Papers by Keyword: Cation

Abstract: The loess produced in South Korea is an eco-friendly material with high gas adsorption performance. Korean loess, however, cannot be used as a structural material because it has a very low compressive strength compared to cement. However, even if it is recommended as an interior material, its large drying shrinkage during drying disturbs wet construction. Therefore, this study aimed to develop a method to reduce the amount of water added while maintaining the consistency required for the plastering work of Korean loess. The experimental results showed that the dispersion of clay particles was improved when Na+ and K+, which are monovalent cations, were added to the loess colloid; the reverse occurred, i.e., aggregation of clay particles, when Ca2+ and Mg2+, which are divalent cations, were added. In addition, the dispersion and aggregation of clay particles affect the consistency of loess. The dispersion allows the loess paste to obtain the required consistency using less water, but the aggregation may exhibit the opposite effect. Accordingly, based on the same consistency, the specimens with less water exhibited less drying shrinkage. The drying shrinkage decreased by 9.23% for the specimen fabricated with the 0.01 M Na2SiO3 aqueous solution.

Abstract: Portland-limestone cement materials are susceptible to sulfate attack at low temperature and high humidity, because such conditions facilitate the formation of thaumasite, detriment to the structural integrity of calcium silicate hydrates (C─S─H). In this work, the effect of the cation associated with sulfates, concentration of sulfate solution, and limestone content in cement, were thermodynamically simulated. MgSO₄ solution is of higher risk, degrading extensively the structural integrity of C─S─H. Although this phase is partially preserved under the effect of Na₂SO₄ and K₂SO₄ solutions, extensive expansion and thaumasite formation occur. The sulfate content of the corrosive solution and the limestone content in cement are the factors mostly intensifying the attack caused by MgSO₄ and Na₂SO₄/K₂SO₄ solutions, respectively.

Abstract: In this paper, the relationship between the components of heavy oil wastewater and thesurface wettability of coagulation particles were studied. The effects of cations (Ca2+, Mg2+, Fe2+,Fe3+), oil content and pH on wettability of coagulated particles surface in heavy oil wastewater werestudied by measuring the contact Angle, and the possible mechanism was discussed. It was foundthat the contact Angle decreased with the increase of pH value. The change of oil content isnegatively correlated with the contact Angle. Surface wettability of coagulated particles arecorrelated with cationic concentration in sewage and standard electrode potential. When cationicconcentration is less than 500 mg/L, surface wettability is positively correlated with standardelectrode potential. When cationic concentration is more than 1000 mg/L, surface wettability ismainly related to the total amount of cationic ions in sewage.

Abstract: The direct reduction of metals from a complex oxide with low iron content by solid carbon and indirect reduction by CO gas were studied in a vertical laboratory resistance furnace at 1300 °C for an hour reduction time. The experimental results were described from the point of view of the electrochemical nature of the metal reduction process, that involves the interaction of ions and electrons in the oxide lattice. The technique was developed by using the two different software programs for the quantitative estimation of the areas, average size and number of the metal forming in a complex oxide with extensive fields of vision. The obtained results of the quantitative characteristics of the metal forming during solid-phase carbo-thermal reduction were presented. The processes of reduction by solid carbon and CO gas based on the areas occupied by metal particles were quantitatively compared. The experimental results and the prospects for further experimental work were assessed and outlined.

Abstract: The aim of the study is to demonstrate that separation of solvated ions in solution of mixed salts under the action of external periodic electric field is caused by the formation of clusters consisting of solvent molecules and surrounding the ions. Such clusters have the dimensions of about 0.1 µm. The study includes the theoretical estimation of cluster dimensions and experimental determination of the external electric field frequency that gives rise to the separation of solvated ions. The results testify that placing the volume distributed electric charge of ion into dielectric liquid is accompanied by the formation of supramolecular particles. We called such particles “clusters”. The linear dimensions of clusters significantly exceed the first and the second radii of solvation (approximately 1 Angstrom) and amount to nearly 0.1 µm. At such sizes, inertial properties of clusters and their natural frequencies may allow controlling their movement by applying an external electric field to solution.

