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.

Preparation and characterization of fouling-resistant composite membranes based on layer-by-layer self-assembly technique

2011 ◽  
Vol 64 (11) ◽  
pp. 2223-2229 ◽  
Author(s):  
J. L. Duan ◽  
H. M. Zhang ◽  
C. C. Wang ◽  
H. Y. Li ◽  
F. L. Yang
Keyword(s):  
Contact Angle ◽  
Protein Adsorption ◽  
Water Contact Angle ◽  
Morphological Changes ◽  
Membrane Surface ◽  
Composite Membranes ◽  
Ammonium Bromide ◽  
Layer By Layer ◽  
Water Contact ◽  
Antifouling Property

This paper introduces a versatile approach for surface modification of 621-terylene filtration fabric (FF) self-assembled by a dynamic layer-by-layer technique. The hexadecyl trimethyl ammonium bromide (HTAB) and cross-linked polyvinyl alcohol microspheres (PVA-MS) were alternatively deposited on support membrane under a pressure of 0.01 MPa to modify FF. Morphological changes and hydrophilicity of the modified FF were characterized in detail by scanning electron micrograph and water contact angle measurements. Results revealed that PVA-MS could be adsorbed mainly on the surface of FF and water contact angle decreased with the increase of HTAB/PVA-MS bilayer numbers indicating an enhanced hydrophilicity for the modified FF. Backwash experiments of the modified FF exhibited much higher stability of PVA-MS. Protein adsorption experiments were conducted to evaluate the antifouling property of the modified FF. Results indicated that protein adsorption of the membrane surface could be obviously improved by modification, which exhibited superior antifouling property of the modified FF.

scholarly journals Effect of Biochar Prepared from Food Waste through Different Thermal Treatment Processes on Crop Growth

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 276
Author(s):  
Hang Jia ◽  
Haoxi Ben ◽  
Fengze Wu
Keyword(s):  
Crop Growth ◽  
Raw Material ◽  
Synthetic Methods ◽  
Thermochemical Conversion ◽  
Growth Trend ◽  
Wheat Growth ◽  
Preparation Methods ◽  
Treatment Processes ◽  
Ft Ir ◽  
The Impact

Biochar is generally accepted and increasingly valued in scientific circles as solid products in the thermochemical conversion of biomass, mainly because of its rich carbon content. The purpose of this research is to investigate the impact of biochar from different sources on wheat growth. In particular, this work focused on the effect of different preparation methods and raw material of biochar on the growth of wheat and aim to find a potential soil substitute that can be used for crop cultivation. Two synthetic methods were evaluated: hydrothermal conversion and pyrolysis. The characterization of biochar was determined to explore the impact of its microstructure on wheat growth. The results show that the yield of biochar produced from high-pressure reactor is significantly higher than that obtained by using microwave reactor. For example, the biochar yield obtained through the former is about six times that of the latter when using steamed bread cooked as biomass raw material. In addition, the growth trend of wheat indicates that biochar has different promoting effects on the growth of wheat in its weight and height. The pyrolyzed carbon is more suitable for wheat growth and is even more effective than soil, indicating that pyrolyzed biochar has more potential to be an alternative soil in the future. Moreover, this research tries to explore the reasons that affect crop growth by characterizing biochar (including scanning electron microscopy (SEM), biofilm electrostatic test (BET) and Fourier transform infrared (FT-IR)). The results indicate that the biochar containing more pits and less hydroxyl functional are more suitable for storing moisture, which is one of the significant factors in the growth of crops. This study provides evidence of the effects of biochar on crop growth, both in terms of microstructure and macroscopic growth trends, which provides significant benefits for biochar to grow crops or plants.

scholarly journals Antimicrobial Properties and Melissopalynology, Proximate and Elemental Analyses of Honey Samples from Three Different Ecozones in Nigeria

