Preparation of Stable Hydrophilic Polyethyleneimine Cross-Linked Graphene Oxide/Titanium Dioxide Membranes for Dye Separation

An excellent novel laminar and hierarchical polyethyleneimine cross-linked graphene oxide/titanium dioxide (GO–TiO2–PEI) membrane was successfully prepared by vacuum filtration technology using polyethyleneimine (PEI) as the cross-linking agent and a GO–TiO2 nanocomposite as the substrate. The resultant membrane (GO–TiO2–PEI) displayed a favorable antifouling performance with bovine serum albumin (BSA) and showed good hydrophilicity and wettability, with a static water contact angle of 13.2∘. The stability of the GO–TiO2–PEI membrane in aqueous solution obviously improved with the cross-linking of PEI compared with that of the GO and GO–TiO2 membranes. The GO–TiO2–PEI membrane also exhibited a satisfactory water flux of 48.6[Formula: see text]L m[Formula: see text] h[Formula: see text] bar[Formula: see text]. The GO–TiO2–PEI membrane exhibited a good performance for effectively separating different dyes including methylene blue (MB), rhodamine B (RB), methyl orange (MO), sunset yellow (SY), new coccine (NC) and amaranth. All the above results suggested that the GO–TiO2–PEI membrane could be used as an excellent stable hydrophilic membrane for efficiently separating dyes from aqueous solution.

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ADSORBATIVE SEPARATION OF DOXYCYCLINE FROM AQUEOUS SOLUTION WITH N,N-DIETHYL N-METHYL CHITOSAN, GUM AND POLYACRYLIC ACID BASED HYDROGELS

Procedings of Azerbaijan High Technical Educational Institutions - PAHTEI-Procedings of Azerbaijan High Technical Educational Institutions ◽

10.36962/pahtei1107202144 ◽

2021 ◽

Vol 11 (07) ◽

pp. 44-53

Author(s):

Mirvari Hasanova Mirvari Hasanova

Keyword(s):

Aqueous Solution ◽

Ion Exchange ◽

Zeta Potential ◽

Polyacrylic Acid ◽

Inorganic Materials ◽

Biologically Active ◽

Cross Linking ◽

Separation And Purification ◽

Inorganic Substances ◽

The Cross

The separation and purification of antibiotics with sorption by ion-exchange materials, as well as their delivery in biological processes by immobilization, are now widely used in biotechnology. There are many scientific studies in the literature on the sorption of antibiotics by polymer-based sorbents and inorganic materials, as well as the study of thermodynamics and kinetics of the process. In the literature, the acquisition of biologically active systems from the sorption of antibiotics by ion-exchange fibers based on various polymers and inorganic substances was carried out. However, the synthesis of selective gels for the effective separation of doxycycline and its delivery in different pH mediums by sorption with biodegradable, biocompatible polysaccharide-containing composites is one of the topical issues. Gel was synthesized from the cross-linking of N,N-diethyl N-methyl derivative of a natural polyaminosaccharide of chitosan by glutaric aldehyde. Also, pH-sensitive hydrogels that can swollen in water were synthesized from the cross-linking of a graft copolymer of cherry source gummiarabic with N-vinylpyrrolidone, as well as synthetic polymer polyacrylic acid with N,N-methylene-bis-acrylamide. The structure of the gels were identified by FTIR and NMR spectroscopy, and the sorption of doxycycline antibiotic from an aqueous solution was investigated. According to the values of zeta potential, the protonation of functional groups in the main macromolecule in an acidic medium leads to a value of zeta potential of 40÷80 mV on the surface of chitosan-based gel and others. Although the chemical structure is different, the isoelectric point is set around pH=6÷8 for all three hydrogels. The dependences of the sorption process on the amount of gels, antibiotic concentration, temperature, and pH medium were studied. The experimental data were analyzed using two adsorption models, Langmuir and Freundlich, with the later system providing the best fit. Doxycycline is adsorbed on the surface of chitosan, gummiarabic and polyacrylic acid based hydrogel composite through by physical interactions. Also, the results of thermodynamic parameters ΔG40 kJ/mol show that the nature of the adsorption process is physical, and spontaneous, too. Keywords: Chitosan, Gummiarabic-arabinogalactane, polyacrylic acid, hydrogel, sorption isoterms, doxycycline, thermodynamica.

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

Nanomaterials ◽

10.3390/nano11112867 ◽

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.

