• 제목/요약/키워드: Calcium hydroxide

검색결과 512건 처리시간 0.031초

칼슘과 마그네슘염을 이용한 염색폐수의 응집처리 (Treatment of Dyeing Wastewater by Flocculation with Calsium and Magnesium salts)

  • 김재용;서완주
    • 환경위생공학
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    • 제17권3호
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    • pp.89-98
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    • 2002
  • The changes of conventional clarification process and an increase in treatment cost are required to meet increasingly stringent regulations related to the treated water quality. Although many enhanced coagulations have introduced to improve organic matter removal, the results to remove color, nitrogen and phosphorus as well as organic material have not been very efficient yet. The removal of waste matters such as SS, organic matter, color and turbidity contained in dyeing wastewater was carried out by using the combination of calcium hydroxide and magnesium sulfate. The flocculation was investigated as a function of coagulant dose, pH, mixing time, settling time and coagulant addition modes such as the sequential addition of the two coagulants and the simultaneous addition of them. The flocculation by the combination of calcium hydroxide and magnesium sulfate was compared with that by aluminum sulfate. The mechanism of flocculation was investigated as well. About 84% of color in dyeing watewater was removed by flocculation with combination of calcium hydroxide and magnesium sulfate.

국내 수돗물의 부식성 특성 및 개선방안 (Characteristics and Improvement of Tap Water Corrosivity in Korea)

  • 김진근;김영관
    • 상하수도학회지
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    • 제25권5호
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    • pp.731-739
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    • 2011
  • To investigate corrosivity characteristics of tap water in Korea, Langelier index (LI) of 30 multi-regional water treatment plants (WTPs) were evaluated. Weekly LI values of 30 WTPs were all negative, which means tap water in Korea might be very corrosive. Maximum LI decrease through water treatment processes was 0.95 under no additional corrosion control process. Based on the correlation results between LI and tap water qualities, pH and calcium concentration were confirmed as major parameters for LI control. Addition of calcium hydroxide with $CO_{2}$ or calcium hydroxide or sodium hydroxide can be chosen based on water quality. Continuous monitoring of LI and related parameters is recommended in water distribution system.

Formocresol이 치수조직(齒髓組織)에 미치는 영향(影響)에 관(關)한 실험적(實驗的) 연구(硏究) (EXPERIMENTAL STUDY ON THE EFFECT OF FORMOCRESOL TO THE PULP TISSUE)

  • 박덕상
    • Restorative Dentistry and Endodontics
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    • 제6권1호
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    • pp.17-25
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    • 1980
  • The purpose of this study was to evaluate the pulpal response against calcium hydroxide and zinc oxide containing various concentration of formocresol (0.1, 0.5, 1, 5, 10, 20 and 30%). The experiment was performed on dog's teeth (75 teeth from 5 dogs: Table 1.) and the teeth were routinly treated in laboratory procedures. Followings are the results obtained through microscopical examination. 1. In zinc oxide group, intlammatory reaction was severe in low concentrated formocresol and the (higher the concentration of formocresol the milder the inflammatory reaction was more evident. 2. In zinc oxide group, inflammatory change was milder at 3 weeks than 1 week, and proliferation of young connective tissue was seen at 3 weeks. 3. In calcium hydroxide group, inflammatory change in relation to the concentration of formocresol was not noticeable. 4. In calcium hydroxide group, repair process with decreased inflammatory reaction and fibrosis, and dentin bridge like layer was found at 3 weeks.

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미세 환경조건에 따른 콘크리트 탄산화 깊이 예측 (Prediction of Depth of Concrete Carbonation According to Microenvironmental Conditions)

  • 박동천
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2021년도 가을 학술논문 발표대회
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    • pp.158-159
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    • 2021
  • When the porous concrete is exposed to the external environment, the internal relative humidity changes from time to time due to the inflow and outflow of moisture. This change in moisture is affected by temperature. The temperature and humidity of concrete is dominant in the carbonation rate, the largest cause of deterioration of concrete. In this study, actual weather data were used as boundary conditions. A carbonization model of concrete temperature and humidity and calcium hydroxide was constructed to perform long-term analysis. There is a slight error in the carbonation formula of the Japanese Academy of Architecture applying the Kishtani coefficient, a representative experimental formula related to carbonization, and the analysis result values. However, considering that it behaves very similarly, it is thought that a fairly reliable numerical analysis model has been established. A slight error is believed to be due to the fact that the amount of residual calcium hydroxide in the carbonated site has not yet been clearly identified.