Abstract: onic Polymer Metal Composites (IPMC) is a new kind of electro-active smart material that has many advantages including bending actuation, large displacement, low weight, low driven voltage, low power consumption, flexibility etc. The mechanical characteristic of IPMC is related to ionic polymer membrane, such as thickness, roughening, cation type and so on. In this paper, the actuation principle of IPMC and fabrication technique of Nafion^TM membrane is presented. The performance of IPMC with Nafion membrane pre-treatment, different cation type and thickness are investigated. Experiment results showed that the fabrication process of ionic polymer membrane Nafion change can improve the performance of IPMC effectively.

Abstract: Based on the high turbidity feature of mine water, Glutinous Rice Starch(St)- Acrylamide(AM) graft polymer cationic flocculant was synthesised by copolymerization with St and AM as materials, ammonium persulfate and sodium hydrogen sulfite as the initiator, 2.3-glycigyl trimethyl ammonium chloride were used as cationic agent. The optimum condition of cation was established through orthogonal experiments: reaction time is 4 hrs, St dosage is 5g, mass ratio of AM and St is 4:1, dosage of initiator is 1.4g, GTA dosage is 2.6g, NaOH dosage is 0.24g, etherification reaction time is 2.5 hrs, reaction temperature is 70°C. The performance of the cationic starch flocculant used as the mine wastewater treating was evaluated.

Abstract: Adsorption isotherms are often required for understanding mobility, fate and bioavailability of contaminants in soils. Those about Pb (II) and Cd (II) on Andosols and Kanto loam were investigated in this work. Results show that adsorption increased with cation equilibrium concentration (10^-4 - 1 meq L^-1) and solution pH (5 - 7), and also that most adsorption isotherms can be simulated precisely with the ion-exchange-based Urano model. The applicability of model in predicting adsorption equilibriums of cations on soils in circumneutral aqueous solution (pH 5 - 7) were experimentally confirmed. There is an exception as to the Pb (II) adsorption on Andosols with the solid-to-liquid phase ratio higher than 1:100, there adsorption isotherms at pH 5 and pH 7 crossed, and the measurement precision decreased. The Urano model equation becomes inapplicable. Further experiment where humus substances (HS) were added indicated that the abnormal phenomenon can be attributed to dissolved HS and their complexation with Pb (II). The dissolution of HS with solution pH has enhanced Pb (II) concentration in solution but hardly reduced the total amount of adsorption on soil.

Abstract: Ion chromatography (IC) has been developed for the simultaneous analysis of cations and anions in the water, food, atmosphere, etc. Chromatography can yield the precise and reproducible data if the experimental condition is kept constant. In the present studies, the major cations and anions in the tap water were determined with the technique of IC. A Dionex ICS-2000 ion chromatograph with a Dionex gradient pump, eluent degassing module and conductivity detector was used. Cations were separated on a CS12 A ion-exchange column, with a CG-12 A guard column, and detected after suppression with CSRS 300 cation electrical self-regenerating suppressor. Anions were separated on an AS 11 HC ion-exchange column, with an AS 11 HC guard column, and detected after suppression with an ASRS 300 anion electrical self-regenerating suppressor. The results indicated that the technique of IC was suitable for the rapid, precise and accurate determination of major cations and anions in the tap water samples. In addition, the acceptable detection limits were obtained for all the cations and anions, and the time of analysis was significantly shortened with the technique of IC.

Abstract: The photocatalytic efficiencies of three commercially available TiO2 samples were evaluated and compared for TiO2 powder dispersed system with respect to pH and the water to be used for the perpetration of TiO2 slurry. All the TiO2 samples of P-25, NT-C, NT-20 showed a significant dependence of the photocatalytic efficiency on pH and exhibited higher photocatalytic efficiency in the pH between 5 and 7. The water used for the preparation of the TiO2 slurry also affected the photocatalytic efficiency of the TiO2 samples presumably due to a few cation ions existing in the water. The photocatalytic properties of TiO2 samples varied significantly depending on the key experimental conditions applied to the TiO2 slurry.