• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.412-417
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• 2007

This study was to elucidate the effects of layered double hydroxides(LDHs) application on the chemical properties of the soils along with the fate of the applied LDHs. The effects of LDHs application were compared with those of calcium carbonate widely used for the neutralization of acidic soils. Incorporation of LDHs into the soil resulted in higher pH value and $Mg^{2+}$ content in soil leachate than that of $CaCO_3$ treatment. There was no significant difference in water-soluble P content in both the treatments. However, $Al^{3+}$ and $Si^{4+}$ contents were decreased by LDHs and $CaCO_3$ treatment, even though a large amount of $Al^{3+}$ was released into soil solution with the disintegration of LDHs framework. LDHs structure in soil was gradually disintegrated from the its original layered structure under acidic condition of soil. Therefore, this study suggests that LDHs could be utilized as a carrier of functional substances to enhance the efficiency of various ago-chemicals without any ill effects on the soil environments.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.2
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• pp.59-66
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• 1998

The feasibility of usage of sludge from water treatment plant and chalk from schools and institutes was investigated to remove the phosphorus in the lakes which induce the eutrophication every year. In this study phosphorus removal efficiencies of sludge and chalk were investigated by changing various factors. Higher phosphorus removal efficiency using larger particle size of chalk was observed which means that the surface area is not an important factor in removing phosphorus in aqueous phase. The proper shaking time and temperature were 2 hours and $25^{\circ}C$, respectively. The removal efficiency using sludge from water treatment plant was almost 100%, which is similar to those of CaO and $Ca(OH)_2$. It means that sludge can be reused in removing phosphorus. It was also found that chalk was better in removing phosphorus under alkaline condition and sludge was better under acidic condition. About 75% phosphorus removal efficiency was observed using sludge from the water sample in Lake Sihwa.

• Geomechanics and Engineering
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• v.15 no.6
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• pp.1135-1141
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• 2018

Volume changes of soils induced by inorganic acids cause severe foundation and superstructure failures in industrial buildings. This study aimed to assess the potential of fly ash to control volume changes in soils under acidic environment. Two soils such as black cotton soil predominant with montmorillonite and kaolin clay predominant with kaolinite were used for the present investigation. Both soils exhibited an increase in swelling subjected to phosphoric acid contamination. Ion exchange reactions and mineralogical transformations lead to an increase in swelling and a decrease in compressibility in black cotton soil, whereas phosphate adsorption and mineral dissolution lead to an increase in swelling and compressibility in case of kaolin clay. Different percentages of Class F fly ash obtained from Ramagundam national thermal power station were used for soil treatment. Fly ash treatment leads to significant reduction in swelling and compressibility, which is attributed to the formation of aluminum phosphate cements in the presence of phosphoric acid.

• Environmental Analysis Health and Toxicology
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• v.6 no.3_4
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• pp.143-148
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• 1991

This study was carried out to develop the low-priced adsorbent by synthesizing the zeolite of high cation exchange capacity with the natural zeolite and to examine the adsorbing ability of this zeolite. The dominant clay minerals were clinoptilolite and mordenite in natural zeolite, while phillipsite in the synthesized zeolite. Adsorption reaction of $NH_4^{+}$on zeolite was reached equilibrium after 2 hrs. The amount of adsorption was increased with increasing the concentration of $NH_4^{+}$or the pH of suspension. The cation exchange capacity of zeolite was slightly decreased below pH 4.0 by acidic treatment. It was estimated that the ability of the synthesized zeolite to remove noxious ions was better than that of the natural zeolite.

• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.35-40
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• 1999

For application of a yellow pigment as food additives, stability of a water-soluble yellow pigment from Bacillus sp. PY123 was investigated. The yellow pigment from Bacillus sp. PY123 was purified with pH treatment, activated carbon and silica gel column chromatography. The partial purified yellow pigment appeared only one spot on silica gel TLC after 12 evaporation and under irradiation of UV 253nm at dark room. Rf value of the pigment was measured at 0.04 and 0.12 with development of a solvent mixture (Butanol : Acetic acid : water = 4 :1:5) and a solvent mixture (Isopropanol : Ammonia : Water = 9 :1: 2), respectively, The partial purified pigment appeared a white fluorescence under UV365nm irradiation. The partial purified yellow pigment had a main peak and a minor peak on HPLC using 20mM phosphate buffer(pH 7.0) at 1ml/min flow rate. The partial purified pigment was stable at heat treatment, acidic pH, oxide-reductants and surfactants.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.2
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• pp.191-197
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• 1994

