Papers by Keyword: Zeta Potential

Abstract: Eggshell membrane is an important bio-material to be used as a raw material in many industries i.e. nano-tissue engineering, drug delivery, cosmetic, and composite materials. The objective of this work was to study the physical, chemical, and thermal properties of eggshell membrane prepared and separated from the hen eggshell waste. Eggshell membrane has initial pH at 7.82 and zeta potential equal to -17.1 mV effect to the instability and begins to agglomerate particles. Furthermore, the physical properties (characteristic, microstructure, particle size, density, and color) and thermal properties (phase transformation and thermal reaction) of eggshell membrane also are reported here.

Abstract: While bioleaching is a proven technology for the efficient recovery of base metals from sulphide minerals, its sustenance is dependent on the continuous availability of ferric ion, Fe³⁺, in soluble form, in bioleach liquor. However, the solubility of ferric ion is low at higher pH thus resulting in the formation of various types of ferric ion precipitates, which decreases leaching efficiency by trapping the leached metals in solution through an adsorption. The effect of initial solution pH on the surface properties of ferric ion precipitates was investigated with a view to establish a relationship between operational pH and surface charge on precipitate and to relate this to the precipitates metal adsorption properties. Ferric ion precipitates recovered from a typical biooxidation process were characterized by XRD, SEM, PSD and zeta potential. Potassium-hydronium jarosite were the main phases identified by X-ray diffraction (XRD) analyses. The SEM results revealed that the precipitates had smooth surfaces with development of sharp edges on the precipitates formed at high pH. The precipitates formed at higher pH had less positive charge and scavenged more copper ions due to the high electrostatic attraction forces. The results from this study revealed that surface charge on a precipitate can give an indication of its metal adsorption capacity and that in order to prevent metal loss and improve extraction efficiency, solution conditions should be maintained such that the resulting precipitates have high positive surface charge to promote high electrostatic repulsion forces.

Abstract: In this work, Poly(Acrylic Acid) (PAA) was employed as nanoparticle stabilizer for TiO₂. Adsorption and encapsulation of nanoparticles in polyelectrolytes impart stability due to stearic and electrostatic effects. Crosslinking of the polymer through UV-Irradiation permanently encapsulates the metal as well as reinforces the polymer cage. The efficient pH and ratio of reactants were optimized then assessed through Dynamic Light Scattering (DLS) for particle size and Zeta Potential Measurements for stability in aqueous solutions. Results showed that among the various TiO₂/PAA ratios, the 1:3 ratio showed minimal changes on the size and Zeta Potential values even when exposed to various pH conditions. Meanwhile at pH 5, TiO₂ attained a positive surface charge, while PAA exists in its deprotonated form, thus maximizing the electrostatic interaction between the two materials. Analysis revealed that in that particular ratio and pH range, particles size and zeta-potential value of 61.79 nm and -36 mV were obtained respectively. Physical morphology of the nanocomposites was characterized through Scanning Electron Microscopy, showing agglomerates of small particles, resulting to larger particles. Further studies shall be done to utilize the potential of the polymer-coated nanoparticles in dry form.

Abstract: There are a lot of studies about colloidal stability of suspensions and emulsions containing clay minerals, but only few about illite containing clays. Due to increasing demand for eco cosmetics, research about the possibility to use natural colloidal particles (clay minerals) as stabilizers also increases. In this study illitic clays were used to investigate the stability of glycerol containing suspensions and safflower oil-in-water emulsions. Three types of clay samples were used – chemically untreated, after removal of carbonates and iron compounds. Viscosity and zeta potential of glycerol suspensions was determined. Samples with the highest viscosity were also the most stable. The removal of iron compounds significantly decreased the viscosity of suspensions and increased the zeta potential

Abstract: Water-based suspensions from commercial Tetragonal stabilized zirconia (3Y-TZP) were produced and characterized with different contents of solids and two different dispersants. According to zeta potential measurements, 3Y-TZP particles showed basic surface characteristics and IEP of around 9 when in aqueous media. The critical volume fraction of solids was about 79.6 wt%, which hindered the processing of more concentrated slurries. Rheological measurements confirmed that well dispersed slurries could be obtained with solid content as high as 79.6 wt.%. The results showed that Triton X-114 was an effective dispersant for preparing well stabilized 3Y-TZP suspensions for the layer-wise slurry deposition process.

Abstract: Recently the study on the convective heat transfer properties of the nanofluids has gained remarkable importance. Nanofluids are stable dispersions of nanoparticles into a base fluid. These are experimentally found to possess enhanced mechanical and heat transfer properties compared to the parent base fluid. Previous studies confirm that of all the nanofluids, the ones prepared using MWCNTs with distilled water as the base fluid produced a maximum enhancement in the thermal conductivity of the dispersant. This widens the potential scope of MWCNTs nanofluids as coolants in different applications. Despite its exceptional properties, preparation of a stable water based MWCNTs nanofluid often involves a tedious process because of their hindrance to disperse in organic solvents. Functionalization is the process of surface modification of CNTs to reduce their hydrophobicity thereby improving their dispersion effect in organic solvents. Functionalization by chemical treatment is the most effective method in maintaining the long term stability of the nanofluids, but these processes often involve treatment with strong chemicals which affects the size distribution and morphology of the carbon nanotubes. The current study investigates the stability and particle size distribution of MWCNTs nanofluids functionalized by different processes and reports the most effective process for functionalization of MWCNTs.

