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Content available remote Destabilization Of Model Wastewater In The Chemical Coagulation Process
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This paper discusses the results of laboratory analyses of the coagulation and flocculation of model wastewater. The investigated wastewater was susceptible to treatment by chemical coagulation. The effectiveness of two commercial coagulants, PAC produced at the DEMPOL-ECO Chemical Plant and PIX manufactured by KEMIPOL, was compared. A mathematical model relying on a second-degree polynomial was used to describe and analyze experimental data. In each case, the parabola minimum point was a precisely determined coagulant dose, regarded as the optimal dose. The application of a coagulant dose higher than the optimal dose reduced the effectiveness of wastewater treatment by coagulation. A detailed analysis of turbidity, suspended solids, total phosphorus and pollutant removal measured by the COD test revealed that PAC was a more effective and a more efficient coagulant than PIX. The risk of coagulant overdosing was greater with the use of PAC than PIX.
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This article describes influence of silanes with different functional group for zeta potential ceramic-high alumnium material. For modification of ceramic material's surfaces we have used five different siliconorganic compounds-silanes: Z-6020, MTMO, TRIAMO, VTMO and A-187. The zeta potential changes under action of silane modifiers of material surfaces were related to pH.
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Due to potential application of rhenium sulphide in medicine and industry, this study is focused on the properties of synthetic and commercial rhenium sulphide. The main reaction of rhenium sulphide preparation involves potassium perrhenate and sodium thiosulphate in the acidic environment giving a mixture of rhenium sulphide and sulphur. The next step is removing sulphur by its dissolution in ether. Stabilization by Povidone K-25 is needed to obtain rhenium sulphide dispersed with the grain size of 0.5–4 m. The extrapolated value of pHiep for synthesised rhenium sulphide is 2.3 whereas for commercial samples this value is lower than 2. For synthetic sample a dependence of zeta potential on the carrier electrolyte concentration is found. It is larger than that for the commercial sample, probably due to surface oxidation during synthesis or purification.
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Polyaniline (PAni) has been classified as an intractable polymer, particularly in its conducting form, the emeraldine salt (ES). Therefore one can consider the mixture of water and PAni as a suspension. The conducting form of PAni can be obtained by a doping process known as ,,acid doping'', in which a strong acid turns PAni from its insulating form, the emeraldine base (EB), into the conducting form, the emeraldine salt. With the objective of establishing a correlation between the doping level and the zeta potential of polyaniline dispersions, polyaniline +HCl aqueous suspensions were prepared. Positive zeta potential values for the various suspensions of PAni showed that it acquired positive charges after the doping process. It was also observed an increase in zeta potential values as HCl concentration increased, which could be correlated to UV-Vis spectra of PAni suspensions.
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The aim of this study was to transform commercially available poly(allylamine hydrochloride) (PAH) into hydrophobically modified strong polyelectrolytes. It was accomplished by reductive amination using hexanal or octanal followed by exhaustive methylation with methyl iodide leading to quaternary ammonium salts. Chemical structures of the obtained polycations and the degrees of substitution with hydrophobic chains were confirmed using spectroscopic methods and an elemental analysis. The structures formed by the modified polymers in aqueous solution were determined using zeta potential measurements, dynamic light scattering (DLS) technique and cryogenic transmission electron microscopy (cryo-TEM). The morphology of the polymer films deposited on a silicon surface was studied using atomic force microscopy (AFM). The microscopic observation confirmed the formation of polymeric micelles with sizes dependent on length of alkyl chains attached to the polycation backbone.
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One of the main problems for the natural stone industry is treatment of huge amount of waste sludge resulting from the cutting and polishing of them to produce slabs or tiles. The effective treatment of this sludge is very important for reducing of the sludge volume and overall operating costs. Previous studies showed that settling rate and water clarity of the supernatant solution can be increased by flocculation process. In this study, detailed electrokinetic studies were performed on the travertine samples received as natural and slurry form. The natural form of the sample was supplied from a travertine quarry while the slurry was taken from the cutting and polishing process wastewater collector pool of the processing plant. The electrokinetic measurements were conducted to find out the effect of suspension pH and the solid content on the surface potential of solid particles show that zeta potential (ζ) of travertine is positive at pH 9.76 over the all solid contents studied in this work. However, ζ of the particles become negative at lower pH values for 1% solid weight content. In contrast, for travertine slurry (6.73% solid weight), different potential variations were determined. The particles were negatively charged between pH 6 and 8. The results highlighted the effect of dissolved specific ions in the waste slurry and sensitivity of ζ to the ionic strength of the solution. The ζ measurements for a raw travertine sample, performed with different amounts of NaCl additions into the solutions, confirmed the above findings. An addition of low amounts of NaCl decreases ζ of the solid surface. Finally, the ζ measurements in the presence of polymer concentration of 0.001% to 0.1 % (wt/vol) clearly indicated that the flocculant molecules are adsorbed extensively on the travertine particles, and increase the surface potential of the particles with increasing reagent concentration.
