• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.101-103
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• 2004

To investigate the evidence for the influence of sea water on Pohang geothermal groundwater, the chemical data for geothermal groundwaters from which are pumped during 48 hours and other hot groundwaters, another groundwater on the well for the purpose of agriculture, were considered. And to predict possible the secondary mineral which are easily to make the clogging, geochemical modeling was carried out using EQ3NR equilibrium solubility code. The results are that 1.4%～3.3%(bulk composition) of sea water were mixed with geothermal groundwater. From the well logging data, when the level of groundwater is drow down, the conductivity is increased in the geothermal groundwater, the existence of transition zone are recognized in the well. The predicted possible secondary minerals are Antigorite [Mg48Si24O85(OH)62], Chrysolite [Mg3Si2O5(OH)4] , Cristobalite, Dolomite, Talc, Tremolite. The recommended cooling temperature of best condition to minimize the production of secondary minerals is same as temperature of geothermal water pumped from the well.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.4
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• pp.340-347
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• 2008

Dissolution process of serpentine in distilled water was systematically investigated for study on pre-treatment of serpentine which was a candidate material for carbon dioxide sequestration. The metallic ions(Ca, Si, Mg etc.) were dissolved in distilled water at ambient condition and their concentrations were changed with dissolution time. The precise evaluation of dissolution process for serpentine dissolved solvent was performed by ion conductivity and pH measurement. Serpentine dissolution in distilled water was evaluated as a stable pre-treatment process without changes of crystallographic structure and chemical structure changes.

• Restorative Dentistry and Endodontics
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• v.39 no.3
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• pp.201-209
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• 2014

Objectives: This study evaluated the solubility, dimensional alteration, pH, electrical conductivity, and radiopacity of root perforation sealer materials. Materials and Methods: For the pH test, the samples were immersed in distilled water for different periods of time. Then, the samples were retained in plastic recipients, and the electrical conductivity of the solution was measured. The solubility, dimensional alteration, and radiopacity properties were evaluated according to Specification No. 57 of the American National Standards Institute/American Dental Association (ANSI/ADA). Statistical analyses were carried out using analysis of variance (ANOVA) and Tukey's test at a significance level of 5%. When the sample distribution was not normal, a nonparametric ANOVA was performed with a Kruskal-Wallis test (${\alpha}$ = 0.05). Results: The results showed that white structural Portland cement (PC) had the highest solubility, while mineral trioxide aggregate (MTA)-based cements, ProRoot MTA (Dentsply-Tulsa Dental) and MTA BIO ($\hat{A}$ngelus Ind. Prod.), had the lowest values. MTA BIO showed the lowest dimensional alteration values and white PC presented the highest values. No differences among the tested materials were observed in the the pH and electrical conductivity analyses. Only the MTA-based cements met the ANSI/ADA recommendations regarding radiopacity, overcoming the three steps of the aluminum step wedge. Conclusions: On the basis of these results, we concluded that the values of solubility and dimensional alteration of the materials were in accordance with the ANSI/ADA specifications. PCs did not fulfill the ANSI/ADA requirements regarding radiopacity. No differences were observed among the materials with respect to the pH and electrical conductivity analyses.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.1010-1015
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• 2008

The effects of heat treatment on the physicochemical properties and mineral composition of sun-dried salt were investigated. The salts parched at high temperature were appeared the higher alkalinity and the lower oxidation-reduction potential (ORP) than the samples without heat treatment. The commercial salts (bamboo salt and yellow loess salt) and the sun-dried salt parched at high temperature had relatively higher sodium ion content (418-450 ppm) compared to that (418.0 ppm) of refined salt. The increase of calcium ion occurred in the salts parched at high temperature compared to the sun-dried salt without heat treatment, but the magnesium ion was vice versa. The commercial salt, yellow loess salt had highest turbidity (0.973) whereas sun-dried salt showed lowest level (0.097) among the tested samples. Turbidity of heat treatment samples decreased as solubility increased. The maximum concentration of dialyzed salt was reached after 4 hr regardless of various processed salts, but those had no difference significantly among the tested samples. The X-ray diffraction patterns of the parched sun-dried salts showed different peak intensity with common salts, and they were similar to the patterns of oxide salts, especially MgO. The maximum value (2.56%) of MgO appeared in the sun-dried salt parched at $1,400^{\circ}C$.

• Resources Recycling
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• v.29 no.6
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• pp.98-103
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• 2020

In this study, the depression behavior of zinc sulfate on the sphalerite with the addition of potassium butyl xanthate was investigated to clear the relationship between zinc sulfate and xanthate in depression of sphalerite. As a result of the experiment, it was confirmed that the depress effect of zinc sulfate on the sphalerite declined with the increase of its addition amount. From the results of SEM-EDS and FT-IR analysis, it was found out that the amorphous precipitate of metal xanthate (Zn-BX) was formed in sphalerite concentrate, when the solubility product of [Zn+]·[BX] in the pulp solution exceeded 3.71×10-11, which is the solubility of Zn-butyl xanthate. It is considered that the Zn-butyl xanthate had a negative effect on the depression of sphalerite.

