Papers by Keyword: Activation

Abstract: In residential and industrial buildings, a special air environment is formed, which contains gas shaped toxic chemical compounds. A significant part of such substances comes from finishing polymer containing materials. Virtually all polymeric materials release certain toxic chemical compounds into the air. The methods and methods of air cleaning are different. One of the ways to solve the problem associated with providing the required standards for the quality of indoor air is the development and use of new efficient building materials using aggregates that have a high sorption capacity. The paper presents the results of a study of the effect of low temperature non-equilibrium plasma on the sorption characteristics of aggregates based on diatomite earth. Studies have been conducted on samples of natural diatomite and quartz sand. When activated by low temperature nonequilibrium plasma, the structure changes, which leads to an increase in the sorption characteristics of the samples under study.

Abstract: Consumer’s preference towards organic material enriched nature based green products in the cosmetics and personal care industry have intensified over the years. This paper shares the synthesis and characterization of an active organic biocarbon material derived from carbonized powdered coconut shell by bicarbonate cured activation for use in charcoal-based cosmetic and personal care products. The optimum conditions for activation was observed at 800 °C, run for 180 min, with a bicarbonate impregnation ratio of 1:3. Experimental design followed Box-Behnken approach. The increase in iodine (757.30 mg/g) and methylene blue number (111.00 mg/g) are indicative of a highly porous biocarbon material that reflects its excellent adsorption capability. Suitability of the biocarbon material for application in charcoal-based cosmetic formulation mixture was supported through proximate, texture, and color analysis. Overall material characteristics are beneficial for effective adsorbent and exfoliant functions in cleansing, detoxifying, and scrubbing.

Abstract: In this work, commercial Viscose (cellulosic based precursor) rayon-based carbon fibers were oxidized to make activated carbon fibers (ACFs). Carbon fibers were made from Viscose fibers in carbonization process at 1200°C. The ultimate carbon fibers possessed carbon content above 94 mass% and fiber dimension about 8 mm. These fibers were activated to make ACFs by oxidizing gas such as steam of carbon dioxide. The experiments were conducted at temperature ranged from 800°C to 900°C with carbonic steam’s flow of 3 l.min^-1. The vaporous benzene adsorbability of activated carbon fibers was then measured by Mark Bell method. The adsorbability (a) and specific surface area (A_BET) of ACFs were determined. The properties of the produced ACFs were investigated and analyzed by SEM and TEM imaging. The results showed that obtained fibers have maximum benzene adsorbability of 4.58 mmol.g^-1 and BET surface area reached 1357 m².g^-1. These activated carbon fibers were able to use for toxic chemical prevention equipment.

Abstract: The paper presents the results of studies on the activation of the surface of carbon and glass fibers by thermal and chemical treatment with acids and mixtures of acids. Carbon and glass fibers with an activated surface are of practical interest for the production of polymer composite materials with high thermal, physical and mechanical characteristics.

Abstract: Aluminum implanted 4H-SiC often shows an unexpected increase of the free hole density at elevated temperatures in Hall Effect measurements. Here we show that this phenomenon cannot solely be traced down to the Hall scattering factor and the presence of excited acceptor states. It is necessary to assume an additional defect center in the lower half of the band gap with ionization energies higher than that of aluminum to explain this behavior. Therefore, we investigated ion-implanted square van-der-Pauw samples with Hall Effect and complementary SIMS measurements. An analysis of the data using the neutrality equation reveals compensation ratios of 20 % to 90 %, depending on the aluminum concentration and the concentration of the deep defect center of up to 50 % of the doping.

Abstract: Implementation of high belite cement in cement production would have strong environmental impact in reduction CO₂ emissions and saving of pure limestone deposits. The goal of the study is to describe the role of alkali and C-S-H activators on hydration of high belite cement. Analytical approach for early hydration is based on combination of isothermal calorimetry, X-ray powder diffraction in-situ, DTA-TG, FT-IR.

Abstract: In this work, it was found out that dicalcium silicate doped with SO₃ shows higher hydraulic activity compared to pure dicalcium silicate. This finding was used to prepare and optimize high-belite cement from SO₃ doped clinkers. The belite cement exhibited the same technological parameters, including short-term strengths, as ordinary Portland cement with a high content of tricalcium silicate. The clinker for belite cement is environmentally and economically advantageous. It is possible to burn the clinker at a temperature of 100 °C lower than conventional clinker and with lower consumption of calcium carbonate. In particular, methods of optical and electron microscopy were used for the research.

Abstract: The article describes the problem of the experimental determination of complex dielectric permittivity for natural, activated, and modified quartz systems. The results of determination of specific surface, complex dielectric permittivity, sands porosity are presented in this article. The authors obtained the empirical equation of complex dielectric permittivity calculation for natural, activated, and modified quartz sands, taking into account the effect of moisture, specific surface, porosity, impurities content into consideration. The modification of the sand surface by means of mechanical beneficiation and ultrasonic treatment leads to reduction of complex dielectric permittivity and specific surface, thus contributing to the increase of the active centers quantity on the sands surface. The modification of the sand surface by polyvinyl alcohol aqueous solution leads to increase of complex dielectric permittivity. Polyvinyl alcohol aqueous solution modification envisages the creation of new active centers by oligomers inoculation to the surface and blocking the clay component and authigenous film ingredients. Among the considered methods, ultrasonic treatment in aqueous solution and mechanical beneficiation are the most efficient and technologically acceptable ways of activation.

Abstract: Improving the efficiency of construction composites is a relevant problem for modern-day material science. One of the ways to solve the problem consists in activating the binders by means of vortex-layer devices. Mathematical transformations produced a formula for calculating the dependency of the number of ferromagnetic-particle collision on the number and velocity of such particles, as well as on the device chamber fill factor. The results obtained by applying the proposed formula differ from D.D. Logvinenko's model by 10% at max. We calculated the impact force, the impulse of the grinding body in the vortex-layer device, as well as the amount of applied energy per unit of mass of the ground material. It was found out that the impact force and the impulse of force were maximized in the test device. At the same time, energy applied over the grinding time necessary to even out the binder dispersion in the vortex-layer device was 2 to 4.8 times greater compared to conventional devices.

Abstract: In order to study the activation process and mechanism of ZrCoCe, highly porous ZrCoCe getter films were grown by the DC magnetron sputtering method. The effect of activation temperature on the surface composition of the porous ZrCoCe getter films were studied by X-ray photoelectron spectroscopy (XPS). The results shows that the surface of air-exposed porous ZrCoCe film is covered with H₂O, CO₂ and hydrocarbons, both Zr and Ce exist in the oxidized state, and zirconium oxide starts to reduce at 300 °C. The activation process also results in a sizable Co segregation at surface. In addition, zirconium carbide can be found in the subsurface region of the film after thermal activation treatment.