scholarly journals Linking the Tuneability and Defouling of Electrically Conductive Polyaniline/Exfoliated Graphite Composite Membranes

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 631
Author(s):  
Lili Xu ◽  
Kunpeng Wang ◽  
Jun Wang ◽  
Darrell Alec Patterson
Keyword(s):  
Membrane Surface ◽  
Electrical Potential ◽  
Composite Membranes ◽  
Fast Response ◽  
Exfoliated Graphite ◽  
Original Position ◽  
Stimuli Responsive ◽  
Applied Potential ◽  
Electrically Conductive ◽  
Graphite Composite

Stimuli responsive membranes, which are able to respond to environmental stimuli, are attracting ever-increasing interests. In this study, we blended exfoliated graphite (EG) into the polyaniline (PANI) and developed PANI/EG composite membranes. The properties of the new generated membranes, especially the stimuli response properties (e.g., electrical tuneability, deformation), were studied. The fouling removal ability of the membrane under applied electrical potential was also investigated by using bovine serum albumin (BSA) as a model foulant. A flat membrane with defect-free surface and good adhesion to the support layer was formed by non-solvent induced phase separation method. The electrical conductivity of the formed PANI/EG composite membrane was (5.10 ± 0.27) ×10−4 S cm−1. The dynamic droplet penetration rate through the membranes showed an increase under applied electrical potential, which gives a preliminary quantitative indication of the electrical tuneability of the membranes. The membrane deformation appeared at a fast response under applied potential and recovered to its original position immediately when removing the applied potential. The application of electrical potential led to the removal of BSA foulant from the membrane surface as indicated by the increase in permeance of the fouled membrane on cleaning with 46.2% flux recovery ratio and increased BSA concentration in the wash solution. The electrically conductive PANI/EG composite membranes are able to respond to electrical stimuli, enabling a new range of potential applications including externally tuneability and in situ removal and control of fouling.

scholarly journals New Synthetic Methods of Novel Nanoporous Polycondensates and Excellent Oxygen Permselectivity of Their Composite Membranes

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 859
Author(s):  
Yu Zang ◽  
Toshiki Aoki ◽  
Masahiro Teraguchi ◽  
Takashi Kaneko ◽  
Hongge Jia ◽  
...  
Keyword(s):  
Contact Angle ◽  
Upper Bound ◽  
Oxygen Permeability ◽  
Membrane Surface ◽  
Composite Membranes ◽  
Synthetic Methods ◽  
Preparation Methods ◽  
First Time

Two kinds of novel nanoporous polycondensates (sc(Rf)) have been synthesized by two new preparation methods consisting of polycondensation and highly selective photocyclicaromataization of 1/3 helical cis-cis polyphenylacetylenes with polymerizable groups. By the original methods, new well-defined sheet polymers having nanopores or nanospaces have been synthesized for the first time. Their composite membranes, containing small amounts (1.0 wt%) of sc(Rf), had ultrahigh oxygen permeability (Po2 > 1000 barrer), and their plots were beyond the Robeson’s upper bound line in the graph of oxygen permselectivity (α = Po2/PN2) versus Po2. Both α and Po2 values were enhanced by adding only small amounts (1.0 wt%) of sc(Rf). One of the sc(Rf)s synthesized on the base membrane surface showed the best performance, i.e., Po2 = 5300 barrer and α = 2.5. The membrane surface was effectively covered by sc(Rf), judging from the contact angle values. It is thought that nanopores and nanospaces created in and between sc(Rf) molecules played an important role for the enhancement of both α and Po2/PN2.

