Effect of Cross-Linking Agent Chemistry and Coating Conditions on Physical, Chemical, and Separation Properties of PVA-Psf Composite Membranes

2013 ◽  
Vol 49 (1) ◽  
pp. 22-29 ◽  
Author(s):  
Derrick S. Dlamini ◽  
Jinwen Wang ◽  
Ajay K. Mishra ◽  
Bhekie B. Mamba ◽  
Eric M. V. Hoek
Keyword(s):  
Composite Membranes ◽  
Cross Linking ◽  
Physical Chemical

scholarly journals Chemically Cross-Linked Graphene Oxide as a Selective Layer on Electrospun Polyvinyl Alcohol Nanofiber Membrane for Nanofiltration Application

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2867
Author(s):  
Myoung Jun Park ◽  
Grace M. Nisola ◽  
Dong Han Seo ◽  
Chen Wang ◽  
Sherub Phuntsho ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Polyvinyl Alcohol ◽  
Self Assembly ◽  
Water Flux ◽  
Composite Membranes ◽  
Cross Linking ◽  
Support Surface ◽  
Eosin Y ◽  
Selective Layer ◽  
Assembly Technique

Graphene oxide (GO) nanosheets were utilized as a selective layer on a highly porous polyvinyl alcohol (PVA) nanofiber support via a pressure-assisted self-assembly technique to synthesize composite nanofiltration membranes. The GO layer was rendered stable by cross-linking the nanosheets (GO-to-GO) and by linking them onto the support surface (GO-to-PVA) using glutaraldehyde (GA). The amounts of GO and GA deposited on the PVA substrate were varied to determine the optimum nanofiltration membrane both in terms of water flux and salt rejection performances. The successful GA cross-linking of GO interlayers and GO-PVA via acetalization was confirmed by FTIR and XPS analyses, which corroborated with other characterization results from contact angle and zeta potential measurements. Morphologies of the most effective membrane (CGOPVA-50) featured a defect-free GA cross-linked GO layer with a thickness of ~67 nm. The best solute rejections of the CGOPVA-50 membrane were 91.01% for Na2SO4 (20 mM), 98.12% for Eosin Y (10 mg/L), 76.92% for Methylene blue (10 mg/L), and 49.62% for NaCl (20 mM). These findings may provide one of the promising approaches in synthesizing mechanically stable GO-based thin-film composite membranes that are effective for solute separation via nanofiltration.

scholarly journals Cross-Linking With Diamine Monomers to Prepare Graphene Oxide Composite Membranes With Varying D-Spacing for Enhanced Desalination Properties

2021 ◽  
Vol 9 ◽  
Author(s):  
Hong Ju ◽  
Jinzhuo Duan ◽  
Haitong Lu ◽  
Weihui Xu
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Water Flux ◽  
Covalent Bond ◽  
Composite Membranes ◽  
Rejection Rate ◽  
High Water ◽  
Cross Linking ◽  
Separation Performance ◽  
X Ray

As a new type of membrane material, graphene oxide (GO) can easily form sub-nanometer interlayer channels, which can effectively screen salt ions. The composite membrane and structure with a high water flux and good ion rejection rate were compared by the cross-linking of GO with three different diamine monomers: ethylenediamine (EDA), urea (UR), and p-phenylenediamine (PPD). X-ray photoelectron spectroscopy (XPS) results showed that unmodified GO mainly comprises π-π interactions and hydrogen bonds, but after crosslinking with diamine, both GO and mixed cellulose (MCE) membranes are chemically bonded to the diamine. The GO-UR/MCE membrane achieved a water flux similar to the original GO membrane, while the water flux of GO-PPD/MCE and GO-EDA/MCE dropped. X-ray diffraction results demonstrated that the covalent bond between GO and diamine can effectively inhibit the extension of d-spacing during the transition between dry and wet states. The separation performance of the GO-UR/MCE membrane was the best. GO-PPD/MCE had the largest contact angle and the worst hydrophilicity, but its water flux was still greater than GO-EDA/MCE. This result indicated that the introduction of different functional groups during the diamine monomer cross-linking of GO caused some changes in the performance structure of the membrane.

Modified Methods in Starch-Based Biodegradable Films

2011 ◽  
Vol 183-185 ◽  
pp. 1635-1641 ◽  
Author(s):  
Jun Feng Su ◽  
Jian Jun Cheng
Keyword(s):  
Mechanical Treatment ◽  
Packaging Material ◽  
Cross Linking ◽  
Attractive Alternative ◽  
Biodegradable Films ◽  
Debranching Enzyme ◽  
Renewable Source ◽  
Physical Chemical ◽  
Plastic Materials ◽  
Starch Debranching Enzyme

With plastics resistance to degradation in nature and lack of effective recycling practice, it has resulted in a serious threat to the environment. Concerns about the environmental pollution caused by plastics have led to serious demands for biodegradable plastic materials made from renewable source. Starch is a biopolymer that has been being an attractive alternative for packaging material. A general overview on the microstructures of starch is given in this essay. The modified methods in biodegradable starch-based films are reviewed, which include physical, chemical and enzymic modification. Physical modification involves ultrasonic, mechanical treatment and addition of additives, such as plasticizer and coupling agent. Chemical modification consists of etherification, esterification, cross-linking, grafting and oxidation. Enzymic modification includes debranching reaction of starch debranching enzyme which contains pulullanase and isoamylase. The biodegradation of starch-based films and the prospects of their future are also detailed.

