scholarly journals Tailored CNTs Buckypaper Membranes for the Removal of Humic Acid and Separation of Oil-In-Water Emulsions

Membranes ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 97
Author(s):  
Eman Elnabawy ◽  
Ibrahim M. A. Elsherbiny ◽  
Ahmed M. A. Abdelsamad ◽  
Badawi Anis ◽  
Abdelwahab Hassan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Humic Acid ◽  
Membrane Surface ◽  
Pure Water ◽  
Size Exclusion ◽  
Organic Liquids ◽  
Separation Performance ◽  
Aspect Ratios ◽  
Oil In Water ◽  
Wide Range

Carbon nanotubes (CNTs) are a robust material and proven as a promising candidate for a wide range of electronic, optoelectronic and environmental applications. In this work, two different methods were utilized for the preparation of CNTs exhibiting different aspect ratios via chemical vapor deposition (CVD). The as-prepared CNTs were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2adsorption isotherms, thermogravimetric analysis and Raman spectroscopy in order to investigate their morphological and structural properties. Free-standing CNTs “buckypaper” membranes were fabricated, characterized and tailored to meet the requirements of two applications, i.e., (1) the removal of humic acid (HA) from water and (2) separation of oil-in-water emulsions. It was revealed that the hydrophobic buckypapers showed high separation performance for Shell oil-in-water emulsions filtration, with up to 98% through the accumulation of oil droplets onto the membrane surface. The absorption capacity of buckypaper membranes for various organic liquids (oil, chloroform and toluene) was evaluated over 10 absorption cycles to investigate their recyclability and robustness. Moreover, surface modification was introduced to the pristine CNTs to increase their surface hydrophilicity and improve the pure water permeability of buckypapers. These modified buckypapers showed high flux for HA solutions and excellent HA rejection efficiency up to 95%via size exclusion and electrostatic repulsion mechanisms.

scholarly journals Improving Water Permeability of Hydrophilic PVDF Membrane Prepared via Blending with Organic and Inorganic Additives for Humic Acid Separation

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4099 ◽  
Author(s):  
Nasrul Arahman ◽  
Sri Mulyati ◽  
Afrillia Fahrina ◽  
Syawaliah Muchtar ◽  
Mukramah Yusuf ◽  
...  
Keyword(s):  
Humic Acid ◽  
Water Permeability ◽  
Polyvinylidene Fluoride ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Cross Flow ◽  
Chemical Compositions ◽  
Separation Performance ◽  
Pvdf Membrane ◽  
Cross Flow Filtration

The removal of impurities from water or wastewater by the membrane filtration process has become more reliable due to good hydraulic performance and high permeate quality. The filterability of the membrane can be improved by having a material with a specific pore structure and good hydrophilic properties. This work aims at preparing a polyvinylidene fluoride (PVDF) membrane incorporated with phospholipid in the form of a 2-methacryloyloxyethyl phosphorylcholine, polymeric additive in the form of polyvinylpyrrolidone, and its combination with inorganic nanosilica from a renewable source derived from bagasse. The resulting membrane morphologies were analyzed by using scanning electron microscopy. Furthermore, atomic force microscopy was performed to analyze the membrane surface roughness. The chemical compositions of the resulting membranes were identified using Fourier transform infrared. A lab-scale cross-flow filtration system module was used to evaluate the membrane’s hydraulic and separation performance by the filtration of humic acid (HA) solution as the model contaminant. Results showed that the additives improved the membrane surface hydrophilicity. All modified membranes also showed up to five times higher water permeability than the pristine PVDF, thanks to the improved structure. Additionally, all membrane samples showed HA rejections of 75–90%.