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The paper presents an estimation of bentonites quality using electrokinetic phenomena occurring in dispersed clay systems. The idea behind the work is to demonstrate the relationship between the rheological parameters of the tested materials, and their zeta potential and consequently determine the suitability of these criteria for preparing drilling fluids.
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Content available remote Synthesis of silver nanoparticles using microorganisms
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Biosynthesis of silver nanoparticles using Penicillium fungi has been reported. The extracellular mechanism of silver nanoparticles creation was investigated by UV-Vis spectroscopy, electron microscopy and laser diffraction. The zeta potential of silver nanoparticles has also been determined.
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The paper presents the advantages of using zeta-potential to explore the surface of textile fabrics. Polyfunctional treatments of crease-resist finish and oil reppelence are studied. Experiments were accomplished according to a central factorial rotatable program with two independent variables. The physical and chemical modificatios inserted in textile structure after treatments were analysed by means of crease recovery angle, capacity of water absorption ofzeta potential. Based on regression equation obtained, one establishes the range of concentrations as "the best compromise" for treatment value of reagents.
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The paper presents the results of the electrodeposition of nickel composite coatings reinforced with the ceramic SiC particles. A Watts type galvanic bath modified with various organic additives was used. These additives were: 2-sulfobenzoic acid imide (LSA), dioctyl sulfosuccinate sodium salt (DSS), sodium dodecyl sulfate (SDS), tris (hydroxymethyl) aminomethane (THAM) and hexamethyldisilizane (HMDS). The nickel composite coating was electrodeposited on a 2xxx aluminum alloy series substrate (EN-AW 2017) with zinc interlayer. Studies concerned the effect of the applied organic additives on properties of composite coatings such as: microstructure, microhardness, adhesion to the substrate, corrosion resistance and roughness. The structure of the coatings was assessed by scanning electron microscopy and light microscopy. Based on the studies of zeta potential it was found that the bath modification had a significant impact on the amount of the ceramic phase embedded in metal matrix. The tests conducted in a model 0.01 M KCl solution were not fully representative of the true behavior of particles in a Watts bath.
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In this study, the flotation of naturally hydrophobic coal particles in salt solutions with different cations (Na+, Ca2+, and Al3+) was investigated to clarify the flotation enhancement mechanism. The surface chemistry aspects were examined using the zeta potential measurements and bubble-particle attachment time experiments. The results of the flotation experiments showed that the presence of electrolytes in the flotation system clearly enhanced the flotation performance in a manner dependent on the type and concentration of the electrolytes. In the experiments, the AlCl3 and NaCl solutions showed the highest and the lowest flotation performance improvements, respectively. The zeta potential measurements showed that AlCl3 had a stronger influence on the surface charge of coal particles than CaCl2 or NaCl did. The induction time measurements indicated that the attachment decreased with increasing salt concentration and ionic valency state. In addition, abundant fine bubbles were generated in higher concentration salt solutions, particularly for the AlCl3 solutions, which prevented from the bubble coalescence and increased froth stability. It is concluded that the addition of salt solutions to a flotation system enhances the coal flotation performance, particularly for high-valence electrolyte solutions, which is attributed to the abundance of finer bubbles in the froth phase, depending on the type and concentration of the electrolyte.
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The main aim of the present investigation was to determine retention behavior and interactions of oligonucleotides with alkylamide stationary phase. Five oligonucleotides, differing in the sequence, were tested. Changes in the composition of the mobile phase, i.e. pH (5.0−7.0) and buffer concentration (30−75 mM) were investigated in detail. In addition, the hydrophobic and electrostatic parameters were measured for the different pH’s and salt concentrations. The theoretical model of interactions between individual elements of the separation system, (e.g. solute, stationary phase, and mobile phase) based on zeta potential measurements, hydrophobic and electrostatic parameters calculation, and molecular modeling, has been considered.
