Stability of a Binary Colloidal Suspension and its effect on Colloidal Processing

1989 ◽  
Vol 155 ◽  
Author(s):  
Wan V. Shih ◽  
Wei-Heng Shih ◽  
Jun Liu ◽  
Ilhan A. Aksay
Keyword(s):  
Particle Size ◽  
Hard Sphere ◽  
Colloidal Particles ◽  
Colloidal Suspension ◽  
Fluid Phase ◽  
Ceramic Processing ◽  
Colloidal Processing ◽  
Interparticle Interactions ◽  
The Stability ◽  
Binary Suspension

The stability of a colloidal suspension plays an important role in colloidal processing of materials. The stability of the colloidal fluid phase is especially vital in achieving high green densities. By colloidal fluid phase, we refer to a phase in which colloidal particles are well separated and free to move about by Brownian motion, By controlling parameters such as pH, salt concentration, and surfactants, one can achieve high packing (green) densities in the repulsive regime where the suspension is well dispersed as a colloidal fluid, and low green densities in the attractive regime where the suspensions are flocculated [1,2]. While there is increasing interest in using bimodal suspensions to improve green densities, neither the stability of a binary suspension as a colloidal fluid nor the stability effects on the green densities have been studied in depth as yet. Traditionally, the effect of using bimodal-particle-size distribution has only been considered in terms of geometrical packing developed by Furnas and others [3,4]. This model is a simple packing concept and is used and useful for hard sphere-like repulsive interparticle interactions. With the advances in powder technology, smaller and smaller particles are available for ceramic processing. Thus, the traditional consideration of geometrial packing for the green densities of bimodal suspensions may not be enough. The interaction between particles must be taken into account.

Green Synthesis of Platinum-encapsulated Nickel Nanocatalyst and Its Microstructure Evaluation

2009 ◽  
Vol 1213 ◽  
Author(s):  
Iliana Medina-Ramirez ◽  
Xu-Bin Pan ◽  
Sajid Bashir ◽  
Jingbo Louise Liu
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Particle Size Distribution ◽  
Colloidal Suspension ◽  
Cost Effective ◽  
X Ray ◽  
Microstructure Evaluation ◽  
Transmission Electron ◽  
Colloidal Method ◽  
The Stability

AbstractPlatinum (Pt) is the most efficient and highly utilized electrocatalsyt; however its high cost hinders its widespread use as a stand-alone catalyst. To remedy this problem, a nickel (Ni) encapsulated by Pt (NiⓔPt) nanocatalyst was fabricated using a cost-effective green colloidal method. The NiⓔPt nanoparticles (NPs) were then characterized using transmission electron microscope (TEM) equipped with X-ray energy dispersive spectroscopy (EDS), and X-ray powder diffraction (XRD) to determine the particle size distribution, morphology, elemental composition, and crystalline phase structure. The surface energetic was also measured using ZetaPALS™ to identify the stability of the colloidal suspension.

Morphological instability in freezing colloidal suspensions

2006 ◽  
Vol 463 (2079) ◽  
pp. 723-733 ◽  
Author(s):  
Stephen S.L Peppin ◽  
M. Grae Worster ◽  
J.S Wettlaufer
Keyword(s):  
Stability Analysis ◽  
Hard Sphere ◽  
Colloidal Suspension ◽  
Colloidal Suspensions ◽  
Unidirectional Solidification ◽  
Constitutional Supercooling ◽  
Interfacial Stability ◽  
Colloidal Systems ◽  
Morphological Instability ◽  
The Stability

We present a linear stability analysis of a planar ice interface during unidirectional solidification of a hard-sphere colloidal suspension. We find that the interface can become unstable due to constitutional supercooling, yielding a new mechanism for pattern formation in colloidal systems. The interfacial stability is shown to depend strongly on the size and concentration of the particles. Increasing the particle radius tends to stabilize the interface, while increasing the concentration has a destabilizing effect. Additional effects that may influence the stability and morphology of such a system are described.

The effects of interparticle interactions and particle size on reversible shear thickening: Hard-sphere colloidal dispersions

2001 ◽  
Vol 45 (5) ◽  
pp. 1205-1222 ◽  
Author(s):  
Brent J. Maranzano ◽  
Norman J. Wagner
Keyword(s):  
Particle Size ◽  
Hard Sphere ◽  
Shear Thickening ◽  
Colloidal Dispersions ◽  
Interparticle Interactions

scholarly journals Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1141
Author(s):  
Georgia Basina ◽  
Hafsa Khurshid ◽  
Nikolaos Tzitzios ◽  
George Hadjipanayis ◽  
Vasileios Tzitzios
Keyword(s):  
Room Temperature ◽  
Colloidal Particles ◽  
Iron Pentacarbonyl ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
Organometallic Synthesis ◽  
X Ray ◽  
Transmission Electron ◽  
Hot Injection ◽  
The Stability

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent.

scholarly journals EFFECT OF NONCLASSICAL POLARIZATION OF Na+ AND K+ ON THE STABILITY OF SOIL COLLOIDAL PARTICLES IN SUSPENSION

