Mechanism analysis of membrane fouling behavior by humic acid using atomic force microscopy: Effect of solution pH and hydrophilicity of PVDF ultrafiltration membrane interface

2015 ◽  
Vol 487 ◽  
pp. 180-188 ◽  
Author(s):  
Xiaorong Meng ◽  
Weiting Tang ◽  
Lei Wang ◽  
Xudong Wang ◽  
Danxi Huang ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Membrane Fouling ◽  
Ultrafiltration Membrane ◽  
Mechanism Analysis ◽  
Membrane Interface ◽  
Solution Ph ◽  
Force Microscopy ◽  
Atomic Force

Phase Transitions in Phospholipid Monolayers Studied by Atomic Force Microscopy and Langmuir-Blodgett Technique

2008 ◽  
Vol 59 (11) ◽  
Author(s):  
Maria Tomoaia-Cotisel ◽  
Aurora Mocanu
Keyword(s):  
Atomic Force Microscopy ◽  
Lipid Membrane ◽  
Phase Behaviour ◽  
Membrane Interface ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Atomic Force ◽  
Phospholipid Monolayers ◽  
Air Water Interface ◽  
Condensed Liquid

The phase behaviour and surface structure of dipalmitoyl phosphatidyl choline (DPPC) monolayers at the air/water interface, in the absence and the presence of procaine, have been investigated by Langmuir-Blodgett (LB) technique and atomic force microscopy. The LB films were transferred on mica, at a controlled surface pressure, characteristic for the expanded liquid to condensed liquid phase transition of pure DPPC monolayers. The results indicate that procaine penetrates into and specifically interacts with phospholipid monolayers stabilizing the lipid membrane interface.

Atomic force microscopy for ultrafiltration membrane imaging

Scanning ◽  
1997 ◽  
Vol 19 (4) ◽  
pp. 281-285 ◽  
Author(s):  
S. A. Centoni ◽  
L. S. Vanasupa ◽  
P. S. Tong
Keyword(s):  
Atomic Force Microscopy ◽  
Ultrafiltration Membrane ◽  
Force Microscopy ◽  
Atomic Force

Image enhancement of polyethersulfone ultrafiltration membrane surface structure for atomic force microscopy

1992 ◽  
Vol 46 (1) ◽  
pp. 167-178 ◽  
Author(s):  
A. K. Fritzsche ◽  
A. R. Arevalo ◽  
M. D. Moore ◽  
C. J. Weber ◽  
V. B. Elings ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Structure ◽  
Image Enhancement ◽  
Membrane Surface ◽  
Ultrafiltration Membrane ◽  
Force Microscopy ◽  
Atomic Force

Probing molecular interactions between humic acid and surface-grafted polyacrylamide using quartz crystal microbalance with dissipation and atomic force microscopy: implications for environmental remediation

2018 ◽  
Vol 15 (6) ◽  
pp. 336 ◽  
Author(s):  
Omar Maan ◽  
Jun Huang ◽  
Hongbo Zeng ◽  
Qingye Lu
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Quartz Crystal Microbalance ◽  
Molecular Interactions ◽  
Environmental Remediation ◽  
Quartz Crystal ◽  
Major Constituent ◽  
Environmental Behaviour ◽  
Force Microscopy ◽  
Atomic Force

Environmental contextPolyacrylamide and its derivatives may enter the natural environment as a consequence of their wide use in various industrial applications. This study demonstrates the application of a quartz crystal microbalance and atomic force microscopy to study the molecular interactions between polyacrylamides and humic acids under various solution chemistries. The knowledge obtained can be used to understand and predict the environmental behaviour of polyacrylamides. AbstractA fundamental understanding of the environmental behaviour of polyacrylamide (PAM) is of importance for guiding environmental remediation. We create a framework for understanding the molecular interactions between PAM and a major constituent present in all natural waters and soil, humic acid (HA), using a quartz crystal microbalance with dissipation (QCM-D) and an atomic force microscope (AFM). A thin film of PAM was grafted on a silica surface silanised with 3-(trimethoxysilyl)propyl methacrylate and the resulting surface was characterised by X-ray photoelectron spectroscopy for the chemical bonds and composition, secondary ion mass spectrometry for the composition and molecular weight, water contact angle measurements for the hydrophilicity, AFM for the morphology, and ellipsometry for the thickness. Surface-grafted PAM was used to study its interactions with HA in aqueous solutions at different pH (2, 7, and 10) and NaCl salt concentrations (1, 10, and 100 mM, within the range of salt concentrations of fresh water) using QCM-D. QCM-D measurements showed that compared with bare silica, the adsorption of HA by PAM-coated silica was greatly reduced at all pHs and salt concentrations, and the adsorption of HA on PAM-coated silica depended on the solution chemistry including solution pH and salt concentration. Hydrogen bonding between PAM and HA is the major driving force for HA to adsorb on PAM. AFM force measurements showed that adhesion between PAM and HA was observed only at acidic conditions. The knowledge obtained from this study will benefit the prediction of the environmental behaviour of PAMs under different conditions in natural/engineered environments and provide guidance for the design of remediation technologies for water and soil.