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Calcium release and physical properties of modified carbonate apatite cement as pulp capping agent in dental application

  • Zakaria, Myrna Nurlatifah;Cahyanto, Arief;El-Ghannam, Ahmed
    • 생체재료학회지
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    • 제22권4호
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    • pp.346-351
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    • 2018
  • Background: Carbonate apatite ($CO_3Ap$) and silica-calcium phosphate composite (SCPC) are bone substitutes with good prospect for dental application. SCPC creates a hydroxyapatite surface layer and stimulate bone cell function while, $CO_3Ap$ induce apatite crystal formation with good adaptation providing good seal between cement and the bone. Together, these materials will add favorable properties as a pulp capping material to stimulate mineral barrier and maintain pulp vitality. The aim of this study is to investigate modification of $CO_3Ap$ cement combined with SCPC, later term as $CO_3Ap-SCPC$ cement (CAS) in means of its chemical (Calcium release) and physical properties (setting time, DTS and pH value). Methods: The study consist of three groups; group 1 (100% calcium hydroxide, group 2 $CO_3Ap$ (60% DCPA: 40% vaterite, and group 3 CAS (60% DCPA: 20% vaterite: 20% SCPC. Distilled water was employed as a solution for group 1, and $0.2mol/L\;Na_3PO_4$ used for group 2 and group 3. Samples were evaluated with respect to important properties for pulp capping application such as pH, setting time, mechanical strength and calcium release evaluation. Results: The fastest setting time was in $CO_3Ap$ cement group without SCPC, while the addition of 20% SCPC slightly increase the pH value but did not improved the cement mechanical strength, however, the mechanical strength of both $CO_3Ap$ groups were significantly higher than calcium hydroxide. All three groups released calcium ions and had alkaline pH. Highest pH level, as well as calcium released level, was in the control group. Conclusion: The CAS cement had good mechanical and acceptable chemical properties for pulp capping application compared to calcium hydroxide as a gold standard. However, improvements and in vivo studies are to be carried out with the further development of this material.

Fly Ash가 다량치환된 모르타르의 압축강도 회복에 관한 기초적 연구 (Fundamental Research on Compressive Strength Recovery of Excessive High-volume Fly Ash Mortar)

  • 최윤호;신세준;한준희;현승용;한민철;한천구
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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    • pp.199-200
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    • 2019
  • The purpose of the research is assessing the possibility of strength recovery for mortar added with accidently high amount of fly ash. For compressive strength at 28 day, the sample painted with sodium hydroxide showed higher compressive strength than the sample painted with calcium hydroxide. Regarding the curing conditions, the curing temperature 65℃ provided better conditions than the curing temperature 20℃ in aspect of solution penetration depth and reactivity of fly ash. In the case of drying after saturation, the case painted with sodium hydroxid 65℃ showed the clearest engrossing mark.

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패각을 이용한 인산칼슘계 화합물의 제조에 관한 연구 (A study on the preparation of phosphatic calcium compounds using the shell resources)

  • 이인곤;김판채
    • 한국결정성장학회지
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    • 제10권2호
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    • pp.171-176
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    • 2000
  • 패각으로부터 얻어지는 고순도의 소석회와 탄산칼슘을 이용하여 인산1수소칼슘, 수산화아파타이트, 골회 및 인산3칼슘과 같은 인산칼슘계 화합물을 제조하였다. 인산2수소칼슘은 고순도의 소석회와 인산용액을 이용하여 제조하였으며, 그리고 인산1수소칼슘을 출발원료로 하여 고상반응법에 의해 골회를 제조하였고 또 수열처리법을 이용하여 수산화아파타이트를 제조하였다. 인산3칼슘의 제조는 골회와 고순도의 탄산칼슘을 혼합한 뒤 고상반응시켜 제조하였다. 본 연구에서는 이상과 같은 인산칼슘계 화합물에 대한 최적의 제고공정 및 제조 조건을 확립하였다.

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근관내 주요 혐기성 병인균에 대한 수종 항생제와 근관충전용 세멘트의 항균효과에 관한 연구 (ANTIMICROBIAL EFFECT OF ANTIBIOTICS AND ROOT CANAL CEMENTS ON THE PREDOMINANT PATHOGENIC ANAEROBIC MICROFLORA IN ROOT CANALS)

