• Journal of the Mineralogical Society of Korea
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• v.16 no.4
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• pp.295-305
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• 2003

This study aims to provide the physicochemical properties of three kinds of organo­smectites which can be diversely used in industries. Some properties of them were compared with Na­smectite. Three kinds of organo­smectites such as Hexadecyltrimethylammonium(HDTMA), Benzyldimethyltetradecylammonium(BDTDA), and Cetylpyridinium(CP) exchanged smectites were manufactured for this study. Three types of organo­smectites showed the alkaline character(pH 9), very low swelling property and viscosity, and a fast flocculation behavior because of strong hydrophobic property in contrast to hydrophilic Na­smectite. Three organo­smectites showed the strong interlayer expansion with basal spacing from $19\AA$ to $23\AA$ compared with the Na­smectite of about 12 $\AA$. Organic cations such as HDTMA, BDTDA, and CP exchanged into smectite were completely decomposed in the temperature range from $250^{\circ}C$ to $400^{\circ}C$. Generally, three organo­smectites showed the similar mineralogical, physicochemical and thermal properties. But their properties are quite different from Na­smectite. Considering economically, CP exchanged smectite would be used for the diverse utilization field in the future time.

• Journal of the Mineralogical Society of Korea
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• v.20 no.1 s.51
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• pp.1-6
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• 2007

Hectorite was synthesized by a two-step hydrothermal process from $Mg(OH)_{2}$, water glass (${\sim}30\;wt%\;SiO_{2}$) and Li-compound at $90{\pm}5^{\circ}C$. The product shows excellent dispersion and swelling properties. The mixture of the starting materials was heated in a glass vessel for the first reaction with continuous stirring and the pH of the solution was adjusted to $6{\sim}8$, resulting in the formation of a precursor of hectorite. The excess salt components were washed out from the resulting slurry and then was matured in the glass vessel for the 2nd reaction. Li compound was added during the reaction. After a 10 h retention, the gel of hectorite was formed. The XRD pattern of the synthesized one was coincided with that of natural hectorite and SEM study revealed uniform grains 50 m in diameter. The d001 basal spacing of the product moved from 12 to $17.4\;{\AA}$ after glycolation treatment. The measured value of CEC and the swelling capacity was 90 cmol/kg and $60{\sim}70\;mL/2\;g$, respectively.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.81-85
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• 2004

Nanoporous materials with nanometer-sized pores, are of great interest in the various applications such as selective adsorbents, heterogeneous catalysts and catalyst supports because of their high porosity, surface area, and size selective adsorption properties. This study is aimed to prepare nanoporous catalytic materials on the basis of two-dimersional clay by pillaring of $SiO_2$ sol particles. $SiO_2$ Pillared Montmorillonite (Si-PILM) was prepared by ion exchanging the interlayer $Ni^{2+}$ ions of clay with $SiO_2$ nano-sized particles of which the surface was modified with nicked polyhydroxy cations sach as $Ni_4(OH)_4^{4+}$. Nano-sized $SiO_2$ particles were formed by the controlled hydrolysis of tetraethyl orthosilicate (TEOS). Upon pillaring of $Ni^+$-modified $SiO_2$ nano particles between the clay layers, the basal spacing was expanded largely to $45{\AA}$ and the extremely large specific surface area ($S_{BET}$) of $760m^2/g$ was obtained.

• Economic and Environmental Geology
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• v.44 no.6
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• pp.503-511
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• 2011

The Upper Devonian Grosmont Formation in northern Alberta, Canada, underlies the erosion unconformity that formed between the Cretaceous and Upper Devonian. The formation is divided into four units on the basis of intercalated shales and showing a typical shelf environment of shallowing-upward. It was possible to separate four units(LG~UG3), considering the seismic interpretation attributes of polarity, continuity, frequency/spacing and amplitude and showing the reflection characteristics of the medium-high amplitude, medium-low frequency, good continuity, and subparallel reflection events. The formation can be interpreted as shelf or platform, based on in-situ core data. However, it is difficult, only with reflection attributes and features, to recognize the boundaries and sedimentary environment of parasequence. Therefore, we try to interprete by parasequence set in this study. The parasequence set was formed by erosion unconformity with systems tracts. The erosion unconformity can be recognized by facies data and karst, erosional surface. Grosmont carbonate deposits ranging from platform and shelf to shelf slope are; by wedge-shaped strata of characterized by complex sigmoid-oblique progradational configurations, reflecting a depositional history of upbuilding and outbuilding in response to sea-level changes. Most of the sedimentary units is interpreted as platforms under regression and lowstand environments that support is evidences. In particular, shale layer at the basal part of the highstand systems tracts represents the regressive to lowstand of sea level.

