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To evaluate the effect of organic compounds on the dissolution rate of amorphous silica, the dissolution of amorphous silica in pure water and in organic electrolyte solutions were investigated at room temperature at pH 6. Based on the kinetic analyses, the dissolution rate constants of amorphous silica in the organic electrolyte solutions were 18–30 times larger than in pure water but less than those...
We show that the surface charge and, hence, the electrophoretic mobility of water droplets dispersed in non-polar oils can be adjusted in magnitude and sign through the addition of ionic surfactants. The positive, native charge of water-in-oil droplets is reduced by increasing the concentration of the anionic surfactant SDS in the water. At high enough SDS concentration, the droplet charge becomes...
In studies of colloids in deep groundwater, a serious problem exists because the properties of the colloids are influenced by changes in the chemistry of groundwater upon exposure to the atmosphere and pressure release during sampling. To collect and analyze colloids in deep groundwater without significantly changing the groundwater chemistry, a microfiltration/ultrafiltration technique, while maintaining...
Several biological and artificial hydrophobic surfaces exhibit self-cleaning mechanisms, which ensure smooth sliding/rolling of liquid droplets, allowing them to sweep pollutant particles away from the surface. While enhancing of the self-cleaning property is a major topic in numerous industrial applications, the underlying physics is not yet fully understood. The first step towards analyzing this...
We report on the formation of entropic ionogels (gels in IL solutions) of laponite platelets in ionic liquid (IL), 1-ethyl-3-methyl imidazolium chloride, solutions at room temperature (0<[IL]<0.05% (w/v)). Self-assembled colloidal networks were formed following a growth mechanism given by, ηr∼(1−t/tgvis)−p for t<tgvis; and G0∼(t/tgrheo−1)β for t>tgrheo where η r , G 0 and...
The Fe(II) and Fe(III) ions uptake by chitosan is distinguished by rapid sorption kinetics in comparison with that of other heavy metals such as Cu(II) and Ni(II).The correlation between the kinetics of dissolved oxygen and Fe(II) ions sorption by chitosan points to the different sorption mechanisms for Fe(II) and Fe(III). The consumption of dissolved oxygen corresponds to the sorbed Fe(II) quantities...
To develop a more efficient support for free titania nanoparticles, the processing of particle-stabilized wet foams into macroporous carbon-covered alumina (CCA) supports was investigated in this study. The prepared supports had hierarchical pore structures consisting of pores with average cell sizes less than 2μm uniformly distributed on the walls of the macropores (>150μm). Furthermore, the carbon...
In this work, a stable aqueous dispersion solution of polymer-modified graphene was prepared by in situ reduction with ethylene glycol from graphene nanosheets (GNs) in the presence of poly (diallyldimethylammonium chloride) (PDDA), in order to obtain a (PtNPs–GNs–PDDA) nanocomposite material, where Pt nanoparticles (PtNPs) with a narrow size distribution of 2–4nm uniformly decorates GNs, being both...
The micellization of amphiphilic biocompatible poly(vinyl acetate)-graft-poly(N-vinyl-2-pyrrolidone) (PVAc-graft-PNVP) graft copolymers, characterized by a constant PVAc backbone and PNVP side chains of low grafting density as well as of variable chain lengths, reveals the formation of star-like micelles with, at 25°C, a partially “frozen-in” PVAc core and a PNVP corona. The interaction of these graft...
Graphene/vanadium oxide (RG/VO x ·nH 2 O) hybrid electrodes with different graphene (RG) amounts were prepared by one-step simultaneous hydrothermal-reduction technology in a suspension of NH 4 VO 3 , NH 2 CSNH 2 and graphite oxide (GO) nanosheets. The hydrothermal treatment made the reduction of GO to RG and the formation of VO x ·nH 2 ...
In water treatment processes, the optimal dosage of coagulant is highly dependent on suspended particle surface charge, size and concentration, pH and composition of water. One way to control the coagulation process can be based on the measurement of the electrophoretic mobility and determination of zeta potential.In this study we investigated the interaction between negatively charged polystyrene...
The interfacial properties of binary surfactant mixtures, prepared by mixing a poly(isobutenyl) succinic anhydride derivative with a series of non-ionic oil soluble (Spans) and water soluble (Tweens) compounds with varying structure (length, presence of double bonds, number of arms) hydrophobic tails, were investigated. The Rosen method was used to characterize the synergism between the two surfactants...
In this paper, rotating electroosmotic flow (EOF) of power-law fluids at high zeta potentials in a slit microchannel is analyzed. The electric double layer (EDL) potential distribution is considered by using nonlinear Poisson–Boltzmann equation. Based upon the analytical charge density distribution, the finite difference method is used to compute numerically rotating EOF velocity profiles of power-law...
Monodisperse spherical TiO 2 particles were prepared by a sol–gel method modified with different glycols at room temperature and were calcined at different temperatures between 400 and 950°C. The synthesized and calcined TiO 2 powders were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG). The TEM images showed particles...
Stable colloidal dispersions of niobium chalcogenides NbQ 2 and NbQ 3 (Q=S, Se) in organic solvents – CH 3 CN, dmf, i PrOH, EtOH, EtOH/H 2 O (vol. 1/1), n-BuOH were prepared by ultrasonication. According to DLS and AFM data the particle size distributions in the dispersions are rather wide: particle sizes vary from 70 to 400nm, and the mean sizes are in range...
The impact of several electrolytes present in seawater on the rheological properties of flocculated alumina suspensions was assessed by using creep testing at pH conditions both above and below the isoelectric point. Flocculated suspensions were obtained by adding a high molecular weight anionic polymer flocculant to a cylinder of alumina suspension and aggregating the suspension using the plunger...
The effect of hydrocarbon chain length of sodium-n-acyl sarcosinate (SNAS) and N-cetylpyridinium chloride (CPC) surfactants has been studied at various mixing ratios and concentrations. The variation of the chain length of the anionic surfactant produces a significant effect on the stability of mixed surfactant systems. The unilamellar vesicles formed by the mixtures are shown to be thermodynamically...
The effects of fatty acids on oppositely charged polyelectrolyte–surfactant interactions are experimentally investigated. It was observed that dodecanoic (lauric) acid (LA) disrupts the well-established reported interaction between the anionic surfactant sodium dodecylethersulfate (SDES) and the cationic polymer guar modified with grafted hydroxypropyl trimethyl ammonium chloride (Jaguar C13 BF)....
We investigate deformation and breakup of double emulsion drops, in a system consisting of an aqueous continuous phase and double emulsion oil drops containing smaller droplets of water. The system is stabilized by the presence of the surfactant polyglycerol polyricinoleate (PGPR). Extensional flow generated in a 4-roll mill is used for these investigations. Steady state deformation is not influenced...
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