Cross-Linking Combined with Surfactant Bilayer Assembly Enhances the Hydrophilic and Antifouling Properties of PTFE Microfiltration Membranes

The inherent strong hydrophobicity of Polytetrafluoroetylene (PTFE) microfiltration membranes results in low separation efficiency and easy contamination. In order to enhance its hydrophilic and antifouling properties, we first modified the PTFE microfiltration membrane by using Polyethylene glycol laurate (PEGML) for first layer deposition and then used Polyvinyl alcohol (PVA)/citric acid (CA) cross-linked coatings for second layer deposition. The Scanning Electron Microscope (SEM) results showed that the fibers and nodes of the modified PTFE microfiltration membrane were coated with PVA/CA hydrophilic coating. FT-IR Spectromete and X-ray photoelectron spectrometer (XPS) analysis results confirmed that crosslinking of PVA and CA occurred and that PEGML and PVA/CA were successfully deposited onto the membrane surface. The modification conditions were optimized by hydrophilicity testing, and the best hydrophilicity of the modified membrane was achieved when the crosslinking content of PEGML was 2 g·L−1, PVA was 5 g·L−1, and CA was 2 g·L−1. PTFE microfiltration membranes modified by the optimal conditions achieved a water flux of 396.9 L·m−2·h−1 (three times that of the original membrane) at low operating pressures (0.05 MPa), and the contact angle decreased from 120° to 40°. Meanwhile, the modified PTFE microfiltration membrane has improved contamination resistance and good stability of the hydrophilic coating.

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Influence of Membrane Vibration on Particles Rejection Using a Slotted Pore Membrane Microfiltration

Membranes ◽

10.3390/membranes11090709 ◽

2021 ◽

Vol 11 (9) ◽

pp. 709

Author(s):

Asmat Ullah ◽

Kamran Alam ◽

Saad Ullah Khan ◽

Victor M. Starov

Keyword(s):

Membrane Fouling ◽

Produced Water ◽

Separation Efficiency ◽

Membrane Surface ◽

Water Separation ◽

Oil Droplet ◽

Pore Blockage ◽

Oil Water Separation ◽

Microfiltration Membranes ◽

Membrane Vibration

A new method is proposed to increase the rejection in microfiltration by applying membrane oscillation, using a new type of microfiltration membrane with slotted pores. The oscillations applied to the membrane surface result in reduced membrane fouling and increased separation efficiency. An exact mathematical solution of the flow in the surrounding solution outside the oscillating membrane is developed. The oscillation results in the appearance of a lift velocity, which moves oil particles away from the membrane. The latter results in both reduced membrane fouling and increased oil droplet rejection. This developed model was supported by the experimental results for oil water separation in the produced water treatment. It was proven that the oil droplet concentration was reduced notably in the permeate, due to the membrane oscillation, and that the applied shear rate caused by the membrane oscillation also reduced pore blockage. A four-times lower oil concentration was recorded in the permeate when the membrane vibration frequency was 25 Hz, compared to without membrane vibration. Newly generated microfiltration membranes with slotted pores were used in the experiments.

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Chitosan/Cellulose Microfiltration Membranes for Endotoxin Removal

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.781-784.1007 ◽

2013 ◽

Vol 781-784 ◽

pp. 1007-1010 ◽

Cited By ~ 1

Author(s):

Nan Nan Wang ◽

Shi Jiang Wang ◽

Tie Wei Shen ◽

Yue Qiang Cao ◽

Guan Gen Ding ◽

...

Keyword(s):

Removal Efficiency ◽

Coating Layer ◽

Water Flux ◽

High Water ◽

Microfiltration Membrane ◽

Microfiltration Membranes ◽

Positively Charged

The aim of this study is the removal of endotoxin from water using a positively charged microfiltration membrane. The membrane was prepared by crosslinking a chitosan (CS) coating layer with glutaraldehyde vapor on a cellulose (CA) microporous substrate. The positively charged CS/CA membrane showed promising removal efficiency of endotoxin at a high water flux.