Abstract: Abstract: This paper use zeta potential test and dynamic viscosity test to research the influence of different factors such as pH value, mass fraction of solid phase and dispersant content on the liquidity of Al2O3 slurry. The test results show that, when the solid-phase mass fraction and particle size are given, the absolute value of zeta potential increases with the rise of pH value, raise at first then descrease with the adding of (NaPO3)6. This article analyzes the phenomena from a legal point of electric double layer effect. The results of liquidity test are consistent with zeta potential test. The optimum value of pH value, mass fraction of solid-phase and dispersant content are determined by formulation design. The study develop a Al2O3 slurry with high fluidity which has an important significant in slip casting process of Al2O3 ceramics.

Abstract: The adsorption of bacteria onto minerals is the premise for bioleaching and plays an important role in minerals oxidation. Understanding of the adsorption kinetics onto the surface will give information on the effectiveness of bioleaching. Three kinds of mixed bacteria (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, Sulfobacillus) were cultured in different substrates - copper concentrate, elemental sulfur and ferrous iron and adsorbed onto different solid surface of elemental sulfur, silica and copper concentrate. Adsorption kinetics was examined and surface properties were investigated by Zeta-potential and FT-IR spectroscopy. Bacterial adsorption equilibrium data for bacteria grown on three different substrates were well fitted to Freundlich isotherms, indicating inhomogeneous and selective adsorption. Microorganisms grown on copper concentrate and S⁰ showed similar adsorption kinetics whereby cell adsorptions proceeded rapidly and reached equilibrium within 30 mins of interaction. With the average K_F value of 46.2, most copper concentrate-grown cells were strongly adsorbed to three solid surfaces. Microorganisms grown on copper concentrate and S⁰ also showed higher hydrophobicity and higher isoelectric point (IEP) (pH 3.4-3.8) as compared to the soluble Fe²⁺-grown cells (pH 2.1), indicating higher amount of EPS and proteins on the surfaces. The FT-IR spectra indicated the presence of COOH, NH₂, OH and PO₄ groups on all cell surfaces. However, more proteinaceous compounds were found on cells grown on copper concentrate and S⁰ substrates.

Abstract: For a variety of applications the use of polymer modified cement mortar (PCM) or polymer modified cement concrete (PCC) is state of the art. It is a matter of common knowledge that interparticular interactions between the mineral and polymer components, more precisely the adsorption behaviour and film formation processes of polymer particles, cause a change of properties in comparison to a concrete without any modification. The affinity of polymer particles to mineral surfaces determines the adsorption behaviour significantly and thus the microstructure formation of the entire system, in which mineral and polymer phases penetrate one another. A quantitative prediction of cementitious surface preferred by non-ionic stabilized polymer particles to adsorb, was aspirated by titration experiments carried out with electroacoustic zeta potential measurements and turbidity measurements of polymer modified pastes carried out by spectrophotometry. Measuring the change of zeta potential of several cementitious components by a stepwise addition of polymer dispersions, do not require a variation of variables of the system. It can be measured without any treatment of the powdery raw materials or dissolution of the considered suspension. Equally the polymer dispersions were used in their original state. Spectrophotometric analyses were used to determine the concentration of polymer particles in the liquid phase of fresh polymer modified cement-paste or pastes of additives like quartz powder. The preparation of dilution series allowed the assessment of desorption behaviour as well as the prediction of the amount of adsorbed particles. Finally affinities of non-ionic stabilized polymer particles to several mineral surfaces in a state constituted, fresh paste could be described as a result of chemical induced repulsive or attractive forces and physical repressions, like the absence of sufficient space in liquid media for dispersed polymer particles. The central role of non-ionic stabilizers in adsorption processes was exposed especially by electroacoustic zeta potential measurements.

Abstract: Copper oxide (CuO) nanofluids are prepared by two step method. CuO nanoparticles are prepared by sol gel method with Copper chloride as precursor and NaOH as a reducing agent. The prepared CuO nanoparticles are characterized by XRD, SEM and Particle size analyzer. XRD measurements reveal a grain size of 72nm .SEM image reveals an inhomogenous mixture of particles from 500 nm to 3500 nm with irregular morphology and few traces of CuO cones.. The particle size distribution of CuO particles is in the range of 1000-1600nm which is in accordance with the SEM results.CuO –Ethylene Glycol nanofluids are prepared by two step method by ultrasonication of obtained CuO particles.The stability of CuO nanofluid is given with a negative zeta potential of-22.5 mv.