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

Frontiers in Chemistry ◽

10.3389/fchem.2021.779304 ◽

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.

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Some properties of 2-5A binding/nucleolytic activities in gel filtered rabbit reticulocyte lysates

Bioscience Reports ◽

10.1007/bf01119625 ◽

1985 ◽

Vol 5 (12) ◽

pp. 1041-1051 ◽

Cited By ~ 4

Author(s):

Joseph M. Wu ◽

Stanley J. Wertheimer ◽

Behruz Eslami ◽

Joanne C. Figuereido ◽

Biswendu B. Goswami

Keyword(s):

Binding Activity ◽

Time Dependent ◽

Cross Linking ◽

Elution Profile ◽

Viral Mrna ◽

Reticulocyte Lysates ◽

Atp Analogs ◽

The Cross ◽

The Stability

Rabbit reticulocyte lysates, gel filtered on Sephadex G-25 with or without ATP (or its analogs), were preincubated at 37°C and their subsequent binding to p3A4,3′-[32P]pCp was studied. Lysates filtered without ATP or in the presence of 0.1 mM 8-bromo-ATP, 1,N6-etheno-ATP, or ITP showed a time-dependent decrease in binding activity. This decrease was completely prevented when lysates were filtered with 0.1 mM ATP, 2′-deoxy-ATP, β-γ-methylene-ATP, or ATP-γ-S. The stability of binding provided by ATP or 2′-deoxy-ATP analogs corresponds to a more active 2–5A dependent endonucleolytic (RNAase L) activity based on studies using [3H] viral mRNA. Chromatography on heparin-agarose showed that ATP-supplemented gel-filtered reticulocyte lysates had a different p3A4,3′-[32P]pCp binding activity elution-profile than lysates gel-filtered in the absence of ATP. Covalent cross-linking of periodate-oxidized p3A4,3′-[32P]pC to gelfiltered lysates, preincubated at 0°C or 37°C for 30 min, showed the following results: (1) all lysates gave a major cross-linking of the radioactive ligand to an 80 000 dalton polypeptide, regardless of the temperature of preincubation, (2) Iysates gel-filtered without ATP, with 0.1 mM ITP, or β-γ-methylene-ATP, showed a significant reduction in the cross-linking of the 80 000 dalton protein, after preincubation at 37°C for 30 min. This decrease was accompanied by an increase in the labeling of two smaller polypeptides.

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Adsorption of azo dyes from aqueous solution by the hybrid MOFs/GO

Water Science & Technology ◽

10.2166/wst.2016.009 ◽

2016 ◽

Vol 73 (7) ◽

pp. 1728-1737 ◽

Cited By ~ 20

Author(s):

Ling Li ◽

Zhennan Shi ◽

Hongyang Zhu ◽

Wei Hong ◽

Fengwei Xie ◽

...

Keyword(s):

Aqueous Solution ◽

Azo Dyes ◽

Metal Organic Framework ◽

Freundlich Isotherm ◽

Order Kinetic ◽

Sunset Yellow ◽

Order Kinetic Model ◽

Metal Organic ◽

Pseudo Second Order ◽

The Stability

In this work, a hybrid of chromium(III) terephthalate metal organic framework (MIL-101) and graphene oxide (GO) was synthesized and its performance in the removal of azo dyes (Amaranth, Sunset Yellow, and Carmine) from water was evaluated. The adsorption for azo dyes on MIL-101/GO was compared with that of MIL-101, and it was found that the addition of GO enhanced the stability of MIL-101 in water and increased the adsorption capacity. The maximum adsorption capacities of MIL-101/GO were 111.01 mg g−1 for Amaranth, 81.28 mg g−1 for Sunset Yellow, and 77.61 mg g−1 for Carmine. The adsorption isotherms and kinetics were investigated, showing that the adsorption fits the Freundlich isotherm and the pseudo-second-order kinetic model. The recyclability of MIL-101/GO was shown by the regeneration by acetone. The high adsorption capability and excellent reusability make MIL-101/GO a competent adsorbent for the removal dyes from aqueous solution.