2017 ◽  
Vol 24 (07) ◽  
pp. 1850019
Author(s):  
DING WU-QUAN ◽  
HE JIA-HONG ◽  
WANG LEI ◽  
LIU XIN-MIN ◽  
LI HANG
Keyword(s):  
Negative Pressure ◽  
Colloidal Particles ◽  
Ion Concentration ◽  
Electrostatic Repulsion ◽  
Adjacent Soil ◽  
Net Pressure ◽  
The Stability ◽  
Two Stages ◽  
Soil Colloids ◽  
Total Average

The study of soil colloids is essential because the stability of soil colloidal particles are important processes of interest to researchers in environmental fields. The strong nonclassical polarization of the adsorbed cations (Na[Formula: see text] and K[Formula: see text] decreased the electric field and the electrostatic repulsion between adjacent colloidal particles. The decrease of the absolute values of surface potential was greater for K[Formula: see text] than for Na[Formula: see text]. The lower the concentration of Na[Formula: see text] and K[Formula: see text] in soil colloids, the greater the electrostatic repulsion between adjacent colloidal particles. The net pressure and the electrostatic repulsion was greater for Na[Formula: see text] than for K[Formula: see text] at the same ion concentration. For K[Formula: see text] and Na[Formula: see text] concentrations higher than 50[Formula: see text]mmol L[Formula: see text] or 100 mmol L[Formula: see text], there was a net negative (or attractive) pressure between two adjacent soil particles. The increasing total average aggregation (TAA) rate of soil colloids with increasing Na[Formula: see text] and K[Formula: see text] concentrations exhibited two stages: the growth rates of TAA increased rapidly at first and then increased slowly and eventually almost negligibly. The critical coagulation concentrations of soil colloids in Na[Formula: see text] and K[Formula: see text] were 91.6[Formula: see text]mmol L[Formula: see text] and 47.8[Formula: see text]mmol L[Formula: see text], respectively, and these were similar to the concentrations at the net negative pressure.

Fluid–fluid phase equilibria in disordered porous media. Nonadditive hard sphere mixture

2001 ◽  
Vol 280 (3) ◽  
pp. 146-152 ◽  
Author(s):  
Oscar Sierra ◽  
Yurko Duda
Keyword(s):  
Porous Media ◽  
Phase Equilibria ◽  
Hard Sphere ◽  
Fluid Phase ◽  
Fluid Phase Equilibria ◽  
Disordered Porous Media

scholarly journals Nanomaterials and nanotechnology for the delivery of agrochemicals: strategies towards sustainable agriculture

2022 ◽  
Vol 20 (1) ◽  
Author(s):  
Changcheng An ◽  
Changjiao Sun ◽  
Ningjun Li ◽  
Bingna Huang ◽  
Jiajun Jiang ◽  
...  
Keyword(s):  
Particle Size ◽  
Food Security ◽  
Chemical Composition ◽  
Labor Cost ◽  
Small Particle Size ◽  
Agricultural Systems ◽  
The Stability ◽  
New Applications ◽  
Chemical Pesticides ◽  
Improve Food Security

AbstractNanomaterials (NMs) have received considerable attention in the field of agrochemicals due to their special properties, such as small particle size, surface structure, solubility and chemical composition. The application of NMs and nanotechnology in agrochemicals dramatically overcomes the defects of conventional agrochemicals, including low bioavailability, easy photolysis, and organic solvent pollution, etc. In this review, we describe advances in the application of NMs in chemical pesticides and fertilizers, which are the two earliest and most researched areas of NMs in agrochemicals. Besides, this article concerns with the new applications of NMs in other agrochemicals, such as bio-pesticides, nucleic acid pesticides, plant growth regulators (PGRs), and pheromone. We also discuss challenges and the industrialization trend of NMs in the field of agrochemicals. Constructing nano-agrochemical delivery system via NMs and nanotechnology facilitates the improvement of the stability and dispersion of active ingredients, promotes the precise delivery of agrochemicals, reduces residual pollution and decreases labor cost in different application scenarios, which is potential to maintain the sustainability of agricultural systems and improve food security by increasing the efficacy of agricultural inputs. Graphical Abstract

scholarly journals Modelling of dynamics of combustion of biomass in fluidized beds

2004 ◽  
Vol 8 (2) ◽  
pp. 107-126 ◽  
Author(s):  
Jaakko Saastamoinen
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Fuel Mixture ◽  
Linear Increase ◽  
Fuel Feed ◽  
New Process ◽  
Fuel Particles ◽  
The Stability ◽  
Fluidized Bed Boilers

New process concepts in energy production and biofuel, which are much more reactive than coal, call for better controllability of the combustion in circulating fluidized bed boilers. Simplified analysis describing the dynamics of combustion in fluidized bed and circulating fluidized bed boilers is presented. Simple formulas for the estimation of the responses of the burning rate and fuel inventory to changes in fuel feeding are presented. Different changes in the fuel feed, such as an impulse, step change, linear increase and cyclic variation are considered. The dynamics of the burning with a change in the feed rate depends on the fuel reactivity and particle size. The response of a fuel mixture with a wide particle size distribution can be found by summing up the effect of different fuel components and size fractions. Methods to extract reaction parameters form dynamic tests in laboratory scale reactors are discussed. The residence time of fuel particles in the bed and the resulting char inventory in the bed decrease with increasing fuel reactivity and differences between coal and biomass is studied. The char inventory affects the stability of combustion. The effect of char inventory and oscillations in the fuel feed on the oscillation of the flue gas oxygen concentration is studied by model calculation. A trend found by earlier measurements is explained by the model.

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