scholarly journals Supported MXene/GO Composite Membranes with Suppressed Swelling for Metal Ion Sieving

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 621
Author(s):  
Zongjie Yin ◽  
Zong Lu ◽  
Yanyan Xu ◽  
Yonghong Zhang ◽  
Liliang He ◽  
...  
Keyword(s):  
Composite Membrane ◽  
Water Purification ◽  
Metal Ion ◽  
High Performance ◽  
Composite Membranes ◽  
Transition Metal Carbide ◽  
Cross Linking ◽  
Metal Carbide ◽  
Ion Exclusion ◽  
The Cross

Novel two-dimensional (2D) membranes have been utilized in water purification or seawater desalination due to their highly designable structure. However, they usually suffer from swelling problems when immersed in solution, which limits their further applications. In this study, 2D cross-linked MXene/GO composite membranes supported on porous polyamide substrates are proposed to improve the antiswelling property and enhance the ion-sieving performance. Transition-metal carbide (MXene) nanosheets were intercalated into GO nanosheets, where the carboxyl groups of GO combined the neighboring hydroxyl terminal groups of MXene with the formation of -COO- bonds between GO and MXene nanosheets via the cross-linking reaction (−OH + −COOH = −COO− + H2O) after heat treatment. The permeation rates of the metal ions (Li+, Na+, K+, Al3+) through the cross-linked MXene/GO composite membrane were 7–40 times lower than those through the pristine MXene/GO membrane. In addition, the cross-linked MXene/GO composite membrane showed excellent Na+ rejection performance (99.3%), which was significantly higher than that through pristine MXene/GO composite membranes (80.8%), showing improved ion exclusion performance. Such a strategy represents a new avenue to develop 2D material-derived high-performance membranes for water purification.

Cross-Linked PIM-1 Membranes with Improved Stability to Aromatics

2020 ◽  
Vol 869 ◽  
pp. 431-436
Author(s):  
Alexey A. Yushkin ◽  
Alexey V. Balynin ◽  
Danila S. Bakhtin ◽  
Richard Kirk ◽  
Peter M. Budd ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Solubility Parameter ◽  
Composite Membranes ◽  
Cross Linking ◽  
Selective Layer ◽  
Aromatic Solvents ◽  
Improved Stability ◽  
The Stability ◽  
Distance Parameter ◽  
Hansen Solubility

Composite membranes were prepared for nanofiltration of aromatic solvents. Cross-linking with AlCl3 was used to improve the stability of the PIM-1 selective layer in aromatic solvents like toluene, benzene and xylene. Nanofiltration performances of obtained membranes were tested with 4 different aromatic hydrocarbons and with 3 solvents from other classes of solvents. Obtained permeability for aromatic hydrocarbons was above 8,5 kg/m2·h·bar and retention of Remazol brilliant blue R dye with molecular mass 626 was up to 96 %. It was shown that permeability results correlated with Hansen solubility parameter and distance parameter between polymer and solvent. PIM-1 has higher permeability for non-polar hydrocarbons due to higher affinity between polymer and solvent.

One-step enhancement of solvent transport, stability and photocatalytic properties of graphene oxide/polyimide membranes with multifunctional cross-linkers

2019 ◽  
Vol 7 (7) ◽  
pp. 3170-3178 ◽  
Author(s):  
Mei-Ling Liu ◽  
Jia-Lin Guo ◽  
Susilo Japip ◽  
Tian-Zhi Jia ◽  
Dan-Dan Shao ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Photocatalytic Performance ◽  
Composite Membranes ◽  
Photocatalytic Properties ◽  
Cross Linking ◽  
One Step ◽  
The Stability ◽  
Solvent Transport ◽  
Polyimide Membranes

Improving the stability and photocatalytic performance of GO/PI composite membranes by a one-step cross-linking method.

Separation of carbon dioxide and nitrogen gases using novel composite membranes

2017 ◽  
Vol 95 (1) ◽  
pp. 57-67 ◽  
Author(s):  
A. Uma Maheswari ◽  
K. Palanivelu
Keyword(s):  
Power Plants ◽  
Composite Membranes ◽  
Environmental Issue ◽  
Cross Linking ◽  
Gas Mixture ◽  
Loading Capacity ◽  
Amine Molecule ◽  
Species Effect ◽  
Optimized Conditions ◽  
Urgent Action

Global warming is the major environmental issue caused by greenhouse gases, especially CO2. This demands urgent action to reduce or offset CO2 emission from power plants, which could be done using facilitated transport membranes (FTMs). In this context, CO2 selective carriers were prepared by blending polyvinyl alcohol (PVA) with three amines: ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA). Then, the composite membranes were prepared using PVA–amine blend as the separation layer and ceramic candle filters as the support layer. The fabricated membrane was characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Furthermore, the effect of amine species, effect of TETA concentration, cross-linking agent content, pressure difference, and the thickness of the membrane on the permeance and selectivity of CO2 over N2 were investigated. The permeance and selectivity of CO2 through the membranes were in the following order: TETA > DETA > EDA. This order is related to the number of nitrogen atoms per amine molecule, which can be correlated to loading capacity and, consequently, to amine reactivity with CO2. Under optimized conditions, for a pure gas experiment, the maximum permeance of 6.9 GPU for CO2 gas and selectivity of 50 over N2 was obtained, whereas in the CO2/N2 gas mixture, the maximum permeance of 8.6 GPU and selectivity of 98 was obtained. The membrane was found to be stable for 264 h.

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