Papers by Keyword: Zeta Potential

Abstract: The objective of this study is to improve the particle suspension stability of drinking water treatment sludge (DWTS) and comparable to other silicate powder which are bentonite, micro silica (micro-SiO₂), and nano-silica (nano-SiO₂). The main dispersion characteristic are related to particle size, and dispersion force. The representative samples of bentonite, micro-SiO₂, nano-SiO₂, and DWTS were dispersed at the same solid content in water. The particle size distribution and chemical composition of samples were analyzed. The suspended samples were measured for Zeta potential at the controlled pH value. Furthermore, turbidity of suspended samples were investigated at various sedimenting time. The results indicated that nano-SiO₂ has the highest Zeta potential value at pH 8-12. The stability of particle dispersion could be implied from turbidity of suspension at various sedimenting time. Bentonite suspension performed more stability than other samples for longer time. However, stability of DWTS particles can be improved by particle size controlling and treatment with dispersion agent to create repulsive force from the charge on the particle surface.

Abstract: Electrophoretic deposition (EPD) with controlled gas evolution by electrolysis was used for producing ceramic green bodies with unidirectional pore channels. The method was applied to alumina, alumina-toughened zirconia, and mullite. It requires stable aqueous suspensions with sufficiently high particle charge for the electrophoresis and appropriate amounts of electrolyte for the gas bubble formation. An anionic polyelectrolyte and ammonia were shown to be a suitable additive combination for all three oxide powders. The amount of polyelectrolyte was chosen for each of the powders on the basis of electroacoustic measurements of the zeta potential. The addition of ammonia solution was necessary in order to obtain the desired porous structures.

Abstract: We found non-ionic polymer containing ester and sulfonyl group, poly (ester-sulfone), showed anode-selective electrophoresis under the electrophoretic deposition (EPD) condition. In this paper we investigated an electrophoretic behavior of vinyl porymer having sulfonyl group in the side chains and compared with the main chain type of poly (ester-sulfone). Herein, we synthesized new poly (methacrylate) containing pendent sulfone to investigate the electrophoretic behavior.

Abstract: A novel technique that makes use of electrophoretic deposition (EPD) in upgrading the quality of Philippine clay, specifically for smectite recovery, was explored in this study. Focus was given on understanding the electrophoretic behavior of smectite and kaolinite to effectively control colloidal stability during EPD. Zeta potential measurements showed that pH has negligible effect on the electrophoretic mobility of smectite, but has an appreciable effect on the mobility of kaolinite with the isoelectric point (IEP) of kaolinite recorded around pH 5. Knowing this behavior, EPD of a 3.5wt% smectite-kaolinite slurry was carried out at pH 5 and pH 10. Separation of clay minerals was expected only at pH 5 where kaolinite is almost immobile. However, analysis of deposits using XRD showed some degree of separation (~60% smectite recovery) for both pH values when EPD was performed using stainless steel electrodes at a specific applied voltage and electrode gap, for twenty minutes, without stirring. Further investigation of EPD design is needed to improve smectite recovery.

Abstract: Tape casting process was used to produce Al₂O₃ substrates in an aqueous system with acrylic latex emulsion as binder. The present work studied the slurry formulations in aqueous medium of Al₂O₃ powders with different particle size distribution and made correlation to the green and sintered tapes. Two commercial alumina powders, one sub-micrometric and other micrometric were used. Compositions of Al₂O₃ slurries with 80 and 83 wt% of solids were prepared by dispersing the powders in water with a dispersant with subsequently additions of 7 and 10 wt% of binder. Sub-micrometric Al₂O₃ resulted in a high densification tapes regardless solid concentration and binder amount in the slurry, though green density was affected. For micrometric alumina, increasing the solid concentration resulted in a little higher final density.

Abstract: A multi-scale method was developed, which utilized intrinsic relationships among zeta potential of particles, rheological properties of suspensions and particle size distribution (PSD), to analyze dispersion behavior of nanoparticles in concentrated suspensions. It was found that PSD of a kind of nanoceria particles by dynamic light scattering (DLS) method in solution A with concentration 5 wt% accorded well with that by direct TEM analysis, which meant the particles had been dispersed well. However, there had a significant difference when the concentration was increased to 20 wt%. When particles concentration increased from 5 wt% to 20 wt%, zeta potential in solution A changed from-150 mV to-100 mV, while zeta potential in solution B changed from-35mV to-45 mV. Variations of zeta potential of particles accorded well with rheological properties of suspensions too, from phenomenological models. When the suspensions composed by solution A and the nanoparticles with concentration about 20 wt% was diluted with its original solution to 5 wt%, the PSD of nanoceria could be measured indirectly, which accorded well with both that of a suspension prepared directly with near concentration and that from TEM images. Then a method to measure PSD of nanoparticles in concentrated suspension was brought forward.

Abstract: In this study, the variation of Zeta potentials and distribution of molecular weight in Extracellular Polymeric Substances (EPS) and soluble microbial products (SMP) were investigated. It is indicated that the salinity is effect on Zeta potentials significantly. When the salinity increased from 0 g/L to 35 g/L, the Zeta potentials decreased gradually. The average molecular weight is mainly over 30 KDa in EPS and SMP at 0 g/L salinity, and is mainly below 10 KDa at 10 g/L and 35 g/L salinity. This result is evident that the variation of molecular weight is contributed to high salinity.

Abstract: The purpose of this study is to understand the electrophoresis of Titanium dioxide (TiO₂) nanoparticles on ceramic membrane. The ceramic substrate was prepared using commercial ceramic filter. The effect of different types of solvent used for suspension was studied. Then, the solvent that give optimum formulation for deposited microstructure on ceramic electrode from the first stage experiment is used to study the effect of concentration on the deposition behavior of TiO₂ nanoparticles during EPD technique. All the TiO₂ suspension were had been characterized using Zetasizer nanoseries. The EPD was performed at 20 V DC field for 10 minutes. The deposited of TiO₂ from both stage of experiment were then analyzed using ESEM. The suspension in organic solvent was found to obtain more deposited particles on ceramic membrane compared to water-based suspension. While, the concentration with 0.5 wt % TiO₂ nanoparticles with zeta potential 53.6 mV was found to get smaller size and uniform microstructure. The adhesion of the TiO₂ deposited layer from entire of the result on the ceramic electrode was fairly good.

Abstract: Article is devoted to studying of influence of additives on rheology of the nanostructured modifier on the basis of silica-containing raw materials. Optimum technological combinations of the plasticizer were defined, which allow to change flow character of a suspension and to give to a material necessary properties. Basic possibility to use additives on a melamine-formaldehyde basis for plasticization of the nanostructured modifiers of silicate structure is proved.

Abstract: The influence of urinary macromolecule chondroitin sulfate A (C₄S) on Zeta potential, aggregation and sedimentation of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) nanocrystallites with a diameter of about 50 nm were investigated using nanoparticle size Zeta potential analyzer and transmission electron microscope. C₄S could increase the absolute value of Zeta potential on surface of nanoCOM and nanoCOD crystallites by adsorbing on crystal surface, it led an increase of the electrostatic repulsion force between the crystallites, so the aggregation and sedimentation of these crystallites were inhibited, and the stability of the suspension of nanoCOM and nanoCOD was improved. In conclusion, C₄S could inhibit the formation of CaOxa stones。