scholarly journals Dependence of Water-Permeable Chitosan Membranes on Chitosan Molecular Weight and Alkali Treatment

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 351
Author(s):  
Ryo-ichi Nakayama ◽  
Koki Katsumata ◽  
Yuta Niwa ◽  
Norikazu Namiki
Keyword(s):  
Molecular Weight ◽  
Water Content ◽  
Alkali Treatment ◽  
Water Flux ◽  
Operating Pressure ◽  
Water Permeation ◽  
Molecular Weights ◽  
Blocking Rate ◽  
Chitosan Membranes ◽  
Lower Water Content

Chitosan membranes were prepared by the casting method combined with alkali treatment. The molecular weight of chitosan and the alkali treatment influenced the water content and water permeability of the chitosan membranes. The water content increased as the NaOH concentration was increased from 1 to 5 mol/L. The water permeation flux of chitosan membranes with three different molecular weights increased linearly with the operating pressure and was highest for the membrane formed from chitosan with the lowest molecular weight. Membranes with a lower water content had a higher water flux. The membranes blocked 100% of compounds with molecular weights above methyl orange (MW = 327 Da). At 60 ≤ MW ≤ 600, the blocking rate strongly depended on the substance. The results confirmed that the membranes are suitable for compound separation, such as in purification and wastewater treatment.

Influence of Multiwall Carbon Nanotube on Polyethersulfone/ Polyvinyl Alcohol Blend Membranes

2014 ◽  
Vol 67 (2) ◽  
Author(s):  
Nur Farahah Mohd Khairuddin ◽  
Ani Idris ◽  
Iqbal Ahmed ◽  
Noordin Mohd Yusof
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Carbon Nanotube ◽  
Polyvinyl Alcohol ◽  
Water Flux ◽  
Multiwall Carbon Nanotube ◽  
Flux Rate ◽  
Molecular Weights ◽  
Blend Membranes ◽  
Multiwall Carbon

This paper investigates the influence of multiwall carbon nanotube (MWCNT) on the morphology and properties of polyethersulfone (PES) and polyvinyl alcohol (PVA) blend membranes. Several membranes were prepared by blending 0.5 wt% MWCNT , 18%wt PES and 1.5wt% PVA of various molecular weights (60, 145 and 200 kDa) in  dimethyl acetate (DMAC) solvent. The membranes were then evaluated in terms of its morphology, contact angle, water flux rate and porosity. The results revealed that MWCNT nanoparticles have decreased the contact angle and increased the flux rate of PES/PVA blend membranes. The presence of MWCNT in the PES/PVA membranes have promoted the formation of fingerlike pores in the membranes structure and thus increased the porosity of the membranes. Besides that, the use of higher molecular weight PVA helped to reduce the contact angle of the membranes reflecting to their hydrophilic nature. However, the use of lower molecular weight PVA was found to enhance the increased of flux rate and porosity of the membrane.

scholarly journals Preparation and Characterization of PVDF/g-C3N4/chitosan Nanocomposite Membrane for the Removal of Direct Blue 14 Dye

2021 ◽  
Author(s):  
Parya Hasanzade ◽  
Parvin Gharbani ◽  
Fahime Derakhshan ◽  
Behnaz Memar Maher
Keyword(s):  
Water Content ◽  
Membrane Fouling ◽  
Polyvinylidene Fluoride ◽  
Pure Water ◽  
Water Flux ◽  
Salt Rejection ◽  
Direct Blue ◽  
Pure Water Flux ◽  
Chitosan Membranes

Abstract Polyvinylidene fluoride (PVDF)/g-C3N4/Chitosan thin film membranes were prepared for removal of Direct Blue 14 dye (an anionic dye) from aqueous solutions. PVDF/g-C3N4/Chitosan membranes were prepared by immersing of PVDF/g-C3N4 membrane in solution containing various concentrations of chitosan. The resulting membranes were characterized by XRD, FESEM, TEM and AFM. Also, pure water flux, salt rejection, water content, antifouling properties of prepared membranes were investigated. The resulting demonstrate that pure water flux was decreased by increasing of chitosan concentration, while water content, antifouling properties and salt rejection were increased. It is found that chitosan has major impact on the membrane structural properties due to transform of the PVDF membrane into hydrophilic ones. It is reported that maximum 93% rejection of Direct Blue 14 was obtained by PVDF/g-C3N4/Chitosan membrane. Compared to the PVDF/g-C3N4 membrane, the experimental results showed that PVDF/g-C3N4/Chitosan membranes demonstrated high potential mainly due to greater hydrophilicity and further minimizing membrane fouling.

