• Journal of Conservation Science
• /
• v.25 no.2
• /
• pp.147-154
• /
• 2009

The change of strength and water vapour diffusion resistant by soluble salts was investigated in the tuff and granite used in many stone monuments of Gyeongju area. With $Na_2SO_4$ and $CaSO_4{\cdot}2H_2O$ were treated the rock samples to understand the difference of solubility. The densities of the tested rocks were increased by the impregnation of $CaSO_4{\cdot}2H_2O$ and $Na_2SO_4$. The flexural strength was increased in the tuff samples but decreased in the granite as the salts increased in the pore. In the tuff, the uniaxial compressive strength was increased by $CaSO_4{\cdot}2H_2O$, but decreased by $Na_2SO_4$. In the granite, it was decreased slightly by $CaSO_4{\cdot}2H_2O$, but increased by $Na_2SO_4$. The water vapour diffusion resistant was increased by the salts in both rocks. As results, it was cleared that the mechanical strength colud be increased in early stage of weathering by the accumulation of salt and water vapour diffusion resistant.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.1
• /
• pp.49-55
• /
• 2008

The feasibility of ionic liquid as a novel absorbent of $SO_2$ for the separation of $SO_2$ from $SO_2/O_2$ mixture in the thermochemical IS(Iodine-Sulfur) cycle was investigated. 1,3-dimethylimidazolium methylsulfate ([DMIm]$MeSO_4$) had shown twenty five times higher solubility of $SO_2$ than that of $O_2$. The dependence of $SO_2$ solubility by [DMIm]$MeSO_4$ on temperature and $SO_2$ partial pressure was examined, which confirmed the possibility of temperature and pressure swing for the separation process. Through cyclic absorption and desorption with temperature swing the stability of [DMIm]$MeSO_4$ in the separation process was also demonstrated. As a result of the experiments carried out, $SO_2$ separation from $SO_2/O_2$ mixture with ionic liquid([DMIm]$MeSO_4$) can be applied to the thermochemical IS cycle.

• Journal of Korean Society of Forest Science
• /
• v.77 no.2
• /
• pp.223-228
• /
• 1988

To select $SO_2$-resistant tree species, leaf disks of 6mm in diameter, cut from the leaves of 6 species (Wistaria floribunda, Magnolia obovata, Rosa multiflora, Liriodendron tulipifera, Robinia pseudo-acacia and Acer palmatum) were floated on 25ml of testing medium and placed on laboratory under fluorescent lamp (1,500 Lux) for 20 hours. Chlorophyll content and acidity of the testing medium were measured. Testing medium was prepared by diluting $H_2SO_4$, $H_2SO_3$ and $Na_2SO_4$ with distilled water for various stoichiometric $SO_2$ concentrations, 0, 25, 50, 100 and 250 ppm. Total chlorophyll content was more decreased after treatment than before treatment, and was decreased more severely in $H_2SO_3$ sources, followed by $H_2SO_4$ and $Na_2SO_4$, sources. Decreasing rate of total chlorophyll content was generally large in Acer palmatum. Magnolia obovata and Wistaria floribunda, and was relatively small in Rosa multiflora, Liriodendron tulipifera and Robinia pseudo-acacia. Decreasing rate of chlorophyll content may be useful index for judging susceptifility of the leaf to $SO_2$. The acidity of the testing medium was generally decreased after treatment, and it means that cell leakage was occurred during treatment. The differences in medium acidity between before and after treatment may be poot index for susceptibility of the leaf to $SO_2$ owing to the difference among tree species in development of leaf mesophyll, acidity maintaining mechanism and butter capacity of the leaf tissue.

