• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.2
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• pp.77-85
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• 2012

This study was carried out to remove (/recover) the uranium from the Uranium-bearing Lime Precipitate (ULP). An oxidative dissolution of ULP with carbonate-acidified precipitation and a dissolution of ULP with nitric acid-hydrogen peroxide precipitation were discussed, respectively. In point of view the dissolution of uranium in ULP, nitric acid dissolution which could dissolved more than 98% of uranium was more effective than carbonate dissolution. However, in this case, uranium was dissolved together with a large amount of impurities such as Al, Ca, Fe, Mg, Si, etc. and some impurities were also co-precipitated with uranium during a hydrogen peroxide precipitation. On the other hand, in the case of carbonate dissolution-acidified precipitation, U was dissolved less than 90%. Therefore, it was less effective than nitric acid dissolution for the volume reduction of radioactive solid waste. However, it was very effective to recover the pure uranium, because impurities were hardly dissolved and hardly co-precipitated with uranium.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.2
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• pp.93-100
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• 2009

This study has been carried out to look into the characteristics of an oxidative-dissolution of fission products (FP) co-dissolved with uranium (U) in a $(NH_4)_2CO_3$ carbonate solution. Simulated FP-oxides which contained 12 components have been added to the solution to examine their dissolution characteristics. It is found that $H_2O_2$ is an effective oxidant to minimize the oxidative-dissolution of FP. In the 0.5 M $(NH_4)_2CO_3$-0.5 M $H_2O_2$ solution, some elements such as Re, Te, Cs and Mo seem to be dissolved together with U, while 98${\pm}$2% for Re and Te, 94${\pm}$2% for Cs, and 29${\pm}$2 % for Mo are dissolved for 2 hours. It is revealed that dissolution rates of Re, Te and Cs are high (completely dissolved within 10${\sim}$20 minutes) due to their high solubility in the $(NH_4)_2CO_3$ solution regardless of the addition of $H_2O_2$, and independent of the concentrations of $Na_2CO_3$ and $H_2O_2$. However, the dissolution ratio of Mo seems to be slightly increased with time and about 33 % for 4 hours, indicating a very slow dissolution rate and also independent of the $(NH_4)_2CO_3$ concentration. It is found that the most important factor for the oxidative-dissolution of FP is the pH of the solution and an effective dissolution is achieved at a pH between 9${\sim}$10 in order to minimize the dissolution of FP.

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.34-34
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• 2005

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.2
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• pp.85-93
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• 2013

This study has been carried out to elucidate the characteristics of the dissolution for Thermal Decomposed Solid Waste of uranium-bearing sludge (TDSW), the removal of impurities by an alkalization in a nitric acid dissolving solution of TDSW, and the selective removal (/recovery) of uranium by an acidification in an carbonate alkali solution, respectively. TDSW generated by thermal decomposition of U-bearing sludge which was produced in the uranium conversion plant operation, was stored in KAERI as a solid-powder type. It is found that the dissolution of TDSW is more effective in nitric acid dissolution than oxidative-dissolution with carbonate. At 1 M nitric acid solution, TDSW was undissolved about 30wt% as a solid residue, and uranium contained in TDSW was dissolved more than 99%. In order to the alkalization for the nitric acid dissolving solution of TDSW, carbonate alkalization is more effective with respect to remove the impurities. At the carbonate alkali solution controlled to about 9 of pH, Al, Ca, Fe and Zn co-dissolved with U in dissolution step was removed about $98{\pm}1%$. On the other hand, U could be recovered more than 99% by an acidification at pH about 3 in a carbonate alkali solution, which was nearly removed the impurities, adding 0.5M $H_2O_2$. It was found that uranium could be selectively recovered (/removed) from TDSW.

• Resources Recycling
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• v.17 no.3
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• pp.42-47
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• 2008

In this work, the dissolution behavior of Pb from the complex sulphide concentrates containing Galena and Arsenopyrite by alkaline oxidative leaching was studied. The influences of leaching temperature, oxygen partial pressure, leaching time and NaOH concentration of leaching solution were examined at the leaching conditions in the range of $100^{\circ}C{\sim}140^{\circ}C$ temperature, $40psi{\sim}100psi\;PO_2$ and $0.5M{\sim}2M$ NaOH concentration. The optimum result was obtained at the leaching condition of leaching temperature $120^{\circ}C$, 100psi $PO_2$, leaching time 30min. and 2M NaOH concentration of leaching solution.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.131-139
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• 2011

This study was carried out to examine the stability of $Na_2CO_3-H_2O_2$ carbonate solution with aging time in the dissolving solution after oxidative dissolution of U by a carbonate solution, the Cs/Re filtrate after selective precipitation of Cs and Re (as a surrogate for Tc), and the acidification filtrate after precipitation of U by acidification, respectively. The compositions of dissolving solution were not changed with ageing time, and the selective precipitation of Re and Cs was also not affected without regard to the aging time of dissolving solution. The successive removal of Cs and Re from a carbonate dissolving solution was possible. However, the recovery yield of U by acidification was decreased with increasing the aging time of the dissolving solution and the Cs/Re-filtrate, respectively, because U was converted from the uranyl peroxocarbonato complex to the uranyltricarbonate in the solution aged for a long time. Accordingly, it is effective that a dissolving solution and a Cs/Re filtrate are treated within the aging of 7 days, respectively, in order to recover U more than 99%. On the other hand, the recovery of U was carried out in order of the oxidative dissolution of U selective precipitation of Re and Cs precipitation of U by acidification. Almost all of U and a part of FP were co-dissolved in oxidative dissolution step. Over 99% of Re and Cs from the FP co-dissolved with U could be removed by a TPPCl (tetraphenylphosphonium chloride) and a NaTPB (sodium tetraphenylborate), respectively. U was precipitated nearly 100% by acidification to pH 4. Therefore, it was confirmed that the validity of recovery of U by precipitation methods from a SF (spent fuel) in the $Na_2CO_3-H_2O_2$ solution.