Preparation of Polyethersulfone Ultrafiltration Membrane Surface Coated with TiO2 Nanoparticles and Irradiated under UV Light

2013 ◽  
Vol 594-595 ◽  
pp. 877-881 ◽  
Author(s):  
Siti Hawa Mohamad ◽  
M.I. Idris ◽  
Hasan Zuhudi Abdullah
Keyword(s):  
Humic Acid ◽  
Uv Light ◽  
Membrane Surface ◽  
Pure Water ◽  
Water Flux ◽  
Dip Coating ◽  
Ultrafiltration Membrane ◽  
Inversion Method ◽  
Pes Membrane ◽  
Coated Membrane

This paper focuses on performance of polyethersulfone (PES) ultrafiltration membrane coated with titanium dioxide (TiO2) nanoparticles and irradiated with UV light. The flat sheet membrane was prepared via phase inversion method, with two types of membrane; TiO2 coated PES membrane and UV irradiated TiO2 coated PES membrane. TiO2 suspension with concentration of 0.01, 0.03 and 0.05 wt.% were prepared and coated on the PES surface via dip coating. Membrane was immersed in all suspension for 15 minutes and 30 minutes. Then, prepared coated membranes were irradiated by 184 Watts UV lamp for 15 minutes. The performance of membranes was examined by permeation of humic acid. The morphology of membranes was analyzed by scanning electron microscopy (SEM). It was revealed that the pure water flux and humic acid permeation of UV irradiated TiO2 coated membrane was higher than TiO2 coated membrane. It can be concluded that TiO2 coated with 0.03 wt.% of suspension, 30 minutes and 15 minutes UV irradiation with 184 Watt light were determined as the optimum conditions for preparation ultrafiltration PES membrane.

Comparison of Film Quality and Step Coverage for Silicon Dioxide Dielectrics Formed by RTCVD Using Tetraethoxysilane and Silane

1994 ◽  
Vol 338 ◽  
Author(s):  
D. S. Miles ◽  
G. S. Harris ◽  
D. Venables ◽  
M. R. Mirabedini ◽  
J. J. Wortman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Vapor ◽  
Breakdown Field ◽  
Promising Candidate ◽  
Cross Sectional ◽  
Aspect Ratios ◽  
Step Coverage ◽  
Transmission Electron ◽  
Wide Range ◽  
Device Applications

ABSTRACTRapid thermal chemical vapor deposition (RTCVD) oxides formed using TEOS and oxygen (O2) are compared with RTCVD oxides formed using silane (SiH4) and nitrous oxide (N2O). These oxides were deposited under varying pressure and gas composition to investigate the film step coverage and electrical properties. Cross-sectional scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used in determining the oxide step coverage. Excellent oxide conformality, greater than 90 %, was achieved with SiH4 and N2O over a wide range of aspect ratios. The average breakdown field obtained for the SiH4/N2O oxides is approximately 13 MV/cm, which is greater than values measured for oxides formed by conventional dry thermal process. Oxides deposited using TEOS typically have an average breakdown field of about 8 MV/cm. We conclude that the SiH4/N2O oxide process for the deposition of SiO2 films in a RTCVD reactor is a very promising candidate for sidewall spacer formation in advanced device applications.

scholarly journals Microcrystalline Cellulose-Blended Polyethersulfone Membranes for Enhanced Water Permeability and Humic Acid Removal

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 660
Author(s):  
Amirul Islah Nazri ◽  
Abdul Latif Ahmad ◽  
Mohd Hazwan Hussin
Keyword(s):  
Humic Acid ◽  
Pore Size ◽  
Composite Membrane ◽  
Microcrystalline Cellulose ◽  
Pure Water ◽  
Water Flux ◽  
Composite Membranes ◽  
Size Exclusion ◽  
Inversion Method ◽  
Water Contact

A novel polyethersulfone (PES)/microcrystalline cellulose (MCC) composite membrane for humic acid (HA) removal in water was fabricated using the phase inversion method by blending hydrophilic MCC with intrinsically hydrophobic PES in a lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) co-solvent system. A rheological study indicated that the MCC-containing casting solutions exhibited a significant increase in viscosity, which directly influenced the composite membrane’s pore structure. Compared to the pristine PES membrane, the composite membranes have a larger surface pore size, elongated finger-like structure, and presence of sponge-like pores. The water contact angle and pure water flux of the composite membranes indicated an increase in hydrophilicity of the modified membranes. However, the permeability of the composite membranes started to decrease at 3 wt.% MCC and beyond. The natural organic matter removal experiments were performed using humic acid (HA) as the surface water pollutant. The hydrophobic HA rejection was significantly increased by the enhanced hydrophilic PES/MCC composite membrane via the hydrophobic–hydrophilic interaction and pore size exclusion. This study provides insight into the utilization of a low-cost and environmentally friendly additive to improve the hydrophilicity of PES membranes for efficient removal of HA in water.

