• Journal of the Korean Ceramic Society
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• v.43 no.5 s.288
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• pp.315-319
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• 2006

There have been some studies on the use of coal waste as a raw material for clay bricks due to the lack of naturally producing minerals. It can help resolving the problems of pollution, forest conservation and flood control by utilizing coal waste. However, high content of carbon materials usually leads to the black core in clay bricks after firing process, and diminishes the mechanical and aesthetical properties of clay brick. In this study, the effect of firing process is investigated for the removal of black core in clay bricks with carbon content. The removal kinetics of black core are also compared and investigated with the firing schedule and black core removal.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.199-205
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• 2023

Arsenic is a highly toxic element, and its contamination is widespread around the world. The natural materials with high selectivity and efficiency toward pollutants are important in wastewater treatment technology. In this study, the mesoporous synthetic hectorite was synthesized by facile hydrothermal crystallization of gels comprising silica, magnesium hydroxide, and lithium fluoride. Additionally, the naturally available clay was modified using zirconium at room temperature. Both synthetic and modified natural clays were employed in the removal of arsenate from aquatic environments. The materials were fully characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform-infrared (FT-IR) analyses. The synthesized materials were used to remove arsenic (V) under varied physicochemical conditions. Both materials, i.e., Zr-bentonite and Zr-hectorite, showed high percentage removal of arsenic (V) at lower pH, and the efficiency decreased in an alkaline medium. The equilibrium-state sorption data agrees well with the Langmuir and Freundlich adsorption isotherms, and the maximum sorption capacity is found to be 4.608 and 2.207 mg/g for Zr-bentonite and Zr-hectorite, respectively. The kinetic data fits well with the pseudo-second order kinetic model. Furthermore, the effect of the background electrolytes study indicated that arsenic (V) is specifically sorbed at the surface of these two nanocomposites. This study demonstrated that zirconium intercalated synthetic hectorite as well as zirconium modified natural clays are effective and efficient materials for the selective removal of arsenic (V) from aqueous medium.

• Journal of the Korean Ceramic Society
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• v.18 no.4
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• pp.219-228
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• 1981

To clarify influences of silicious raw materials on mineralogcal and petrological properties in clinkering process clay, shale, quartzite, sand and coal ash have been used as silicious raw materials. The tests on thermal properties, reactivity and burnability of raw mixtures which have different silicious raw materials respectively have been made by means of X-ray diffractometry, differential thermal analysis, optical microscopy and transmission electron microscopy. Limestone contains coarse crystalline grains which show 0.1-1.0mm and its decarbonation temperature is 86$0^{\circ}C$. Reaction temperatures among raw mixtures have been determined by X-ray diffractometry and their results are as follows; clay minerals under 1, 00$0^{\circ}C$, mica group, 100$0^{\circ}C$-110$0^{\circ}C$, feldspar group, 1, 10$0^{\circ}C$-1, 20$0^{\circ}C$ and quartz 1, 20$0^{\circ}C$-1, 30$0^{\circ}C$. Burnabilities of raw mixtures of different temperatures have been found that they mainly depend upon their mineral contents in silicious raw materials and their order is as follows; $clay\geq shale\gg quartzite \geq sand$.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.4
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• pp.239-246
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• 2008

This research tried to find out the optimum fabrication method of calcined clay granules comprising zeolite. Kaolin clay and natural zeolite powder were used as raw materials of calcined clay, and silica stone powder was used for controlling the porosity of the granules. The granulation was performed with two kinds of granulators: a pan granulator and a high-shear mixer granulator. Various granules were fabricated by the mixing ratios and the rotation speeds of the granulators, and were heated from 400 to $700^{\circ}C$ at $100^{\circ}C$ interval. The crushing strength, pore size distribution, and CEC of the granules were measured. The evaluation method for the resistance of granules to human treading was created and the tests were conducted at dry and wet conditions. The resistance and crushing strength improved in proportion to the rotation speed of the granulator and the heating temperature, but the CEC decreased. The pellet made by the pan granulator did not have the strength against treading upon heating to below $700^{\circ}C$, but the pellet made by the high-shear mixer granulator endured the treading test upon heating to over $500^{\circ}C$

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.5
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• pp.535-541
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• 1996

A seed pelleting technique was developed for easy handling of small tobacco seeds (variety, NC82) and for direct seeding in temperary planting bed or in field. The mixture of pelleting material, binder and seeds were moulded in cylindrical holes sized 2 mm diameter and 2 mm height in a plastic plate. Bentonite and cellulose powder were good materials to make pellets with CMC as binder, and bentonite formed the hardest pelleted seeds among the materials. The number of the pelleted seeds made with the same weight of the materials was different with materials used and the number of seeds contained in a pelleted seed could be controlled by mixture ratio of materials and seeds. The seedless pellets ranged 6.9 to 16.0% at the ratio of pelleting material and seed for 2~3 seeds in a pellet. The moisture absorption rate at 100% RH and $25^{\circ}C$ was greater in the order of clay < bentonite < cellulose. Germination rates of pelleted seeds with bentonite and cellulose were similar to that of usual seed, but it was significantly lower with clay pelleted seeds.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.3
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• pp.147-152
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• 2010

