• Title/Summary/Keyword: charge mobility

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A Study on Librarians' Awareness of Construction of Libraries Based on Smart-Digital Environment (스마트디지털 환경 기반 도서관 구축에 관한 사서 인식 연구)

  • Kang, Pil Soo;Noh, Younghee;Kim, Yoon Jeong
    • Journal of the Korean BIBLIA Society for library and Information Science
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    • v.32 no.1
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    • pp.5-33
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    • 2021
  • This Study seeks for a plan for promotion of smartification of digital services for improving convenience in use and user services of public libraries in smart digital environment. Thus, in this Study, a survey on awareness of a plan for revitalization of digital data and smart libraries has been conducted for the persons in charge of digital data and librarians from public libraries. The result of this Survey are as follows: first, the introduction of smart libraries was effective by first implementing them in small and medium-sized cities with high interest in in information technology, and spreading them to public libraries in metropolitan cities and special autonomous cities; second, it is analyzed that the essential factor of success in introduction of smart libraries is the contents free from the terminals and the upgrade of computer equipment of users available for the use of these services. Terminals are to be individually utilized by smartphone users but it is necessary for upgrade and introduction of 5G which can secure the mobility of users including open type Wi-Fi; third, it is discovered that the information technology the applicability of which is expected to be easy while introducing smart libraries is RFID, which has been already generalized, and bigtata technology. The introduction of IoT technology in which the stakeholders of public libraries in metropolitan cities and special self-governing cities must be considered first.

Changes of Mineralogical Characteristics of Precipitates in Acid Mine Drainage of the Dalsung Mine and Related Changes of Trace Elements (달성광산 산성광산배수 침전물의 시간에 따른 광물상 특성 변화 및 이에 따른 미량원소의 거동 변화)

  • Yoon, Young Jin;Kim, Yeongkyoo;Lee, Seong-joo
    • Economic and Environmental Geology
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    • v.55 no.5
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    • pp.531-540
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    • 2022
  • Various iron minerals that precipitate in acid mine drainage have a great influence on the concentration change and mobility of trace elements in the drainage during phase transition to other minerals as well as the precipitation process. This study investigated the change of mineral properties and the behaviors of trace elements influenced by pH and time for the precipitates collected from the acid mine drainage treatment system of the Dalsung mine, where schwertmannite is mainly precipitated. However, the main mineral precipitated in the drainage was goethite, suggesting schwetmannite has already undergone a phase transition to goethite to some extent, and it was observed that at higher pH, the peak width at half maximum of XRD peak was narrower. This can be interpreted as the transformation of small amount of amorphous schwetmannite to goethite or an increase in the crystallinity of goethite, and it showed that the higher the pH, the greater this change was. The concentration of Fe was also greatly affected by the pH values, and as the pH increased, the concentration of Fe in the drainage decreased. With increasing time, the Fe concentration increased and then decreased, which can be interpreted to indicate the dissolution of schwertmannite and precipitation of goethite. This mineral change probably resulted in the rapid increase of the concentration of S at initial stage, but its concentration was stabilized later. The concentration of S is also related to the stability of schwetmannite, showing a high concentration at a low pH at which schwertmannite is stable and a low concentration at a high pH at which goethite is stable. The trace elements present as cations in the drainage also showed a close relationship with the pH, generally the lower the pH, the higher the concentration, due to the solubility changes by the pH, and the precipitation and the changes in mineral surface charge at high pH. On the other hand, in the case of As, existing as an anion, although it showed a high concentration at low pH, its concentration increased with time at all pH values, which is probably related to the concentration of Fe which can be coprecipitated in the drainage, and the increase of As concentration with time is also considered to be related to the decrease in schwertmannite rather than the mineral surface charge.

Heavy Metal Contamination around the Abandoned Au-Ag and Base Metal Mine Sites in Korea (국내 전형적 금은 및 비(base)금속 폐광산지역의 중금속 오염특성)

  • Chon Hyo-Taek;Ahn Joo Sung;Jung Myung Chae
    • Economic and Environmental Geology
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    • v.38 no.2 s.171
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    • pp.101-111
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    • 2005
  • The objectives of this study we to assess the extent and degree of environmental contamination and to draw general conclusions on the fate of toxic elements derived from mining activities in Korea. 인t abandoned mines with four base-metal mines and four Au-Ag mines were selected and the results of environmental surveys in those areas were discussed. In the base-metal mining areas, the Sambo Pb-Zn-barite, the Shinyemi Pb-Zn-Fe, the Geodo Cu-Fe and the Shiheung Cu-Pb-Zn mine, significant levels of Cd, Cu, Pb and Zn were found in mine dump soils developed over mine waste materials, tailings and slag. Furthermore, agricultural soils, stream sediments and stream water near the mines were severely contaminated by the metals mainly due to the continuing dispersion downstream and downslope from the sites, which was controlled by the feature of geography, prevailing wind directions and the distance from the mine. In e Au-Ag mining areas, the Kubong, the Samkwang, the Keumwang and the Kilkok mines, elevated levels of As, Cd, Cu, Pb and Zn were found in tailings and mine dump soils. These levels may have caused increased concentrations of those elements in stream sediments and waters due to direct dis-charge downstream from tailings and mine dumps. In the Au-Ag mines, As would be the most characteristic contaminant in the nearby environment. Arsenic and heavy metals were found to be mainly associated with sulfide gangue minerals, and mobility of these metals would be enhanced by the effect of oxidation. According to sequential extraction of metals in soils, most heavy metals were identified as non-residual chemical forms, and those are very susceptible to the change of ambient conditions of a nearby environment. As application of pollution index (PI), giving data on multi-element contamination in soils, over 1.0 value of the PI was found in soils sampled at and around the mining areas.

