• Bulletin of the Korean Chemical Society
• /
• v.33 no.10
• /
• pp.3184-3190
• /
• 2012

Color impurity in industrial effluents pose a significant risk to human health and the environment, so much effort has been expended to degrade them using various methods, including the use of clay minerals as adsorbent. The purpose of this study was to advance understanding of the mechanisms for the removal of methylene blue (MB) from aqueous solutions onto montmorillonite as an adsorbent. Preliminary experiments showed that montmorillonite was effective for this purpose and adsorption equilibrium could be reached in about 24 h. Adsorption capacity of the clay decreased with increase in temperature and ionic strength, and increased with in pH. The fitness of equilibrium data to common isotherm equations such as the Langmuir, Freundlich, Elovich, Temkin and Dubinin-Radushkevich were tested. The Langmuir equation fitted to equilibrium data better than all tested isotherm models. Thermodynamic activation parameters such as ${\Delta}G^0$, ${\Delta}S^0$ and ${\Delta}H^0$ were also calculated and results were evaluated. As result montmorillonite clay was found as effective low cost adsorbent for removal of cationic dyes from waste waters.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.6
• /
• pp.581-586
• /
• 2010

Generally, electrokinetic potential has been considered as an intensive property. In other words, electrokinetic potential is not affected by the amount of particulate matter. Montmorillonite, one of essential inorganic matter, was chosen to measure electrokinetic potential. The result of electrokinetic potential measuring experiment showed that the value observed to decrease as the amount of montmorillonite clay increased. This is due to the fact that total ions that adsorbed per unit mass were decreased as the amount of montmorillonite was increased. As a result, electrokinetic potential is considered as an extensive property. By using these results, total interaction energy of suspension was also checked, and revealed that total interaction energy was decreased as the amount of montmorillonite increased.

• Polymer(Korea)
• /
• v.25 no.6
• /
• pp.818-825
• /
• 2001

Polycarbonate(PC)/montmorillonite (MMT) nanocomposites were prepared by solution and melt mixing methods. A d-spacing of the nanocomposites was measured by an X-ray diffractometer. Neat montmorillonite (MMT-Na) and MMTs modified by dodecyl ammonium (MMT-DA) or dimethyl hydrogenated tallow 2-ethylhexyl ammonium (MMT-25A) were used. The d-spacing value of PC/MMT-25A and PC/MMT-DA was higher than that of PC/MMT-Na. The d-spacing increased from around 12 to $37AA$ depending on the mixing method. PC was more readily introduced to the gallery of MMT as the molecular weight of PC reduced and the mixing time increased. PC/MMT-25A showed higher thermal stability by thermogravimetric analysis (TGA) than PC/MMT-DA and PC/MMT-Na.

• Nuclear Engineering and Technology
• /
• v.8 no.2
• /
• pp.69-76
• /
• 1976

This experiment has been carried out for the removal of long-lived radioactive-nuclides (Sr-90, Ru-106, Cs-137 and Ce-144) contained in the low-level radioactive effluents from the spent fuel reprocessing plant and nuclear power plant, in order to determine the decontaminability of various chemical coagulants and domestic clay mineral (montmorillonite). Phosphate process showed prominent efficiency for the removal of Ce-144, and lime-soda process did good removal efficiency for Sr-90. About Cs-137 copper-ferrocyanide process is much desirable. In phosphate or lime-soda process, most favorable removal efficiency was obtained at more than pH 11. The montmorillonite treated with sodium chloride showed a considerable improvement in the removal of the radioactive-nuclides. By a combined chemicals-montmorillionite process, the radioactive-nuclides could be more effectively removed than by the only chemicals process.

• Applied Chemistry for Engineering
• /
• v.10 no.4
• /
• pp.615-619
• /
• 1999

Polyether-clay nanocomposite was not polymerized with stearyltrimethylammonium ion exchanged montmorillonite, but it was self-polymerizable when heated with both stearyltrimethylammpmoim and m-phenylenediammonium ions intercalated montmorillonite to form polyether-clay nanocomposites. Molcular disperion of montmorillonite within the crosslinked epoxy matrix verified using X-ray diffraction and transmission electron microscopy found that the final product contains a uniform dispersion of exfoliated $10{\AA}$ thin clay layers seperated by $250{\sim}500{\AA}$of polyether polymer, thus verifying the nanocomposite structure.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.21 no.4
• /
• pp.427-438
• /
• 2023

Thermodynamic sorption modeling can enhance confidence in assessing and demonstrating the radionuclide sorption phenomena onto various mineral adsorbents. In this work, Ca-montmorillonite was successfully purified from Bentonil-WRK bentonite by performing the sequential physical and chemical treatments, and its geochemical properties were characterized using X-ray diffraction, Brunauer-Emmett-Teller analysis, cesium-saturation method, and controlled continuous acid-base titration. Further, batch experiments were conducted to evaluate the adsorption properties of Cs(I) and Sr(II) onto the homoionic Ca-montmorillonite under ambient conditions, and the diffuse double layer model-based inverse analysis of sorption data was performed to establish the relevant surface reaction models and obtain corresponding thermodynamic constants. Two types of surface reactions were identified as responsible for the sorption of Cs(I) and Sr(II) onto Ca-montmorillonite: cation exchange at interlayer site and complexation with edge silanol functionality. The thermodynamic sorption modeling provides acceptable representations of the experimental data, and the species distributions calculated using the resulting reaction constants accounts for the predominance of cation exchange mechanism of Cs(I) and Sr(II) under the ambient aqueous conditions. The surface complexation of cationic fission products with silanol group slightly facilitates their sorption at pH > 8.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.11
• /
• pp.4001-4004
• /
• 2011

Various 5-substituted 1H-tetrazole derivatives were synthesized in a simple and environmentally benign method from the reaction of aryl and benzyl nitriles with sodium azide in solvent-free media using montmorillonite K-10 clay as solid recyclable heterogeneous acidic catalyst and microwave irradiation in good yields and short reaction times.

• Journal of the Korean Ceramic Society
• /
• v.22 no.6
• /
• pp.53-57
• /
• 1985

Korean montmorillonite from Youngil district was characterized by Alkylammonium derivatives. This method was very sensitive to the basal plane spacing d and the charge in the layer charge. The result include the values of average layer charge, charge distribution, equivalent area. interlayer cationic exchange capacity (C, E, C) and total C. E. C.

• Journal of the Korean Ceramic Society
• /
• v.16 no.4
• /
• pp.201-205
• /
• 1979

Domestic Yungil bentonite (montmorillonite) was treated with 1N sodium hydroxide solution in an autoclave at several temperatures, between 100 to 200℃, for 1 to 24 hrs. The products were examined by X-ray diffraction analysis. The following concecutive reaction was valid. montmorillonite→amorphous aluminosilicate→analcime The reaction rate constants k and k' at 200℃ were 0.35hr-1 and 0.22hr-1, respectively. The activation energies for the conversion from montmorillonite to amorphous aluminosilicate and from amorphous aluminosilicate to analcime were 10 kcal/mol and 12kcal/mol, respectively.

• Journal of the Korean Ceramic Society
• /
• v.20 no.3
• /
• pp.205-210
• /
• 1983

The determination of charge density and charge distribution in montmorillonite are discussed. The method is based on cation exchange of the inorganic interlayer cations against decylammonium ion and molecular intercalation of n-alcanol. The results obtained from Yougil-bentonite show that charge density of 0.37 per unit formula and cation exchange capacity of 102.5 meq/100g.