s):  
Electron Microscope ◽  
Carbon Nanofibers ◽  
Photoelectron Spectroscopy ◽  
Solution Concentration ◽  
Dimethyl Formamide ◽  
Ultrafine Fibers ◽  
X Ray ◽  
Scanning Electron ◽  
Pan Fibers

Ultrafine fibers were electrospun from polyacrylonitrile (PAN)/N,N-dimethyl formamide (DMF) solution as a precursor of carbon nanofibers. The effects of solution concentration, applied voltage and flow rate on preparation and morphologies of electrospun PAN fibers were investigated. Morphologies of the green fibers, stabilized fibers and carbonized fibers were compared by scanning electron microscope (SEM). The diameter of PAN nanofibers is about 450nm and the distribution of diameter is well-proportioned. Characterization of the elements changes of fibers were performed by X-ray photoelectron spectroscopy (XPS).

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