Study of Iodide Adsorption on Organobentonite using X-ray Absorption Spectroscopy (X-선 흡수분광기를 이용한 유기벤토나이트의 요오드 흡착연구)

  • Yoon, Ji-Hae;Ha, Ju-Young;Hwang, Jin-Yeon;Hwang, Byoung-Hoon;Gordon E. Brown, Jr.
    • Journal of the Mineralogical Society of Korea
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    • v.22 no.1
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    • pp.23-34
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    • 2009
  • The adsorption of iodide on untreated bentonite and bentonites modified with organic cation (i.e., hexadecylpyridinium chloride monohydrate ($HDP^+$)) was investigated, and the organobentonites were characterized using uptake measurements, ${\mu}$-XRD, and electrophoretic mobilities measurement. Uptake measurements indicate that bentonite has a high affinity for $HDP^+$. Our ${\mu}$-XRD study indicates that organobentonites significantly expanded in basal spacing and organic cations were substantially intercalated into the interlayer spaces of bentonite. The electrophoretic mobility indicates that organobentonite tht is modified with organic cations in excess of the CEC of bentonite is completely different from untreated bentonite in the surface charge distribution. We found significant differences in adsorption capacities of iodide depending on the bentonite properties as follows: iodide adsorption capacities were 439 mmol/kg for the bentonite modified with $HDP^+$ at an equivalent amount corresponding to 200% of the CEC of bentonite whereas no adsorption of iodide was observed for the untreated bentonite. The molecular environments of iodine adsorbed on organobentonites were further studied using I K-edge and $L_{III}$-edge x-ray absorption spectroscopy (XAS). The X-ray absorption near-edge structure (XANES) of iodine spectra from organobentonites was similar to that of KI reference solution. Linear combination fitting of EXAFS data suggests the fraction of iodine reacted with the organic compound increased with increasing loading of the organic compound on organobentonites. In this study, we observed significant differences in the adsorption environments of iodide depending on the modified property of bentonite and suggest that an organobentonite has potential as reactive barrier material around a nuclear waste repository containing anionic radioactive iodide.

Mineralogical and Geochemical Characteristics of the Precipitates in Acid Mine Drainage of the Heungjin-Taemaek Coal Mine (흥진태맥 석탄광 산성광산배수 침전물의 광물학적 및 지구화학적 특성)

  • Shin, Ji-Hwan;Park, Ji-Yeon;Kim, Yeongkyoo
    • Economic and Environmental Geology
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    • v.54 no.2
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    • pp.299-308
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    • 2021
  • Fe(II) released from mining activities is precipitated as various Fe(III)-oxyhydroxides when exposed to an oxidizing environment including mine drainage. Ferrihydrite, one of the representative precipitated Fe(III) minerals, is easy to adsorb heavy metals and other pollutants due to the large specific surface area caused by very low crystallinity. Ferrihydrite is transformed to thermodynamically more stable goethite in the natural environment. Hence, information on the transformation of ferrihydrite to goethite and the related mobility of heavy metals in the acid mine drainage is important to predict the behaviors of those elements during ferrihydrite to goethite transition. The behaviors of heavy metals during the transformation of ferrihydrite to goethite were investigated for core samples collected from an AMD treatment system in the Heungjin-Taemaek coal mine by using X-ray diffraction (XRD), chemical analysis, and statistical analysis. XRD results showed that ferrihydrite gradually transformed to goethite from the top to the bottom of the core samples. Chemical analysis showed that the relative concentration of As was significantly high in the core samples compared with that in the drainage, indicating that As was likely to be adsorbed strongly on or coprecipitated with iron oxyhydroxide. Correlation analysis also indicated that As can be easily removed from mine drainage during iron mineral precipitation due to its high affinity to Fe. The concentration ratio of As, Cd, Co, Ni, and Zn to Fe generally decreased with depth in the core samples, suggesting that mineral transformation can increase those concentrations in the drainage. In contrast, the concentration ratio of Cr to Fe increased with depth, which can be explained by the chemical bond of iron oxide and chromate, and surface charge of ferrihydrite and goethite.