Effect of the molecular weight and its distribution of polyvinylidene fluoride on the relationship between the spinning process, microstructure and properties of hollow fiber membranes via thermally induced phase separation

2018 ◽  
Vol 89 (7) ◽  
pp. 1311-1320 ◽  
Author(s):  
Nana Li ◽  
Zhe Chang ◽  
Qingchen Lu ◽  
Changfa Xiao ◽  
Junyi Wu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Polyvinylidene Fluoride ◽  
Crystallization Behavior ◽  
Water Flux ◽  
Thermally Induced Phase Separation ◽  
Thermally Induced ◽  
Molecular Weights ◽  
Spinning Process ◽  
The Relationship

Polyvinylidene fluoride (PVDF) is an important material in the preparation of ultrafiltration membranes via the thermally induced phase separation (TIPS) method. In this paper, four PVDF hollow fiber membranes with different molecular weights were prepared via the TIPS method by using dibutyl phthalate and dioctyl phthalate as a mixed diluent. The relationship between the molecular weight of PVDF and its distribution, phase separation, crystallization behavior and spinning process has been systematically studied. The effects of three factors on the microstructure and properties of the PVDF membrane have been analyzed. The flow behaviors of the PVDF/diluent and PVDF melt were tested by a capillary rheometer and a melt flow rate instrument, respectively. A phase diagram of the membrane solution was determined by thermal polarizing microscope and differential scanning calorimetry. The crystallization behavior and angle of orientation of the membrane were tested by using a differential scanning calorimeter and a sound velocity orientation measurement instrument. The microstructures, such as the pore structure and crystalline grain structure, were observed by field emission scanning electron microscopy. Meanwhile, the properties of the membrane were examined from the view of water flux, porosity and tensile testing. The results showed that changes in the polymer molecular weights affected not only the dynamics but also the thermodynamics of phase separation in membrane formation. As the PVDF molecular weight increased, the phase separation region increased, but the membrane structure became denser. A wide molecular weight distribution easily produced large pores. Then, the water flux decreased first and then increased.

scholarly journals Effects of polyacrylamide molecular weight and mass concentration on water transport characteristics of iron tailings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bo Sun ◽  
Chunjuan Lyu ◽  
Rutian Bi ◽  
Lu Xia ◽  
Xu Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hydraulic Conductivity ◽  
Water Content ◽  
Mass Concentration ◽  
Water Retention ◽  
Saturated Hydraulic Conductivity ◽  
Infiltration Capacity ◽  
Molecular Weights ◽  
Saturated Water ◽  
Saturated Water Content

AbstractIron tailings have few macropores which severely inhibit infiltration and transport of soil water. Polyacrylamide (PAM) can regulate soil water, but it is rarely used when remediating tailings matrix. In this research, PAM of four molecular weights of 300w, 600w, 800w, and 1000w were selected as amendments, and were each applied at five mass concentrations of 0% (CK), 0.01%, 0.04%, 0.08%, and 0.16% to observe their effects on water transport in iron tailings using column simulations in the laboratory. After adding PAM, the water retention and saturated water content of iron tailings increased significantly (P < 0.05). With increases in PAM molecular weight and mass concentration, the saturated hydraulic conductivity showed a downward trend, but the saturated hydraulic conductivity increased after a dry–wet cycle. With the increase of PAM mass concentration, adding PAM of 1000w molecular weight to iron tailing decreased infiltration capacity, but treatments of other molecular weights all initially increased then decreased infiltration capacity. The greatest improvement on infiltration capacity of iron tailings was observed with the addition of PAM of 300w molecular weight and 0.01% mass concentration. Adding PAM increased the vertical depth of the saturation zone of iron tailings (P < 0.05) with a maximum depth of 20.83 cm. The Kostiakov model more accurately simulated water infiltration of iron tailings compared with the Horton and Philip models. On the whole, when PAM of low molecular weight and concentration was added to iron tailings, PAM increased stable infiltration, saturated water content, and water retention. It also inhibited saturated hydraulic conductivity of iron tailings. Therefore, in practice, it is necessary to select the appropriate molecular weight and mass concentration of PAM according to the dominant limiting factors and remediation needs of the matrix.