Relationships between surface structure and adsorption properties of smoke components were investigated in surface-modified and un-modified activated carbon filter cigarettes. Commercially available activated carbon was treated with nitric acid and hydrogen peroxide as oxidant, and their pore volume, surface structure, BET surface area, pore type and size were studied. BET surface area and pore volume were decreased by nitric acid treatment, but median pore diameter was 8.1 $\AA$, which showed better development of pore compared with that of un-modified activated carbon, 6.9 $\AA$. In case of hydrogen peroxide treatment, BET surface area and pore volume were increased. Their pore was found to be a slit type based on V-t plot analysis. Neutralization capacities for bases of different strength (NaHCO3, Na2CO3, NaOEt and NaOH) showed that the majority of the acidic surface groups are of weak acidity. Modification of the activated carbon surface led to a slight change in adsorption properties when analyzing the smoke of triple-filter cigarette with surface-modified activated carbon.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.43-46
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• 2004

Multi-walled carbon nanotubes (MWNTs) produced by chemical vapor deposition were treated with acidic solution for purification and oxidization of CNTs. The surface modification of the oxidized CNTs was achieved by amine treatment and oxygen plasma treatment. The functionalized CNTs were embedded in the epoxy resin by sonication method and the resulting composite was investigated by FESEM. Rheological and mechanical properties of nanocomposites were measured by AR2000 and Instron. The rheological properties and dispersion of modified CNTs/epoxy composites were improved as CNTs were modified, because the modification of CNTs led to a improvement interaction between the CNTs and the epoxy resin. In addition to this, mechanical properties are also improved because of the effective stress transfer between the CNTs and the polymer.

• YAKHAK HOEJI
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• v.38 no.4
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• pp.451-454
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• 1994

In accordance with reported references, 8-methyl-8,14-cycloberbine was derived from berberinephenolbetaine. On acidic treatment the 8-methyl-8,14-cycloberbines were converted easily to the compounds $1{\sim}7$ in good yields. We developed a novel method for a synthesis of the C8-N bond adduct compounds 8 and 9 from 8-methyl-8,14-cycloberbine by treatment with oxalyl chloride, and 1,3-dichloroaceton.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.8
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• pp.1011-1019
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• 1998

The natural dyestuff(squid ink) was manufactured from squid ink by boiling in 0.1% NaOH solution and powdering in freeze dryer. Cotton, wool, silk and nylon fabrics were dyed under several conditions using the manufactured squid ink to investigate the dyeability and color fastness. Dyeing was operated in acidic dyebath of pH 4 because the squid ink is anionic. Dyeabilities on wool, silk and nylon fabrics were good, especially silk fabrics were dyed deeper than others because of being amine group. But dyeability on cotton fabrics was low and developed with chitosan treatment. All the dyed fabrics showed excellent in color fastness to crocking and laundering. Also light fastness of them were excellent except nylon. The light fastness of dyed-nylon fabrics was as poor as grade 1, but they could be improved to grade 4 by aftertreatment with gallicacid. Useing the natural dyestuff-squid ink powder, we could execute whenever we want to dye fabrics in the adequate concentration. Dyeabilities were developed according to repeating times of dyeing and the increased dye concentration. We could recycle the wasting sources.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.43.2-43.2
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• 2010

Most of previous methods for the dispersions of carbon nanotube were achieved by various chemical functionalizations. In this study, however, we generated highly water dispersed carbon nanofibers by altering intrinsic materials property only, such as crystallinity of outer layers of carbons, without chemical treatment. Although most of chemical functionalization requires acidic treatment and may degrade their chemical functions by interacting with other molecules, suggested strategy demonstrated a simple but chemically non-degradable carbon nanotube for the application of various medical applications, such as drug delivery system and implant coatings.Furthermore, protein adsorption was increased by the reducing surface crystalinity since outer activated surface induced more adsorption of oxygen and eventually greater protein adsorption than pristine carbon nanofibers.