• Resources Recycling
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• v.29 no.5
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• pp.28-37
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• 2020

In this study, the effect of precipitation temperature, ammonium chloride amount and addition method, vanadium and sodium hydroxide content of the solution on the precipitation of ammonium metavanadate were examined by using the sodium vanadate(NaVO₃) solution in alkali region as a starting material. As the pH of solution decreased, the addition amount of ammonium chloride and the vanadium content of the solution increased, the precipitation rate of ammonium metavanadate increased. In this research condition, the basic conditions for obtaining more than 90% of precipitation yield were 10,000mg/L of vanadium content, 2equivalents of ammonium chloride addition, room temperature, and 2 hours of precipitation time. The size of precipitated particles decreased with increasing precipitation rate. Especially when liquid ammonium chloride was injected into the solution, the precipitation rate was the slowest and the particle size of the precipitate was the largest. After the primary precipitation by adding ammonium chloride as a solid, the secondary precipitation was carried out by adding new reactants. At this time, the precipitation with added ammonium chloride solid was not affected by the precipitates present in the solution. However, when liquid ammonium chloride was added, new precipitate was deposited on the surface of the precipitate present in the solution, increasing its size. Due to the difference in ammonium metavanadate solubility to temperature, the precipitation temperature at the vanadium content of 10,000mg/L in the solution affected the precipitation rate of ammonium metavanadate and the precipitation temperature did not affect the precipitation rate at a high concentration of more than 30,000mg/L vanadium content in the solution.

• Korean Journal of Food Science and Technology
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• v.39 no.2
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• pp.152-157
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• 2007

In an attempt to develop functional salts having beneficial health effects, we experimentally prepared three functional salts by fortification with soluble seaweed minerals (Hizikia mineral salt, HMS), fucoidan (fucoidan salt, FS) and laver extracts (laver salt, LS). To characterize the functional salts, their physicochemical properties and in vitro functionalities, such as pH, color, mineral composition, solubility, oxidation-reduction potential, sensory properties, angiotesin converting enzyme (ACE) inhibitory activity, and bile acid binding capacity were investigated. The functional salts revealed slightly lower NaCl concentrations, but showed a variety of pH values compared with conventional table salt. The pH values of HMS, FS, and LS were 11.3, 6.8, and 6.5, respectively. The oxidation-reduction potentials (ORP) of the functional salts varied from -229 mV to 38 mV, significantly lower than refined salt. The functional salts were significantly darker in color than refined salt, and the mineral composition of HMS was considerably enriched compared to refined salt, particularly in potassium ion. As a result of the sensory evaluation, FS and LS were comparatively palatable in saltiness, pungency, bitterness, and overall acceptance compared with refined salt. It was also found that one functional salt had ACE inhibitory activity (54.8% in LS) and another had bile acid binding capacity (80.7% in FS).

• Restorative Dentistry and Endodontics
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• v.45 no.3
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• pp.35.1-35.17
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• 2020

Epoxy resin-based sealers are currently widely used, and several studies have considered AH Plus to be the gold-standard sealer. However, it still has limitations, including possible mutagenicity, cytotoxicity, inflammatory response, and hydrophobicity. Drawing upon the advantages of mineral trioxide aggregate, calcium silicate-based sealers were introduced with high levels of biocompatibility and hydrophilicity. Because of the hydrophilic environment in root canals, water resorption and solubility of root canal sealers are important factors contributing to their stability. Sealers displaying lower microleakage and stronger push-out bond strength are also needed to endure the dynamic tooth environment. Although the physical properties of calcium silicate-based sealers meet International Organization for Standardization recommendations, and they have consistently reported to be biocompatible, they have not overcome conventional resin-based sealers in actual practice. Therefore, further studies aiming to improve the physical properties of calcium silicate-based sealers are needed.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.5
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• pp.530-537
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• 1998

The proportion of dry matter (DM) and mineral elements (Ca, Mg, P, Na, K, Zn) released from eight feeds (2 rice straws, RSI and RS2; 2 grasses, NB21 and guinea; 2 leguminous fodders, glyricidia and erythrina; jak leaves and rice bran) were studied using the nylon bag procedure. Bag incubations up to 10 days were performed in the rumen of cows fed on a ration consisting of 50% wheat straw and 50% hay. Both the type of feed and the incubation time in the rumen significantly influenced (p < 0.01) the proportion of minerals released. In legumes, jak leaves and rice bran about 80% of the potentially degradable DM fraction was solubilized within 24 h in the rumen, and with the grasses, rice straws and jak leaves a considerable proportion of DM was released between 48 and 240 h in the rumen. During the early hours of incubation (up to 24 h) there were distinct differences between and within the feed classes in their ability to release all mineral elements studied. In all test feeds, high proportions of Mg and K were released within 24 h. Some feeds showed a tendency to ad/absorb Ca (grasses, rice straws and rice bran), P (jak leaves, rice straws), Na (glyricidia and rice bran) and Zn (jak leaves) from water and rumen fluid, and this was partly related to the low initial concentration. In terms of absolute quantity of mineral released, legumes (erythrina is superior to glyricidia) are a good source of Ca, Mg, P and Zn, and jak leaves a good source of Ca and Na. Within grasses, guinea contains appreciable quantity of available Mg and P. Rice bran is rich in available Mg, P and Zn.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.367-371
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• 2012

Waste printed circuit boards (WPCBs) contain valuable metals such as Cu, Ni, Au, Ag, and Pd. For an effective recycling of WPCBs, it is essential to recover the valuable metals. In recent years, recycling processes have come to be necessary for separating noble metals from WPCBs due to an increasing amount of electronic device wastes. However, it is well known that glass reinforced epoxy resins in the WPCBs are difficult materials to separate into elemental components, namely metals, glass fibers and epoxy resins in the chemical recycling process. $K_3PO_4$ as a catalyst in dimethylformamide (DMF) and N-Methyl-2-pyrrolidone (NMP) was used to depolymerize epoxy resins for recovering metallic and non-metallic components from WPCBs. Reactions of WPCBs were carried out at temperatures $160{\sim}200^{\circ}C$ for 2~12 h. The recycled glass fiber from WPCBs was analyzed by thermogravimetric analyzer (TGA) and evaluated the degree of solubility of the epoxy resin for separation efficiencies of the WPCBs.