Preparation of hydrophilic modified polyvinylidene fluoride (PVDF) ultrafiltration membranes by polymer/non-solvent co-induced phase separation: effect of coagulation bath temperature

2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiaoming Zhang ◽  
Qingchen Lu ◽  
Nana Li
Keyword(s):  
Phase Separation ◽  
Membrane Fouling ◽  
Membrane Structure ◽  
Polyvinylidene Fluoride ◽  
Membrane Surface ◽  
Pure Water ◽  
Bath Temperature ◽  
Coagulation Bath ◽  
Separation Performance ◽  
Coagulation Bath Temperature

Abstract Membrane separation technology is widely used in wastewater purification, but the issue of membrane fouling could not be ignored. Hydrophilic modification is an effective method to reduce membrane fouling. Therefore, in this work, a hydrophilic modified polyvinylidene fluoride (PVDF) ultrafiltration membrane was prepared by polymer/non-solvent co-induced phase separation, and the effect of coagulation bath temperature on the membrane structure and performance was systematically investigated based on the previous study. With the increased of the coagulation bath temperature, the phase separation process changed from delayed to instantaneous, and the membrane surface changed from porous to dense, while the macropore structures and sponge-like pores appeared on the cross-section. Meanwhile, the pure water flux decreased from 229.3 L/(m2·h) to 2.08 L/(m2·h), the protein rejection rate increased from 83.87% to 100%, and the surface water contact angle increased from 63° to 90°. Thus, excessively high coagulation bath temperature adversely affected the permeate and separation performance, as well as antifouling performance of the membrane. This study enriched the research for preparing separation membranes by polymer/non-solvent co-induced phase separation and provided a practical and theoretical reference for controlling the membrane structure and properties by changing the coagulation bath temperature.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

Microwaves: Application in Electron Microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 140-141
Author(s):  
Anthony S-Y Leong ◽  
David W Gove
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Chemical Reactions ◽  
Electromagnetic Waves ◽  
Tissue Fixation ◽  
Primary Method ◽  
Dipolar Molecules ◽  
Wide Range ◽  
Time Required ◽  
Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

Recent Progress and Plans in Computer-Controlled High Resolution Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 154-155
Author(s):  
W.J. de Ruijter ◽  
Peter Rez ◽  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
Digital Processing ◽  
High Resolution Electron Microscopy ◽  
Objective Lens ◽  
Linear Filter ◽  
Contrast Transfer Function ◽  
Image Displacement ◽  
Spatially Resolved ◽  
Wide Range ◽  
On Line

Digital computers are becoming widely recognized as standard accessories for electron microscopy. Due to instrumental innovations the emphasis in digital processing is shifting from off-line manipulation of electron micrographs to on-line image acquisition, analysis and microscope control. An on-line computer leads to better utilization of the instrument and, moreover, the flexibility of software control creates the possibility of a wide range of novel experiments, for example, based on temporal and spatially resolved acquisition of images or microdiffraction patterns. The instrumental resolution in electron microscopy is often restricted by a combination of specimen movement, radiation damage and improper microscope adjustment (where the settings of focus, objective lens stigmatism and especially beam alignment are most critical). We are investigating the possibility of proper microscope alignment based on computer induced tilt of the electron beam. Image details corresponding to specimen spacings larger than ∼20Å are produced mainly through amplitude contrast; an analysis based on geometric optics indicates that beam tilt causes a simple image displacement. Higher resolution detail is characterized by wave propagation through the optical system of the microscope and we find that beam tilt results in a dispersive image displacement, i.e. the displacement varies with spacing. This approach is valid for weak phase objects (such as amorphous thin films), where transfer is simply described by a linear filter (phase contrast transfer function) and for crystalline materials, where imaging is described in terms of dynamical scattering and non-linear imaging theory. In both cases beam tilt introduces image artefacts.

