scholarly journals Novel negatively-charged membrane adsorbers made using combination of photopolymerization and immersion precipitation

2016 ◽  
Vol 81 (4) ◽  
pp. 419-431 ◽  
Author(s):  
Tanja Tomkovic ◽  
Filip Radovanovic ◽  
Branimir Grgur ◽  
Aleksandra Nastasovic ◽  
Dana Vasiljevic-Radovic ◽  
...  
Keyword(s):  
Glycidyl Methacrylate ◽  
Sulfonic Acid ◽  
Sodium Sulfite ◽  
Conductometric Titration ◽  
Submicron Particles ◽  
Precipitation Process ◽  
Force Microscopy ◽  
Atomic Force ◽  
Membrane Dynamic ◽  
Methacrylate Copolymer

A novel method combining a traditional immersion precipitation process for making membranes with photopolymerization and crosslinking of functional monomers included in the casting solution was used to prepare asymmetric polyethersulfone membranes with submicron particles incorporating glycidyl methacrylate copolymer. In order to introduce sulfonic groups epoxide rings of glycidyl methacrylate were opened using two methods. The first method was functionalization with sodium sulfite, and the second method was functionalization with sulfuric acid and then grafting with 2-acrylamido-2-methylpropane sulfonic acid. Obtained membranes were characterized using infrared spectroscopy, conductometric titration and water permeability measurements. Scanning electron microscopy and atomic force microscopy were used to investigate the surface morphology and topology of membrane. Dynamic adsorption of Rhodamine B as a model dye was used to demonstrate suitability of these novel membranes for membrane adsorption since the adsorption capacity for dye cations was much better for both functionalized membrane with sodium sulfite and grafted membrane with 2-acrylamido-2-methylpropane sulfonic acid compared to the nonfunctionalized membrane.

scholarly journals Characterization of thin films containing zirconium, oxygen, and sulfur by scanning electron and atomic force microscopy

1999 ◽  
Vol 14 (9) ◽  
pp. 3725-3733 ◽  
Author(s):  
A. Fischer ◽  
F. C. Jentoft ◽  
G. Weinberg ◽  
R. Schlögl ◽  
T. P. Niesen ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sulfonic Acid ◽  
Homogeneous Nucleation ◽  
Chemical Deposition ◽  
Self Assembled Monolayers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Assembled Monolayers ◽  
Scanning Electron

Oxidic zirconium films prepared by chemical deposition from aqueous medium on sulfonic acid terminated self-assembled monolayers attached to an oxidized silicon surface were investigated with scanning electron microscopy and atomic force microscopy. Bulk precipitate forms in the 4 mM Zr(SO4)2 · 4H2O, 0.4 N HCl deposition medium at 343 K after approximately 30 min. Precipitate particles (200 nm and larger) were found embedded in the oxidic zirconium film and adsorbed on top of the film; they could be washed off, but patches of the film were removed. Working with unstable deposition solutions, in which homogeneous nucleation occurs, leads to preparation-inherent flaws in the film.

scholarly journals SYNTHESIS OF SPINEL Mn3O4 AND SPINEL Mn3O4/ZrO2 NANOCOMPOSITES AND USING THEM IN PHOTO-CATALYTIC DECOLORIZATION OF Fe(II)-( 4,5- DIAZAFLUOREN-9-ONE 11) COMPLEX

2020 ◽  
Vol 17 (34) ◽  
pp. 689-699
Author(s):  
Mohammed Kareem HAYAWI ◽  
Mohanad Mousa KAREEM ◽  
Luma Majeed AHMED
Keyword(s):  
Model Material ◽  
Spherical Particles ◽  
Ratio Method ◽  
Nano Composites ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mole Ratio Method ◽  
Co Precipitation