  • 배광식
    • Restorative Dentistry and Endodontics
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    • 제18권2호
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    • pp.515-525
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    • 1993
  • The purpose of this study was to evaluate the susceptibility of anaerobic microorganisms to certain antibiotics and root canal cements. Prevotella intermedia(Bacteroides intermedius) ATCC 25611(serotype A), Fusobacterium nucleatum ATCC 25586, Actinomyces viscosus ATCC 15987 which are the predominant pathogenic anaerobes in dental root canals were cultured in BHI for 48 hours(Fig.1). After each $200{\mu}l$ of those broths with microorganisms was streaked on each surface of blood agar plate, 2 to 5 antibiotic discs which are impregnated with Tetrncycline, Erythromycin, Ampicillin, Clindamycin, or Vancomycin were applied on each surface of blood agar plate and cultured for 5 days anaerobically in the anaerobic chamber (Fig.2). 15 antibiotic discs for each kind of antibiotics and each species of microorganisms were tested. Also each kind of root canal cement tubes which include Zinc oxide eugenol cement, Zinc phosphate cement, Calcium hydroxide powder+DD.W., Calcium hydroxide paste(Pulpdent Tempcanal), or Vitapex(Table 1) were applied on the inoculated BAPs after $200{\mu}l$ of each experimental species of microorganisms was streaked on the surface of blood agar plates, and they were cultured for 5 days anaerobically in the anaerobic chamber(Fig.3). The sensitivity(antimicrobial effect) was determined by the diameter of the inhibition zone. The results are as follows: 1. The results of antibiotic susceptibility test(Table 2) 1) All of the tested antibiotics had antimicrobial activity with various degrees. 2) In Prevotella intermedia (old Bacteroides intermedius), the diameter of inhibition zone to Erythromycin($37.87mm{\pm}2.20$) was largest, those to Tetracycline($26.20mm{\pm}2.96$), Vancomycin($21.53mm{\pm}1.96$), Clindamycin($18.73mm{\pm}0.96$) was smaller than former orderly, and That to Ampicillin ($7.87mm{\pm}0.83$) was smallest. 3) In Actinomyces viscosus, the diameter of inhibition zone to Erythromycin($28.73mm{\pm}1.22$) was largest, those to Ampicillin($21.73mm{\pm}1.03$), Clindamycin($21.33mm{\pm}1.59$) was similarly next order, that to Vancomycin($19.00mm{\pm}1.96$) was smaller than Clindamycin, and that to Tetracycline($11.93mm{\pm}0.70$) was smallest. 4) In Fusobacterium nucleatum, the diameter of inhibition zone to Ampicillin($31.07mm{\pm}1.91$) was largest, that to Erythromycin($28.87mm{\pm}0.92$), Clindamycin($20.47mm{\pm}1.51$), Vancomycin ($16.73mm{\pm}0.96$), Tetracycline ($12.13mm{\pm}1.06$) are smaller than former orderly. 2. The results of root canal cements and pastes(Table 3) 1) The external diameter of tube is 4mm, so 4mm of the inhibition zone diameter means non-susceptable. Prevotella intermedia (old Bacteroides intermedius) was non-susceptable to Calcium hydroxide powder+D.D.W., Calcium hydroxide paste(pulpdent Tempcanal), and Actinomyces viscosus was non-susceptable to Zinc phosphate cement, Calcium hydroxide powder + D.D.W., Calcium hydroxide paste(pulpdent Tempcanal). 2) In Prevotella intermedia (old Bacteroides intermedius), the diameter of inhibition zone to Zinc oxide eugenol cement($13.67mm{\pm}3.30$) was largest, that to Vitapex($9.20mm{\pm}2.96$), Zinc phosphate cement($6.13mm{\pm}2.07$) was smaller than former. 3) In Actinomyces viscosus, the diameter of inhibition zone to Zinc oxide eugenol cement($17.40mm{\pm}5.20$) was largest and that to Vitapex($8.80mm{\pm}1.70$) was next order. 4) In Fusobacterium nucleatum, the diameter of inhibition zone to Vitapex($42.33mm{\pm}17.2$) was largest and those to Calcium hydroxide paste(Pulpdent Tempcanal)($14.47mm{\pm}3.72$) and Zinc oxide eugenol cement($8.93mm{\pm}2.71$), Zinc phosphate cement($8.20mm{\pm}2.27$), Calcium hydroxide powder+D.D.W.($5.53mm{\pm}2.10$)was next orderly. And then In Zinc oxide eugenol cement and Zinc phosphate cement group, two of fifteen samples showed no inhibition zone, in Calcium hydroxide powder + D.D.W. group, 8 of 15 samples showed no inhibition zone.

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수산화칼슘-유지놀 화합물의 물성 (PROPERTIES OF CALCIUM HYDROXIDE-EUGENOL COMPOUND)