In this study, the artificial coarse aggregate was manufactured by using coal ash and low grade clay. The characteristics of a coal ash-clay system were investigated using XRD, XRF, TG-DTA, SEM and Dilatometer with various coal ash contents. The chemical compositions are the fly ash, bottom ash and clay, $Al_2O_3$ are 28.5 wt%, 32.4 wt% and 18.1 wt%, and $SiO_2$ are 33.0 wt%, 53.7 wt% and 68.4 wt% in weight ratio, respectively. The shrinkage of specimens started at around $850^{\circ}C$ and changed little up to $1100^{\circ}C$, but increased markedly at above $1100^{\circ}C$. The shrinkage rate is strongly related to the decarbonization amount of coal ash. At the sintering temperature $1150^{\circ}C$, it was found that quartz, mullite, anorthite and albite phase exist in all specimens. It was found that bottom-clay system specimen sintered at $1150^{\circ}C$ had a good compressive strength of 87.5 kg/$cm^2$, and the compressive strength of bottom-clay specimen was higher than that of fly-clay system specimen. The reusability of coal ash as a raw material in the process of shotcrete resources such as artifical coarse aggregate is highly expected.

• Journal of Marine Bioscience and Biotechnology
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• v.6 no.1
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• pp.17-25
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• 2014

Periodically, harmful algal blooms (HABs) have occurred, with impacts on various areas including public health, tourism, and aquatic ecosystems, especially aquacultured and caged fisheries. To prevent or manage invasions of HABs into fish farms on an emergency basis, many methods have been proposed. Frequently over the past 30 years in coastal countries, treatments of clay and clay mixed with polyaluminum chloride (PAC) and chitosan have been tested for HAB-removal effectiveness in both the laboratory and the field. In Korea, yellow loess clay (hwangto) has been dispersed using electrolytic clay dispensers, both to decrease the amount of yellow loess clay's usage in containers and enhance HAB-removal efficiency. However, this emergency method has limitations, among which is the requirement for more effective controlling agents for field applications. Thus, in this paper, we review technologies for clay-based red tides prevention and control and their limitations, and, further, introduce next-generation algicidal technologies for the emergency protection of fish farms.

• Journal of Conservation Science
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• v.33 no.6
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• pp.497-506
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• 2017

An investigation on the records of old document was conducted to identify the producing area of white clay and there were on-the-spot surveys to secure raw materials of white clay pigment. Based on the survey results, six raw materials were obtained from the region of Gangwon-do and Gyeongsang-do, South Korea and white clay pigment was subsequently manufactured by applying the hydraulic elutriation method. The results show that the major constituent minerals of YBW, HBW, and MCW were quartz and plagioclase, whereas SGW, HOW, and HGW were composed of clay minerals such as kaolinite and illite. HGW showed the highest $L^*$-value of 92.9. HOW and HGW showed an opacity of 94.1% and 89.6%, respectively, and they had excellent spreadability (270.3 mm and 223.3 mm, respectively). Therefore, HGW, HOW, and SGW have excellent characteristics in terms of color, opacity, and spreadability, and are considered to be highly applicable as white pigments for the Dancheong.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.211-220
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• 2012

The numerical modeling and simulation have been used increasingly as tools for examining and interpreting the bulk structure and properties of materials. The use of molecular dynamics (MD) simulations to model the structure of materials is now both widespread and reasonably well understood. In this research, we introduced the numerical method to calculate the physico-chemical properties such as a diffusion coefficient and a viscosity of clay mineral. In this research, a series of MD calculations were performed for clay mineral and clay-water systems, appropriate to a saturated deep geological setting. Then, by using homogenization analysis (HA), the diffusion coefficients are calculated for conditions of the spatial distribution of the water viscosity associated with some configuration of clay minerals. This result of numerical analysis is quite similar to the previous experimental results. It means that the introduced numerical method is very useful to calculate the physico-chemical properties of clay minerals under various environmental conditions.

• Current Research on Agriculture and Life Sciences
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• v.31 no.1
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• pp.18-24
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• 2013

This work attempted to fabricate organic/inorganic nanocomposite by combining organic cellulose nanofibrils (CNFs), isolated by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation of native cellulose with inorganic nanoclay. The morphology and dimension of CNFs, and tensile properties and thermal stability of CNF/clay nanocomposites were characterized by transmission electron microscope (TEM), tensile test, and thermogravimetry (TG), respectively. TEM observation showed that CNFs were fibrillated structure with a diameter of about $4.86{\pm}1.341nm$. Tensile strength and modulus of the hybrid nanocomposite decreased as the clay content of the nanocomposite increased, indicating a poor dispersion of CNFs or inefficient stress transfer between the CNFs and clay. The elongation at break increased at 1% clay level and then continuously decreased as the clay content increased, suggesting increased brittleness. Analysis of TG and derivative thermogravimetry (DTG) curves of the nanocomposites identified two thermal degradation peak temperatures ($T_{p1}$ and $T_{p2}$), which suggested thermal decomposition of the nanocomposites to be a two steps-process. We think that $T_{p1}$ values from $219.6^{\circ}C$ to $235^{\circ}C$ resulted from the sodium carboxylate groups in the CNFs, and that $T_{p2}$ values from $267^{\circ}C$ to $273.5^{\circ}C$ were mainly responsible for the thermal decomposition of crystalline cellulose in the nanocomposite. An increase in the clay level of the CNF/clay nanocomposite predominately affected $T_{p2}$ values, which continuously increased as the clay content increased. These results indicate that the addition of clay improved thermal stability of the CNF/clay nanocomposite but at the expense of nanocomposite's tensile properties.