• Title/Summary/Keyword: Heavy ion

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Photocatalytic Property of Nano-Structured TiO$_2$ Thermal Sprayed Coating - Part II: TiO$_2$ -WO$_3$ Coating - (나노구조 TiO$_2$용사코팅의 미세조직 제어 공정기술 개발과 광촉매 특성평가 - Part II: TiO$_2$- WO$_3$ 코팅 -)

  • 이창훈;최한신;이창희;김형준;신동우
    • Journal of Welding and Joining
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    • v.21 no.4
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    • pp.46-55
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    • 2003
  • TiO$_2$-WO$_3$(8.2wt%) coatings were prepared by the APS (Atmospheric Plasma Spraying) process to clarify the relationship between the process parameters(H$_2$ gas flow rate of plasma 2nd gas and spraying distance) of the APS coating and photo-decomposition efficiency kinetics of the MB(methylene blue) aqueous solution decomposition and to understand the effect of addition of WO$_3$ on photocatalytic properties of TiO$_2$ sprayed coating. Further, the temperature and velocity of flying particles were measured by DPV-2000 to investigate the relationship between microstructure of coatings and process parameters. Properties of coatins were investigated by XRD, SEM, XPS, RAMAN, UV/VIS spectrometer. In case of the TiO$_2$-WO$_3$(8.2wt%) coating, it had a lower anatase fraction than that of pure-TiO$_2$ coatings because of flying in the higher temperature plasma plume by the heavy weight of TiO$_2$, WO$_3$. And, when WO$_3$ added powders were spayed, the doping effects of W ions substituted into the Ti ion sites was not occured during melting and solidification cycles of spraying. It was found that the addition of WO$_3$ was ineffective effective on increasing photo-decomposition efficiency of TiO$_2$ sprayed coating.

Characteristics of Suspended Fine-Grained Particles in Settling Columns (침강수주에서 부유된 광물성 미립자의 특성)

  • Kim Jong-Woo;Yoon Sei-Eui;Lee Jong-Tae
    • Proceedings of the Korea Water Resources Association Conference
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    • 2005.05b
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    • pp.393-398
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    • 2005
  • Suspended fine mineral particles are deposited at the areas with low flow velocity and low transportation capacity in rivers, reservoirs and lakes. It can be contaminated by heavy metals. Examples of problem fields art dredging of sediment, water pollutants, and maintenance of navigation channels and construction works. To deal with the settling problems it is necessary to understand tile physico-chemical characteristics of cohesive sediment under varying density of particle and ion addition(NaOH, HCl, NaCl), which is dissolved in river, because fine-grained cohesive sediment can lead to flocculation with the physico-chemical influences and takes different characteristics. Experiments with fresh and saline water are followed with fine-grained sediments(alumina and quartz) in settling columns. Settling velocity of suspended fine particles in still water was measured with a pressure sensor(maximum 10 mbar). Until the initial concentration of 20,000 mg/1 of alumina and quartz the settling velocity was on the increase. Above this initial concentration was it on the decrease. In an acid condition, which causes strong flocculation, average settling velocity of quartz powder was high. In an alkaline water low average settling velocity of it was observed. However, alumina behaved exactly contrarily.

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Removal of copper ion from the waste water by Manganese Nodules using fixed bed and column (고정형(固定形) Bed와 컬럼을 이용(利用)한 망간 단괴(團塊)에 의한 폐수(廢水) 중의 구리이온 제법(除去))

  • Park, Kyung-Ho;Nam, Chul-Woo;Kang, Nam-Hee
    • Resources Recycling
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    • v.20 no.5
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    • pp.64-68
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    • 2011
  • The typical properties of manganese nodules are its high porosity and high specific surface area and manganese in nodules is existed as ${\delta}$-MnO$_2$. These properties suggest that manganese nodules ran be used as an adsorbent for heavy metal ions. This study investigated the practical applicability for the removal of copper ions in the waste water by manganese nodules as an adsorbent using fixed column and fix bed systems. Manganese nodules of 1kg (size 1-3 cm) can absorb 4.0g Cu in fixed column system and 2.3g Cu in fixed bed system from waste water for 3 hours respectively.

Rice Growth Response and Soil Quality by Domestic Wastewater Irrigation on Rice Paddy Field - Lysimeter experiment - (하수종말처리장 방류수를 논 관개용수로 처리시 벼 생육 및 토양환경 영향 조사 - 라이시미터 재배실험 -)

  • Cho, Jae-Young;Park, Seung-Woo;Son, Jae-Gwon;Park, Bong-Ju;Li, Long-Gen
    • Journal of Korean Society of Rural Planning
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    • v.12 no.2 s.31
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    • pp.49-56
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    • 2006
  • The application of domestic wastewater on rice paddies results in the accumulation of sodium(Na$^+$) to the soil. Excessive concentration of sodium may cause the deterioration of the physical characteristics of the soil, change in the osmosis of the soil, destruction of soil aggregates as well as ion toxicity due to sodium accumulation. Using domestic wastewater as irrigation water should be preceded by measures to prevent or control the soil salinization caused by sodium. Agricultural reuse of domestic wastewater were found not to cause serious problems with food safety due to heavy metals. However, pre-treatment using ultraviolet or ozone is recommended to reduce the number of bacteria and gem and for public health reasons. Using domestic wastewater has shown that reducing the standard application of chemical fertilizers by as much as 50% reduced the harvesting index by only 10%. This study has shown that it is feasible to reuse domestic wastewater on rice paddies. In order to facilitate the application, it is deemed necessary to establish wastewater treatment technologies in the future, to review criteria for recycling domestic wastewater for agricultural purposes such as conditions of soil and cropping system and to resolve conflicts with farmers and public health issues.