• Resources Recycling
• /
• v.7 no.5
• /
• pp.33-40
• /
• 1998

The formation reation of anhydrite (CaSO$_{4}$) depends upon the amount and velocity of the SO$_{3}$(g) and CaO(s) produced in the process of the thermal decomposition of alunite[K$_{2}SO_{4}{\cdot}Al_{2}(SO_{4})_{3}{\cdot}4Al(OH)_{3}$] and limestone (CaCO$_{3}$) respectively. Therefore, this study had carried out to investigate the amount and velocity of SO$_{3}$(g) produced by roasting alunite and pyrolytic materials. In air, alunite was transfouned into KAl(SO$_{4})_{2}$ and Al$_{2}O_{3}$ by dehydration at 500~580$^{\circ}C$. The dehydration velocity of alunite was found to be kt=(1-(1-${\alpha})^{1/3})^{2}$, the activation energy, 73.01 kcal/mol. SO$_{3}$(g) ware slowly produced by the thermal decomposition of KAl(SO$_{2})_{2}$, at 580~700$^{\circ}C$, rapidly, at 700~780$^{\circ}C$, The pyrolysis velocity of KAl(SO$_{4})_{2}$ was found to be kt=1-(1-${\alpha})^{1/1}$; activation energy, 66.84kcal/mol. The SiO$_{2}$ and kaolinite in alunite ore scarcely affected the temperature and velocity in which SO$_{3}$(g) were produced.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.8
• /
• pp.1265-1272
• /
• 2007

A solid acid catalyst, NiSO4/CeO2-ZrO2 was prepared simply by promoting ZrO2 with CeO2 and supporting nickel sulfate on CeO2-ZrO2. The support of NiSO4 on ZrO2 shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperatures because of the interaction between NiSO4 and ZrO2. The surface area of 10-NiSO4/1-CeO2-ZrO2 promoted with CeO2 and calcined at 600 oC was very high (83 m2/g) compared to that of unpromoted 10-NiSO4/ZrO2 (45 m2/g). This high surface area of 10-NiSO4/1-CeO2-ZrO2 was due to the promoting effect of CeO2 which makes zirconia a stable tetragonal phase as confirmed by XRD. The role of CeO2 was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity of the sample, and high thermal stability of the surface sulfate species. 10-NiSO4/1- CeO2-ZrO2 containing 1 mol% CeO2 and 10 wt% NiSO4, and calcined at 600 oC exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation.

• Journal of Sensor Science and Technology
• /
• v.1 no.1
• /
• pp.59-66
• /
• 1992

To develop the highly sensitive TLD radiation sensors, $BaSO_{4}$ : Eu-PTFE TLDs are fabricated by polymerizing the PTFE(polytetrafluoroethylene) with $BaSO_{4}$ : Eu TL phosphors. The $BaSO_{4}$ : Eu TL phosphors having the highest sensitivity of $X/{\gamma}$-rays are obtained by sintering at $1000^{\circ}C$ in $N_{2}$ atmosphere a mixture of $BaSO_{4}$ powder with 1mol% Eu($Eu_{2}O_{3}$), 6mol% $NH_{4}Cl$ and 5mol% $(NH_{4})_{2}SO_{4}$ which were co-precipitated in dilute sulfuric acid and then dried. The activation energy, frequency factor and kinetic order of $BaSO_{4}$ : Eu TL phosphor are 1.17eV, $3.6{\times}10^{11}/sec$ and 1.25, respectively. And the spectral peak of $BaSO_{4}$ : Eu is about 425nm. The optimum TL Phosphor content and thickness of the $BaSO_{4}$ : Eu-PTFE TLD are 40wt% and $105.7mg/cm^{2}$. The optimum polymerization temperature and time for fabrication of $BaSO_{4}$ : Eu-PTFE TLDs are $380^{\circ}C$ and 2 hours in air, respectively. The linear dose range to ${\gamma}$ rays is 0.01-20Gy and fading rate is about 10%/60hours.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.6
• /
• pp.600-608
• /
• 2015

