• Title/Summary/Keyword: 산 침출

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Stabilization of Covalently Cross-Linked SPEEK/Cs-Substituted HPA Composite Membranes for Water Electrolysis ($Cs^+$치환에 따른 수전해용 공유가교 SPEEK/HPA 복합막의 안정화)

  • Jee, Bong-Chul;Ha, Sung-In;Song, Min-Ah;Chung, Jang-Hoon;Moon, Sang-Bong;Kang, An-Soo
    • Journal of Hydrogen and New Energy
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    • v.22 no.1
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    • pp.1-12
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    • 2011
  • To improve the mechanical properties, such as durabilities and antioxidative characteristics, the covalently cross-linked (CL-) SPEEK (sulfonated polyether ether ketone)/Cs-substituted HPA (heteropoly acid) organic-inorganic composite membranes (CL-SPEEK/Cs-HPAs), have been intensively investigated. The composite membrane were prepared by blending cesium-substituted HPAs (Cs-HPAs), including tungstophosphoric acid (TPA), molybdophosphoric acid (MoPA), and tungstosilicic acid (TSiA) with cross-linking agent content of 0.01 mL. And composite electrolytes composed of Cs-HPAs, prepared by immersion (imm.) and titration (titr.) methods to increase the stability of HPAs in water, were applied to polymer electrolyte membrane electrolysis (PEME). As a result, the proton conductivity of Cs-substituted composite membranes increased rapidly over $60^{\circ}C$ but mechanical properties, such as tensile strength, decreased in accordance with added Cs content. The bleeding-out of Cs-TPA membranes by titration method (50 vol.% Cs) decreased steadily to 2.15%. In the oxidative stability test by Fenton solution, the durability of membranes with Cs-HPA significantly increased. In case of CL-SPEEK/ Cs-TPA membrane, duration time increased more than 1200 hours. It is expected that even though CL-SPEEK/Cs-MoPA membrane shows the high proton conductivity, electrocatalytic activity and cell voltage of 1.80 V for water electrolysis, the CL-SPEEK/Cs-TPA (imm.) is more suitable as an alternative membrane in real system with the satisfactory proton conductivity, mechanical properties, anti-oxidative stability and cell voltage of 1.89 V.

A Study to Recover Si from End-of-Life Solar Cells using Ultrasonic Cleaning Method (초음파 세척법을 이용한 사용 후 태양광 셀로부터 Si 회수 연구)

  • Lee, Dong-Hun;Go, Min-Seok;Wang, Jei-Pil
    • Resources Recycling
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    • v.30 no.5
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    • pp.38-48
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    • 2021
  • In this study, we determine the optimal process conditions for selectively recovering Si from a solar cell surface by removal of impurities (Al, Zn, Ag, etc.). To selectively recover Si from solar cells, leaching is performed using HCl solution and an ultrasonic cleaner. After leaching, the solar cells are washed using distilled water and dried in an oven. Decompression filtration is performed on the HCl solution, and ICP-OES (Inductively Coupled Plasma Optical Emission spectroscopy) full scan analysis is performed on the filtered solution. Furthermore, XRD (X-ray powder diffraction), XRF (X-ray fluorescence), and ICP-OES are performed on the dried solar cells after crushing, and the purity and recovery rate of Si are obtained. In this experiment, the concentration of acid solution, reaction temperature, reaction time, and ultrasonic intensity are considered as variables. The results show that the optimal process conditions for the selective recovery of Si from the solar cells are as follows: the concentration of acid solution = 3 M HCl, reaction temperature = 60℃, reaction time = 120 min, and ultrasonic intensity = 150 W. Further, the Si purity and recovery rate are 99.85 and 99.24%, respectively.

Enhanced hydrogen fermentation of food waste (음식물쓰레기를 이용한 수소발효 시 효율향상에 관한 연구)

  • Han, Sun-Kee;Kim, Hyun-Woo;Shin, Hang-Sik
    • Journal of the Korea Organic Resources Recycling Association
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    • v.11 no.4
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    • pp.105-113
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    • 2003
  • Successful operation of a reactor can be accomplished when it is operated at proper D depending on the state of degradation. Operation at high D leads to the washout of biomass in the reactor while operation at low D leads to product inhibition due to the accumulation of excess VFA. These appear to limit the production of hydrogen to reach a higher level. Operation by D control was performed to improve the efficiency of hydrogen fermentation of food waste. Although simple organic matters were rapidly degraded in the early stage (day 1-2), proper VFA concentration and pH values were kept in the reactor at D of $4.5d^{-1}$, which was previously reported to be optimum initial D. High butyrate/acetate (B/A) ratios over 3.2 were obtained. Without D control, the reduction of simple organic matters after day 2 caused the decrease of VFA production and the increase of pH. Hydrogen production also decreased, as microbial proliferation was less than microbial loss by washout. However, the reactor performance was dramatically improved at D control from 4.5 to $2.3d^{-1}$. It showed the highest B/A ratios over 2.0 among the reactors on day 4-7. The second hydrogen peak appeared on day 4, resulting in the highest fermentation efficiency (70.8%) among the reactors. It was caused by the enhanced degradation of slowly degradable matters. The COD removed was converted to hydrogen (19.3%), VFA (36.5%), and ethanol (15.0%). Therefore, the strategy using D control, depending on the state of degradation, was effective in improving the efficiency of hydrogen fermentation.