Study of Properties of Expanded Graphite – Polymer Porous Composite by Acoustic Emission Method

2013 ◽  
Vol 58 (4) ◽  
pp. 1331-1336 ◽  
Author(s):  
J. Berdowski ◽  
S. Berdowska ◽  
F. Aubry
Keyword(s):  
Acoustic Emission ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Physical And Mechanical Properties ◽  
Expanded Graphite ◽  
Composite Membranes ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Graphite Composite ◽  
Wide Range

Abstract The purpose of this paper was to investigate the physical and mechanical properties of compressed expanded graphite (CEG) and their porous derivatives after impregnation, polymerization; and carbonization by the use of acoustic emission method (AE). The mechanical and structural characteristics of compressed expanded graphite and their three groups of porous composites after each technological process are presented and discussed. The measurements of acoustic emission parameters in these materials were carried out at wide range of frequency of the waves (0.1÷2.5 MHz). The changes of two of parameters: - AE pulses counts rate and spectrum distribution of AE waves - are presented in this paper. The analysis of the respective parameters AE also gives possibility to determine the micro- and macro structural changes of materials at different levels of technological processes. Applications of these materials as catalysts with high specific surface make them very interesting subject of study. Also compressed expanded graphite composite membranes prepared from furfuryl alcohol polymers are promising for gas separation.

Programmable Skins based on Core-Shell Microsphere/Nanotube/Polymer Composites

2015 ◽  
Vol 1800 ◽  
Author(s):  
Balaji Panchapakesan ◽  
Cagdas Onal ◽  
James Loomis
Keyword(s):  
Polymer System ◽  
Liquid Hydrocarbon ◽  
Core Shell ◽  
Stimuli Responsive ◽  
Electrically Conductive ◽  
Dimensional Changes ◽  
Stimuli Responsive Polymers ◽  
Thermally Responsive ◽  
New Findings ◽  
The Matrix

ABSTRACTIn this paper, we describe unique thermally responsive polymer system based on nanotube-elastomers dispersed with core-shell expanding microspheres (phase-change material). Upon thermal or infrared stimuli, liquid hydrocarbon cores encapsulated within the microspheres vaporize, expanding the surrounding shells and stretching the matrix. Microsphere transformation resulted in visible dimensional changes associated with macroscopic volume increase (>500%), reduction in density (>80%), and increase in elastic modulus (>675%). Additionally, electrically conductive nanotubes allowed for expansion dependent electrical responses. We present our new findings on expansion dependent superhydrophobicity in these materials and present some outlook and comparison of our stimuli responsive polymers with other material systems for future origami based applications.

scholarly journals Dual Functional Ultrafiltration Membranes with Enzymatic Digestion and Thermo-Responsivity for Protein Self-Cleaning

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 85 ◽  
Author(s):  
Anbharasi Vanangamudi ◽  
Ludovic Dumée ◽  
Mikel Duke ◽  
Xing Yang
Keyword(s):  
Surface Engineering ◽  
Vinylidene Fluoride ◽  
Membrane Surface ◽  
Surface Protein ◽  
Composite Membranes ◽  
Enzymatic Digestion ◽  
Combined Effect ◽  
Functional Sites ◽  
Nylon 6,6 ◽  
Self Cleaning

Controlling surface–protein interaction during wastewater treatment is the key motivation for developing functionally modified membranes. A new biocatalytic thermo-responsive poly vinylidene fluoride (PVDF)/nylon-6,6/poly(N-isopropylacrylamide)(PNIPAAm) ultrafiltration membrane was fabricated to achieve dual functionality of protein-digestion and thermo-responsive self-cleaning. The PVDF/nylon-6,6/PNIPAAm composite membranes were constructed by integrating a hydrophobic PVDF cast layer and hydrophilic nylon-6,6/PNIPAAm nanofiber layer on to which trypsin was covalently immobilized. The enzyme immobilization density on the membrane surface decreased with increasing PNIPAAm concentration, due to the decreased number of amine functional sites. An ultrafiltration study was performed using the synthetic model solution containing BSA/NaCl/CaCl2, where the PNIPAAm containing biocatalytic membranes demonstrated a combined effect of enzymatic and thermo-switchable self-cleaning. The membrane without PNIPAAm revealed superior fouling resistance and self-cleaning with an RPD of 22%, compared to membranes with 2 and 4 wt % PNIPAAm with 26% and 33% RPD, respectively, after an intermediate temperature cleaning at 50 °C, indicating that higher enzyme density offers more efficient self-cleaning than the combined effect of enzyme and PNIPAAm at low concentration. The conformational volume phase transition of PNIPAAm did not affect the stability of immobilized trypsin on membrane surfaces. Such novel surface engineering design offer a promising route to mitigate surface–protein contamination in wastewater applications.

