• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.301-310
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• 2006

Smectites were synthesized from Na-P type and Na-A type zeolites by the hydrothermal synthetic method, and their physicochemical properties were studied. The optimal synthetic conditions for producing smectite were $290^{\circ}C$, 72 hr and $75{\sim}100kgf/cm^2$ in autogenous pressure. pHs of initial reaction solutions for the synthesis of smectites from Na-P type and Na-A type zeolite s were pH 6 and pH 10, respectively. The synthetic smectite was confirmed as $12{\AA}$-beidellite by a series of analysis such as X-ray diffraction analysis with random and oriented mounts, ethylene glycol treatment, and Greene-Kelly test, and their several physicochemical properties were studied.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.217-227
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• 2023

Crystalline calcium carbonate (CaCO₃) occurs in various geological and aqueous environments as calcite, aragonite, and vaterite. These minerals also have practical applications in engineered settings. Synthetic methods of calcium carbonate have been developed for scientific research and technical applications. For example, these methods have become widely adopted for studying the formation of CaCO₃ minerals and (geo-)chemical processes involving these minerals in natural and engineered systems. Furthermore, these methods have the potential to be applied in various technical and biomedical fields. Water-based synthesis is particularly important for simulating the formation of calcium carbonate minerals in natural aqueous environments. This review paper describes the procedures and experimental conditions for water-based synthetic methods of each calcium carbonate polymorph, compares the morphological and structural features of the resulting crystals, and analyzes the crystallization mechanisms.

• Journal of the Mineralogical Society of Korea
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• v.11 no.2
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• pp.117-125
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• 1998

Crystallization behavior of platinum minerals within Pt-Sb-Bi bearing ore magmas and mineralogical properties of the existing minerals were investigated at 1,00$0^{\circ}C$ by synthetic experiment. High purity reagents were used as starting materials and silica tubings as containers. Reaction products were analysed by reflecting microscopy, X-ray diffraction, electron probe microanalysis, and micro-hardness test. Stable minerals at 1,00$0^{\circ}C$ are platinum, electron probe microanalysis, and micro-hardness test. Stable minerals at $1,000^{\circ}C$ are platinum, stump-flite (PtSb) and geversite (PtSb2). They are in equilibrium with liquid (ore magma). Platinum contains considerable amount of Sb of 7.5 at.%, whereas Bi only up to 0.9 at.%. Pure stumpflite is hexagonal with space group P63/mmc, and unit cell parameters are a=4.1318(6), c=5.483(1)$\AA$. VHN50=417(2)$\AA$. Geversite has cubic structure with space group Pa3. Cell parameters are a=6.4373(2)$\AA$ and Vicker hardness values VHN50=663.5 (566~766). Both stumpflite and geversite show solid solution and their end-members are Pt48.8Sb40.7-Bi10.5, and Pt33.7-Sb59.8Bi6.5, respectively. Although stumpflite (m.p. $1,043^{\circ}C$) and unnamed PtBi (m.p. 7$65^{\circ}C$) do not form a complete solid solution at $1,000^{\circ}C$, they are known, at $600^{\circ}C$, to form a continuous solid solution. Geversit (m.p. $1,226^{\circ}C$) also forms complete solid solution with insizwaite (m.p. $660^{\circ}C$). Unit cell dimensions of the minerals above increases with the amount of Bi substituting for Sb.

• Journal of the Korean Ceramic Society
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• v.31 no.9
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• pp.1076-1086
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• 1994