The spinel structure Mn3O4 and the spinel Mn3O4/ZrO2 nano-composites particles were synthesized successfully as photocatalysts by employing the co-precipitation process and ultrasonic technique, respectively. The morphology of the top mention prepared photocatalysts was distinguished using X-ray diffraction (XRD) technology and atomic force microscopy (AFM) and indicated that the mean crystal sizes and particle sizes for all studied samples were nanometric. In addition, the optical properties of the obtained photocatalysts were investigated using a UV-Visible spectrophotometer with Labsphere diffuse reflectance accessory to measure the bandgaps of them. Based on the Tauc equation, the bandgaps (Bg) for the studied photocatalysts were determined. The bandgaps are indirect for all samples, and it is increased in values for the nanocomposites with the increasing the ratio of ZrO2. So, the sequence of bandgaps values is: Bg spinel Mn3O4 Bg Comp.1 Bg Comp.2 Bg Comp.3 Bg ZrO2, and equal to 2.21 eV 3.15 eV 4.51 eV 4.26 eV 5.29 eV. The research revealed that the spinel Mn3O4 and the spinel Mn3O4 ZrO2 nano-composites particles were quasispherical and spherical particles respectively. Moreover, the incorporation of spinel Mn3O4 particle with ZrO2 particle was successfully carried out that was proved by XRD and AFM analyses. This work discovered that the photocatalytic reaction response via employing Fe(II)-(4,5-Diazafluoren-9-one 11) complex as model material under UV-A lamp with the use of the studied photocatalysts. The primary photo experiments for these photocatalysts found that the decolorization of Fe(II)-(4,5-Diazafluoren-9-one 11) complex is not active without addition of H2O2, that attitude is due to the very high stability of these complex with having an octahedral structure, which was proved with using mole ratio method. Whereas, after the addition of H2O2 to the aqueous solution of these complex, the activity with using the spinel Mn3O4 ZrO2 nanocomposite 3 was found to be the double active than that using the spinel Mn3O4 alone, and the sequence of phootdecolorization efficiency (E%) is being: E% composite 3 E% composite 2 E% composite 1 E% spinel Mn3O4.

scholarly journals Effect of Stabilizer on Gold Leaching with Thiourea in Alkaline Solutions

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 89
Author(s):  
Wenjuan Li ◽  
He Shang ◽  
He Zhou ◽  
Yongsheng Song ◽  
Shuilin Zheng ◽  
...  
Keyword(s):  
Activation Energy ◽  
Sodium Silicate ◽  
Cyclic Voltammetry Curve ◽  
Sodium Sulfite ◽  
Alkaline Solutions ◽  
Gold Leaching ◽  
Force Microscopy ◽  
Atomic Force ◽  
Alkaline Thiourea ◽  
The Stability

The present work investigated the comparison of the effects of Na2SO3 and Na2SiO3 on thiourea stabilization, and a systematic study was undertaken to establish the effects of these stabilizers on the stability of alkaline thiourea, both qualitatively and quantitatively. The effects of these stabilizers on the activation energy of alkaline thiourea gold leaching was also studied. The results showed that sodium silicate was more suitable as a stabilizer in this system than sodium sulfite because the peak current of gold dissolution with sodium sulfite was higher than that with sodium silicate, but the inhibition of thiourea decomposition by the former was less obvious than that of sodium silicate in the cyclic voltammetry curve. The quartz crystal microbalance results showed that the quality decreased to about 100 ng cm2 in the presence of a stabilizer, while it increased to 300 ng cm2 in the absence of the stabilizer. It is inferred that gold can be dissolved by alkaline thiourea in the presence of a stabilizer, while it cannot without a stabilizer because of the decomposition of thiourea. This assumption was confirmed by atomic force microscopy measurements. The surface activation energy of Au dissolution decreased from 183.76 to 98.07 kJ/moL with the addition of sodium silicate, indicating that Au dissolution was promoted with the chemical.

scholarly journals The selectivity of poly(2-vinylpyridine-block-methyl methacrylate) copolymer films: an AFM study