As a candidate for cheap oxygen carrier, $CaSO_4$ based oxygen carriers have been developing. However, research on reaction characteristics and side reaction of $CaSO_4$ based oxygen carrier is very limited. There are many possible reactions for main components of syngas from coal. In this study, we prepared three $CaSO_4$ based oxygen carriers ($CaSO_4$-$Fe_2O_3$/bentonite, $CaSO_4$-$K_2CO_3$/bentonite, $CaSO_4$-CaO/bentonite) and performed reduction tests by hydrogen. Cyclic reduction-oxidation tests up to $5^{th}$ cycle are also conducted using hydrogen as fuel. Reduction reactivity of those $CaSO_4$ based oxygen carriers were compared with that of NiO based oxygen carrier (OCN703-1100). Real weight change fractions of $CaSO_4$ based oxygen carriers were higher than theoretical oxyen transfer capacity and reactivity of these particles decreased with the number of cycle increased. To check possible side reaction of $CaSO_4$ based oxygen carriers, $CaSO_4$ decomposition tests were carried out and $SO_2$ was detected even at $700^{\circ}C$. Consequently, we could conclude that $CaSO_4$ based oxygen carriers decompose and release $SO_2$ and this reaction lead reactivity decay of $CaSO_4$ based oxygen carries.

• Polymer(Korea)
• /
• v.38 no.1
• /
• pp.103-107
• /
• 2014

Poly(acrylonitrile-butadiene-styrene) (ABS) composite sheets containing titanium dioxide ($TiO_2$), barium sulfate ($BaSO_4$), calcium carbonate ($CaCO_3$) were prepared by using a co-rotating twin screw extruder, and the reflectance and flexural modulus of the composite sheets were measured. The fillers were well dispersed in ABS matrix. The reflectance of composite sheet was increased with increasing $TiO_2$ and $BaSO_4$ content. Sheet having $TiO_2$ 20 wt% composition, with 5~20 wt% $BaSO_4$ resulted in more than 95% of reflectance. The flexural modulus of composite sheet was increased from 1864 MPa for $ABS/TiO_2/BaSO_4$ 85/10/5 (w/w/w) to 3134 MPa for $ABS/TiO_2/BaSO_4$ 55/20/25 (w/w/w).

• Journal of the Korean Geographical Society
• /
• v.44 no.4
• /
• pp.429-446
• /
• 2009

To understand the sulfur flux and cycle in the forest catchment, the hydrological processes and chemical variation of soil solution, groundwater and stream water were analyzed at the Matsuzawa catchment located in the Kiryu Experimental Basin, Shiga Prefecture, central Japan. Unsaturated soil layer at the upper slope of catchment was the source area of ${SO_4}^{2-}$, and deep soil layer and groundwater were the sink zone of ${SO_4}^{2-}$. The vertical distribution of ${SO_4}^{2-}$ concentrations in groundwater affected seasonal variation of ${SO_4}^{2-}$ concentrations in stream water, as groundwater level changed. It is reasonable to assume that each hydrological processes in the forest catchment play an important roles in the retention and discharge of ${SO_4}^{2-}$.

• Korean Journal of Soil Science and Fertilizer
• /
• v.20 no.4
• /
• pp.327-332
• /
• 1987

Soil samples were collected from the paddy soils growing two crops of rice and garlic in Kyung-pook province. To obtain the basic information on the application of S-fertilizer in the garlic field, the adsorption and release amount of $SO_4{^{-2}}$ in subsoil samples were determined. The ranges of $SO_4{^{-2}}$ contents in surface and sub-soil were 59-117 and 34-102 ppm, respectively. The amount of $SO_4{^{-2}}$ adsorbed by soil samples was found to be more at lower pH and higher concentration of $SO_4{^{-2}}$. The $SO_4{^{-2}}$ adsorption constants in Freundlich equation tended to be higher at lower pH. It is apparent that most of $SO_4{^{-2}}$ was released in the first extraction. However, the lower the pH of extracted solution, the more the $SO_4{^{-2}}$ contents was released by distilled water.