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Nutritional components and antioxidant activities of Nelumbo nucifera Gaertner flower and its wine (연화 및 연화주의 영양성분 및 항산화활성)

  • Kwak, Woo-Sun;Lee, Sun-Kyu;Lee, Ki-Jin;Kim, Kye-Hoon;Kim, Hey-Ran;Lee, Hyo-Ku;Oh, Ji-Won;Lee, Ok-Hwan
    • Food Science and Preservation
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    • v.21 no.3
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    • pp.373-380
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    • 2014
  • This study was conducted to investigate the nutritional components and antioxidant activities of Nelumbo nucifera Gaertner flower (lotus flower, LF) and its wine (lotus flower wine, LF wine). The moisture, crude protein, crude fat, crude ash, and carbohydrate contents of the LF were 85.90, 1.91, 0.30, 1.04, and 10.85%, respectively, and of the LF wine, 92.87, 1.70, 0.30, 0.15, and 5.17%, respectively. The total amino acids in the LF and the LF wine were 2,168 and 6,341 mg/kg, respectively. Palmitic acid (38.63%) was a major fatty acid in the crude fat of the LF, and oleic acid (76.24%) was a major fatty acid in the crude fat of the LF wine. The levels of potassium in the LF ($390.91{\pm}9.60mg/100g$) and the LF wine ($27.40{\pm}1.86mg/100g$) were higher than those of the other minerals. The total phenol and flavonoid contents of both the lotus flower water extract (LFW) and the lotus flower ethanol extract (LFE) were higher than those of the LF wine. In addition, the highest antioxidant activities and ORAC values were obtained from the LFW and the LFE. In conclusion, we found that the LF and the LF wine have potential as natural antioxidants due to their higher bioactive compound contents such as their total phenol and flavonoid contents.

Isolation of Synthetic Detergent Decomposing Microorganisms in Wastewater and Synthetic Detergent Decomposition Characterization of the Microorganisms (폐하수중 합성세제분해균의 분리(分離) 및 합성세제 (ABS) 분해특성(分解特性))

  • Lee, Hong-Jae;Heo, Jong-Soo;Cho, Ju-Sik;Han, Mun-Gyu;Choi, Jeong-Ho;Lee, Chun-Hee
    • Korean Journal of Environmental Agriculture
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    • v.12 no.2
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    • pp.144-152
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    • 1993
  • A bacterium which degrades efficiently synthetic detergents was isolated from the polluted waters, activated sludge of wastewater treatment plants or polluted soil. This bacterium showed considerably higher growth rate in the agar plate containing $2,000{\mu}g/ml$ of synthetic detergents than any other isolated strains, was identified as a Pseudomonas fluorescens or strains similar to it. The strain was named as a Pseudomonas fluorescens S1. Optimum pH and temperature for the growth of the Pseudomonas fluorescens S1 were pH 7.0 and $30^{\circ}C$, respectively. The strain was resistant to streptomycin and gentamycin, but sensitive to kanamycin. The strain was greatly resistant to zinc chloride, lead nitrate and copper sulfate, but unable to grow in the presence of relatively low concentrations of mercury chloride and silver nitrate. This strain utilized benzene, catechol, cyclohexane and xylene as a sole carbon source. The strain was well grown in the medium containing ABS 10,000${\mu}g$/ml. Degradation of ABS was 55% and 60% at 20${\mu}g$/ml and 100${\mu}g$/ml of ABS, respectively. Benzene ring was degraded 45% in 100${\mu}g$/ml of ABS. During the incubation of the strain in the medium containing ABS 100${\mu}g$/ml and COD 10,000${\mu}g$/ml for 4 days, degradation of ABS and COD were reduced to 40${\mu}g$/ml and 3,200${\mu}g$/ml, respectively. Total amino acid content of the Pseudomonas fluorescens S1 grown with 1,000${\mu}g$/ml of ABS was 115mg/g cell, whereas its content was decreased in the bacterium grown without synthetic detergent by 9.4%.

