Stability of dispersions of colloidal alumina particles in aqueous suspensions

Singh, Bhupendra; Menchavez, Ruben L.; Takai, Chika; Fuji, Masayoshi; Takahashi, Minoru

doi:10.1016/j.jcis.2005.04.091

Cited by 179 publications

(89 citation statements)

References 9 publications

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“…It can be seen from Fig. 4 that as pH increases, the surface charge of the alum sludge, which is pH dependent [16], changes from positive to negative. This gives valuable information regarding the changing nature of the surface of the alum sludge.…”

Section: The Ph Dependence Of Adsorption Capacitymentioning

confidence: 95%

Characteristics and mechanisms of phosphate adsorption on dewatered alum sludge

Yang

Zhao

Babatunde

et al. 2006

Separation and Purification Technology

372

153

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The adsorption characteristics of phosphate adsorption on the dewatered alum sludge were identified as a function of pH and ion strengths in solution. In addition, adsorption mechanisms were investigated by conducting batch tests on both the hydrolysis and P-adsorption process of the alum sludge, and making a comparative analysis to gain newer insights into understanding the adsorption process. Results show that the adsorption capacity decreased from 3.5 to 0.7 mg-P/g-sludge when the solution pH was increased from 4.3 to 9.0, indicating that adsorption capacity is

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Section: The Ph Dependence Of Adsorption Capacitymentioning

confidence: 95%

Characteristics and mechanisms of phosphate adsorption on dewatered alum sludge

Yang

Zhao

Babatunde

et al. 2006

Separation and Purification Technology

372

153

View full text Add to dashboard Cite

show abstract

“…As can been seen from Table 1, there is a significant difference not only in the particle size, but also the zeta potential when comparing aged S-P3MEET (À50.5 ± 6.2 mV) and fresh S-P3MEET (À28.0 ± 9.2 mV). Since the magnitude of the zeta potential represents the electrostatic repulsion between particles [52], the increase in zeta potential value (more negative) results in increased physical stability of the dispersion. This explains why fresh S-P3MEET ages.…”

Section: Mechanism Of S-p3meet Agingmentioning

confidence: 99%

Solution aging and degradation of a transparent conducting polymer dispersion

Jacobs

Friedrich

et al. 2016

Organic Electronics

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a b s t r a c tAs organic electronics improve, there is increased research interest on the longevity and stability of both the device and individual material components. Most of these studies focus on post deposition degradation and aging of the film. In this article, we examine the stability of polyelectrolyte dispersions before film coating. We observe substantial differences in the solution properties of the transparent conducting polymer, S-P3MEET, when comparing fresh versus aged dispersions and relate these solution differences to film properties. The aged dispersion contains large agglomerates and exhibits a typical shear-thinning rheological behavior, which results in non-uniformity of the spin-coated films. Near edge X-ray absorption fine structure measurements were used to differentiate the changes in bonding and oxidation states and show that aged S-P3MEET is more highly self-doped than fresh S-P3MEET. We also show that addition of acid, salt or heat to fresh S-P3MEET can accelerate the degradation/aging process but are subjected to different mechanisms. Conductivity measurements of S-P3MEET films illustrate that there is a tradeoff between increased work function and decreased conductivity upon perfluorinated ionomer (PFI) loading. The formation of nanostructure in solution is also correlated to film morphology variations obtained from atomic force microscopy. We expect that dispersion aging is a process that commonly exists in most solution-dispersed polyelectrolyte materials and that the methodologies presented in this paper might be beneficial to future degradation/stability studies.

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“…On the other hand, the suspension at pH 3.5 rapidly initiated sedimentation, leaving a clear supernatant and reducing the dispersion volume ( Figure 6). The instability of this suspension can be attributed to the rapid agglomeration of the particles, thus resulting in a lower dispersion volume 14 . …”

Section: Zeta Potential and Rheological Behaviour Of The Suspensionsmentioning

confidence: 99%

“…The interaction of polyelectrolytes with alumina particles and factors such as pH, ionic strength of the medium and solids concentration interfere with the stability of the suspension 4,[12][13][14] . For this reason, the investigation of the rheological behaviour of alumina suspensions is essential in colloidal processing since rheological parameters directly influence the casting rate and quality of the formed bodies.…”

Section: Introductionmentioning

confidence: 99%

Humic Acid as Dispersant of an Alumina Suspension and its Rheological Behaviour

Souza

Bragança

2018

Mat. Res.

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Humic acid was extracted and employed as a dispersant in an alumina suspension. The higher zeta potential for HA (-42 mV) was measured at pH 11 showing that an electrostatic repulsion might occur in the alumina/HA suspension. As a consequence of the long chain molecules of HA it was also expected a steric effect on deflocculation. The best dispersion conditions for the alumina suspension (28 vol%) were found with 0.016 wt% HA, close to the viscosity achieved with a commercial sodium polyacrylate. The rheological characterisation showed results beneficial for the slip casting process, such as slightly thixotropy and pseudoplastic behaviour. The excellent colloidal stability at pH 11 as evidenced through rheological and sedimentation tests was attributed to the polyelectrolyte nature of the HA. From deflocculated suspensions it was possible to obtain high density pieces by slip casting method.

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Stability of dispersions of colloidal alumina particles in aqueous suspensions

Cited by 179 publications

References 9 publications

Characteristics and mechanisms of phosphate adsorption on dewatered alum sludge

Characteristics and mechanisms of phosphate adsorption on dewatered alum sludge

Solution aging and degradation of a transparent conducting polymer dispersion

Humic Acid as Dispersant of an Alumina Suspension and its Rheological Behaviour

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