• Environmental Engineering Research
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• v.25 no.2
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• pp.186-196
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• 2020

Pillared clays with Zr and Fe/Cu/Zr polycations have been prepared from natural clays found in large deposits of Kazakhstan and assessed as catalysts for the catalytic wet peroxide oxidation (CWPO), using 4-nitrophenol (4-NP) as model compound. The performance of the catalysts was followed by measuring the concentration of 4-NP, H₂O₂ and the total organic carbon (TOC), considering C_4-NP = 5 g L^-1, $C_{H_2O_2}$ = 17.8 g L^-1, C_cat = 2.5 g L^-1, initial pH = 3.0 and T = 50℃. At those selected conditions, the pillared clays showed higher activity than natural clays in the CWPO of 4-NP. The conversion of the model pollutant was complete when Fe/Cu/Zr-PILCs were used, with the TOC removal reaching 78.4% after 24 h with the best Fe/Cu/Zr-PILC. The H₂O₂, 4-NP and TOC time-evolution was well described by a kinetic model based on TOC lumps in three blocks, considering the initial TOC (corresponding to 4-NP), the production of oxidizable intermediates and the formation of refractory products.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.282-290
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• 1982

Several cation exchanged-layer silicate catalysts were prepared from acid clay mainly consisted of montmorillonite, and their catalytic activities for the ethylene polymerization were studied at room temperature. It was found that over$Ni^{2+}$ -Mont, dimerization of ethylene to n-butene proceeded selectively.$Ni^{2+}$ -Mont was activated by evacuation at elevated temperature, giving a maximum temperature, 150$^{\circ}$C . The variations in catalytic activities were closely correlated to the acidity of the catalysts.$Cr^{3+}$ -Mont exhibited a high activity for the polymerization, showing, a maximum at the evacuation temperature of 450$^{\circ}C$. The active site in $Cr^{3+}$-Mont was considered to be $Cr^{3+}$ ion.

• Explosives and Blasting
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• v.18 no.3
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• pp.99-106
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• 2000

The geology of Nogsan industrial estate area, Pusan, Korea consists mainly of andesitic rocks, rhyolitic rocks and hornblende granite. They are then intruded by basic and acidic dikes. All of the igneous activities in this area are in Cretaceous time, that is the lower part of Silla group in Gyoungsang basin. Andesitic volcanic rocks are distributed in two separate basines: Saengok basin and Doodong basin. Although both basines contain andesite and andesitic breccia(Kab), younger andesitic activity was more active to the western Doodong basin giving very little influence on the eastern Saengok basin. Sediments in the area are quarternaly alluvium and colluvium. Alluvium is very thick and consists mainly of silt and clay deposited as delta deposits at the mouth of Nakdong river. Colluvium in the area is short distributary channel deposits. The area is largely filled with socks and sediments to build industrial estates especially on the delta deposits at Shinhodong area and on the shoreline mud bed between Yongwondong and Shinhodong. A careful investigation to avoid the possibility of a large scale mud flow is suggested because it could be trigered by many reason such as an earthquake or a flood on the land where a heavily loaded salt-water may soaked into the muddy bed lying on the granitic basement gently dipping toward the ocean. Althouth the area is in the Yangsan fault zone no ground evidence of fault can be seen despite the RESTEC sattlite image gives excelent traces of linearments in the area.

• Journal of Navigation and Port Research
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• v.33 no.2
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• pp.161-166
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• 2009

Lactobacillus sp., Acetobacter sp. and yeast were the most dominant organisms in the EM stock culture and subculture product. Lactic acid bacteria and yeast were able to grow in the fermentation process utilizing seawater. EM treatment of higher concentrations using EM stock culture and EM clay balls (1% or 4%) contributed to an early removal of malodor and an increase of DO in the polluted sediments, indicating an odor-removing activity of EM. The EM treatment of higher concentrations (1% or 4%) somewhat appeared to modify the microbial communities within the sediments, which was confirmed by existence of a few unique fragments from the stock culture based on PCR-DGGE. It still remains to be elucidated that EM cultures were directly involved in the malodor removal and potential sediment bioremediation.