  • 박준철;권태경;김성교
    • Restorative Dentistry and Endodontics
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    • 제24권2호
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    • pp.408-415
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    • 1999
  • 수산화칼슘은 높은 항균성으로 인해 최근에 근관소독제로 사용이 추천되고 있는 약제이다. 본 연구자는 근관내에 수산화칼슘을 투약한 후에 산화아연유지놀계 시멘트로 근관 충전을 하는 경우 근관시멘트의 물성의 변화를 경험할 수 있었다. 본 연구의 목적은 수산화칼슘을 근관내에 투약 후 근관충전재로 산화아연유지놀계 시멘트를 사용하는 경우 발생하는 근관시멘트의 물성변화를 알아보기 위함이다. 이를 위하여 수산화칼슘-유지놀 화합물의 불성 중 용해도, 흡수성, 피막도 및 변연폐쇄성을 기성 산화아연유지놀계 근관 시멘트인 Tubli-seal$^{(R)}$과 비교하여 연구하였다. 용해도와 흡수생의 측정을 위하여 ADAS No. 57에 따라 지름 20mm 두께 15mm인 시편을 제작하여 $37^{\circ}C$ 50ml의 증류수에 7일간 침잠후 무게의 변화를 측정하였고, 피막도 측정을 위하여 ADAS No. 57에 따라 두 유리판 사이에 실험물질을 위치시키고 15 Kg의 하중을 가한 후에 두께의 증가를 측정하였다. 마지막으로 변연폐쇄성 측정을 위해서는 우치 상아질 면과 아크릴 봉 사이에 실험물질을 위치시킨 후 3일 동안 Pelican ink에 침잠시킨 후 색소의 침투 면적을 계산하여 다음과 같은 결과를 얻었다. ${\cdot}$ 수산화칼슘-유지놀 화합물의 흡수성은 59.72${\pm}$17.75%로 측정되어 3.15${\pm}$0.76%로 측정된 Tubli-seal$^{(R)}$에 비해 유의하게 높게 나타났다(p<0.05). ${\cdot}$ 수산화칼슘-유지놀 화합물의 용해도가 20.98${\pm}$2.94%로 측정되어 2.52${\pm}$0.49%로 측정된 Tubli-seal$^{(R)}$에 비해 유의하게 높게 나타났다(p<0.05). ${\cdot}$ 수산화칼슘-유지놀 화합물의 피막도가 0.36${\pm}$0.03 mm로 측정되어 0.12${\pm}$0.01mm로 측정된 Tubli-seal$^{(R)}$에 비해 유의하게 높게 나타났다(p<0.05). ${\cdot}$ 수산화칼슘-유지놀 화합물의 미세누출은 3일 동안의 색소 침투면적이 57.63${\pm}$25.85%로 측정되어 28.05${\pm}$23.46%로 측정 된 Tubli-seal$^{(R)}$에 비해 유의하게 높게 나타났다(p<0.05).

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매립지 복토재로의 활용을 위한 하수슬러지 내 중금속의 고형화/안정화 (Solidification/Stabilization of Heavy Metals in Sewage Sludge Prior to Use as a Landfill Cover Material)

  • 박연진;신원식;최상준;이훈하
    • 대한환경공학회지
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    • 제32권7호
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    • pp.665-675
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    • 2010
  • 본 연구에서는 하수슬러지를 매립지 복토재로 재활용하기 위해 래들슬래그, 시멘트, 인회석, 소석회를 첨가하여 하수 슬러지 내 중금속(Cd, Cu, Ni, Pb, Zn)의 용출을 평가하였다. 하수슬러지의 용출 평가는 EDTA (ethylenediaminetetraacetic acid) 추출법과 TCLP (Toxicity Characteristic Leaching Procedure)를 통해 이루어졌으며, 중금속 결합 기작은 연속추출(sequential extraction)을 통해 평가하였다. EDTA 용출 결과 하수슬러지에 래들슬래그/시멘트/소석회의 투입량이 증가할수록 하수슬러지 내 중금속의 용출이 감소하였다. 그러나 인회석을 투입했을 때는 중금속 용출의 감소 효과가 거의 나타나지 않았으며, 이는 EDTA가 인회석에 의한 중금속 고정화를 방해하였기 때문이다. TCLP 용출 결과 하수슬러지 내 슬래그, 시멘트 또는 소석회의 투입량이 증가하여 용출액의 pH가 7 이상일 때는 Cu의 용출 농도가 원하수슬러지의 용출농도보다 증가하는 것으로 나타났다. 그러나 인회석은 투입량이 증가할수록 중금속의 용출 농도가 감소하는 것으로 나타났다. 혼합 고화제를 투입한 하수슬러지의 중금속 용출 결과, 하수슬러지의 중량비 100%를 기준으로 래들슬래그 20%와 소석회 10%를 투입한 혼합물이 최적의 고화 혼합 비율이며, 이 때 EDTA 추출법과 TCLP로 용출한 중금속의 농도가 가장 낮게 나타났다. 이러한 결과는 하수슬러지 내 중금속 결합이 약한 결합인 exchangeable fraction과 carbonate fraction에서 강한 결합인 organic fraction으로 이동하였음을 연속추출(SM&T, formaly BCR)을 통해 확인할 수 있었다. 하수슬러지와 고화제를 최적의 비율로 혼합한 혼합물을 폐기물공정시험법으로 중금속 용출을 평가한 결과 Cu가 기준농도 이상으로 검출되었다. 그러나 TCLP에 따른 하수슬러지의 용출시험 결과 Ba, Cd, Cr, Pb의 항목에서 미국 환경보호청의 용출 기준을 만족하였다.