This study covers synthetic effect of the various hydrothermal treatments on formation of artificially made kaolinite mineral. The hydrothermal treatment includes the temperature treatment with time duration, addition of seeds, particle size of the starting material used, pH variation and the different types of organic acids. A colloidal silica and alumina sol which are commercially available are used for this study. A colloidal silica and alumina sol are mixed by the atomic ratio of Al/Si = 1, based on the theoretical kaolinite composition and calcined at $600^{\circ}C$ for 8 hours duration. It was found that the kaolinitic clay mineral was well developed; thereby, the different patterns of crystalline mineral are appeared. Spherical type as a crystal form was distinctively formed at the temperature of 20$0^{\circ}C$ to 25$0^{\circ}C$ with short duration time, while platy type as a crystal was highly yielded at 300~35$0^{\circ}C$. Moreover, by adding more than 20 wt% of seed as the natural kaolinitic clay to the starting material is widely distributed and developed when 2 ${\mu}{\textrm}{m}$ or less particle size of the starting material is used; also, when they are heat-treated at the temperature of 25$0^{\circ}C$ with 5 hours duration. With respect of the effect of pH variation on formation of the synthetic kaolinite minerals, the crystalline minerals are highly yielded at less than pH 2 and gradually diminished at more than pH9. Regarding to the effect of different acids on development of the kaolinite mineral, the organic acids with high chelating capacity produces good formation of crystalline minerals; whereas, amine radical-(NH2) is not an effective agent to generate the crystalline minerals.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.522-533
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• 2014

Bionanotechnology has revolutionized nanomaterial synthesis by providing a green synthetic platform using biological systems. Among such biological systems, microalgae have tremendous potential to take up metal ions and produce nanoparticles by a detoxification process. The present study explores the intracellular and extracellular biogenic syntheses of silver nanoparticles (SNPs) using the unicellular green microalga Scenedesmus sp. Biosynthesized SNPs were characterized by AAS, UV-Vis spectroscopy, TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activity. Intracellular nanoparticle biosynthesis was initiated by a high rate of $Ag^+$ ion accumulation in the microalgal biomass and subsequent formation of spherical crystalline SNPs (average size, 15-20 nm) due to the biochemical reduction of $Ag^+$ ions. The synthesized nanoparticles were intracellular, as confirmed by the UV-Vis spectra of the outside medium. Furthermore, extracellular synthesis using boiled extract showed the formation of well scattered, highly stable, spherical SNPs with an average size of 5-10 nm. The size and morphology of the nanoparticles were confirmed by TEM. The crystalline nature of the SNPs was evident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilization of SNPs. Furthermore, the synthesized nanoparticles exhibited high antimicrobial activity against pathogenic gram-negative and gram-positive bacteria. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials in a large-scale system that could be of great use in biomedical applications.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.747-756
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• 2012

The purpose of this study was to investigate adsorption characteristics of organo-clays for removal of p-xylene. As part of efforts to examine the adsorption capacities of some organo-clays for p-xylene, batch isotherm tests were carried out. Organo-clay minerals were synthesized under hydrothermal conditions using Na-montmorillonite as host clay and dimethyldioctadecylammonium (DMDA) bromide and benzyldimethyldodecylammonium (BDDA) chloride as organic surfactants, respectively. All synthetic organo-clay minerals were characterized by powder x-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDX). The modification using dimethyldioctadecylammonium (DMDA) bromide showed the higher adsorption ability for p-xylene than benzyldimethyldodecylammonium (BDDA) chloride. On the other hand, the maximum adsorption capacity, $Q_{max}$ of DMDA modified montmorillonite estimated by Langmuir model was 27.0 mg/g, which was the higher value than other organo-clays.

• Journal of the Korean Chemical Society
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• v.50 no.4
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• pp.321-327
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• 2006

red 1 and acid blue 92, anionic dyes, were removed from synthetic wastewater by the surfactant-modified clay minerals. Two different clays, such as Korean clay(M78) and Japanese clay(KJ) were treated with three different sulfactants, CTMA, DSDMA and TMSA. The surfactant-modified clay minerals such as M-1(CTMA), M-3(TMSA), KJ-1(CTMA) and KJ-3(TMSA), showed high removal efficiencies with dyes, while M-2(DSDMA) and KJ-2(DSDMA) could adsorb both dyes with relatively low efficiencies. Furthermore, almost 100% absorption of both dyes onto M-1(CTMA) and KJ-3(TMSA) revealed the possibility that these materials can be used for the removal of hazardous organic dyes from wastewater.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.11-11
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• 2021

