Papers by Keyword: Zeta-Potential

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Authors: M. Mansoor
Abstract: A step-by-step, hierarchical approach is explored in the present work to purify and functionalize carbon nanotubes synthesized by chemical vapor deposition. Attempts are made to purify and functionalize CNTs without extinguishing their aspect ratios. The carbon impurities are removed by thermal oxidation, whilst the unprotected metallic catalyst particles are eliminated by wet oxidation, subsequently; CNT bundles are de-roped by surfactant assisted sonication. Finally, protected metallic catalyst particles are removed and functional groups (hydroxyl and carboxyl) are attached by acid treatment and wet oxidation, respectively. The derivate CNTs are characterized using zeta potential measurements, TGA, XRD, FTIR and SEM. The characterization showed that in optimum experimental conditions the catalytic particles are removed upto 80%, the carbon impurities are eliminated upto 95% and chemical functionalities of hydroxyl and carboxyl is occurred with noticeable de-roping of the CNT bundles.
Authors: Ho Chang, Kuan Lin Tsai, Tsing Tshih Tsung
Abstract: In this paper investigates the dynamic stability of Fe3O4 magnetorheological fluid produced by Submerged Arc Nanoparticle Synthesis System which our team has modified, that is, the dynamic stability of magnetic microparticle in Brownian motion. Through this modified system, parameters such as the exact peak current, the time of discharge and off time, and voltage can be preset. The results of the experiment show that the Fe3O4 magnetorheological fluid produced by the modified submerged arc nanoparticle synthesis system has wt 20% and vol 1% surfactants after being mixed with water. After being placed aside for one day and 15 days respectively, the average diameters of the two nanofluid measured with particle size analyzer and TEM are both 40nm. Furthermore, after analyzed through Brookhaven ZetaPlus the zeta potential of the two nanofluid both reach 40mv, which proves that the magnetic nanofluid show superior performance of suspension.
Authors: G. Gu, Li Jun Su, Guan Zhou Qiu, Y. Hu
Abstract: Acidithiobacillus caldus and Leptospirillum ferriphilum cells grown in different energy substances (ferrous ion, sulfur and pyrite) were used. The adhesion of A. caldus and L. ferriphilum cells on pyrite and their effect on pyrite surface properties were studied by adsorption, zeta-potential and FT-IR methods, and the corrosion images of pyrite interaction with bacteria were examined using atomic force microscopy. Research showed that pyrite isoelectric point (IEP) after interaction with bacterial cells shifted towards cells isoelectric point, and the shift degree in case of interaction with A. caldus was observed to be much more pronounced than for interaction with L. ferriphilum, which can be due to higher affinity of A. caldus towards pyrite. The FT-IR spectra of pyrite treated with bacterial cells revealed the presence of the cell functional groups signifying cells adsorption. Although the adsorption density of A. caldus on pyrite was higher than that of L. ferriphilum, L. ferriphilum with strong ability to oxidize ferrous ion showed better leaching efficiency than A. caldus with strong ability to oxidize sulfur for pyrite leaching. The results demonstrated that more important of indirect action (L. ferriphilum) than direct action (A. caldus) on pyrite.Introduction Bacterial adsorption to minerals is an initial step in bacterial leaching for metal recovery [1]. It has been reported that bacterial adhesion is dependent not only on the biochemical properties of the organism but also on the interfacial properties of the various interfaces existing in a bioleaching system[2].The bacteria-mineral interactions result in the changes of their surface properties. The elucidation of their alternate will be beneficial for bioleaching processes. Both Acidithiobacillus caldus and Leptospirillum ferriphilum are known for their ability to inhabit acidic environments and derive energy from oxidation of inorganic substances with natural occurrence in ore deposits and acid mine drainage and high affinity towards sulfide minerals [3-5]. In this work, the alterations of surface properties of pyrite after interaction with L. ferriphilum and A. caldus are studied, and the changes in surface properties caused by bacterial adsorption are discussed with reference to bioleaching behavior of pyrite.