2016 ◽  
Vol 8 (3) ◽  
pp. 326-333 ◽  
Author(s):  
Peter A. ADEONIPEKUN ◽  
Tiwalade A. ADENIYI ◽  
David EDEN
Keyword(s):  
Antimicrobial Properties ◽  
Pollen Grains ◽  
Antimicrobial Activities ◽  
Proximate Analysis ◽  
Preparation Methods ◽  
Antimicrobial Studies ◽  
Elemental Analyses ◽  
Lowland Rainforest ◽  
Sudan Savanna ◽  
First Time

Honey samples from three different ecozones - coastal freshwater (Ogba), lowland rainforest (Oka-Akoko) and montane Sudan savanna (Mambilla plateau) – were subjected to melissopalynological, proximate and elemental analyses, as well as antimicrobial studies. The aim of the research was to determine the contribution of pollen, if any, in the antimicrobial activities of the studied honey samples. Standard preparation methods were adopted for these studies. The Mambilla honey recorded the highest pollen diversity, while that of Oka-Akoko and Ogba regions had similar diversity, both having lower values. The Ogba honey however contained the highest abundance of pollen. Proximate analysis showed that the Mambilla honey also recorded the highest values of moisture, ash, protein, fats and oil, as well as potassium and reducing sugars. Antimicrobial investigation revealed the highest antimicrobial activities for the Mambilla honey, followed by Oka-Akoko and Ogba against Staphylococcus aureus (gram positive) and Pseudomonas aeruginosa (gram negative). Moisture content, proteins and carbohydrates were significantly different, with positive and negative trends respectively, when related with the antimicrobial activities of the honey samples. The pollen contents were also qualitatively different. This is the first time the antimicrobial activity of honey is ever traced to pollen contents.  More conclusions can be accurately made only after further research upon pollen grains directly.

scholarly journals EVALUATION OF BACTERIAL CELLULOSE-SODIUM ALGINATE FORWARD OSMOSIS MEMBRANE FOR WATER RECOVERY

2018 ◽  
Vol 80 (3-2) ◽  
Author(s):  
Ngan T. B. Dang ◽  
Liza B. Patacsil ◽  
Aileen H. Orbecido ◽  
Ramon Christian P. Eusebio ◽  
Arnel B. Beltran
Keyword(s):  
Contact Angle ◽  
Bacterial Cellulose ◽  
Sodium Alginate ◽  
Water Flux ◽  
Forward Osmosis ◽  
Composite Membranes ◽  
Membrane Thickness ◽  
Water Recovery ◽  
Sem Images ◽  
Salt Rejection

Water resources are very important to sustain life. However, these resources have been subjected to stress due to population growth, economic and industrial growth, pollution and climate change. With these, the recovery of water from sources such as wastewater, dirty water, floodwater and seawater is a sustainable alternative. The potential of recovering water from these sources could be done by utilizing forward osmosis, a membrane process that exploits the natural osmotic pressure gradient between solutions which requires low energy operation. This study evaluated the potential of forward osmosis (FO) composite membranes fabricated from bacterial cellulose (BC) and modified with sodium alginate. The membranes were evaluated for water flux and salt rejection. The effect of alginate concentrations and impregnation temperatures were evaluated using 0.6 M sodium chloride solution as feed and 2 M glucose solution as the draw solution. The membranes were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Contact Angle Meter (CAM). The use of sodium alginate in BC membrane showed a thicker membrane (38.3 μm to 67.6 μm), denser structure (shown in the SEM images), and more hydrophilic (contact angle ranges from 28.39° to 32.97°) compared to the pristine BC membrane (thickness = 12.8 μm and contact angle = 66.13°). Furthermore, the alginate modification lowered the water flux of the BC membrane from 9.283 L/m2-h (LMH) to value ranging from 2.314 to 4.797 LMH but the improvement in salt rejection was prominent (up to 98.57%).

scholarly journals The Modification of PVDF Membrane via Crosslinking with Chitosan and Glutaraldehyde as the Crosslinking Agent