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The stability of colloidal systems is very important in numerous already existing and new formulations. In most cases if such systems are not characterized by an appropriate stability they can not find any useful applications. The opposite process to the stabilization is the flocculation. Generally, it is undesirable. However, in a few cases the flocculation is very useful, for example in  the wastewater treatment. That is why the methods used to determine stabilizing-flocculating properties of the colloidal systems are of significant importance.The paper describes types of stability and flocculation as well as the factors influencing those processes, e.g. the addition of polymers or surfactants. The methods presented in this paper are UV-VIS spectrophotometry,  turbidimetry, zeta potential and density measurements.
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Herein, we report a facile green synthesis of Cu2O nanoparticles (NPs) using copper sulfate as precursor salt and hydrazine hydrate as reducing agent in presence of bio-surfactant (i.e. leaves extract of arka – a perennial shrub) at 60 to 70 °C in an aqueous medium. A broad band centered at 460 nm in absorption spectrum reveals the formation of surfactant stabilized Cu2O NPs. X-ray diffraction pattern of the surfactant stabilized NPs suggests the formation of only Cu2O phase in assistance of a bio-surfactant with the crystallite size of ∼8 nm. A negative zeta potential of −12 mV at 8.0 pH in surfactant stabilized Cu2O NPs hints non-bonding electron transfer from O-atom of saponin to the surface of NP. Red-shift in the vibrational band (Cu–O stretching) of Cu2O from 637 cm−1to 640 cm−1 in presence of bio-surfactant suggests an interfacial interaction between NPs and O-atoms of –OH groups of saponin present in the plant (i.e. Calotropis gigantea) extract. From X-ray photoelectron spectroscopy spectra, a decrease in binding energy of both 2p3/2and 2p1/2 bands in Cu2O with saponin molecules as compared to bulk Cu atom reveals a charge transfer interaction between NP and saponin surfactant molecules. Transmission electron microscopy images show crystalline nature of Cu2O NPs with an fcc lattice.
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Surface wettability plays an essential role in many processes and materials applications. It depends mainly on the surface roughness and chemical composition, thus through a controlled modification of these parameters, the wettability can be restrained. Glass is an inorganic solid material, composed mainly of amorphous silica, which surface, due to the presence of reactive hydroxyl groups, can be quite easily chemically modified. This feature can be used to control the wettability of glass by reaction with organic compounds. In this study, the esterification of glass silanol groups with n-alkyl alcohols (Cn/H2n+1/OH, n=3, 4, 6, 8, 10) was employed to modify its wettability. The effect of such modification on the physicochemical properties of glass surface was comprehensively investigated and characterised by the water contact angle, surface free energy, zeta potential, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) measurements. We demonstrate that the wettability of the esterified glass surface is strongly dependent on both the chain length of used alcohol and modification time. The alcohol molecule binds to the glass surface through a Si-O-C bond, leading to the formation of a monolayer that does not significantly affect the surface morphology and zeta potential. Conducted studies provided a broader view of the influence of this technique for modifying surface wettability on its physicochemical properties.
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The influence of polyvinylpyrrolidone (PVP) adsorption on the silica suspension stability was studied. The effects of silica content, polymer addition and suspension dilution with water were examined. The turbidimetry method was applied to examine stability of the investigated systems as a function of time. It was shown that the suspension without polymer was characterized by the smallest stability, whereas the systems containing PVP (before and after dilution) are successively stable. The specific conformation of PVP chains on the solid surface is responsible for the stabilization–flocculation properties of PVP in the colloidal suspension.
