Investigation on the Sedimentation Behavior of the α-Al2O3 Aqueous Suspension by the Combination of Two Dispersants

2011 ◽  
Vol 474-476 ◽  
pp. 687-692
Author(s):  
Fei Zhou Li ◽  
Yu Qiang Han ◽  
Bian Guo
Keyword(s):  
Zeta Potential ◽  
Ph Value ◽  
Aqueous Suspension ◽  
Sintered Sample ◽  
Dispersion Effect ◽  
Arabic Gum ◽  
Stability Behavior ◽  
Sedimentation Behavior ◽  
Different Types ◽  
The Stability

The effect of three different types dispersants on the stability behavior of alumina aqueous suspension were investigated by through sedimentation experiment , Zeta potential ,and residual porosity of sintered sample. The results showed that the optimal content and optimal sedimentation pH value of the three different types dispersants were 1.0% and aging at pH9 for PAA-NH4, 0.8% and nearly independent of pH value for Arabic gum , 0.4, 0.2 and aging at pH9 for PAA-NH4 and Arabic gum，respectively. The dispersion effect of the three different type dispersants was PAA-NH4and Arabic gum> PAA-NH4 > Arabic gum. Studies have shown that the combination of PAA-NH4 and Arabic gum has a better effect than one of them on the stability of suspension. Compared with single dispersant, the sedimentation volumes of the two dispersants dispersing suspension is reduced 3%, the dosage of dispersants is reduced 26.7%.

scholarly journals Abundant distinct types of solutions for the nervous biological fractional FitzHugh–Nagumo equation via three different sorts of schemes

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Abdel-Haleem Abdel-Aty ◽  
Mostafa M. A. Khater ◽  
Dumitru Baleanu ◽  
E. M. Khalil ◽  
Jamel Bouslimi ◽  
...  
Keyword(s):  
Nervous System ◽  
Expansion Method ◽  
B Spline ◽  
Stability Behavior ◽  
Nerve Impulses ◽  
Dynamical Behaviors ◽  
Different Types ◽  
Nagumo Equation ◽  
The Stability

Abstract The dynamical attitude of the transmission for the nerve impulses of a nervous system, which is mathematically formulated by the Atangana–Baleanu (AB) time-fractional FitzHugh–Nagumo (FN) equation, is computationally and numerically investigated via two distinct schemes. These schemes are the improved Riccati expansion method and B-spline schemes. Additionally, the stability behavior of the analytical evaluated solutions is illustrated based on the characteristics of the Hamiltonian to explain the applicability of them in the model’s applications. Also, the physical and dynamical behaviors of the gained solutions are clarified by sketching them in three different types of plots. The practical side and power of applied methods are shown to explain their ability to use on many other nonlinear evaluation equations.

Study on Influence of Polyethylene Glycol on Dispersion of Pyrite Powder in Aqueous Solution

2012 ◽  
Vol 554-556 ◽  
pp. 349-352
Author(s):  
Dan Li ◽  
Zhou Lan Yin ◽  
Qi Yuan Chen
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonding ◽  
Polyethylene Glycol ◽  
Spectroscopic Analysis ◽  
Ph Value ◽  
Aqueous Suspension ◽  
Dispersion Stability ◽  
The Stability ◽  
High Degree ◽  
Effective Additive

The influences of three kinds of polyethylene glycol (PEG), namely PEG-200, PEG-1000 and PEG-20000, on the dispersion stability of pyrite powder in aqueous solution were investigated by spectrophotometry. The results indicated that the stability of pyrite powder dispersed in aqueous solution was remarkably dependent upon the molecular weight and content of PEG, pH value of suspension, and ultrasonication power. Among three kinds of polyethylene glycol, PEG-20000 was the most effective additive to improve the dispersion stability and wettability of pyrite powder in water. When 8% PEG-20000 was employed as the dispersant, the best dispersion stability of pyrite powder in aqueous solution could be obtained under the conditions of pH at 5-6 and 100-W ultrasonication power. The FTIR spectroscopic analysis showed that the adsorption between the polyethylene glycol and pyrite ore powder was formed by hydrogen bonding. The adsorption of polyethylene glycol onto the surface of pyrite powder via hydrogen bonding provided a high degree of steric stabilization, which effectively prohibited the aggregation of pyrite powder, and thus the dispersion stability of as-formed aqueous suspension was promoted.