Single asperity tribochemical wear of silicon by atomic force microscopy

2009 ◽  
Vol 24 (1) ◽  
pp. 173-178 ◽  
Author(s):  
Futoshi Katsuki
Keyword(s):  
Atomic Force Microscopy ◽  
Frictional Force ◽  
Ph Value ◽  
Ph Dependence ◽  
Bond Rupture ◽  
Solution Ph ◽  
Crystal Silicon ◽  
Force Microscopy ◽  
Single Asperity ◽  
Atomic Force

Measurements of single asperity wear on oxidized silicon surface in aqueous potassium hydroxide (KOH) using atomic force microscopy (AFM), where the single crystal silicon tip was used both to tribologically load and image the surface, is presented. AFM was also operating in the lateral (frictional) force mode to investigate the pH dependence of kinetic friction between the tip and the SiO2 surface. It was shown that the Si tip wear amount strongly depended on the solution pH value and was at a maximum at around pH 10. It was also found that the Si removal volume in mol was approximately equal to that of SiO2 irrespective of the solution pH value. This equality implies that the formation of the Si–O–Si bridge between one Si atom of the tip and one SiO2 molecule of the specimen at the wear interface. The surface of the Si tip is then oxidized. Finally, the bond rupture by the tip movement will occur, the dimeric silica (OH)3Si–O–Si(OH)3, including the Si–O–Si bridge, is dissolved in the KOH solution. The frictional signal is also sensitive to the pH values of the solution and peaked at around pH 10. These results indicate that the removal behavior of the Si tip and SiO2 surface would be affected by the frictional force between the Si and the SiO2, because of an increased liquid temperature and a compressive stress in Si and SiO2 networks. Strong influence is observed by the pH of the ambient solution confirming the important role of the OH− in the wear mechanism. Pressure dependence of the microwear behavior under aqueous electrolyte solutions has also been investigated. A microscopic removal mechanism, which is determined by interplay of the diffusion of water in Si and SiO2, is presented.

scholarly journals Effect of Acidithiobacillus ferrooxidans on Humic-Acid Passivation Layer on Pyrite Surface

Minerals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 422 ◽  
Author(s):  
Hongying Yang ◽  
Wenjie Luo ◽  
Ying Gao
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Pyrite Oxidation ◽  
Passivation Layer ◽  
Pyrite Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Leaching Experiments ◽  
Bacterial Adsorption ◽  
Number Of Bacteria

The effect of Acidithiobacillus ferrooxidans on the humic-acid passivation layer on pyrite surfaces was studied by atomic-force microscopy, leaching experiments, and adsorption experiments. Atomic-force-microscopy results showed that humic-acid was adsorbed onto the pyrite surface. The bacteria grew and reproduced on the humic-acid layer. Leaching experiments showed that the humic-acid passivation layer prevented the oxidation of pyrite by Fe3+ under aseptic conditions. Bacteria destroyed the humic-acid layer, promoted pyrite oxidation, and increased the oxidation of pyrite from 1.64% to 67.9%. Bacterial adsorption experiments showed that the humic-acid passivation layer decreased the speed of bacterial adsorption on the pyrite surface but had no effect on the number of bacteria adsorbed on the pyrite surface. The maximum number of bacteria adsorbed by pyrite with and without the humic-acid layer was 4.17 × 1010 cells∙mL−1 and 4.4 × 1010 cells∙mL−1, respectively. Extracellular polymeric stratum layer of bacteria cultured at different concentrations of humic-acid was extracted and analyzed. This layer could destroy the humic-acid layer and promote pyrite oxidation.

scholarly journals Study of a Model Humic Acid-type Polymer by Fluorescence Spectroscopy and Atomic Force Microscopy

2012 ◽  
Vol 03 (07) ◽  
pp. 478-484
Author(s):  
Marcilene Ferrari Barriquello ◽  
Fábio de Lima Leite ◽  
Daiana Kotra Deda ◽  
Sérgio da Costa Saab ◽  
Nelson Consolin-Filho ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Fluorescence Spectroscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Acid Type

scholarly journals Observing Effects of Calcium/Magnesium Ions and pH Value on the Self-Assembly of Extracted Swine Tendon Collagen by Atomic Force Microscopy

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Xuan Song ◽  
Zhiwei Wang ◽  
Shiyu Tao ◽  
Guixia Li ◽  
Jie Zhu
Keyword(s):  
Atomic Force Microscopy ◽  
Metal Ions ◽  
Self Assembly ◽  
Food Packaging ◽  
Ph Value ◽  
The Self ◽  
Solution Ph ◽  
Collagen Concentration ◽  
Force Microscopy ◽  
Atomic Force

Self-assembly of extracted collagen from swine trotter tendon under different conditions was firstly observed using atomic force microscopy; then the effects of collagen concentration, pH value, and metal ions to the topography of the collagen assembly were analyzed with the height images and section analysis data. Collagen assembly under 0.1 M, 0.2 M, 0.3 M CaCl2, and MgCl2 solutions in different pH values showed significant differences (P < 0.05) in the topographical properties including height, width, and roughness. With the concentration being increased, the width of collagen decreased significantly (P < 0.05). The width of collagen fibers was first increased significantly (P < 0.05) and then decreased with the increasing of pH. The collagen was assembled with network structure on the mica in solution with Ca2+ ions. However, it had shown uniformed fibrous structure with Mg2+ ions on the new cleaved mica sheet. In addition, the width of collagen fibrous was 31~58 nm in solution with Mg2+ but 21~50 nm in Ca2+ solution. The self-assembly collagen displayed various potential abilities to construct fibers or membrane on mica surfaces with Ca2+ ions and Mg2+ irons. Besides, the result of collagen self-assembly had shown more relations among solution pH value, metal ions, and collagen molecular concentration, which will provide useful information on the control of collagen self-assembly in tissue engineering and food packaging engineering.

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