Colloid Journal最新文献

Human industrial activity is accompanied by the formation of vast volumes of water contaminated with radionuclides, including radium-226, which create serious danger to people. Graphene nanostructures are among the most promising materials for purifying water from radionuclides. This work has been devoted to investigating the efficiency of few-layer graphene synthesized under conditions of self-propagating high-temperature synthesis from cellulose and wastes of the woodworking industry (technical lignin, tree bark) for purifying water from radium-226. The key advantage of the method chosen for synthesis of few-layer graphene is the possibility to synthesize large volumes of the material at an acceptable cost, which is extremely important for industrial applications. It has been found that the synthesized samples of few-layer graphene can efficiently purify water from radium-226 (the degree of sorption is higher than 99%). It has also been shown that the degree of desorption upon repeated washing with water does not exceed 0.5%.

Improving thermal ice melting efficiency is very important in the practical application of anti-icing surfaces. This work investigated the thermal ice melting performance of micro-nano-structured surfaces fabricated by femtosecond laser. To the best of our knowledge, we found that the micro-nano-structured surfaces significantly improve the ice melting time for the first time. The shortest melting time was on the porous micro-nano-structured surface, about one third of the original surface. Moreover, it was proven that the accelerated ice melting surface had good durability. The research in this paper showed that the micro-nano-structured surfaces are very suitable for the surface that needs to be heated to melt ice, providing essential guidance for the design of the anti-icing surface.

In this research work, a new biocompatible microemulsion containing castor oil has been formulated to increase the solubility of celecoxib, as a well-known anti-inflammatory drug. In this formulation castor oil has also anti-inflammatory properties. The proposed oil-in-water microemulsion composed of Tween 80 as surfactant, isobutanol as co-surfactant, and castor oil as the oil phase. In the first step, the phase diagrams of the proposed colloid systems with surfactant to co-surfactant mass ratios of 4 : 1 and 2 : 1 were prepared at ambient temperature. Then, using the obtained phase diagrams, the appropriate formulations were selected by combining different percentages of water, oil, surfactant and co-surfactant in the microemulsion region. Some of physico-chemical properties, such as electrical conductivity, density, refractive index, surface tension and particle size of the selected microemulsion formulations have been determined at 298 K. After that, the solubility of celecoxib in the selected formulations was determined and compared with other reported microemulsion formulations. Interesting results from this section indicated that the solubility of celecoxib significantly increased compared to pure water and the previous proposed formulations. The results of this study can be used to provide suitable formulations based on the biocompatible microemulsions for celecoxib in pharmaceutical industry.

Nickel oxide nanoparticles (NiO NPs) are synthesized using olive leaf extract (OLE), which contains a range of polyphenols. These polyphenols serve as both reducing and capping agents, stabilizing the nanoparticles. Aqueous nickel acetate is employed as a precursor. Simultaneously, exfoliated graphene (EG) is obtained via electrochemical exfoliation of graphite in aqueous solutions. These materials were employed as electroactive components in supercapacitor applications. Characterization of NiO and EG involved thermogravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and scanning/transmission electron microscopy (SEM/TEM), alongside Brunauer−Emmett−Teller (BET) analysis, confirming the formation of crystalline NiO NPs with a cubic phase and Fm-3m space group. Micrographs revealed nanoscale dimensions for both NiO and EG with a substantial surface area, as verified by BET analysis. Symmetric (NiO/NiO, EG/EG) and asymmetric (NiO/EG) supercapacitors were fabricated using the doctor blade method. Electrode evaluation, employing field-emission scanning electron microscopy FESEM, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), demonstrated promising morphological and electrochemical characteristics. At low scan rates, both symmetric and asymmetric supercapacitors exhibited a notable gravimetric capacitance (221, 111, and 162 F g^–1 at 1 mV s^–1). Additionally, they revealed higher power density (173, 137, and 161 W kg^–1 at 10 mV s^–1), showcasing pseudocapacitive and electric double-layer capacitor (EDLC) behavior for NiO NPs and EG, respectively. This research significantly contributes valuable insights by presenting a sustainable synthesis route for NiO NPs, developing high-performance supercapacitor electrodes, and achieving a comprehensive understanding of the electrochemical behavior of NiO NPs and EG.