Effect of Finite Thickness Flexible Boundary Upon the Stability of a Poiseuille Flow

1990 ◽  
Vol 57 (4) ◽  
pp. 1056-1060 ◽  
Author(s):  
Mauro Pierucci ◽  
Pedro G. Morales
Keyword(s):  
Poiseuille Flow ◽  
Finite Thickness ◽  
Stress Distributions ◽  
Stability Equation ◽  
Stability Behavior ◽  
Different Types ◽  
Improved Stability ◽  
Numerical Instabilities ◽  
The Stability ◽  
Sommerfeld Equation

The stability behavior, the stress, and velocity distributions for a plane Poiseuille flow bounded by a finite thickness elastic layer is studied. The analysis is performed by utilizing the coupled relationships between the Orr-Sommerfeld stability equation for the fluid and the Navier equations for the solid. The numerical instabilities experienced in the solution of the Orr-Sommerfeld equation have been overcome with the use of Davey’s orthonormalization technique. This study focuses only on the Tollimen-Schlichting instabilities. This mode is the most unstable of the three different types of instabilities. The results show that certain combinations of parameters can lead to improved stability conditions. Under these conditions the normal and shear stress distributions may behave completely different in certain regions of the fluid.

Selection of Polyanions as Complexation Agent in the Formation of Nanochitosan by Polyelectrolyte Complex Method

2019 ◽  
Vol 948 ◽  
pp. 140-145
Author(s):  
Al Dina N. Khoerunisa ◽  
Prihati Sih Nugraheni ◽  
Mohammad Fahrurrozi ◽  
Wiratni Budhijanto
Keyword(s):  
Particle Size ◽  
Polyelectrolyte Complex ◽  
Ph Value ◽  
Average Particle Size ◽  
Aqueous Dispersion ◽  
Complex Method ◽  
Average Particle ◽  
Arabic Gum ◽  
Mixing Ratios ◽  
The Stability

The aqueous dispersion of nanochitosan was prepared by polyelectrolyte complex (PEC) method with various mixing ratios of chitosan and polyanions, i.e., chitosan-glucomannan, chitosan-hyaluronic acid, and chitosan-Arabic gum. The formation of nanochitosan was carried out by adding the polyanion solution dropwise into the acid solution of chitosan. The study aimed to determine the best polyanion among the variations tested in this study, concerning the targeted particle size and the stability of the dispersion over time. Particle size distribution was observed by Particle Size Analyzer (PSA). The result indicated that Arabic gum gave the smallest average particle size, i.e. 192.5 nm, at a chitosan/polyanion mass ratio of 3:1 and pH value of 4.

Stability of nano-sized titanium dioxide in an aqueous environment: effects of pH, dissolved organic matter and divalent cations

2013 ◽  
Vol 68 (2) ◽  
pp. 276-282 ◽  
Author(s):  
X. N. Yang ◽  
F. Y. Cui
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Organic Matter ◽  
Zeta Potential ◽  
Dissolved Organic Matter ◽  
Ph Value ◽  
Divalent Cations ◽  
Aqueous Environment ◽  
Nano Tio2 ◽  
The Stability

Nano-sized titanium dioxide in the aquatic environment has a potential impact on the environment and human health. In this study, the impact of pH value, dissolved organic matter (DOM) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles (nano-TiO2) in an aqueous environment was investigated in batch tests. The results showed that the particle size of nano-TiO2 was not sensitive to pH value but was inversely proportional to zeta potential. The nano-TiO2 becomes more stable with surface zeta potential, accompanied by small particle size and high dispersion. In the presence of DOM, the particle size was smaller and the stability of nano-TiO2 could be enhanced. This might be a synergistic effect of the ligand exchange and electrostatic force. Particle size increased with the addition of Ca2+ and the stability decreased.