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Characteristics of Heavy Metal Contamination in Residual Mine Tailings Near Abandoned Metalliferous Mines in Korea (국내 폐금속광산 주변 잔류광미의 중금속 오염특성)

  • Jung, Goo-Bok;Kim, Won-Il;Lee, Jong-Sik;Lee, Jae-Saeng;Park, Chan-Won;Koh, Mun-Hwan
    • Korean Journal of Environmental Agriculture
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    • v.24 no.3
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    • pp.222-231
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    • 2005
  • Most of the tailings have been left without any management in abandoned metalliferous mines and have become the main source of heavy metal contamination of agricultural soils and crops in the these areas. To compare of environmental assessment of heavy metals in tailings derived from various 25-metalliferous mines in Korea, 3 different analysis methods such as water soluble, 0.1 M-HCl extractable, and total acid digestion method (aqua regia) were used. The chemical composition of water soluble in mine tailing were in the order ${SO_4}^{2-}>Ca^{2+}>Mn^{2+},\;Na^+,\;Al^{3+}>Mg^{2+},\;Fe^{3+}>Cl^-$. Specially, pH, EC, ${SO_4}^{2-},\;and\;Ca^{2+}$ concentrations in tailing varied considerably among the different mines. The average total concentrations of Cd, Cu, Pb, Zn, and As in tailing were 31.8, 708, 4,961, 2,275 and 3,235 mg/kg, respectively. Specially, the contents of Cd, Zn and As were higher than those of countermeasure values for soil contamination (Cd : 4, Zn : 700 and As : 15 mg/kg in soil) by Soil Environmental Conservation Act in Korea. The rates of water soluble heavy metals to total contents in tailings were in the order Cd > Zn > Cu > Pb > As. The rates of 0.1M-HCl extractable Cd, Cu, Pb, Zn, and As (1M-HCl) to total content were 17.4, 10.2, 6.5, 6.8 and 11.4% respectively. The enrichment factor of heavy metals in tailings were in the order As > Pb > Cd > Cu > Zn. The pollution index in tailing Au-Ag mine tailing were higher than those of other mine tailing. As a results of enrichment factor and pollution index for heavy metal contaminations in mine tailing of metalliferous mines, the main contaminants are mine waste materials including tailings.

Microbial Leaching of Iron from Magnetite (미생물을 이용한 자철석으로부터 철 침출에 관한 연구)

  • Roh, Yul;Oh, Jong-Min;Seo, Yong-Jae;Jang, Hee-Dong
    • Journal of the Mineralogical Society of Korea
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    • v.19 no.4 s.50
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    • pp.265-275
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    • 2006
  • It is in its infancy to use bacteria as a novel biotechnology for leaching precious and heavy metals from raw materials. The objective of this study was to investigate biogeochemical processes of iron leaching from magnetite reduction by iron-reducing bacteria isolated from intertidal flat sediments, southwestern part of Korea. Microbial leaching experiments were performed using commercial magnetite, Aldrich magnetite, in well-defined mediums with and without bacteria. Water soluble Fe production was determined by ICP analysis of bioleached samples in comparison to uninoculated controls, and the resulting precipitated solids were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The extent of iron leaching from magnetite in the aerobic conditions (Fe = 107 ppm) was higher than that in the anaerobic environments (Fe = 94 ppm). In the anaerobic conditions, Fe(III) in commercial magnetite was also reduced to Fe(II), but no secondary mineral phases were observed. Amorphous iron oxides formed in the medium under aerobic conditions where there was sufficient supply of oxygen from the atmosphere. SEM observation suggests that the reduction process involves dissolution-precipitation mechanisms as opposed to solid state conversion of magnetite to amorphous iron oxides. The ability of bacteria to leach soluble iron and precipitate amorphous iron oxides from crystalline magnetite could have significant implications for biogeochemical processes in sediments where Fe(III) in magnetite plays an important role in the largest pool of electron acceptor as well as the tool as a novel biotechnology for leaching precious and heavy metals from raw materials.

Influence of Ultrasonification on Extraction Yield and Chemical Property of Green Tea Infusion (초음파 처리가 녹차 침출액의 추출 수율 및 화학적 특성에 미치는 영향)

