• Title/Summary/Keyword: Precipitate

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Application of Bacteria Isolated from Dok-do for Improving Compressive Strength and Crack Remediation of Cement-sand Mortar (독도산 탄산칼슘형성세균에 의한 모르타르 균열보수와 압축강도 증진)

  • Park, Sung-Jin;Lee, Na-Young;Kim, Wha-Jung;Ghim, Sa-Youl
    • Microbiology and Biotechnology Letters
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    • v.38 no.2
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    • pp.216-221
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    • 2010
  • This study shows an application of microbiologically induced carbonate precipitate for strength improvement and crack remediation of cement-sand mortar. Seven calcium carbonate-forming bacteria (CFB) were isolated from Dok-do and partially identified by DNA sequence analysis of the 16s rRNA gene. Crystal aggregates were apparent around the bacterial colonies grown on an agar medium. These strains showed strain specific $CaCO_3$ precipitation on urea-$CaCl_2$ medium. Among 7 isolates, Arthrobacter nicotinovorans KNUC601, Microbacterium resistens KNUC602, Agrobacterium tumefaciens KNUC603, Exiguobacterium acetylicum KNUC604, and Bacillus thuringiensis KNUC606 showed a repairing of artificial forced cracks in cement-sand mortar. Compressive strength of cement-sand mortar consolidated with Stenotrophomonas maltophilia KNUC605 was increased around 14.07% compared with that of negative control.

The Recovery of Silver from Thiourea Leaching Solution by Cementation Technique (침전법을 이용한 Thiourea 용출용액으로부터 Silver 회수)

  • Kim, Bong-Ju;Cho, Kang-Hee;Choi, Nag-Choul;Park, Cheon-Young
    • Economic and Environmental Geology
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    • v.46 no.1
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    • pp.29-37
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    • 2013
  • In order to apply the silver cementation method using Fe powder from pregnant thiourea leaching solution. Parameters such as the amount of Fe powder addition, agitation speed, and temperature were investigated. The silver cementation rate was increased by the increasing of Fe powder addition, agitation speed, and temperature. The highest silver cementation rate was found when the addition of Fe powder was 50 g/L at the agitation speed of 500 rpm. The silver cementation rate increase with increasing temperature according to the Arrhenius equation and obeys $1^{st}$ order kinetics. The activation energy from the kinetics data was found to be between 13.73 KJ/mol and 17.02 KJ/mol. In the XRD analysis, goethite was detected in the precipitate of the thiourea leach solution. This indicates that an oxidation-reduction reaction had occurred in the thiourea solution due to the addition of the Fe powder.

The Microstructure and Interfacial Reaction between Sn-3.5wt.%Ag-1wt.%Zn and Cu Substrate (Sn-3.5wt.%Ag-1wt.%Zn 땜납과 Cu기판간의 미세조직 및 계면반응)

  • Baek, Dae-Hwa;Seo, Youn-Jong;Lee, Kyung-Ku;Lee, Doh-Jae
    • Journal of Korea Foundry Society
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    • v.22 no.2
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    • pp.89-96
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    • 2002
  • This study examined the effects of adding Zn to Sn-3.5Ag solder on the microstructure changes and behavior of interface reaction of the solder joint with Cu substrate. The solder/Cu joints were examined with microscope to observe the characteristics of microstructure changes and interfacial reaction layer with aging treatment for up to 120 days at $150^{\circ}C$. Results of the microstructure changes showed that the microstructures were coarsened with aging treatment, while adding 1%Zn suppresses coarsening microstructures. The Sn-3.5Ag/Cu had a fast growth rate of the reaction layer in comparison with the Sn-3.5Ag-1Zn at the aging temperature of $150^{\circ}C$. Through the SEM/EDS analysis of solder joint, it was proved that intermetallic layer was $Cu_6Sn_5$ phase and aged specimens showed that intermetallic layer grew in proportion to $t^{1/2}$, and the precipitate of $Ag_3Sn$ occur to both inner layer and interface of layer and solder. In case of Zn-containing composite solder, $Cu_6Sn_5$ phase formed at the side of substrate and Cu-Zn-Sn phase formed at the other side in double layer. It seems that Cu-Zn-Sn phase formed at solder side did a roll of banrier to suppress the growth of the $Cu_6Sn_5$ layer during the aging treatment.