Stability Analysis of Nano-Sized Titanium Dioxide in Aqueous Environment

2011 ◽  
Vol 374-377 ◽  
pp. 869-874 ◽  
Author(s):  
Xiao Nan Yang ◽  
Fu Yi Cui ◽  
Xiao Ying Mu ◽  
Zhi Wei Zhao
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Zeta Potential ◽  
Ph Value ◽  
Electrostatic Force ◽  
High Dispersion ◽  
Aqueous Environment ◽  
Tio2 Nps ◽  
The Stability ◽  
The Impact

Nano-sized titanium dioxide in aquatic environment poses potential impact on environment and human health. In this research, the impact of pH value, humic acid (HA) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles(NPs) in the aqueous enviorment was investigated using a batch test. The results showed that the particle size of TiO2 NPs was not sensitive to the pH value but presented inversely proportional to zeta potential. The TiO2 NPs become more stable along with surface zeta potential, accompany with small particle size and high dispersion. In the presence of HA, the particle size was smaller and TiO2 NPs could be stabilized. This might be synergistic effect of the ligand exchange and electrostatic force. Meanwhile, NPs particle size increased with the addition of Ca2+ and the stability of TiO2 NPs became decreased.

Impact of Humic Acid on the Charge Behavior and Coagulation of TiO2 Nanoparticles Suspension

2013 ◽  
Vol 726-731 ◽  
pp. 2384-2388 ◽  
Author(s):  
Feng Gong ◽  
Li Zhu Zhang ◽  
Li Wang
Keyword(s):  
Humic Acid ◽  
Zeta Potential ◽  
Removal Efficiency ◽  
Ph Value ◽  
Fate And Transport ◽  
High Concentration ◽  
Water Treatment Process ◽  
The Stability ◽  
The Impact ◽  
Nanoparticles Suspension

In order to understanding of the fate and transport of TiO2 nanoparticles (Nps) in the water treatment process, this study focused on the impact of humic acid (HA) on the aggregation and charge behavior of TiO2 Nps, and investigated the removability of TiO2 Nps stabilized by HA during the coagulation process. Malvern Zetasizer nanoZS measured the changes of size and zeta potential of HA capped TiO2 Nps (HA-TiO2). Uv-vis spectrometer examined the aggregation behavior of TiO2 and HA-TiO2 NPs at different pH value. Jar tests were conducted to evaluate the removal efficiency of TiO2 NPs. HA adsorbed on the surface of TiO2 Nps could decrease the zeta potential values and enhance the stability of TiO2 Nps. TiO2 Nps could be effectively removed by aluminum sulfate (AS) under favorable condition. HA could influence the removal of TiO2 Nps during the coagulation processes. Low concentration of HA rejected the removal efficiency of TiO2 Nps, however, high concentration of HA promoted removing effectiveness.

scholarly journals Microencapsulation Preservation of the Stability and Efficacy of Citrus Grandis Oil-Based Repellent Formulation against Aedes aegypti during Storage

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3599
Author(s):  
Norashiqin Misni ◽  
Zurainee Mohamed Nor ◽  
Rohani Ahmad ◽  
Nur Raihana Ithnin ◽  
Ngah Zasmy Unyah
Keyword(s):  
Relative Humidity ◽  
Essential Oil ◽  
Zeta Potential ◽  
Aedes Aegypti ◽  
Essential Oils ◽  
Ph Value ◽  
Physical Stability ◽  
Storage Conditions ◽  
Mosquito Repellent ◽  
The Stability