  • Kim, Byung-Chul;Kang, Sung-Won;Chung, Chang-Ho;Heo, Ho-Jin;Lee, Seung-Cheol;Cho, Sung-Hwan;Choi, Sung-Gil
    • Journal of agriculture & life science
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    • v.44 no.5
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    • pp.91-99
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    • 2010
  • The objective of this work was to investigate the influence of ultrasonification on extraction yield and chemical properties of green tea infusion. Changes in total soluble matter(TSM), vitamin C, total phenolic compounds, flavonols, catechins, caffeine, free amino acids contents in green tea infusion(GTI) influenced by ultrasonification at $60^{\circ}C$ of extraction temperature for 1, 5, 30, and 60 min were investigated. The amount of infused TSM increased about 5.3% by ultrasonification for 60min. Vitamin C contents also increased 0.21, 0.16, 0.31 mg/g from 1 to 30 min by ultrasonification. However, vitamin C decreased from 2.47 to 2.22 mg/g at 60min. Total phenol compounds contents increased about 10~13 mg/g on all extraction times by ultrasonification. Flavonols such as, myricetin, quercetin, kaempferol were increased to doubled contents as an influence of ultrasonification. Catechins such as, EGCG, EGC, ECG, EC, (+)-C and caffeine contents showed same tendency as the results of vitamin C. On the other hand, result of free amino acids showed different tendency. All amounts of free amino acids did not increase by ultrasonification. Consequently, content of bioactive compounds such as, vitamin C, total phenolic, flavonols and catechins in green tea infusion were influenced by ultrasonification.

Assessment Techniques of Heavy Metal Bioavailability in Soil - A critical Review (토양 중 중금속 생물유효도 평가방법 - 총설)

  • Kim, Kwon-Rae;Owens, Gary;Naidu, Ravi;Kim, Kye-Hoon
    • Korean Journal of Soil Science and Fertilizer
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    • v.40 no.4
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    • pp.311-325
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    • 2007
  • The concept of metal bioavailability, rather than total metal in soils, is increasingly becoming important for a thorough understanding of risk assessment and remediation. This is because bioavailable metals generally represented by the labile or soluble metal components existing as either free ions or soluble complexed ions are likely to be accessible to receptor organismsrather than heavy metals tightly bound on soil surface. Consequently, many researchers have investigated the bioavailability of metals in both soil and solution phases together with the key soil properties influencing bioavailability. In order to study bioavailability changes various techniques have been developed including chemical based extraction (weak salt solution extraction, chelate extraction, etc.) and speciation of metals using devices such as ion selective electrode (ISE) and diffusive gradient in the thin film (DGT). Changes in soil metal bioavailability typically occur through adsorption/desorption reactions of metal ions exchanged between soil solution and soil binding sites in response to changes in environment factors such as soil pH, organic matter (OM), dissolved organic carbon (DOC), low-molecular weight organic acids (LMWOAs), and index cations. Increasesin soil pH result in decreases in metal bioavailability through adsorption of metal ions on deprotonated binding sites. Organic matter may also decrease metal bioavailability by providing more negatively charged binding sites, and metal bioavailability can also be decreases as concentrations of DOC and LMWOAs increase as these both form strong chelate complexeswith metal ions in soil solution. The interaction of metal ions with these soil properties also varies depending on the soil and metal type.

Lithium Extraction from Smectitic Clay Occurring in Lithium-bearing Boron Deposits in Turkey (터키 리튬 함유 붕소광상에서 산출하는 스멕타이틱-점토로부터의 리튬 추출)

  • Lee, Won-Jong;Yoon, Soh-joung;Chon, Chul-Min;Heo, Chul-Ho;Lee, Gill-Jae;Lee, Bum-Han;Cicek, Murat
    • Journal of the Mineralogical Society of Korea
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    • v.29 no.4
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    • pp.167-177
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    • 2016
  • Smectitic clays, occurring in Kırka and Bigadiç boron evaporite deposits formed in Miocene playa lake environment in Turkey, contain $LiO_2$ 0.02-0.21% and 0.16-0.30%, respectively, and boron tailings are also reported to contain $LiO_2$ 0.04-0.26%. Lithium in smectitic clays was identified to be retained in hectorite. The XRD results revealed that hectorite was contained in 25.7% and 79.7% of Kırka and Bigadiç deposit samples respectively. In this study, we selected a clay sample from each deposit with lithium content of ~0.18% and estimated extractable lithium by acid treatment and roasting method commercially applicable to lithium resources, such as lepidolite and hectorite. When 1 g of crushed clay (particle size less than $74{\mu}m$) was reacted with 200 mL of 0.25 M HCl solution, the amount of lithium dissolved increased with the increase of reaction time up to 10 hours for both samples. Reaction time longer than 10 hours did not significantly increased the amount of lithium dissolved. After 10 hours of reaction, 89% of lithium in the clay sample from the Kırka deposit was dissolved, while 71% of lithium was dissolved from the Bigadiç deposit tailing sample. 87% of lithium in the clay sample from the Kırka deposit was extracted and 82% of lithium was extracted from the Bigadiç deposit tailing sample by the roasting extraction method, where clays were leached after a thermal treatment at $1,100^{\circ}C$ for 2 hours with $CaCO_3$ and $CaSO_4$.