• Geomechanics and Engineering
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• v.32 no.6
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• pp.601-613
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• 2023

Low liquid limit silt, widely distributed in the middle and down reaches of Yellow River, has the disadvantages of poor grading, less clay content and poor colloidal activity. It is very easy to cause vehicle jumping at the bridge-embankment transition section when the low liquid limit silt used as the backfill at the abutment back. In this paper, a series of laboratory tests were carried out to study the physical and mechanical properties of the low liquid limit silt used as back filling. Ground granulated blast furnace slag (GGBFS) was excited by active MgO and hydrated lime to solidify silt as abutment backfill. The optimum ratio of firming agent and the compaction and mechanical properties of reinforced soil were revealed through compaction test and unconfined compressive strength (UCS) test. Scanning electron microscope (SEM) test was used to study the pore characteristics and hydration products of reinforced soil. 6% hydrated lime and alkali activated slag were used to solidify silt and fill the model of subgrade respectively. The pavement settlement regulation and soil internal stress-strain regulation of subgrade with different materials under uniformly distributed load were studied by model experiment. The effect of alkali activated slag curing agent on curing silt was verified. The research results can provide technical support for highway construction in silt area of the Yellow River alluvial plain.

• The Journal of Engineering Geology
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• v.27 no.4
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• pp.489-500
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• 2017

It is not rare that pseudotachylite, dark colored rock with glassy texture, is recognizable in deep core samples drilled up to 900 m from the surface. Pseudotachylite with widths varying few to 20 cm is sharply contacted or interlayered with the host rocks composed of Jurassic granite and Precambrian amphibolite gneiss, showing moderately ductile deformation or slight folding. Pseudotachylite occurring at varying depths in the deep drill core are slightly different in texture and thickness. There is evidence of fault gouge at shallower depths, although brittle deformation is pervasive in most drill cores and pseudotachylite is identified at random depth intervals. Under scanning electron microscope (SEM), it is evident that the surface of pseudotachylite is characterized by a smooth, glassy matrix even at micrometer scale and there is little residual fragments in the glass matrix except microcrystals of quartz with embayed shape. Such textural evidence strongly supports the idea that the pseudotachylite was generated through the friction melting related to strong seismic events. Based on X-ray diffraction (XRD) quantitative analysis, it consists of primary minerals such as quartz, feldspars, biotite, amphibole and secondary minerals including clay minerals, calcite and glassy materials. Such mineralogical features of fractured materials including pseudotachylite indicate that the fractured zone might form at low temperatures possibly below $300^{\circ}C$, which implies that the seismic activity related to the formation of pseudotachylite took place at shallow depths, possibly at most 10 km. Identification and characterization of pseudotachylite provide insight into a better understanding of the paleoseismic activity of deep grounds and fundamental information on the stability of candidate disposal sites for high-level radioactive waste.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.1
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• pp.23-28
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• 1987

A series of field and laboratory experiments were conducted to find out the changes of some soil chemical constituents in different soil depth with three different soil textures as Bongnam-clayey, Gwanghwal-silty loam and Mangyeong fine sandy soil on the assessment of reclamation duration in Fluvio-marine soil. The result obtained were summarized as follows; 1. Exchangeable potassium, calcium, magnessium, sodium with manganes, silica and cation exchange capacity were remarkably decreased with assessment of reclamation duration. Decreasing tendency was pronounced more in sandy soil than silty loam or clayly soil. 2. Soil organic matter content in top soil was increased with increasing of reclamation years. From reclamation time, about 30 years in clayly and about 80 years in silty loam and sandy soil were necessary for the maintanance of averaged organic matter content to 2.5%. 3. Potassium activity ratio ($K/{\sqrt{Ca+Mg+Na}}$) was differed with soil depth, soil texture and assessment of reclamation duration. About 50 years is may be necessary for the maintanance of potassium activities ratio in ordinary paddy soil of 0.05-0.2. 4. Percent of adsorbed sodium (PAS), ratio of adsorbed sodium (RAS) and ratio of sodium adsorbtion(RSA) were remarkably decreased with assessment of reclamation duration. Specially, decreasing tendency was pronounced more in sandy soil than silty loam and clayly soil 5. Amount of clay content in subsoil was appearently decreased during 30 years of reclamation, but clay contents in top soil was appearently decreased 50 years after reclamation.