• Clean Technology
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• v.28 no.3
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• pp.249-257
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• 2022

The adsorption equilibria of nitrogen on a region of nanoporous carbonaceous adsorbent with local molecular orientation (LMO) were calculated by grand canonical Monte Carlo simulation at 77.16 K. Regions of LMO of identical size were arranged on a regular lattice with uniform spacing. Microporosity was predominately introduced to the model by removing successive out-of-plane domains from the regions of LMO and tilting pores were generated by tilting the basic structure units. This pore structure is a more realistic model than slit-shaped pores for studying adsorption in nanoporous carbon adsorbents. Their porosities, surface areas, and pore size distributions according to constrained nonlinear optimization were also reported. The adsorption in slit shaped pores was also reported for reference. In the slit shaped pores, a clear hysteresis loop was observed in pores of greater than 5 times the nitrogen molecule size, and in capillary condensation and reverse condensation, evaporation occurred immediately at one pressure. In the LMO pore model, three series of local condensations at the basal slip plane, armchair slip plane and interconnected channel were observed during adsorption at pore sizes greater than about 6 times the nitrogen molecular size. In the hysteresis loop, on the other hand, evaporation occurred at one or two pressures during desorption.

• Journal of the Mineralogical Society of Korea
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• v.22 no.1
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• pp.23-34
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• 2009

The adsorption of iodide on untreated bentonite and bentonites modified with organic cation (i.e., hexadecylpyridinium chloride monohydrate ($HDP^+$)) was investigated, and the organobentonites were characterized using uptake measurements, ${\mu}$-XRD, and electrophoretic mobilities measurement. Uptake measurements indicate that bentonite has a high affinity for $HDP^+$. Our ${\mu}$-XRD study indicates that organobentonites significantly expanded in basal spacing and organic cations were substantially intercalated into the interlayer spaces of bentonite. The electrophoretic mobility indicates that organobentonite tht is modified with organic cations in excess of the CEC of bentonite is completely different from untreated bentonite in the surface charge distribution. We found significant differences in adsorption capacities of iodide depending on the bentonite properties as follows: iodide adsorption capacities were 439 mmol/kg for the bentonite modified with $HDP^+$ at an equivalent amount corresponding to 200% of the CEC of bentonite whereas no adsorption of iodide was observed for the untreated bentonite. The molecular environments of iodine adsorbed on organobentonites were further studied using I K-edge and $L_{III}$-edge x-ray absorption spectroscopy (XAS). The X-ray absorption near-edge structure (XANES) of iodine spectra from organobentonites was similar to that of KI reference solution. Linear combination fitting of EXAFS data suggests the fraction of iodine reacted with the organic compound increased with increasing loading of the organic compound on organobentonites. In this study, we observed significant differences in the adsorption environments of iodide depending on the modified property of bentonite and suggest that an organobentonite has potential as reactive barrier material around a nuclear waste repository containing anionic radioactive iodide.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.361-361
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• 2017