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Synthesizing Ag/PDA/PES Antibacterial Membrane for Natural Organic Molecules Removal

E3S Web of Conferences ◽

10.1051/e3sconf/20186505023 ◽

2018 ◽

Vol 65 ◽

pp. 05023 ◽

Cited By ~ 2

Author(s):

Kok Poh Wai ◽

Chai Hoon Koo ◽

Yean Ling Pang ◽

Woon Chan Chong ◽

Woei Jye Lau

Keyword(s):

Membrane Surface ◽

Pure Water ◽

Water Flux ◽

X Ray Diffraction ◽

X Ray ◽

Membrane Performance ◽

Dope Solution ◽

And Performance ◽

Pes Membrane ◽

Contact Angle Analysis

Silver nanoparticles (NP) was successfully immobilized on polydopamine (PDA) supported polyethersulfone (PES) membrane via a redox reaction. Polyvinylpyrrolidone (PVP) was added into membrane dope solution as a pore-forming agent. Four pieces of membranes (M1, M2, M3 and M4) were fabricated with different active layer coatings to compare their morphological and performance properties. The differences between each sample were highlighted as follow: M1 (pristine PES), M2 (PES+PVP), M3 (PDA/PES+PVP) and M4 (Ag/PDA/PES+PVP). All membranes were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and contact angle analysis. The membrane performance was examined using pure water permeability (PWP) test, antibacterial test and humic acid (HA) rejection test. Pristine M1 membrane showed that PWP of 27.16 LMH/bar and HA rejection of 84 %. In this study, it was found that the addition of PVP as a pore agent into the membrane M2 increased water flux but slightly deteriorated HA rejection. Coating of PDA on M3 and immobilizing silver NP on M4 membrane surface have improved HA rejection but compromised PWP. The results showed that membrane M4 carried excellent antibacterial property and highest HA rejection among all fabricated membranes.

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Enhancing the permeation and fouling resistance of PVDF microfiltration membranes by constructing an auto-soak surface

RSC Advances ◽

10.1039/c6ra18714e ◽

2016 ◽

Vol 6 (114) ◽

pp. 113267-113274 ◽

Cited By ~ 6

Author(s):

Xinzhen Zhao ◽

Changkun Liu

Keyword(s):

Water Treatment ◽

Plasma Treatment ◽

Polyvinylidene Fluoride ◽

Separation Efficiency ◽

Fouling Resistance ◽

Microfiltration Membrane ◽

Microfiltration Membranes

A new kind of hydrophilic polyvinylidene fluoride microfiltration membrane with an auto-soak surface was fabricated by plasma treatment and interfacial crosslinking to improve the separation efficiency and fouling resistance in water treatment.

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Metal Titanate (ATiO3, A: Ni, Co, Mg, Zn) Nanorods for Toluene Photooxidation under LED Illumination

Applied Sciences ◽

10.3390/app112210850 ◽

2021 ◽

Vol 11 (22) ◽

pp. 10850

Author(s):

Anna P. Souri ◽

Natalia Andrigiannaki ◽

Marilena Moschogiannaki ◽

Vasiliki Faka ◽

George Kiriakidis ◽

...

Keyword(s):

Electron Microscopy ◽

Ethylene Glycol ◽

Separation Efficiency ◽

Heterogeneous Photocatalysis ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Vis Spectroscopy ◽

Ft Ir ◽

Toluene Photooxidation

The increasing air pollution taking place in virtue of human activity has a novel impact in our health. Heterogeneous photocatalysis is a promising way of degrading volatile organic compounds (VOCs) that makes the quest of new and improved photocatalysts of great importance. Herein, perovskite-related materials ATiO3 with A = Mg, Ni, Co, Zn were synthesized through an ethylene glycol-mediated root, with ethylene glycol being used as a solvent and ligand. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), UV-vis spectroscopy, Raman spectroscopy, Fourier transform infrared (FT-IR), and photoluminescence spectroscopy (PL) were used in order to confirm the structure, the nanorod morphology, their absorption in UV-vis, and the separation efficiency of photogenerated charge carriers. The highest photoactivity was observed for ZnTiO3 in which 62% of toluene was decomposed after 60 min under LED illumination (54 mW/cm2).

