RATE PROCESS OF THE COAGULATION OF NANOPARTICLES

Nanometer-sized gold particles dispersed in organic liquids coagulate under the influence of addition of salt or illumination of Mie resonance irradiation. It is derived that the van der Waals attractive force can be enhanced by the excitation of surface plasmon, hence the rate of coagulation is accelerated through the DLVO (Derjaguin, Landau, Verway, Overbeek) potential among the particles. The coagulation rate and the stability ratio are calculated within a framework of DLVO theory.

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Communication: On the Stability and Necessary Electrophoretic Mobility of Bare Oil Nanodroplets in Water

10.26434/chemrxiv.12451796.v1 ◽

2020 ◽

Author(s):

Saranya Pullanchery ◽

Sergey Kulik ◽

halil okur ◽

Hilton. B. de Aguiar ◽

Sylvie Roke

Keyword(s):

Electrophoretic Mobility ◽

Dlvo Theory ◽

Air Bubbles ◽

Oil Droplets ◽

Cleaning Procedure ◽

Charged Droplets ◽

Oil In Water ◽

The Creation ◽

The Stability ◽

The 19Th Century

Hydrophobic oil droplets, particles and air bubbles can be dispersed in water as kinetically stabilized dispersions. It has been established since the 19th century that such objects harbor a negative electrostatic potential roughly twice larger than the thermal energy. The source of this charge continues to be one of the core observations in relation to hydrophobicity and its molecular explanation is still debated. What is clear though, is that the stabilizing interaction in these systems is understood in terms of electrostatic repulsion via DLVO theory. Recent work [Carpenter et al., PNAS 116 (2019) 9214] has added another element into the discussion, reporting the creation of bare near-zero charged droplets of oil in water that are stable for several days. Key to the creation of the droplets is a rigorous glassware cleaning procedure. Here, we investigate these conclusions and show that the cleaning procedure of glassware has no influence on the electrophoretic mobility of the droplets, that oil droplets with near-zero charge are unstable, and provide an alternative possible explanation for the observations involving glass surface chemistry.

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A New Generalized Morse Potential Function for Calculating Cohesive Energy of Nanoparticles

Energies ◽

10.3390/en13133323 ◽

2020 ◽

Vol 13 (13) ◽

pp. 3323 ◽

Cited By ~ 1

Author(s):

Omar M. Aldossary ◽

Anwar Al Rsheed

Keyword(s):

Potential Function ◽

Cohesive Energy ◽

Morse Potential ◽

Attractive Force ◽

Repulsive Interaction ◽

Additional Parameter ◽

Generalized Potential ◽

The Stability ◽

Experimental Values ◽

Generalized Morse Potential

A new generalized Morse potential function with an additional parameter m is proposed to calculate the cohesive energy of nanoparticles. The calculations showed that a generalized Morse potential function using different values for the m and α parameters can be used to predict experimental values for the cohesive energy of nanoparticles. Moreover, the enlargement of the attractive force in the generalized potential function plays an important role in describing the stability of the nanoparticles rather than the softening of the repulsive interaction in the cases when m > 1.

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Bentonite Nanoparticle Stability and the Effect of Fulvic Acids: Experiments and Modelling

Colloids and Interfaces ◽

10.3390/colloids4020016 ◽

2020 ◽

Vol 4 (2) ◽

pp. 16

Author(s):

Holger Seher ◽

Horst Geckeis ◽

Thomas Fanghänel ◽

Thorsten Schäfer

Keyword(s):