2018 ◽  
Vol 18 (1) ◽  
pp. 1
Author(s):  
Romaya Sitha Silitonga ◽  
Nurul Widiastuti ◽  
Juhana Jaafar ◽  
Ahmad Fauzi Ismail ◽  
Muhammad Nidzhom Zainol Abidin ◽  
...  
Keyword(s):  
Contact Angle ◽  
Vinylidene Fluoride ◽  
Membrane Surface ◽  
Pure Water ◽  
Water Flux ◽  
Crosslinking Agent ◽  
Hydrophobic Properties ◽  
Pvdf Membrane ◽  
Pure Water Flux ◽  
Modified Membrane

Poly(vinylidene fluoride) (PVDF) has outstanding properties such as high thermal stability, resistance to acid solvents and good mechanical strength. Due to its properties, PVDF is widely used as a membrane matrix. However, PVDF membrane is hydrophobic properties, so as for specific applications, the surface of membrane needs to be modified to become hydrophilic. This research aims to modify PVDF membrane surface with chitosan and glutaraldehyde as a crosslinker agent. The FTIR spectra showed that the modified membrane has a peak at 1655 cm-1, indicating the imine group (–N=C)- that was formed due to the crosslink between amine group from chitosan and aldehyde group from glutaraldehyde. Results showed that the contact angle of the modified membrane decreases to 77.22° indicated that the membrane hydrophilic properties (< 90°) were enhanced. Prior to the modification, the contact angle of the PVDF membrane was 90.24°, which shows hydrophobic properties (> 90°). The results of porosity, Ɛ (%) for unmodified PVDF membrane was 55.39%, while the modified PVDF membrane has a porosity of 81.99%. Similarly, by modifying the PVDF membrane, pure water flux increased from 0.9867 L/m2h to 1.1253 L/m2h. The enhancement of porosity and pure water flux for the modified PVDF membrane was due to the improved surface hydrophilicity of PVDF membrane.

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.

Study on lignin-free lignocellulosic biomass and PSF-PEG membrane compatibility

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 1063-1075
Author(s):  
Abiodun A. Amusa ◽  
Abdul L. Ahmad ◽  
Jimoh K. Adewole
Keyword(s):  
Contact Angle ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Lignocellulosic Biomass ◽  
Biomedical Applications ◽  
Composite Membranes ◽  
Hydroxyl Groups ◽  
Chemical Pretreatment ◽  
Physical And Chemical ◽  
Porosity Measurements

Lignocellulosic biomass was delignified by combining physical and chemical pretreatment techniques. Then, a polysulfone-polyethylene glycol blend, which was compatible with the lignin-free biomass (0 wt% to 3.0 wt%), was used to fabricate composite membranes. The presence of hydroxyl groups after the pretreatment was evaluated via Fourier transform infrared spectroscopy. The rheology of the polymer solutions was assessed via the viscometric method. Also, the hydrophobicity of the fabricated membranes was determined using contact angle and porosity measurements. The fabricated membranes with near superhydrophobic properties (a contact angle of approximately 140°) based on this study revealed that contactor systems and biomedical applications would benefit from this modification.

Ceramic composite membranes based on Bi3Ru3O11 – Bi1,6Er0,4O3 for obtaining of oxygen

2021 ◽  
Vol 6 ◽  
pp. 22-28
Author(s):  
P. E. Dergacheva ◽  
◽  
I. V. Kulbakin ◽  
S. V. Fedorov ◽  
A. S. Lysenkov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Ceramic Composite ◽  
Oxygen Permeability ◽  
Total Porosity ◽  
Composite Membranes ◽  
Ceramic Composites ◽  
Argon Atmosphere ◽  
Pure Oxygen ◽  
Total Conductivity ◽  
Temperature Dependence Of Conductivity