Authors: Chang Hui Yang, Qun Pan, Jiong Zhu
Abstract: In this work, the adsorption of naphthalene-based water reducer (FDN) on slag ground with or without the composite retarder YP-3 and PN (YP) in alkali-activated slag cement (AASC) activated by water glass (WG) has been studied in detail. The results show that the effect of the adsorption of water reducer on AASC depends directly on the dosage of the water reducer and on the composite retarder used. For example, mixed slag particles adsorb thrice as much water reducer FDN than pure slag particles at 1% mass of the slag, and the absolute value increment of the zeta potential of the AASC suspension containing the composite retarder is 8.61 mV, compared with 1.99 mV in the system without the composite retarder. Moreover, the AASC pastes activated by WG containing the retarder YP show better rheological properties and lower fluidity loss over time.
Authors: Martin Reischl, Karin Stana-Kleinschek, Volker Ribitsch
Abstract: The determination of electrokinetic properties such as the zeta-potential of polymer samples with classical methods is laborious and time-consuming. For this reasons, a reliable, fast, and easy to use measurement system based on streaming potential measurement was developed. In this novel measurement system, streaming potential is created by an oscillating flow of a small amount of electrolyte solution through the sample media. In addition, this setup allows direct titration and therefore time-resolved monitoring of changes in zeta-potential in a seconds timescale. With this instrument, the concentration- as well as the time-dependent adsorption behaviour of various non-ionic, anionic and cationic surfactants on a novel, regenerated cellulosic polymer was investigated. This new cellulose-based, fibrous textile polymer is permanently cationised, not only at the surface but throughout the whole fibre. The results show that even very low concentrations of surfactant, due to its charge and chemical composition, highly influence the surface charge of the polymer in a large range. Furthermore, the results for this new textile material are compared with other textile fibres, e. g. wool.
Authors: Davood D. Ganji, Mofid Gorji-Bandpy, Mehdi Mostofi
Abstract: In this paper, Poisson-Boltzmann equation and Navier-Stokes equation will be solved by Homotopy Perturbation method (HPM). Working fluid in this paper is assumed to be non-Newtonian which follows power law model. Zeta potential that is used for the potential in near wall area of a tube will be small enough in order to use some simplifications. In this paper, Poisson-Boltzmann equation for a 30 nm diameter nanotube with large zeta potential has been solved by Homotopy Perturbation Method (HPM). According to the literature, results have been compared with numerical solutions and consistency of the results has been considered. Results show that HPM can approach to this problem reliably.
Authors: Mikolaj Szafran, K. Jach, A. Tomaszewska-Grzeda
Authors: Ran Wang, Xiao Chun Wang, Yan Qiu Wang
Abstract: A γ-glycidyloxypropyltrimethoxysilane (GPTMS) modified titania hydrosol was prepared. The influence of GPTMS modification on the tatania sol was investigated by dimension dispersion, Zeta potential, FT-IR, and the ultraviolet transmittance of the treated PET fabric. The results show that the Zeta potential of nano-particles increased from 2.1mV to 35.6mV. And there was no obvious difference in dimension dispersion and FT-IR between the tatania gel and the modified-tatania gel. The ultraviolet transmittance of the PET fabric treated the modified-sol and the unmodified-sol also did not show significant shift.
Authors: Quan Xiao Liu, Wen Cai Xu, Yu Bin Lv, Jin Li Li
Abstract: Filler is one of the most important components of paper. Silica is a kind of excellent filler for its special chemical structure. Silica was prepared in the laboratory, and applied into paper. The dispersion properties of the silica with different sizes in paper sheets, the effect of smash on dispersion property of silica in paper sheets, the effect of silica on the zeta potential of newspaper pulp system, the effect of retention agent cationic polyacrylamide on zeta potential of newspaper pulp system and the effect of silica on properties of paper sheet were measured. The results show that the fineness of the silica used in paper is the most important factor which affects the dispersion. The addition of silica and the use of retention agent cationic polyacrylamide increase the zeta potential of the newspaper pulp system. The addition of precipitated silica increases the whiteness of paper slightly and the opacity obviously.
Authors: A. Kudyba, Margarida M. Almeida, H.T. Hintzen, J.C.T. van der Heijde, J. Laven, R. Metselaar
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