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Increasing Rejection in Microfiltration Using Vibrating Membrane

10.20944/preprints202108.0393.v1 ◽

2021 ◽

Author(s):

Asmat Ullah ◽

Kalam Alam ◽

Saad Ullah Khan ◽

Victor M. Starov

Keyword(s):

Membrane Fouling ◽

Produced Water ◽

Separation Efficiency ◽

Membrane Surface ◽

Water Separation ◽

Pore Blockage ◽

Oil Water Separation ◽

Microfiltration Membranes ◽

New Type ◽

New Generation

A new method is proposed to increase rejection in microfiltration by applying membrane oscillation using a new type of microfiltration membranes with slotted pores. The oscillations applied to the membrane surface result in reducing membrane fouling and increasing separation efficiency. An exact mathematical solution of the flow in the surrounding solution outside the oscillating membrane is developed. The oscillation results in appearance of the lift velocity, which moves oil particles away from the membrane. The latter results in both reducing membrane fouling and increasing oil droplets rejection. This developed model was supported by the experimental results for oil water separation in produced water treatment. It was proven that oil droplet concentration reduced notably in the permeate due to the membrane oscillation and that applied shear rate caused by the membrane oscillation is also reduce pore blockage. New generation of microfiltration membranes with slotted pores was used in the experiments.

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Atomic Layer Deposition of LiF and Lithium Ion Conducting (AlF3)(LiF)x Alloys Using Trimethylaluminum, Lithium Hexamethyldisilazide and Hydrogen Fluoride

10.26434/chemrxiv.5459653 ◽

2017 ◽

Author(s):

Younghee Lee ◽

Daniela M. Piper ◽

Andrew S. Cavanagh ◽

Matthias J. Young ◽

Se-Hee Lee ◽

...

Keyword(s):

Lithium Ion ◽

Atomic Layer ◽

Mass Gain ◽

Alloy Film ◽

Ex Situ ◽

X Ray ◽

Layer Deposition ◽

Ion Conducting ◽

Good Agreement

<div>Atomic layer deposition (ALD) of LiF and lithium ion conducting (AlF3)(LiF)x alloys was developed using trimethylaluminum, lithium hexamethyldisilazide (LiHMDS) and hydrogen fluoride derived from HF-pyridine solution. ALD of LiF was studied using in situ quartz crystal microbalance (QCM) and in situ quadrupole mass spectrometer (QMS) at reaction temperatures between 125°C and 250°C. A mass gain per cycle of 12 ng/(cm2 cycle) was obtained from QCM measurements at 150°C and decreased at higher temperatures. QMS detected FSi(CH3)3 as a reaction byproduct instead of HMDS at 150°C. LiF ALD showed self-limiting behavior. Ex situ measurements using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) showed a growth rate of 0.5-0.6 Å/cycle, in good agreement with the in situ QCM measurements.</div><div>ALD of lithium ion conducting (AlF3)(LiF)x alloys was also demonstrated using in situ QCM and in situ QMS at reaction temperatures at 150°C A mass gain per sequence of 22 ng/(cm2 cycle) was obtained from QCM measurements at 150°C. Ex situ measurements using XRR and SE showed a linear growth rate of 0.9 Å/sequence, in good agreement with the in situ QCM measurements. Stoichiometry between AlF3 and LiF by QCM experiment was calculated to 1:2.8. XPS showed LiF film consist of lithium and fluorine. XPS also showed (AlF3)(LiF)x alloy consists of aluminum, lithium and fluorine. Carbon, oxygen, and nitrogen impurities were both below the detection limit of XPS. Grazing incidence X-ray diffraction (GIXRD) observed that LiF and (AlF3)(LiF)x alloy film have crystalline structures. Inductively coupled plasma mass spectrometry (ICP-MS) and ionic chromatography revealed atomic ratio of Li:F=1:1.1 and Al:Li:F=1:2.7: 5.4 for (AlF3)(LiF)x alloy film. These atomic ratios were consistent with the calculation from QCM experiments. Finally, lithium ion conductivity (AlF3)(LiF)x alloy film was measured as σ = 7.5 × 10-6 S/cm.</div>

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Synthesis and Evaluation of Levulinic Ester as Biodiesel Additives

Revista de Chimie ◽

10.37358/rc.20.8.8275 ◽

2020 ◽

Vol 71 (8) ◽

pp. 21-26

Author(s):

Elena-Emilia Oprescu ◽

Cristina-Emanuela Enascuta ◽

Elena Radu ◽

Vasile Lavric

Keyword(s):

