Characterising the sedimentation of bidisperse colloidal silica using analytical centrifugation

Chen, Hangyu; Jia, Xiaodong; Fairweather, Michael; Hunter, Timothy N.

doi:10.1016/j.apt.2023.103950

Cited by 3 publications

(7 citation statements)

References 59 publications

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“…Weak gel behavior can greatly slow down (several days) particle sedimentation. This time will depend on several factors such as particle size, dispersity, density in accordance with the Stockes law [ 49 ].…”

Section: Resultsmentioning

confidence: 99%

Exopolysaccharide from marine microalgae belonging to the Glossomastix genus: fragile gel behavior and suspension stability

Dulong,

Rihouey,

Gaignard

et al. 2023

Bioengineered

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With the aim to find new polysaccharides of rheological interest with innovated properties, rhamnofucans produced as exopolysaccharides (EPS) in a photobioreactor (PBR) and an airlift bioreactor (ABR) by the marine microalgae Glossomastix sp. RCC3707 and RCC3688 were fully studied. Chemical characterizations have been conducted (UHPLC – MS HR). Analyses by size-exclusion chromatography (SEC) coupled online with a multiangle light scattering detector (MALS) and a differential refractive index detector showed the presence of large structures with molar masses higher than 10 6 g.mol −1 . The rheological studies of these EPS solutions, conducted at different concentrations and salinities, have evidenced interesting and rare behavior characteristic of weak and fragile hydrogels i.e. gel behavior with very low elastic moduli (between 10 −2 and 10 Pa) and yield stresses (between 10 −2 and 2 Pa) according to the EPS source, concentration, and salinity. These results were confirmed by diffusing wave spectroscopy. Finally, as one of potential application, solutions of EPS from Glossomastix sp. have evidenced very good properties as anti-settling stabilizers, using microcrystalline cellulose particles as model, studied by multiple light scattering (MLS) with utilization in cosmetic or food industry. Compared to alginate solution with same viscosity for which sedimentation is observed over few hours, microalgae EPS leads to a stable suspension over few days.

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Section: Resultsmentioning

confidence: 99%

Exopolysaccharide from marine microalgae belonging to the Glossomastix genus: fragile gel behavior and suspension stability

Dulong,

Rihouey,

Gaignard

et al. 2023

Bioengineered

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“…It is noted that the reason that / 0 ¼ 0.03 was chosen as the highest total volume fraction simulated was due to the experimental limitations of the LUMiSizer in measuring bidisperse systems at greater concentrations, as discussed in a previous publication by the current authors. 44 Above this concentration, the transmitted light was totally extinguished in either particle zone, making it impossible to detect an interface between the faster and slower settling species. In contrast, the proposed model would be able to simulate any concentration below the effective maximum packing fraction.…”

Section: B Simulations Under Centrifugal Conditions For Both Particle...mentioning

confidence: 99%

“…The colloidal silicas used were Angstrom Sphere V R silica powder, with nominal quoted mean sizes of 100, 500, and 800 nm (Fiber Optic Center, Inc., USA). The particles were initially characterized with SEM to confirm that their sizes were close to the manufacturer's estimates, as used in the modeling (see the previous paper by the current authors 44 ). The particle densities (q p ) were measured as 2.20 g/cm 3 for 100 nm silica particles and 1.92 g/cm 3 for 500 and 800 nm particles, using a Pycnomatic ATC gas pycnometer (Thermo Electron, USA).…”

Section: A Materialsmentioning

confidence: 99%

“…For a complete description of the technique, please refer to a previous publication by the current authors. 44 To verify the sedimentation under Earth gravity conditions, a Turbiscan V R (Formulation, France) Earth gravity optical analyzer was used. Here, 500:800 nm particle dispersions were placed in 20 ml sedimentation cells.…”

Section: B Experimental Sedimentation Testsmentioning

confidence: 99%

“…Previous experimental studies of the same systems indicated that high centrifugal speeds of >3000 rpm are required to gain representative data with low noise levels, due to the additional Brownian motion of the smaller 100 nm particles. 44 One of the resulting limitations of such high centrifuge speeds is the large disparity in timescale of the two species, due to the greater size ratio. Indeed, here the larger 500 nm particles in suspension settled within just 77 s, while the smaller 100 nm particles settled in a similar time to the smaller particles in the 500:800 simulations (approximately 1000 s).…”

Section: B Simulations Under Centrifugal Conditions For Both Particle...mentioning

confidence: 99%

See 2 more Smart Citations

Simulation of bidisperse colloidal centrifugal sedimentation using a mixture viscosity model

Chen,

Sykes,

Kivan

et al. 2023

Physics of Fluids

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Understanding the sedimentation behavior of bidisperse colloidal suspensions is critical in determining their stability and separation. While centrifugation is often used to accelerate separation, the settling of bidisperse colloids and their phase separation under these conditions is complex and difficult to predict explicitly. As an alternative, this work proposes a one-dimensional advection-diffusion model that uses an effective maximum volume fraction with a bidisperse viscosity scheme, which reflects important characteristics of bidisperse sedimentation while remaining computationally efficient. The influence of Derjaguin–Landau–Verwey–Overbeek interactions on packing fraction and dispersion viscosity is also considered. A numerical implementation is described using an adaptive finite-difference solver, which can be used for concentration profile and settling rate prediction of both species under variable acceleration. Validation experiments with silica suspensions in two size ratios (500:800 and 100:500 nm) and various total concentrations are performed using an analytical centrifuge, with results also being compared to Richardson–Zaki empirical predictions. The model is shown to be a very good fit to the data for both size ratio dispersions at three mixing ratios, with differences <10%. Slightly higher levels of variation were detected for the 500:800 nm system, owing to the smaller size ratio and resulting greater effect of uncounted secondary hydrodynamic factors, which enables the limits of the mixture viscosity model to be established. Nevertheless, this work highlights that mixture viscosity modeling combined with effective maximum volume fraction modifications can provide critical insights into the effect of bidisperse suspension dynamics on separation efficiencies.

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Hindered settling of a log-normally distributed Stokesian suspension

Li,

Botto

2024

J. Fluid Mech.

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Settling velocity statistics for dilute, non-Brownian homogeneous suspensions of polydisperse spheres having a log-normal size distribution are generated from Stokesian dynamics simulations, as a function of the total volume fraction $\phi$ and normalised width $\alpha$ of the particle size distribution. Several hundred instantaneous configurations are averaged to obtain reliable statistics. The paper reports data for the average and fluctuating settling velocity of each particle class in a suspension that is widely polydisperse – previous work was limited to only two or three classes, and the average settling velocity of each particle class was in most cases not reported – and provides an assessment of the accuracy of the analytical models proposed by Batchelor, Richardson & Zaki, Davis & Gecol and Masliyah–Lockett–Bassoon in predicting the simulation data. A limited comparison with dynamic simulations in which the particle microstructure is allowed to evolve in time is also included.

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Characterising the sedimentation of bidisperse colloidal silica using analytical centrifugation

Cited by 3 publications

References 59 publications

Exopolysaccharide from marine microalgae belonging to the Glossomastix genus: fragile gel behavior and suspension stability

Exopolysaccharide from marine microalgae belonging to the Glossomastix genus: fragile gel behavior and suspension stability

Simulation of bidisperse colloidal centrifugal sedimentation using a mixture viscosity model

Hindered settling of a log-normally distributed Stokesian suspension

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