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Stability of the Cross Linking Component of the Biosensor Receptor Layer after Addition of Gold Nanoparticles

Pomiary Automatyka Robotyka ◽

10.14313/par_239/49 ◽

2021 ◽

Vol 25 (1) ◽

pp. 49-52

Author(s):

Aleksandra Kłos-Witkowska ◽

Vasyl Martsenyuk

Keyword(s):

Gold Nanoparticles ◽

Conformational Changes ◽

Cross Linking ◽

Relative Percentage ◽

Pure Protein ◽

The Cross ◽

The Stability ◽

Changes Over Time ◽

Over Time ◽

Receptor Layer

In this study, the stability of the receptor layer component of a biosensor after addition of gold nanoparticles was investigated. Accelerated conformational changes under the influence of Au were demonstrated. The relative percentage changes over time between the pure protein and the Au doped protein were calculated. It was shown that these changes are greater with time and exceed 20 % in the last days of the experiment.

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A Hydroxyapatite-Collagen Composite Useful to Make Bioresorbable Scaffolds for Bone Reconstruction

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.76.133 ◽

2010 ◽

Vol 76 ◽

pp. 133-138 ◽

Cited By ~ 2

Author(s):

Giulio D. Guerra ◽

Caterina Cristallini ◽

Elisabetta Rosellini ◽

Niccoletta Barbani

Keyword(s):

Weight Ratio ◽

Average Diameter ◽

Cross Linking ◽

Bone Reconstruction ◽

Scanning Calorimetry ◽

Bioresorbable Scaffolds ◽

Micro Particles ◽

Ft Ir ◽

The Cross ◽

The Stability

Composites between hydroxyapatite (HA) and collagen (Col) may be used to make bioresorbable scaffolds for bone reconstruction. A suspension of micro-particles (average diameter ≅ 30 µm) of HA annealed at 1100°C in Col solution (80:20 HA to Col weight ratio) was manufactured in films by casting, and then some films were cross-linked by glutaraldehyde vapours. Cross-linked sponges were obtained by treating the suspension with transglutaminase, and by lyophilizing the so obtained gel. Characterization by scanning electron microscopy, water sorption test, Col release in water, thermogravimetric analysis and differential scanning calorimetry shows that the cross-linking enhances the stability of the composite. Conversely, neither the interactions between HA and Col, detected by spotlight FT-IR, nor the degradation by collagenase, which is a requirement for the bioresorbibility, are affected by the cross-linking.

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Elasticity of networks with permanent and thermoreversible cross-links

MRS Proceedings ◽

10.1557/proc-1234-qq04-01 ◽

2009 ◽

Vol 1234 ◽

Cited By ~ 2

Author(s):

Jack F. Douglas

Keyword(s):

Elastic Properties ◽

Cross Linking ◽

Simplified Models ◽

Flexible Chain ◽

Fiber Networks ◽

Cross Links ◽

The Cross ◽

The Stability

AbstractSimplified models of flexible chain and stiff fiber networks are introduced to address how the network elasticity becomes modified when the cross-linking is thermoreversible in nature and changes in the stability of the network with deformation. These idealized models apparently able to capture many aspects of the elastic properties of real networks.

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Preparation and Characterization of a Hydrophilic Polysulfone Membrane Using Graphene Oxide

Journal of Chemistry ◽

10.1155/2019/3164373 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Hoan Thi Vuong Nguyen ◽

Thu Hong Anh Ngo ◽

Khai Dinh Do ◽

Minh Ngoc Nguyen ◽

Nu Thi To Dang ◽

...

Keyword(s):

Contact Angle ◽

Graphene Oxide ◽

Water Contact Angle ◽

Water Flux ◽

Feed Solution ◽

Contact Angle Measurement ◽

Angle Measurement ◽

Inversion Method ◽

Water Contact ◽

Polysulfone Membrane

In general, the polysulfone (PSf) membranes are popular choices for water treatment because they have high thermal stability and good chemical resistance. On the other hand, the filtration capacity of the polysulfone membrane is limited because of its low water flux and poor antifouling ability, which are caused by the low surface hydrophilicity of the membranes. In this research, blending of graphene oxide (GO) or graphene oxide-titanium dioxide (GO-TiO2) mixture into the polysulfone matrix had been carried out through the phase inversion method to enhance the hydrophilic and antifouling properties. Methods such as energy-dispersive X-ray spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle measurement were used to examine the surface properties of the prepared membranes. Experimental results have led to a conclusion that graphene oxide can be stabilized into prepared membranes, and then, by reducing the water contact angle values, the surface of these membranes becomes hydrophilic, which increases the permeability and the water flux of methylene blue from the aqueous feed solution, improving the membrane’s antifouling resistance.

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