• Korean Journal of Medicinal Crop Science
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• v.16 no.1
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• pp.44-50
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• 2008

The cultivation boundary areas and biological activator efficacies of Vitex rotundifolia, Tetragonia tetragonoides and Glehnia littoralis were investigated. Investigation of coastal areas revealed the East and West cultivation boundary areas of Vitex rotundifolia and Gelhnia littoralis to be the Taean Peninsula, Taean-gun and Gangwon-do, Donghae-City. The East and West coastal cultivation boundary areas of Tetragonia tetrragonoides are Jeollanam-do and Kyeongsangbuk-do, Ulleung-gun. The natural habitat is less than 200 m from the coastal area. Most of the Vitex rotundifolia, Tetragonia tetragonoides and Glehnia littoralis grow naturally in a region of mixed sand, clay and loam, in direct sunlight. No dominant vegetation was located. To analyze anti-inflammatory efficacy, RAW 264.7 cells were used. Vitex rotundifolia, Tetragonia tetragonoides and Glehnia littoralis inhibited inflammation by 37%, 12% and 10% in $100{\mu}g/m{\ell}$, respectively. However, the anti-inflammatory efficacy of Glehnia littoralis was invalid. Analysis of anti-cancer activity was accomplished using HL-60 cells. Glehnia littoralis revealed 60% and 72% inhibition activity in $100{\mu}g/m{\ell},\;and\;200{\mu}g/m{\ell}$ respectively. No cytotoxicity inhibition activity was investigated in Vitex rotundifolia and Tetragonia tetragonoides.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.395-401
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• 2009

The smectite-illite (SI) reaction is a ubiquitous process in siliciclastic sedimentary environments. For the last 4 decades the importance of smectite to illite (S-I) reaction was described in research papers and reports, as the degree of the (S-I) reaction, termed "smectite illitization", is linked to the exploration of hydrocarbons, and geochemical/petrophysical indicators. The S-I transformation has been thought that the reaction, explained either by layer-by-layer mechanism in the solid state or dissolution/reprecipitation process, was entirely abiotic and to require burial, heat, and time to proceed, however few studies have taken into account the bacterial activity. Recent laboratory studies showed evidence suggesting that the structural ferric iron (Fe(III)) in clay minerals can be reduced by microbial activity and the role of microorganisms is to link organic matter oxidation to metal reduction, resulting in the S-I transformation. In abiotic systems, elevated temperatures are typically used in laboratory experiments to accelerate the smectite to illite reaction in order to compensate for a long geological time in nature. However, in biotic systems, bacteria may catalyze the reaction and elevated temperature or prolonged time may not be necessary. Despite the important role of microbe in S-I reaction, factors that control the reaction mechanism are not clearly addressed yet. This paper, therefore, overviews the current status of microbially mediated smectite-to-illite reaction studies and characterization techniques.

• The Korean Journal of Ecology
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• v.28 no.4
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• pp.181-188
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• 2005

Methods used to study carbon sequestration by soil aggregates have often excluded the concentric spatial variability and other dynamic processes that contribute to resource accessibility and solute transport within aggregates. We investigated the spatial gradients of carbon (C) and nitrogen (N) from the exterior to interior layers within macroaggregates, $6.3\sim9.5$ mm, sampled from conventional tillage (CT) and no tillage (NT) sites of a Hoytville silt clay loam. Spatial gradients in C accumulation within macroaggregates were related to the differences in C dynamics by determining the sizes and the turnover rates of fast C and slow C pools in the concentric layers of aggregates. Aggregate exteriors contained more labile C and were characterized by greater C mineralization rates than their interiors in both management systems. In contrast, C in the interior layers of aggregates was more resistant in both systems. These results indicated the spatial differentiation of C dynamics within macroaggregates, i.e., exterior layers as a reactive site and interior layers as a protective site. Greater total C distribution in the exterior layers of NT aggregates indicated more influx of C from the macropores in interaggregate space than C. mineralization (net gain of C), whereas lower C distribution within the exterior layers of CT aggregates indicated net loss of C by greater C mineralization than C influx. We found total C increased approximately 1.6-fold by the conversion of CT soils to NT management systems for a period of 36 years. Differences in total accumulation and the spatial distribution of C within aggregates affected by management were attributed to the differences in aggregate stability and pore networks controlling the spatial heterogeneities of resource availability and microbial activity within aggregates.