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A low-grade copper ore from Mpanda Mineral Field (MMF), Tanzania containing 0.90% Cu, 10.40% Fe and 58.3% SiO2 was subjected to beneficiation adopting selective dispersion, flocculation and flotation techniques. Based on the mineralogical characterization of the sample chalcopyrite, pyrite and quartz were identified as the major minerals. The isoelectric point of MMF ore was observed to be at pH 2.7, signifying that the ore was highly siliceous. The addition of sodium trisilicate and xanthan gum shifted the zeta potential of ore to more electronegative values. Adsorption of xanthan gum on chalcopyrite and silica indicated that the maximum adsorption was at pH 2.3 for chalcopyrite and the adsorption isotherm exhibited L2 type of the Giles classification. On the contrary, no adsorption of xanthan gum on silica was observed. The ground ore was selectively dispersed and flocculated at pH 9.7 using 30 ppm of sodium trisilicate and 30 ppm of xanthan gum. The grade of CuFeS2 was improved to 19.8% after 3 desliming stages. Flotation of the flocculated portion was carried out at pH 10.30 using 30 g/t of potassium amyl xanthate and potassium ethyl xanthate (1:1) , 40 g/t of Na2S as a sulphidising agent and methyl iso-butyl carbinol (MIBC) as a frother yielding a rougher concentrate with silica and chalcopyrite grades of 8.4% and 23.5% respectively with corresponding recoveries of 4.8% and 92.8% respectively. Additionally, rougher concentrate was subjected to cleaner flotation yielding silica and chalcopyrite grades of 1.8% and 29.2 % respectively and with recoveries of 1.2% and 89.1% respectively.
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In this study, the specific effects of Na+ and Ca2+ ions on natural hydrophobic Teflon particles and flat Teflon surfaces were investigated using zeta potential and contact angle measurements, respectively. The zeta potential measurements showed that the surface charge of Teflon was negative at all pH values in the absence of salt ions, and became the positive with the increased salt concentration, and obtained an iso electric point (iep) between pH 3 and 4. The results also indicated that Ca+2 ions more adsorbed on the Teflon surface compared to Na+ ions in the case of the compression of the electrical double layer. The contact angle measurements with Teflon sample showed that while the flat Teflon had a contact angle of 107° at pure water, and the contact angle considerably reduced as a function of salt concentration. This decrease was more effective in the presence of Ca2+ ions rather than Na+ ions. While calcium is a strong water structure maker cation, sodium is a weak structure maker cation, but the role of calcium is more effective at the Teflon-water interface according to zeta potential and contact angle measurements. It is revealed that the Ca+2 ions have a specific effect on Teflon surface due to low salt concentrations and ion charges. The different effects of these cations on Teflon-water interface can be attributed to use in mineral processing, especially in flotation enrichment.
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In this study, some electrokinetic and surface properties of MBAOM-GMA copolymers synthesized from 2-[(methoxy-1,3-benzothiazole-2-yl) amino]-2oxoethyl methacrylate (MBAOM) and glycidyl methacrylate (GMA) monomers were investigated. Accordingly, (i) pH-dependent zeta (ζ) potential changes of the copolymers were investigated under a constant ionic strength (in 1.10-3mol/dm3 NaCl) and the corresponding isoelectric points (iep) were determined, (ii) zeta potential changes depending on the salt concentration in the presence of mono-, di- and tri-valent metal salts were examined, (iii) contact angles (θ) of the copolymers with water were measured and their wetting behavior was assessed, and (iv) surface free energies (SFE) of the copolymers were determined by Acid-Base approach using Van Oss-Chaudhury-Good method. The compositions of the copolymers were 77% MBAOM - 23% GMA, 45% MBAOM - 55% GMA, and 19% MBAOM - 81% GMA. FeCl3, CaCl2, and KCl salts were used for the salt solutions for the zeta potential measurements. As a result, (i) it was determined that the chemical structure of methacrylate copolymers showed a decisive effect on both electrokinetic and surface properties, (ii) the hydrophobic character of copolymer increased with the increase of the GMA ratio, and correspondingly, the SFE decreased, and (iii) the iep of the copolymers varied between pH 3.1-3.7 depending on composition.
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Influence of aqueous phase properties and process parameters on kaolinite particle zeta potential was quantified by electrophoresis experiments. The results indicated that pH strongly altered the zeta potential of kaolinite and it decreases at the beginning and then increases in the range of pH = 2–13. The activity of different cations changes the zeta potential and has the following tendency of Al3+ > Ca2+ > Mg2+ > Na+ and the zeta potential increases due to heterocoagulation of different mineral particles in suspension. It was found that the zeta potential of kaolinite particles increases after the suspension was stirred and decreases at the beginning, and then increases with soaking time. The FTIR results showed that the zeta potential takes into account ion adsorption and the change of Si–O, Al–O and Al–OH groups on the surface of the kaolinite particles.
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