Ferns have been consumed as food in many countries for centuries. As rich sources of protein, fiber, minerals, vitamins, essential amino acids, and fatty acids, ferns provide important nutrients to humans. Eastern bracken (Pteridium aquilinum var. latiusculum (Desv.) Underw. ex A. Heller) is the most popular edible fern in South Korea where, additionally, it has long been used as an edible wild leaf vegetable. Recently, the production of eastern brackens in South Korea (2018) has reached 14,032 tons, for an annual revenue of 83.5 billion won, and even more eastern brackens are marketed if imports are taken into account as well. Most of the common ferns can be propagated using spores. However, fern farmers cultivate seedlings through traditional propagation methods, such as root pruning or rhizome division. These propagation methods exhibit limitations in forming roots and growing-points and are labor intensive. Quality seedlings of eastern bracken can be obtained through spore propagation, but the spores are fine and difficult to handle in the field. In addition, it would require appropriate environmental control. The production of synthetic seeds using encapsulation technology is easy to establish and it can be used to achieve high productivity at low cost. Synthetic seeds contain explants embedded into a seed foam, and they overcome the limitations of micropropagation and offer the possibility of using plug seedlings. Synthetic seed matrix, such as sodium alginate, has the advantages of low cost, low toxicity, and gel stability. The present study aimed to develop and produce synthetic seeds for the commercial exploitation of eastern bracken. Furthermore, we verified spore germination and the extent of gametophyte and sporophyte development achieved with our new synthetic seeds, whose production was intended to solve current problems with the handling, storage, and transportation of eastern bracken.

• Journal of the Korean Chemical Society
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• v.11 no.1
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• pp.38-43
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• 1967

In order to explain the positive catalytic action of copper compound for the rate of leaching of zinc sulfide minerals, the electrode and redox potentials of both synthetic and natural sulfides were measured at various conditions of temperatures and pressures. The potentials of Chalcopyrite and copper sulfide were considerably higher than that of zinc sulfide, whereas lead sulfide and Galena had slightly lower potentials than that of zinc sulfide. At elevated temperatures and pressures, the same tendency was obtained. By means of comparing the calculated and measured values of potentials for sulfides, it was suggested that the electrode potentials in acid solution were generated by oxidation of sulfur ion. As a result, it was concluded that the catalytic action of copper compound in the leaching of synthetic zinc sulfide should be arised from the galvanic action between sulfides keeping intimate contact one another in which copper sulfide worked as cathodic and zinc sulfide as anodic part analogous to the metal corrosion under galvanic action.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.147-154
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• 1984

Two Fe-hydrous oxide A,B and one Al-hydroxide minerals were synthesized precipitating Fe $Cl_3$ and $AlCl_3$ with alkali solution(NaOH) at pH 6.0, 12.0 and 4.5 respectively, for precise understanding of physico-chemical and surface charge characteristics of soils in which these minerals are dominant. Identification of these final products, effect of free and amorphous materials on X-ray diffraction analysis, particle size distribution and surface change characterics of these minerals were performed. Fe-hydroxide A and B were identified as great deal of X-ray amorphous material and as goethite with large amount of X-ray amorphous material, respectively. Dehydration by oven at $105^{\circ}C$ of these minerals exhibited akaganeite peaks with low X-ray amorphous hump and pure goethite peaks for Fe-hydroxide A and B, respectively. Both minerals, however, turned into hematite upon firing at $550^{\circ}C$. On the other hand, Al-hydroxide identified as mixture of gibbsite and bayerite of around 7:3 ratio. Application of sodium dithionite and ammonium oxalate solutions for removal of free or amorphous Fe and Al from these minerals revealed that only peak intensities of Al-hydroxide system were enhanced upon Al-extraction by oxalate solution even though dithionite solution was much powerful to extract Fe from Fe-hydrous oxide systems. Original(wet) Fe-hydrous oxide A has the highest specific surface and surface charge development(negative and positive), and the greatest amount of less than $2{\mu}m$ sized particles. Specific surface and clay sized particles(less than $2{\mu}m$) of Fe-hydrous oxide A, however, were drastically reduced upon dehydration($P_2O_5$ and oven drying) compare to the rest minerals. The Z.P.C. of these synthetic minerals were 8.0-8.5, 7.5-8.0 and 5.5-6.0 for Fe-hydrous oxide A, B and Al-hydroxide, respectively.