The NPK are known as macro elements that affect crop growth and yield. In 1989, Cambodia Agricultural Research and Development Institute (CARDI) gave a recommendation rate of fertilizer on rice production based on soil types. This recommended rate of NPK seems however relatively low as compared to farmers' practices nowadays and the amount in the neighboring countries. The CARDI recommended rate for Prateah Lang soil type is 50kg N, $25kg\;P_2O_5$, $25kg\;K_2O\;ha^{-1}$ while recent farmers' practice rates are 55 - 64kg N, 24 - 46kg $P_2O_5$, $30kg\;K_2O\;ha^{-1}$. However, the overuse of chemical fertilizer will lead to un-preferable plant growth, insect pest, disease and economic yield. Thus, we examined the effect of different NPK application rates on the growth and yield components in Prateah Lang soil type in Takeo province to investigate appropriate rates for improving rice productivity with economic efficiency. This study was conducted from July to November during wet season in 2013. A multi-locational trial with 6 treatments (T0 - T5) of NPK rates in 5 locations (trial 1 - 5) with 3 replications was conducted. The different combinations of NPK application were employed from 0, 50, 60, 80, 100, $120kg\;N\;ha^{-1}$, 0, 25, 30 45, $60kg\;P_2O_5\;ha^{-1}$ and 0, 15, 25, 30, $45kg\;K_2O\;ha^{-1}$. Urea, DAP and KCl were used for fertilization. Split application was employed [basal: 20% of N, 100% of P and K, top dressing-1st: 40% of N (30DAT), 2nd: 40% of N (PI stage)]. Three-week-old seedlings of var. Phka Rumdoul were transplanted with 2 - 3 seedlings $hill^{-1}$ with $20cm{\times}20cm$ spacing. Plant length, tiller number at the maximum tillering stage and yield components were measured. The different rates of NPK application affected some yield components. The panicle number per hill was the most important key component followed by the spikelet number per panicle. However, the other parameters such as the filled grain percentage and 1000 grains weight had small effect or weak relation with the yield. Although the panicle number per hill had a significantly positive correlation with the stem number per hill, it was not correlated with the percentage of productive culms. The variation in the grain yield among the 5 trials was small and the difference was not significant. Although the yield tended to be higher at higher N and P application, there was no significant difference above 60kg N and $30kg\;P_2O_5$. The yield was the highest at 15, 30 and $45kg\;K_2O$ followed by $25kg\;K_2O$. The relationships between N, P and the stem number per hill were significantly linear positive, though it was not linear between K and the stem number. From these results, to increase rice productivity in the target area, farmers' effort to increase N and P input rather than CARDI recommendation up to 60kg N and $30kg\;P_2O_5$ will be sufficient considering economic efficiency. Besides, the amount of K application should be reconsidered.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.363-363
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• 2017

The NPK are known as macro elements that affect crop growth and yield. In 1989, Cambodia Agricultural Research and Development Institute (CARDI) gave a recommendation rate of fertilizer on rice production based on soil types. This recommended rate of NPK seems however relatively low as compared to farmers' practices nowadays and the amount in the neighboring countries. The CARDI recommended rate for Prateah Lang soil type is 50kg N, 25kg P2O5, 25kg K2O ha-1 while recent farmers' practice rates are 55 - 64kg N, 24 - 46kg P2O5, 30kg K2O ha-1. However, the overuse of chemical fertilizer will lead to un-preferable plant growth, insect pest, disease and economic yield. Thus, we examined the effect of different NPK application rates on the growth and yield components in Prateah Lang soil type in Takeo province to investigate appropriate rates for improving rice productivity with economic efficiency. This study was conducted from July to November during wet season in 2013. A multi-locational trial with 6 treatments (T0 - T5) of NPK rates in 5 locations (trial 1 - 5) with 3 replications was conducted. The different combinations of NPK application were employed from 0, 50, 60, 80, 100, 120kg N ha-1, 0, 25, 30 45, 60kg P2O5 ha-1 and 0, 15, 25, 30, 45kg K2O ha-1. Urea, DAP and KCl were used for fertilization. Split application was employed [basal: 20% of N, 100% of P and K, top dressing-1st: 40% of N (30DAT), 2nd: 40% of N (PI stage)]. Three-week-old seedlings of var. Phka Rumdoul were transplanted with 2 - 3 seedlings hill-1 with $20cm{\times}20cm$ spacing. Plant length, tiller number at the maximum tillering stage and yield components were measured. The different rates of NPK application affected some yield components. The panicle number per hill was the most important key component followed by the spikelet number per panicle. However, the other parameters such as the filled grain percentage and 1000 grains weight had small effect or weak relation with the yield. Although the panicle number per hill had a significantly positive correlation with the stem number per hill, it was not correlated with the percentage of productive culms. The variation in the grain yield among the 5 trials was small and the difference was not significant. Although the yield tended to be higher at higher N and P application, there was no significant difference above 60kg N and 30kg P2O5. The yield was the highest at 15, 30 and 45kg K2O followed by 25kg K2O. The relationships between N, P and the stem number per hill were significantly linear positive, though it was not linear between K and the stem number. From these results, to increase rice productivity in the target area, farmers' effort to increase N and P input rather than CARDI recommendation up to 60kg N and 30kg P2O5 will be sufficient considering economic efficiency. Besides, the amount of K application should be reconsidered.