Using hot uniaxial pressing in an argon atmosphere with a stress of 35 MPa and with a holding at 800 °C for 1 hour, ceramic composites of Bi3Ru3O11 – 50, 65 wt % Bi1,6Er0,4O3 were obtained. It was found that phase composition of the composites does not change during gas chromatographic testing at 800 °C and well corresponds to the specified one. Microstructure of the obtained composites was tested and the formation of dense composites with a total porosity of less than 1% and with a uniform distribution of the Bi3Ru3O11 and Bi1,6Er0,4O3 components in bulk of material was demonstrated. Transport properties (total conductivity, oxygen fluxes and selectivity of separating oxygen over nitrogen) of the obtained composites at 600 – 800 °C had been investigated. Thus, at 800 °C the electrical conductivity of Bi3Ru3O11 – 50, 65 wt % Bi1,6Er0,4O3 was about 200 and 50 Ohm–1∙cm–1, respectively, while the metallic nature of their temperature dependence of conductivity is correlated to that for the Bi3Ru3O11. The value of oxygen permeability for the obtained ceramic composites of about 7∙10–9 mol·cm–1·s–1 at 800 °C, which is compared to other membrane materials based on bismuth oxide, demonstrated the potential of their further use in the tasks for obtaining of pure oxygen from air.

scholarly journals The string of diamonds is nearly tight for rumour spreading

2019 ◽  
Vol 29 (2) ◽  
pp. 190-199
Author(s):  
Omer Angel ◽  
Abbas Mehrabian ◽  
Yuval Peres
Keyword(s):  
Upper Bound ◽  
Real Numbers ◽  
Vertex Graph ◽  
First Time

AbstarctFor a rumour spreading protocol, the spread time is defined as the first time everyone learns the rumour. We compare the synchronous push&pull rumour spreading protocol with its asynchronous variant, and show that for any n-vertex graph and any starting vertex, the ratio between their expected spread times is bounded by $O({n^{1/3}}{\log ^{2/3}}n)$. This improves the $O(\sqrt n)$ upper bound of Giakkoupis, Nazari and Woelfel (2016). Our bound is tight up to a factor of O(log n), as illustrated by the string of diamonds graph. We also show that if, for a pair α, β of real numbers, there exist infinitely many graphs for which the two spread times are nα and nβ in expectation, then $0 \le \alpha \le 1$ and $\alpha \le \beta \le {1 \over 3} + {2 \over 3} \alpha $; and we show each such pair α, β is achievable.

scholarly journals Fabrication of a Novel Antifouling Polysulfone Membrane with in Situ Embedment of Mxene Nanosheets

2019 ◽  
Vol 16 (23) ◽  
pp. 4659 ◽  
Author(s):  
Zhen Shen ◽  
Wei Chen ◽  
Hang Xu ◽  
Wen Yang ◽  
Qing Kong ◽  
...  
Keyword(s):  
Contact Angle ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Water Contact Angle ◽  
Bovine Serum ◽  
Composite Membranes ◽  
Recovery Ratio ◽  
Water Contact ◽  
Polysulfone Membrane

Membrane fouling is still a critical issue for the application of ultrafiltration, which has been widely used in water treatment due to its efficiency and simplicity. In order to improve the antifouling property, a new 2D material MXene was used to fabricate composite ultrafiltration membrane with the approach of in situ embedment during the phase inversion process in this study. Scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), water contact angle, bovine serum albumin rejection and porosity measurements were utilized to characterize the prepared membranes. Due to the hydrophilicity of the MXene, the composite membranes obtained higher hydrophilicity, confirmed by the decreased water contact angle. All the modified membranes had a high bovine serum albumin rejection above 90% while that of the pristine polysulfone membrane was 77.48%. The flux recovery ratio and the reversible fouling ratio of the membranes were also improved along with the increasing content of the MXene. Furthermore, the highest flux recovery ratio could also reach 76.1%. These indicated the good antifouling properties of MXene composite membranes. The enhanced water permeability and protein rejection and excellent antifouling properties make MXene a promising material for antifouling membrane modification.

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