Fulvic Acid ◽

Electrokinetic Potential ◽

Background Electrolyte ◽

Fulvic Acids ◽

Structural Formula ◽

Stability Ratio ◽

Potential Measurement ◽

Ζ Potential ◽

Scanning Transmission ◽

The Stability

In this study, the critical coagulation concentration (CCC) for FEBEX bentonite colloids is determined by colloid coagulation studies under variation of pH, electrolyte concentration, and fulvic acid (GoHy-573FA) content. For CaCl2 electrolyte solution, a pH-independent Ca-CCC of 1 mmol L−1 is found. In the case of NaCl background electrolyte, a pH-dependent Na-CCC can be determined with 15 ± 5 mmol L−1 at pH 6, 20 ± 5 mmol L−1 at pH 7, 200 ± 50 mmol L−1 at pH 8, 250 ± 50 mmol L−1 at pH 9, and 350 ± 100 mmol L−1 at pH 10, respectively. The addition of 1 mg L−1 dissolved organic carbon in the form of fulvic acid (FA) increases the Ca-CCC to 2 mmol L−1. An association of FA with FEBEX bentonite colloids as surface coating can clearly be identified by scanning transmission X-ray microscopy (STXM). The experimental bentonite stability results are described by means of an extended DLVO (Derjaguin–Landau–Verwey–Overbeek) approach summing up hydration forces, short-range Born repulsion, van der Waals attraction, and electrical double layer repulsion. The measured zeta (ζ)-potential of the bentonite colloids is applied as platelet face electrokinetic potential and the edge electrokinetic potential is estimated by the combination of silica and alumina ζ-potential data in the ratio given by the FEBEX bentonite structural formula. Adjusting the montmorillonite face electrokinetic potential by a maximum of ±15.9 mV is sufficient to successfully reproduce the measured stability ratios. Due to the uncertainty in the ζ-potential measurement, only semiquantitative calculations of the stability ratio can be given.

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FIV Characteristics of U-Tubes Due to Relocation of the Tube Support Plate

Volume 4: Fluid Structure Interaction ◽

10.1115/pvp2005-71491 ◽

2005 ◽

Author(s):

Ki-Wahn Ryu ◽

Hyung-Jin Kim ◽

Chi-Yong Park

Keyword(s):

Aspect Ratio ◽

Steam Generator ◽

Mode Shapes ◽

Design Stage ◽

Parameter Study ◽

Stability Ratio ◽

Integrity Assessment ◽

Support Plate ◽

Aspect Ratios ◽

The Stability

Fluid-elastic instability and turbulence excitation for an under developing steam generator are investigated numerically. The stability ratio and the amplitude of turbulence excitation are obtained by using the PIAT (Program for Integrity Assessment of Steam Generator Tube) code from the information on the thermal-hydraulic data of the steam generator. The aspect ratio, the ratio between the height of U-tube from the upper most tube support plate (h) and the width of two vertical portion of U-tube (w), is defined for geometric parameter study. Several aspect ratios with relocation of tube support plates are adopted to study the effects on the mode shapes and characteristics of flow-induced vibration. When the aspect ratio exceeds value of 1, most of the mode shapes at low frequency are generated at the top of U-tube. It makes very high value of the stability ratio and the amplitude of turbulent excitation as well. We can consider that the local mode shape at the upper side of U-tube will develop the wear phenomena between the tube and the anti-vibration bars such as vertical, horizontal, and diagonal strips. It turns out that the aspect ratio reveals very important parameter for the design stage of the steam generator. The appropriate value of the aspect ratio should be specified and applied.

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Nanoscale Laser Processing of Hollow Silica Microbeads Assisted by Surface Plasmon Resonance of Gold Particles

Chemistry Letters ◽

10.1246/cl.2011.1411 ◽

2011 ◽

Vol 40 (12) ◽

pp. 1411-1413 ◽

Cited By ~ 1

Author(s):

Koji Furukawa ◽

Tatsuya Kameyama ◽

Ken-ichi Okazaki ◽

Takayuki Yako ◽

Masashi Otsuki ◽

...

Keyword(s):

Surface Plasmon Resonance ◽

Surface Plasmon ◽

Plasmon Resonance ◽

Laser Processing ◽

Hollow Silica ◽

Gold Particles

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Study of Plasmon Fields Propagation on Roughness Metal Surfaces

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.811.186 ◽

2013 ◽

Vol 811 ◽

pp. 186-191

Author(s):

J.C. Juarez-Morales ◽

Ma. Lourdes Granados-Marin

Keyword(s):

Refractive Index ◽

Metal Surface ◽

Surface Plasmon ◽

Effective Refractive Index ◽

Optical Field ◽

Small Perturbations ◽

Surface Optical ◽

The Stability ◽

Surface Fields ◽

Plasmon Modes

Associating a perturbation term for the effective refractive index which may depend ontime or position we describe the extremal features for the surface plasmon fields propagating on aroughness metal surface. This representation allows us to interpret the surface optical field as ageodesic flow which in principle enables us to associate coherence features to plasmon modes andto analyze the stability of the surface fields under small perturbations of the refractive index.

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