Measurement of Water Content Distribution in Catalyst Coated Membrane at Water Permeation Condition by Magnetic Resonance Imaging

2010 ◽  
Author(s):  
Takahiro Suzuki ◽  
Yuichiro Tabuchi ◽  
Shohji Tsushima ◽  
Shuichiro Hirai ◽  
Koichiro Aotani ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Water Content ◽  
Content Distribution ◽  
Polymer Electrolyte Membrane ◽  
Water Flux ◽  
Dew Point ◽  
Resonance Imaging ◽  
Water Permeation ◽  
Coated Membrane

Through-plane water content distribution in a polymer electrolyte membrane (PEM) and water flux across the membrane were measured under different water permeation conditions using magnetic resonance imaging (MRI) and a dew point measurement system. We placed the PEM by itself or as a catalyst coated membrane (CCM) in an experimental cell, and we subjected them to several water permeation conditions that had different water activities across the membrane. We compared the water content distribution and water flux of samples, and the results showed the membranes exhibited different water content distribution between the PEM and the CCM. The differences suggest that the rate-determining process of the water transport phenomena across the membrane, which are diffusion through the membrane and interfacial transport across the membrane-gas interface, changed according to whether the membrane is used by itself or as a CCM.

Polymerization of Vinyl Chloride by Organometallic Compounds. Effect of Moisture in the Monomer

1993 ◽  
Vol 58 (11) ◽  
pp. 2559-2564
Author(s):  
Miloslav Kolínský ◽  
Jaroslava Michalcová ◽  
Václava Jíšová ◽  
Rudolf Lukáš
Keyword(s):  
Molecular Weight ◽  
Water Content ◽  
Vinyl Chloride ◽  
Organometallic Compounds ◽  
Heat Stability ◽  
Molecular Weights ◽  
Effect Of Moisture ◽  
The Stability ◽  
Water Contents

The effect of moisture in vinyl chloride (VC) on its polymerization initiated with tert-butyllithium was investigated. The conversion curves thus obtained and the dependences of molecular weights of isolated products show that within range 6.5 - 80 ppm. vol. water in vinyl chloride and the mole ration t-BuLi/VC 0.0004 - 0.03 the conversion of vinyl chloride decreases, while the molecular weight of PVC increases. The distribution curves of molecular weights become broader with increasing water content in the monomer, and their maxima are shifted to higher molecular weights. The water content up to 40 ppm. vol. in vinyl chloride does not affect the heat stability of PVC. At higher water contents the stability decreases.

Investigation by HPLC of the Catabolism of Recombinant Tissue Plasminogen Activator in the Rat

1988 ◽  
Vol 60 (01) ◽  
pp. 107-112 ◽  
Author(s):  
Roy Harris ◽  
Louis Garcia Frade ◽  
Lesley J Creighton ◽  
Paul S Gascoine ◽  
Maher M Alexandroni ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Half Life ◽  
Recombinant Tissue Plasminogen Activator ◽  
Rat Plasma ◽  
High Molecular Weight Complex ◽  
Molecular Weights ◽  
Major Activity ◽  
Tissue Plasminogen