Maximum Yield ◽

Strength Distribution ◽

Point Of View ◽

Reaction Parameters ◽

X Ray ◽

Ethyl Levulinate ◽

Ft Ir ◽

Ir Analysis ◽

Biodiesel Blend ◽

Acid Strength Distribution

In this study, the SO42-/TiO2-La2O3-Fe2O3 catalyst was prepared and tested in the conversion of fructose to ethyl levulinate . The catalyst was characterized from the point of view of the textural analysis, FT-IR analysis, acid strength distribution, X-ray powder diffraction and pyridine adsorption IR spectra. The influence of the reaction parameters on the ethyl levulinate yield was study. The maximum yield of 37.95% in levulinate esters was obtained at 180 �C, 2 g catalyst and 4 h reaction time. The effect of ethyl levulinate addition to diesel-biodiesel blend in different rates, i.e, 0.5, 1, 2.5, 5 (w.t %) on density, kinematic viscosity and flash point was evaluated and compared with the European specification.

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Thermal Behaviour of Candesartan Active substance and in pharmaceutical compounds

Revista de Chimie ◽

10.37358/rc.17.8.5787 ◽

2017 ◽

Vol 68 (8) ◽

pp. 1895-1902

Author(s):

Ioana Cristina Tita ◽

Eleonora Marian ◽

Bogdan Tita ◽

Claudia Crina Toma ◽

Laura Vicas

Keyword(s):

Thermal Behaviour ◽

Active Substance ◽

Pharmaceutical Research ◽

Pharmaceutical Product ◽

Nitrogen Atmosphere ◽

Pure Substance ◽

Scanning Calorimetry ◽

X Ray ◽

Ft Ir

Thermal analysis is one of the most frequently used instrumental techniques in the pharmaceutical research, for the thermal characterization of different materials from solids to semi-solids, which are of pharmaceutical relevance. In this paper, simultaneous thermogravimetry/derivative thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) were used for characterization of the thermal behaviour of candesartan cilexetil � active substance (C-AS) under dynamic nitrogen atmosphere and nonisothermal conditions, in comparison with pharmaceutical product containing the corresponding active substance. It was observed that the commercial samples showed a different thermal profile than the standard sample, caused by the presence of excipients in the pharmaceutical product and to possible interaction of these with the active substance. The Fourier transformed infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRPD) were used as complementary techniques adequately implement and assist in interpretation of the thermal results. The main conclusion of this comparative study was that the TG/DTG and DSC curves, together with the FT-IR spectra, respectively X-ray difractograms constitute believe data for the discrimination between the pure substance and pharmaceutical forms.

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Enhancement of Chloroprene/Natural/Butadiene Rubber Nanocomposite Properties Using Organoclays and Their Combination with Carbon Black as Fillers

Polymers ◽

10.3390/polym13071085 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1085

Author(s):

Patricia Castaño-Rivera ◽

Isabel Calle-Holguín ◽

Johanna Castaño ◽

Gustavo Cabrera-Barjas ◽

Karen Galvez-Garrido ◽

...

Keyword(s):

Mechanical Properties ◽

Carbon Black ◽

High Performance ◽

Rubber Matrix ◽

Butadiene Rubber ◽

X Ray Diffraction ◽

X Ray ◽

Rubber Blends ◽

Ft Ir ◽

Chloroprene Rubber

Organoclay nanoparticles (Cloisite® C10A, Cloisite® C15) and their combination with carbon black (N330) were studied as fillers in chloroprene/natural/butadiene rubber blends to prepare nanocomposites. The effect of filler type and load on the physical mechanical properties of nanocomposites was determined and correlated with its structure, compatibility and cure properties using Fourier Transformed Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and rheometric analysis. Physical mechanical properties were improved by organoclays at 5–7 phr. Nanocomposites with organoclays exhibited a remarkable increase up to 46% in abrasion resistance. The improvement in properties was attributed to good organoclay dispersion in the rubber matrix and to the compatibility between them and the chloroprene rubber. Carbon black at a 40 phr load was not the optimal concentration to interact with organoclays. The present study confirmed that organoclays can be a reinforcing filler for high performance applications in rubber nanocomposites.

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