Precipitation of Cu as the sulphide from Sulphate solution containing Cu, Ni and Co (구리, 니켈, 코발트 혼합용액으로부터 침전법에 의한 구리의 분리)

  • Park Kyung-Ho;Jung Sun-Hee;Park Jin-Tae;Nam Chul-Woo;Kim Hong-In
    • Resources Recycling
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    • v.14 no.6 s.68
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    • pp.16-20
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    • 2005
  • The selective sulphide precipitation of copper from sulphate solution containing nickel and cobalt was studied with adding $Na_{2}S$ solution. Precipitation efficiency of copper increased with raising pH of solution and increasing the amount of $Na_{2}S$ added and lowing its concentration. The increase in reaction time and temperature also improved the precipitation of copper. However, attempts to selectively precipitate copper met with limited success because of co-precipitation of nickel and cobalt. With adding $20\%$ $Na_{2}S$, 3 times equivalent of Cu, at pH 1.0 of solution, $25^{\circ}C$ and 30 minutes of reaction time, precipitation efficiencies of copper, nickel and cobalt were $94.1\%$, $4.3\%$ and $4.5\%$ respectively.

Recovery of Valuable Metals from the Desulfurizing Spent Catalyst Used in Domestic Petrochemical Industry (국내 석유공장의 탈황 폐촉매로부터 유가금속의 회수에 관한 연구)

  • 김종화;양종규
    • Resources Recycling
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    • v.4 no.3
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    • pp.2-9
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    • 1995
  • The rccoverg and separation pracess of nikcl, vanadium and molybdenum from spent dcsulfilrizing catalyst ofpetrochemical rndustries was studied. Tnis process was canied out wet process which is consist of roasting, ammonialeaching and solve111 exDaction techniqcs. The metal ions of NI, V and Mo as vduable compollents were treated byroasting them a1 low lernperatuc, 400$^{\circ}$C in first dep, and then dlssah'ed nu1 at 80$^{\circ}$C wlth ammonium cabonate mlulion.Aftcr cooling them a1 room tempertaure, vanadium wa rccavered from mathcr iiquur in thc f n m of precipitate, sodiumvanadales The Secand slep, roasting the catalyst which is added sodium carbonate ul IOOO"C, was employed. Leachingwith distilled ~ a l e rga ve a iwo phase resultant, solutio~c~a ntaning Ni, V and Mo and solid residue containing sibca,alurmniu~n and iron. A solvcnt exlclction technique uslng vvriuus extractanls, MSP-8, TOIUC, LIX64Pi was eflecnve farthc extraclion and scparation ol thrcc mcfals from thc ammonical 11qou1 thc ammonical 11qou1.

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X-ray Absorption Spectra Analysis for the Investigation of the Retardation Mechanism of Iodine Migration by the Silver Ion Added to Bentonite (벤토나이트에 첨가한 은 이온에 의한 아이오딘 이동 저지 메커니즘 규명을 위한 X-선 흡수 스펙트라 분석)

  • Kim, Seung-Soo;Kim, Min-Gue;Baik, Min-Hoon;Choi, Jong-Won
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.8 no.3
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    • pp.201-205
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    • 2010
  • Most of iodine was captured by the block when NaI solution flowed through a bentonite block sorbed silver to retard the migration of iodine released from high-level radioactive wastes. In order to understand in detail the mechanism for the retardation of the iodine by the silver ion, X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectra of the silver sorbed bentonite before and after the contact with iodide were compared with those of AgO, $Ag_2O$ and AgI as references. This examination suggests that the silver ion sorbed on the bentonite is desorbed, and then it retards the migration of iodine by forming the cluster of AgI precipitate.

Effect of various cleaners and mordants to bond strength of light curing glass ionomer cements to dentin (Smear layer 제거와 금속 이온 처리가 광중합형 글라스아이오노머와 상아질간의 결합강도에 미치는 영향)

  • Lee, Won-Seob;Park, Sang-Jin
    • Restorative Dentistry and Endodontics
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    • v.19 no.1
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    • pp.45-63
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    • 1994
  • 128 freshly extracted human molars were used to study the interaction between dentinal smear layer removal with various agents, and the shear bond strength of a light cured glass ionomer cement to dentin. It was proposed that the removal of smear layers using acidic cleaners followed by incorporation of Fe mordant with dentin could enhanced the infiltration of monomer component in light curing glass ionomer cement and resulted in a high bond strength. For the first treatment process for removal of smear layers on the surfaces of dentin, 50 % citric acid, 10% maleic acid and 10 % phosphoric acid were used, and for the second treatment process, 15% ferric chloride, 6.8% ferric oxalate or 30% potassium oxalate were used. Distilled water was used as a control. After double sequential treatment on dentin, a light curing glass ionomer cement was bonded to dentin. After being immersed in water at 31'C for 24 hours, shear bond strengths were measured Instron testing machine(Model No.4202, USA). Surface changes were also observed using SEM (Hitachi, S-2300, Japan) after treatment process with each agents. The following conclusions were drawn : 1. Dentin surface cleaned with maleic acid and treated with ferric oxalate showed the highest bond strength with light curing glass ionomer cement. 2. Bond strengths of glass ionomer cement to dentin treated with maleic acid or citric acid were the highest, and that treated with phosphoric acid showed the lowest. 3. The effect of ferric oxalate on shear bond strength to dentin was always higher than that of ferric chloride. 4. The smear layers were clearly removed and the orifices of dentinal tubules were opened widely by the citric acid, maleic acid and phosphoric acid. 5. The orifices of dentinal tubules opened after using the first solution were closed with the treatment of ferric chloride. 6. The precipitate like crystals were formed on dentin surfaces and tubules, but a significant decrease in bond strength of glass ionomer cement to dentin surface treated with potassium oxalate.