Remediation of Copper-Contaminated Soil using Low Molecular Weight Organic Acid Flushing Technique (저분자량 유기산 세척을 이용한 오염토양으로부터의 Cu제거에 관한 연구)

  • 이기철;강순기;공성호
    • Journal of the Korean Society of Groundwater Environment
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    • v.5 no.1
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    • pp.30-36
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    • 1998
  • For successful soil flushing process selection of appropriate flushing reagents is essential. Futhermore, obtaining operating parameters for site remediation application through various bench-scale tests is also important. In this research a series of organic acids (acetic, citric, oxalic, and succinic acids) were tested for flushing capability. Copper-contaminated natural soil was used as a test medium, and flushing experiments were performed with batch system. All the organic acids used did not provide effective flushing conditions at concentration of 1 mM. At the acid concentration of 50 and 100 mM copper was removed efficiently although 50 and 100 mM did not show any significant differences in removal efficiencies. Citric acid and oxalic acid removed copper more efficiently than the others, and especially, citric acid showed over 87% of removal efficiency of copper at near neutral pH of 5 to 7. Speciation of extracted copper using GEOCHEM simulation showed majority of extracted copper existed as complexed with organic acids and only small portion of organic acids were complexed with copper indicating promising application of soil flushing with organic acid to heavy metal-contaminated site remediation.

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Lead Adsorption onto a Domestic Ca-Bentonite (국산 칼슘-벤토나이트에 대한 납 흡착)

  • 고은옥;이재완;조원진;현재혁;강철형;전관식
    • Journal of Korea Soil Environment Society
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    • v.5 no.1
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    • pp.55-63
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    • 2000
  • Bentonite has low hydraulic conductivity and high sorption capacity to limit hazardous heavy metals migration, and thus it has been considered as a liner material for the landfill of hazardous wastes. With a domestic bentonite sorption tests were carried out to investigate the adsorption isotherm and the effect of solution chemistry and temperature on adsorption. Freundlich isotherm was applied to fit the experimental data of lead adsorption, which fitted them well. Freundlich constants and correlation coefficient were calculated to be $K_{F}$\;=\;1.14$, n = 1.70, and $r^{2}\;=\;0.99$, respectively. The distribution coefficients($K_{d}$) for the adsorption of lead decreased with increasing initial lead concentration. The IL increased with increasing the pH of solution and sharply increased at pH > 7, which was attributed to the precipitation of lead species. The IL decreased with increasing the ion strength of solution. The $K_{d}$ gave a small increase with the concentration of ${SO_4}^{-2}$, whereas it had a nearly constant level with the concentration of ${HCO_3}^{-}$ in solution. An increase in the temperature of experimental solution increased the $K_{d}$.

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Burnup Measurement of Irradiated Uranium Dioxide Fuel by Chemical Methods (화학적 방법에 의한 핵연료의 연소도 측정)

  • Kim, Jung-Suk;Han, Sun-Ho;Suh, Moo-Yul;Joe, Kih-Soo;Eom, Tae-Yoon
    • Nuclear Engineering and Technology
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    • v.21 no.4
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    • pp.277-286
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    • 1989
  • Destructive methods are used for the turnup determination of an irradiated PWR fuel. One of the methods includes U, Pu, Nd-148 and Nd-(145+146) determination by an isotope dilution mass spectrometry using triple spikes (U-233, Pu-242 and Nd-150). The method involves two sequential ion exchange resin separation procedures. Pu is eluted from the first anion exchange resin column (Dowex AG 1$\times$8) with 12 M HCl-0.1 M HI mixed solution, followed by U elution with 0.1 M HCl. Nd is isolated from other fission products on the second anion exchange resin column (Dowex AG 1$\times$4) with a nitric acid-methanol eluent. Each fraction is analysed by thermal ionization mass spectrometry. The difference between Nd-148 and Nd-(145+146) method is found with an average 2.07%. The results are compared with those by the heavy element method using U and Pu isotopes and by the destructive y-spectrometric measurement of Cs-137. The dependences of isotope composition of U and Pu on burn-up, and correlation between those isotopes are illustrated graphically.