• Corrosion Science and Technology
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• v.6 no.4
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• pp.198-205
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• 2007

The initial stages of electrochemical oxidative CuI film formation on Cu(111), as studied by means of Cyclic Voltammetry (CV), in-situ Scanning Tunneling Microscopy (STM) and ex-situ Synchrotron X-ray Photoemission Spectroscopy (SXPS), indicate a significant acceleration of copper oxidation in the presence of iodide anions in the electrolyte. A surface confined supersaturation with mobile CuI monomers first leads to the formation of a 2D-CuI film via nucleation and growth of a Cu/I-bilayer on-top of a pre-adsorbed iodide monolayer. Structurally, this 2D-CuI film is closely related to the (111) plane of crystalline CuI (zinc blende type). Interestingly, this film causes no significant passivation of the copper surface. In an advanced stage of copper dissolution a transition from the 2D- to a 3D-CuI growth mode can be observed.

• Biomolecules & Therapeutics
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• v.10 no.1
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• pp.1-6
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• 2002

The particle size of medicinal materials is an Important physical property that affects the phar-maceutical behaviors such as dissolution, chemical stability, and bioavailability of solid dosage forms. The size reduction of raw medicinal powder is needed to formulate insoluble drugs or slightly soluble medicines and to improve the pharmaceutical properties such as the solubility, the pharmaceutical mixing, and the dispersion. The objective of the present study is to evaluate physiological activity of amorphous and nano-particle prep-arations of insoluble drug, ursodeoxycholic acid (UDCA), which were made by three types of fine grinding mills. The change of physical properties of ground UDCA was conformed by Mastersiger microplus and X-ray diffraction. We have investigated hepatoprotective effects of the nano-particle preparations of UDCA by plan-etary mill, vibration rod mill and jet mill in $CCI_4$-induced oxidatively injured mouse liver. The results showed that nano-particle preparations of UDCA all decreased reactive oxygen sepecies generation and lipid peroxi-dation in $CCI_4$-induced oxidative stress mice. Among them, nano-particle preparations by vibration rod mill and jet mill showed more significantly hepatoprotective effects compared to intact UDCA and planetary mill-ground UDCA. These results suggest that ground UDCA with vibration rod mill and jet mill shows a high amorphous state and the improved dissolution.

• Journal of Yeungnam Medical Science
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• v.40 no.4
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• pp.328-334
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• 2023

An aging population and changes in dietary habits have increased the incidence of diabetes, resulting in complications such as diabetic foot ulcers (DFUs). DFUs can lead to serious disabilities, substantial reductions in patient quality of life, and high financial costs for society. By understanding the etiology and pathophysiology of DFUs, their occurrence can be prevented and managed more effectively. The pathophysiology of DFUs involves metabolic dysfunction, diabetic immunopathy, diabetic neuropathy, and angiopathy. The processes by which hyperglycemia causes peripheral nerve damage are related to adenosine triphosphate deficiency, the polyol pathway, oxidative stress, protein kinase C activity, and proinflammatory processes. In the context of hyperglycemia, the suppression of endothelial nitric oxide production leads to microcirculation atherosclerosis, heightened inflammation, and abnormal intimal growth. Diabetic neuropathy involves sensory, motor, and autonomic neuropathies. The interaction between these neuropathies forms a callus that leads to subcutaneous hemorrhage and skin ulcers. Hyperglycemia causes peripheral vascular changes that result in endothelial cell dysfunction and decreased vasodilator secretion, leading to ischemia. The interplay among these four preceding pathophysiological factors fosters the development and progression of infections in individuals with diabetes. Charcot neuroarthropathy is a chronic and progressive degenerative arthropathy characterized by heightened blood flow, increased calcium dissolution, and repeated minor trauma to insensate joints. Directly and comprehensively addressing the pathogenesis of DFUs could pave the way for the development of innovative treatment approaches with the potential to avoid the most serious complications, including major amputations.

• Economic and Environmental Geology
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• v.35 no.1
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• pp.55-66
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• 2002

There are several abandoned coal mines around Donghae mine area in the Taebaek coal field. Two major creeks, Soro and Sanae, are contaminated with the colored precipitates formed from the coal mine drainages. Bed rocks of the study area consist of limestone, shale, and sandstone. Limestone consisted mainly of calcite and dolomite, and shale of quartz, pyropyllite and chlorite, and sandstone of quatz and illite. Coal coal spoil dumps composed mainly of pyrite and chlorite. The oxidative dissolution of sulfide minerals leads to acid mine drainage and adds the metal ions in the stream water. The ion concentrations of Fe, Ca, Mg, Al, Si, SO$_{4}$in the stream polluted by AMD are generally higher than those in the unpolluted stream water. High concentrations of Ca and Mg, Al and Si can be resulted from dissolution of carbonate minerals such as calcite, dolomite and aluminosilicates such as chlorite, pyrophyllite. Although the Fe, Al, Si, SO$_{4}$ contents are considerbly high in the acid water released from the mine adits, they become decreased downstream due to dilution of unpolluted water and precipitation of oxide/hydroxide and sulfate minerals on the bottom of stream.