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A Study on the Cementation of Cu, Ni and Co Ions with Mn Powders in Chloride Solution (염산용액중에서 망간분말에 의한 구리, 니켈 및 코발트 이온의 세멘테이션에 관한 연구)

  • 안재우;안종관;박경호
    • Resources Recycling
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    • v.9 no.3
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    • pp.3-12
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    • 2000
  • A Study on the cementation for the recovery of Cu, Ni and Co with Mn metallic powders in leaching solution from the manganese nodule that have removed Fe ions was studied. The results showed that the recovery efficiencies of metal ions with Mn powders increased when the temperature, pH and the concentration of chloride ions were increased in mixed solution. And the recovery efficiencies of Cu was 98% and not changed with the addition amounts of Mn powders but, in case of Co and Ni, the recovery efficiencies were increased with the addition amounts. The particle size of precipitate was about $5\mu\textrm{m}$. From the results of experiment we proposed the two-step cementation process for the recovery of Cu, Ni and Co with Mn powders.

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Preparation of Castable Refractories by Recycling of Aluminum Dross (알루미늄드로스를 재활용한 캐스타블내화물 제조)

  • Park Hyungkyu;Lee Hooin;Lee Jinyoung
    • Resources Recycling
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    • v.12 no.3
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    • pp.46-53
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    • 2003
  • Recycling of aluminum dross is an important issue in the secondary aluminum industries. In this study, aluminum dross generated in the domestic secondary aluminum industry was processed to use it as raw material for producing alumina refractories. Sample dross was classified according to its size. The dross smaller than 1 mm was leached with sodium hydroxide solution to extract the remained aluminum from the dross into the solution. and then aluminum hydroxide precipitate was recovered from the leach liquor. The waste residue in the leaching was washed, dried and roasted. Most remained metallic components in the residue was changed into oxide through the processes. The roasted dross was made into alumina castable refractories by mixing with aggregates and a binder. Bending strength of the tested castable specimen was over $25\;kg/\textrm{m}^2$ and compressive strength over $80\;kg/\textrm{cm}^2$, which satisfied the Korean Standard value respectively. From the results, it was suggested that this process could be applicable to recycling of aluminum dross.

Removal of Arsenic in Synthesis Method and Characteristics of Fe(III)-ettringite (비소제거를 위한 Fe(III)-ettringite 합성방법 및 특성 연구)

  • Hong, Seong-Hyeok;Park, Hye-Min;Choi, Won-Ho;Park, Joo-Yang
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.1
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    • pp.15-21
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    • 2011
  • Arsenic is one of the most abundant contaminant found in waste mine tailings, because of it's carcinogenic property, the countries like United states of America and Europe have made stringent regulations which govern the concentration of arsenic in drinking water. The current study focuses on different treatment methods for removal of arsenic from waste water. Treatment method the high strength arsenic waste water is treated with Fe(III)-ettringite by co-precipitation method. Number of experiments were carried out to decide the optimal dosage of Fe(III)-ettringite to treat arsenic waste water. The Fe(III)-ettringite was synthesized by taking appropriate equivalent ratios of calcium oxide and ferric chloride in proportion to the arsenic. The best removal efficiencies of 94% were observed at a As/(Ca: Fe) ratio of 1:3. The maximum removal of arsenic was observed in pH range of 12. But as the pH increases the arsenic removal efficiency decreases as portlandite is formed in the pH above 12. The analysis of surface of precipitate conform the needle like structure of ettringite. This treatment technique has promising features such as, the chemicals required in the treatment as well as the sludge generated can be reduced. The operating pH range is in alkaline region which is advantageous over traditional treatment process which has lower pH. Also the co-precipitation not only helps in removal of arsenic but also heavy metals.