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GC-MS Analysis of Organophosphorus Pesticide Residue in Seawater From the Kwangyang Bay, Korea (광양만 해수 중 유기인 잔류 농약성분의 GC-MS 분석)

  • Park, Mi-Ok;Park, Jeom-Sook
    • Journal of Environmental Science International
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    • v.15 no.4
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    • pp.293-304
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    • 2006
  • Sea water samples collected in August, 1994 from 20 stations in the Kwangyang Bay were analyzed by gas chromatography/mass spectrometry-selected ion monitoring (GC/MS-SIM) to investigate persistence and distribution pattern of four organophosphorus pesticides (DDVP, Diazinon, IBP, EDDP). Except for IBP, the contamination by DDVP, Diazinon, and EDDP in marine aquatic environment in Korea has not been reported previously. In this study, however, all these four pesticides were detected in all stations (except DDVP) and their concentrations were in ng/L level. The concentrations ranged from detection limit to 15.3ng/L for DDVP, 1.8-27.7ng/L for Diazinon, 7.3-63.5ng/L for IBP, and 22.2-1100.1ng/L for EDDP. It is noteworthy that the measured concentrations of IBP and EDDP in this study would be much lower than usual, since the use of IBP and EDDP was less than 50% of average annual consumption due to unusually dry and hot weather condition in the summer of 1994. It was very surprising to find that the highest concentrations of organophosphorus pesticides were observed at stations near Daesa Streamlet instead of Seomjin River, which has more point source of the pesticides. This result suggests that the small river discharge during heavy ram period in summer can give harmful effect on marine biota (both wild and aqua-cultured) with its organophosphorus pesticide residue, despite of their short residence time in aquatic environment. In order to protect the marine life properly from acute toxicity of the organophosphorus pesticides, it needs to be emphasized that monitoring the level of agricultural pesticides in river run-off should be done during active consumption period rather at regular intervals.

Syntheses of Tetradentate Nitrogen-Oxygen(N2O2)) Ligands with Substituents and the Determination of Stability Constants of Their Heavy(II) Metal Complexes (치환기를 가진 질소-산소(N2O2)계 네 자리 리간드의 합성과 중금속(II)이온 착화합물의 안정도상수 결정)

  • Kim, Sun-Deuk;Seol, Jong-Min
    • Journal of Environmental Science International
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    • v.21 no.4
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    • pp.421-435
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    • 2012
  • Novel $N_2O_2$ tetradentate ligands, H-3BPD and H-2BPD were synthesized. Hydrochloric acid salts of Br-3BPD, Cl-3BPD, Br-2BPD and Cl-2BPD having Br and Cl substituents at the $para$ position of the phenol hydroxyl group, were synthesized. The ligands were characterized by C. H. N atomic analysis, $^1H$ NMR, $^{13}C$ NMR, UV-visible, and mass spectra. The proton dissociation constants ($logK_n{^H}$) of the phenol hydroxyl group and secondary amine of the synthesized $N_2O_2$ ligands were shown by four step wise values. The orders of the calculated overall proton dissociation constants ($log{\beta}_p$) were Br-3BPD < Cl-3BPD < H-3BPD in case of 3BPD and Br-2BPD < Cl-2BPD < H-2BPD in case of 2BPD respectively. The order agreed well with that of $para$ Hammett substituent constants(${\delta}_p$). The stability constants($logK_{ML}$) of the complexes between the synthesized ligands and transition metal(II) ions agreed with the order of $log{\beta}_p$ of the ligands. The order of the $logK_{ML}$ value of the each transition metal (II) ion was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II), which agreed well with that of Iriving-Williams series.

Possible Uses of Reclaimed Wastewater Effluent Treated Using Birm Filtration Along UF, and Analysis on Membrane Fouling (하수방류수 재이용을 위한 Birm filter + UF 적용시 용도별 사용 가능성 및 막오염 특성)

  • Jung, Jin-Hee;Lee, Seung-Chul;Sung, Nak-Chang;Choi, Young-Ik
    • Journal of Environmental Science International
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    • v.25 no.11
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    • pp.1467-1474
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    • 2016
  • In response to the water shortage problem, continued attempts are being made to secure consistent and reliable water sources. Among various solutions to this problem, wastewater effluent is an easy way to secure the necessary supply, since its annual output is consistent. Furthermore, wastewater effluent has the advantage of being able to serve various purposes, such as cleaning, sprinkling, landscaping, river management, irrigation, and industrial applications. Therefore, this study presents the possible use of reclaimed industrial wastewater treated with Birm filters and a UF membrane, along with an analysis on membrane fouling. The preprocessing stage, part of the reclamation process, used Birm filters to minimize membrane fouling. Since this study did not consider heavy metal levels in the treated water, the analyses did not include the criterion for irrigation water quality. However, the wastewater reclaimed by using Birm filters and a UF membrane met every other requirement for reclaimed water quality standards. This indicated that the treated water could be used for cleaning, channel flow for maintenance, recreational purposes, and industrial applications. The analysis on the fouling of the Birm filter and UF membrane required the study of the composition and recovery rate of the membrane. According to SEM and EDX analyses of the UF membrane, carbon and oxygen ion composition amounted to approximately 57%, whereas inorganic matter was not detected. Furthermore, the difference in the recovery rates of the distressed membrane between acidic and alkaline cleaning was more than ~78%, which indicated that organic rather than inorganic matter contributed to membrane fouling.