Preparation of Chitosan-Alginate/PES Pervaporation Membranes for Bioethanol Dehydration

2015 ◽  
Vol 1123 ◽  
pp. 182-186 ◽  
Author(s):  
Mumpuni Asih Pratiwi ◽  
Ronny Windu Sudrajat ◽  
Sri Sutanti ◽  
Heru Susanto
Keyword(s):  
Surface Morphology ◽  
Surface Chemistry ◽  
Composite Membrane ◽  
Membrane Surface ◽  
Composite Membranes ◽  
Solution Concentration ◽  
Wave Number ◽  
Water Mixture ◽  
Coating Solution ◽  
Degree Of Swelling

In the last decade pervaporation membrane has become an antractive dehydration processs for azeotropic ethanol-water mixture. In this paper, chitosan-alginate/polyethersulfone (PES) composite membranes were prepared (by coating method) characterized as pervaporation membranes. The composite membranes were then examined to purify ethanol-water mixture. The characterization included degree of swelling both in water and ethanol, permeability measurement, surface morphology (by SEM) and surface chemistry (by FTIR). The results show that the increase in concentration of coating solution increases the degree of swelling in the water on the one hand, whereas the permeability and the degree of swelling in the ethanol decreases on the other hand. The highest permeability was obtained for the composite membrane prepared from a coating solution concentration of 1% with the ratio of chitosan to alginate was 0,33. The surface chemistry shows that the increase in concentration of chitosan - alginate solution increases the intensity of a specific wave number of C-O and C-N groups. Surface morphology indicates that the PES membrane surface is clearly covered by chitosan - alginate mixture. Performance examination demonstrates that the composite membrane prepared by 3% a coating solution (with the ratio of chitosan to alginate 3) can increase the bioethanol concentration from 95.5% to 99.6%.

Polysulfone Activated Carbon Composite Membranes

2010 ◽  
Vol 660-661 ◽  
pp. 1081-1086 ◽  
Author(s):  
Priscila Anadão ◽  
Laís Fumie Sato ◽  
Hélio Wiebeck ◽  
Francisco Rolando Valenzuela-Díaz
Keyword(s):  
Activated Carbon ◽  
Membrane Surface ◽  
Composite Membranes ◽  
Carbon Composite ◽  
Van Der Waals Interactions ◽  
Membrane Properties ◽  
Mechanical Resistance ◽  
Scanning Electron Micrographs ◽  
Polysulfone Membrane ◽  
Hydrophilic Material

The addition of a fourth component in the system composed by polymer/ solvent/ non-solvent is a technique generally employed to enhance membrane properties. Since polysulfone presents low hydrophilicity, which can hamper filtration performance, the addition of a hydrophilic material can be an important technique to improve this property. Therefore, the main purpose of this work is to understand the influence of addition of the activated carbon in the system polysulfone/ NMP/ water in terms of membrane morphology, hydrophilicity, thermal and mechanical resistance. From scanning electron micrographs, it could be seen that membrane surface became denser with the addition of higher activated carbon contents and the cross-section morphology was not changed. Acid-base interactions were favored with the activated carbon addition and the availability of Lifshtiz-van Der Waals interactions was decreased, being these two properties very important to avoid fouling formation onto membrane surface. The glass transition temperatures of the polysulfone composite membranes with higher activated carbon contents were increased. However, all activated carbon contents brittled the composite membranes in relation to the pristine polysulfone membrane.

Antifouling behaviours of PVDF/nano-TiO2 composite membranes revealed by surface energetics and quartz crystal microbalance monitoring

RSC Advances ◽  
2014 ◽  
Vol 4 (82) ◽  
pp. 43590-43598 ◽  
Author(s):  
Qiaoying Wang ◽  
Zhiwei Wang ◽  
Jie Zhang ◽  
Jie Wang ◽  
Zhichao Wu
Keyword(s):  
Interaction Energy ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Membrane Surface ◽  
Composite Membranes ◽  
Nano Tio2 ◽  
Surface Energetics

Introducing nano-TiO2 improved the interaction energy between the membrane surface and foulant; however, aggregation of nano-TiO2 facilitated foulant adsorption on pore walls.

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