Solution chemistry effects on the solvation shell of metal ions

2020 ◽  
Author(s):  
Xiangwen Wang ◽  
Dimitrios Toroz ◽  
Seonmyeong Kim ◽  
Simon Clegg ◽  
Gun-Sik Park ◽  
...  
Keyword(s):  
Metal Ions ◽  
Pure Water ◽  
Solvation Shell ◽  
Solution Chemistry ◽  
Chemical Characteristics ◽  
Velocity Autocorrelation Function ◽  
Ionic Solvation ◽  
General Terms ◽  
Alkaline Earth Metal Ions ◽  
Wide Range

<div> <p>As natural aqueous solutions are far from being pure water, being rich in ions, the properties of solvated ions are of relevance for a wide range of systems, including biological and geochemical environments. We conducted ab initio and classical MD simulations of the alkaline earth metal ions Mg<sup>2+</sup> and Ca<sup>2+</sup> and of the alkali metal ions Li<sup>+</sup>, Na<sup>+</sup>, K<sup>+</sup> and Cs<sup>+</sup> in pure water and electrolyte solutions containing the counterions Cl<sup>–</sup> and SO<sub>4</sub><sup>2–</sup>. Through a detailed analysis of these simulations, this study reports on the effect of solution chemistry (composition and concentration of the solution) to the ion–water structural properties and interaction strength, and to the dynamics, hydrogen bond network, and low-frequency dynamics of the ionic solvation shell. Except for the ion–water radial distribution function, which is weakly dependent on the counter-ions and concentrations, we found that all other properties can be significantly influenced by the chemical characteristics of the solution. Calculation of the velocity autocorrelation function of magnesium ions, for example, shows that chlorine ions located in the second coordination shell of Mg<sup>2+</sup> weaken the Mg(H<sub>2</sub>O)<sub>6</sub><sup>2+</sup> hydration ‘cage’ of the cation. The result reported in this study suggest that ionic solvation shell can be significantly influenced by the interactions between other ions present in solution ions, especially those of opposite charge. In more general terms, the chemical characteristics of the solution, including the balance between ion-solvent and ion-ion interactions, could result in significant differences in behavior and function of the ionic solvation shell.</p> </div>

Coagulation/flocculation/ultrafiltration for natural organic matter removal in drinking water production

2004 ◽  
Vol 4 (5-6) ◽  
pp. 215-222 ◽  
Author(s):  
A.R. Costa ◽  
M.N. de Pinho
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Water Production ◽  
Cellulose Acetate Membranes ◽  
Wide Range ◽  
Drinking Water Production

Membrane fouling by natural organic matter (NOM), namely by humic substances (HS), is a major problem in water treatment for drinking water production using membrane processes. Membrane fouling is dependent on membrane morphology like pore size and on water characteristics namely NOM nature. This work addresses the evaluation of the efficiency of ultrafiltration (UF) and Coagulation/Flocculation/UF performance in terms of permeation fluxes and HS removal, of the water from Tagus River (Valada). The operation of coagulation with chitosan was evaluated as a pretreatment for minimization of membrane fouling. UF experiments were carried out in flat cells of 13.2×10−4 m2 of membrane surface area and at transmembrane pressures from 1 to 4 bar. Five cellulose acetate membranes were laboratory made to cover a wide range of molecular weight cut-off (MWCO): 2,300, 11,000, 28,000, 60,000 and 75,000 Da. Severe fouling is observed for the membranes with the highest cut-off. In the permeation experiments of raw water, coagulation prior to membrane filtration led to a significant improvement of the permeation performance of the membranes with the highest MWCO due to the particles and colloidal matter removal.

Sign in / Sign up

Export Citation Format

Share Document