Essential oils have been widely used as an active ingredient in mosquito repellent products. However, essential oils are highly unstable and prone to degradation when exposed to the environment during storage. Microencapsulation techniques help to maintain the stability of molecules in essential oils that are sensitive to environmental stress, and therefore improve shelf life. In this study, the physical stability and efficacy of a repellent formulation consisting of encapsulated Citrus grandis essential oil (CGEO) were evaluated under different storage conditions over a 12-month period by comparing the formulation with a non-encapsulated formulation. The formulations were both stored under two different storage conditions, i.e., 25 ± 2 °C/60% ± 5% relative humidity (RH) and 40 ± 2 °C/75% RH ± 5%, for 12 months. Droplet size, zeta potential, and pH value were measured after 1, 6, and 12 months of storage to determine their stability. For the study of efficacy, each formulation was tested against Aedes aegypti under laboratory conditions. We found that the microencapsulated formulation’s physical characteristics showed insignificant changes as compared with the non-encapsulated formulation during storage. The microencapsulated formulation demonstrated better repellent effects, sustaining high protection (>80%) for 4 more hours of exposure after 12 months of storage as compared with the non-encapsulated formulation that demonstrated high protection for only an hour post application. Microencapsulation helped to preserve the stability of the formulation, which resulted in high protection being maintained for over 12 months of storage.

Effects of pH and Dispersant Concentration on Properties of Li1.075Nb0.625Ti0.45O3 Aqueous Suspension

2011 ◽  
Vol 266 ◽  
pp. 26-29
Author(s):  
Shao Chun Li ◽  
Yong Juan Geng ◽  
Qi Long Zhang ◽  
Hui Yang
Keyword(s):  
Zeta Potential ◽  
Direct Relationship ◽  
Ph Value ◽  
Aqueous Suspension ◽  
Aqueous Media ◽  
Potential Measurement ◽  
Optimum Ph ◽  
Effects Of Ph ◽  
Rheological Test ◽  
Good Agreement

The dispersion behavior of the solid solution Li1.075Nb0.625Ti0.45O3 (LNT) in aqueous media was studied. Optimum dispersing conditions were investigated in terms of zeta potential, sedimentation, and rheology measurements. Zeta potential measurement showed that the isoelectric point (IEP) of the LNT particles was shifted from pH 3.7 to pH 2.6 after adsorption of PAA-NH4 and made the LNT surface more electronegative. Good agreement between zeta potential, sedimentation, and rheological test was found, which identified an optimum pH value of 10 and an optimum dispersant concentration of about 0.6 wt%. The green microstructures of the casting tapes bear a direct relationship to the state of dispersion of the slurries. The results showed that PAA-NH4 is a suitable dispersant for obtaining well-dispersed LNT slurries.

scholarly journals Adsorption of itaconic acid from aqueous solutions onto alumina

2008 ◽  
Vol 73 (8-9) ◽  
pp. 825-834 ◽  
Author(s):  
Jelena Gulicovski ◽  
Ljiljana Cerovic ◽  
Slobodan Milonjic ◽  
Ivanka Popovic
Keyword(s):  
Itaconic Acid ◽  
Ph Value ◽  
Point Of Zero Charge ◽  
Alumina Powder ◽  
Alumina Surface ◽  
Aqueous Processing ◽  
Degree Of Dissociation ◽  
Sedimentation Behavior ◽  
Acidic Alumina ◽  
The Stability

Itaconic acid, IA (C5H6O4), was investigated as a potential flocculant for the aqueous processing of alumina powders. The adsorption of IA, as a function of its concentration and pH value of the solution, onto the alumina surface was studied by the solution depletion method. The stability of the suspensions in the presence of itaconic acid was evaluated in light of the surface charge of the alumina powder used, the degree of dissociation of IA, as well as the sedimentation behavior and rheology of the suspensions. It was found that the adsorption process is extremely pH dependent; the maximum adsorption of IA onto alumina surface occurring at a pH close to the value of the first IA dissociation constant, pKa1. Also, IA does not influence the value of the point of zero charge of alumina. It was shown that IA represents an efficient flocculant for concentrated acidic alumina suspensions.

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