SummaryThe catabolism of recombinant tissue plasminogen activator (rt-PA) was investigated after injection of radiolabelled material into rats. Both Iodogen and Chloramine T iodination procedures yielded similar biological activity loss in the resultant labelled rt-PA and had half lives in the rat circulation of 1 and 3 min respectively. Complex formation of rt-PA was investigated by HPLC gel exclusion (TSK G3000 SW) fractionation of rat plasma samples taken 1-2 min after 125I-rt-PA injection. A series of radiolabelled complexes of varying molecular weights were found. However, 60% of the counts were associated with a single large molecular weight complex (350–500 kDa) which was undetectable by immunologically based assays (ELISA and BIA) and showed only low activity with a functional promoter-type t-PA assay. Two major activity peaks in the HPLC fractions were associated with Tree t-PA and a complex having a molecular weight of ̴ 180 kDa. HPLC fractionation to produce these three peaks at various timed intervals after injection of 125I-rt-PA showed each to have a similar initial rate half life in the rat circulation of 4-5 min. The function of these complexes as yet is unclear but since a high proportion of rt-PA is associated with a high molecular weight complex with a short half life in the rat, we suggest that the formation of this complex may be a mechanism by which t-PA activity is initially regulated and finally cleared from the rat circulation.

Permeability Enhancing and Chemotactic Activities of Lower Molecular Weight Degradation Products of Human Fibrinogen

1981 ◽  
Vol 45 (01) ◽  
pp. 090-094 ◽  
Author(s):  
Katsuo Sueishi ◽  
Shigeru Nanno ◽  
Kenzo Tanaka
Keyword(s):  
Molecular Weight ◽  
Degradation Products ◽  
Electron Microscopic Observation ◽  
Chemotactic Activity ◽  
Lower Molecular Weight ◽  
Electron Microscopic ◽  
Human Fibrinogen ◽  
Rabbit Skin ◽  
Molecular Weights ◽  
Active Fragments

SummaryFibrinogen degradation products were investigated for leukocyte chemotactic activity and for enhancement of vascular permeability. Both activities increased progressively with plasmin digestion of fibrinogen. Active fragments were partially purified from 24 hr-plasmin digests. Molecular weights of the permeability increasing and chemotactic activity fractions were 25,000-15,000 and 25,000 respectively. Both fractions had much higher activities than the fragment X, Y, D or E. Electron microscopic observation of the small blood vessels in rabbit skin correlated increased permeability with the formation of characteristic gaps between adjoining endothelial cells and their contraction.These findings suggest that lower molecular weight degradation products of fibrinogen may be influential in contributing to granulocytic infiltration and enhanced permeability in lesions characterized by deposits of fibrin and/or fibrinogen.

Toxicity of Heparinoids, with Special Reference to the Precipitation of Fibrinogen

1964 ◽  
Vol 12 (01) ◽  
pp. 232-261 ◽  
Author(s):  
S Sasaki ◽  
T Takemoto ◽  
S Oka
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Anticoagulant Activity ◽  
Molecular Structures ◽  
Severe Reaction ◽  
Clinical Use ◽  
Molecular Weights ◽  
Close Relationship

SummaryTo demonstrate whether the intravascular precipitation of fibrinogen is responsible for the toxicity of heparinoid, the relation between the toxicity of heparinoid in vivo and the precipitation of fibrinogen in vitro was investigated, using dextran sulfate of various molecular weights and various heparinoids.1. There are close relationships between the molecular weight of dextran sulfate, its toxicity, and the quantity of fibrinogen precipitated.2. The close relationship between the toxicity and the precipitation of fibrinogen found for dextran sulfate holds good for other heparinoids regardless of their molecular structures.3. Histological findings suggest strongly that the pathological changes produced with dextran sulfate are caused primarily by the intravascular precipitates with occlusion of the capillaries.From these facts, it is concluded that the precipitates of fibrinogen with heparinoid may be the cause or at least the major cause of the toxicity of heparinoid.4. The most suitable molecular weight of dextran sulfate for clinical use was found to be 5,300 ~ 6,700, from the maximum value of the product (LD50 · Anticoagulant activity). This product (LD50 · Anticoagulant activity) can be employed generally to assess the comparative merits of various heparinoids.5. Clinical use of the dextran sulfate prepared on this basis gave satisfactory results. No severe reaction was observed. However, two delayed reactions, alopecia and thrombocytopenia, were observed. These two reactions seem to come from the cause other than intravascular precipitation.

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