RSC Advances ◽  
2019 ◽  
Vol 9 (29) ◽  
pp. 16455-16466
Author(s):  
Sana Rahim ◽  
Adnan Murad Bhayo ◽  
Ghayas Uddin Siddiqui ◽  
Aneela Maalik ◽  
Najma Memon ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Methyl Methacrylate ◽  
Force Microscopy ◽  
Copolymer Films ◽  
Atomic Force ◽  
Vinyl Pyridine ◽  
Methacrylate Copolymer ◽  
Surface Morphologies

In this study, the surface morphologies of poly(2-vinyl pyridine-block-methyl methacrylate), P(2VP-MMA), copolymer films were analyzed by atomic force microscopy.

Cryogenic atomic force microscopy

1991 ◽  
Vol 49 ◽  
pp. 54-55
Author(s):  
K. A. Fisher ◽  
M. G. L. Gustafsson ◽  
M. B. Shattuck ◽  
J. Clarke
Keyword(s):  
Room Temperature ◽  
Rapid Freezing ◽  
Cryogenic Temperatures ◽  
Soft Or ◽  
Electrically Conductive ◽  
Force Microscopy ◽  
Flexible Molecules ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

AFM study of the dynamics of α-alumina surface faceting during high-temperature processing

1995 ◽  
Vol 53 ◽  
pp. 334-335 ◽  
Author(s):  
Michael W. Bench ◽  
Jason R. Heffelfinger ◽  
C. Barry Carter
Keyword(s):  
High Temperature ◽  
Thin Foil ◽  
Sem Analysis ◽  
Conductive Coatings ◽  
Force Microscopy ◽  
Minimal Sample ◽  
Atomic Force ◽  
Formation And Evolution ◽  
High Temperature Processing ◽  
Nominal Surface

To gain a better understanding of the surface faceting that occurs in α-alumina during high temperature processing, atomic force microscopy (AFM) studies have been performed to follow the formation and evolution of the facets. AFM was chosen because it allows for analysis of topographical details down to the atomic level with minimal sample preparation. This is in contrast to SEM analysis, which typically requires the application of conductive coatings that can alter the surface between subsequent heat treatments. Similar experiments have been performed in the TEM; however, due to thin foil and hole edge effects the results may not be representative of the behavior of bulk surfaces.The AFM studies were performed on a Digital Instruments Nanoscope III using microfabricated Si3N4 cantilevers. All images were recorded in air with a nominal applied force of 10-15 nN. The alumina samples were prepared from pre-polished single crystals with (0001), , and nominal surface orientations.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

Morphology and development of flow-pattern defect with extended nonagitated Secco etching

1994 ◽  
Vol 52 ◽  
pp. 868-869
Author(s):  
Y. Pan
Keyword(s):  
Flow Pattern ◽  
Silicon Crystal ◽  
Gate Oxide ◽  
Crystal Growth Rate ◽  
Etch Depth ◽  
Force Microscopy ◽  
Etch Pit ◽  
Float Zone ◽  
Atomic Force ◽  
Multiple Step

The D defect, which causes the degradation of gate oxide integrities (GOI), can be revealed by Secco etching as flow pattern defect (FPD) in both float zone (FZ) and Czochralski (Cz) silicon crystal or as crystal originated particles (COP) by a multiple-step SC-1 cleaning process. By decreasing the crystal growth rate or high temperature annealing, the FPD density can be reduced, while the D defectsize increased. During the etching, the FPD surface density and etch pit size (FPD #1) increased withthe etch depth, while the wedge shaped contours do not change their positions and curvatures (FIG.l).In this paper, with atomic force microscopy (AFM), a simple model for FPD morphology by non-crystallographic preferential etching, such as Secco etching, was established.One sample wafer (FPD #2) was Secco etched with surface removed by 4 μm (FIG.2). The cross section view shows the FPD has a circular saucer pit and the wedge contours are actually the side surfaces of a terrace structure with very small slopes. Note that the scale in z direction is purposely enhanced in the AFM images. The pit dimensions are listed in TABLE 1.

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