The kinetics of the synthesis of silica nanoparticles (<50 nm) has been studied under the conditions of heterogeneous hydrolysis of tetraethoxysilane (TEOS) using L-arginine as an alkaline catalyst. The rates of silica formation have been determined in a temperature range of 10–95°C at catalyst concentrations of 6–150 mM. It has been shown that the activation energy of the process depends on catalyst concentration and varies in a range of 21.5–13.9 kJ/mol, while decreasing linearly with increasing concentration of L-arginine in the system. The criterion of maintaining the monodispersity has been estimated for SiO₂ particles being grown “onto seeds.” The density of submicron-sized silica particles has been experimentally determined as depending on the annealing temperature. Within a temperature range of 200–1000°C, the particle density varies from 2.04 to 2.20 g/cm³.

An approach based on the direct numerical solution of the Boltzmann kinetic equation is proposed to take into account the influence of homogeneous nucleation on the mass transfer intensity in the evaporation/condensation (recondensation) problem. On the basis of the comparison between the scales of the formation time of a critical-size droplet and the time of supersaturation propagation, it is shown that it is possible to describe the considered problem in two stages, i.e., without taking into account the influence of droplets at the first stage and with taking into account their influence at the second stage. The calculation results show that, in the case of immobile droplets, there is a strong influence of bulk condensation on the intensity of the evaporation/condensation process.

Due to their unique properties, organosols of silver nanoparticles are widely used in optical and semiconductor devices, to produce electrically and thermally conductive films, as catalysts, antibacterial materials, etc. This work proposes a simple and highly productive method for the preparation of silver organosols, which have a metal concentration as high as 1800 g/L and contain spherical nanoparticles with low polydispersity and a median size of 9.1 nm. The method consists in the initial preparation of silver nanoparticle hydrosols with a concentration of higher than 30 g/L followed by the transfer of the NPs into an organic phase of o-xylene. A set of physical research methods has been employed to study the regularities of the extraction of silver nanoparticles with o-xylene in the presence of cetyltrimethylammonium bromide (CTAB) and ethanol and to determine the optimal process conditions, under which the extraction degree is as high as 62.5%. It has been found that bromine anions contained in CTAB molecules cause the aggregation of some amount of silver nanoparticles with the formation of silver metal sediment in the aqueous phase. According to X-ray photoelectron spectroscopy data, the sediment contains bromide ions (up to 4 at %) on the particle surface. Organosols synthesized under optimal conditions are stable for more than 7 months and withstand repeated cycles of drying and redispersing. Silver organosols have been used to obtain metal films with an electrical conductivity of about 68 500 S/cm, which increases to 412 000 and 509 500 S/cm (87.8% of the electrical conductivity of bulk silver) after thermal treatment at 150 and 250°C, respectively.

The objective of this work is an attempt to introduce into scientific practice the method of “mechanochemical recrystallization” in solid-phase systems with small additives of a liquid solvent. Dimethyl sulfoxide (DMSO), a universal bipolar aprotic solvent, has been used as the additive. As an example, the mechanical activation of reaction AgNO₃ + NH₄I + z NH₄NO₃ (diluent) + yS + xDMSO = AgI + yS* + (z+1)NH₄NO₃ + xDMSO has been studied, where z ≈ 5, y ≈ 1, and x ( ll ) 1 are molar fractions. The formation of sulfur (S*) and silver iodide (AgI) nanoparticles has been revealed, and/or S*/AgI nanocomposites with controlled contents of the components have been synthesized. The use of NH₄NO₃, which is a non-target product of the mechanosynthesis, as a diluent leads to the stabilization of nanoparticle sizes. The nanoparticles are formed in the medium of DMSO due to the conventional recrystallization (continuous process of dissolution–crystallization of sulfur) or the reactional recrystallization (process of dissolution of AgNO₃ and NH₄I followed by their interaction with the AgI crystallization) rather than the direct mechanical activation. The former and latter mechanisms are realized when obtaining S* and AgI, respectively. The target products (S*, AgI, and S*/AgI) are purified from water-soluble components (NH₄NO₃, DMSO) by washing in an ultrasonic bath. The proposed technical solution of the problem has been realized in planetary ball mills with different milling tools.

This work is devoted to studying the stability of polymer coatings formed from reactive copolymers of glycidyl methacrylate and fluoroalkyl methacrylates and applied onto textured aluminum and cotton textile surfaces. The stability is determined with respect to the action of aggressive media and mechanical stress. The resulting coatings provide the achievement of long-term stable heterogeneous wetting with initial contact angles as large as 170°, thus preventing the penetration of corrosive agents into the hierarchical structure. The study has shown the influence of the composition of the reactive copolymers containing 3–7 fluorine atoms in a monomer unit on the stability of the polymer coatings with respect to the prolonged exposure to media with different acidities, as well as to cavitation, and abrasive wear.