• 자원리싸이클링
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• 제9권3호
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• pp.3-12
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• 2000

철 성분을 미리 제거한 망간단과의 합성염산침출용액중에서 구리, 니켈 및 코발트 성분을 회수하기 위하여 금속망간분말을 이용한 세멘테이션 연구를 수행하였다. 합성염산용액의 pH와 반응온도를 변화시켜 실험한 결과 pH, 반응온도 그리고 염소이온농도가 증가할수록 망간분말에 의한 구리, 니켈 및 코발트의 회수율은 증가하였으며 망간분말의 첨가량을 각 금속함량의 1.0배 당량에서 2.0배 당량까지 변화시키면서 실험한 결과 니켈 및 코발트의 경우는 회수율이 증가하였으나 구리의 경우는 거의 일정하게 98%이상의 회수율을 나타내었다. 또한 망간분말에 의해 치환된 석출물의 크기는 약 $5\mu\textrm{m}$ 정도였다. 한편 본 연구결과 구리, 니켈 및 코발트의 혼합용액에서 망간분말에 의해 구리성분을 먼저 회수하고 남은 여액으로부터 니켈 및 코발트를 회수할 수 있는 2단계 세멘테이션 공정을 제시하였다.

• 한국지반환경공학회 논문집
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• 제12권4호
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• pp.17-24
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• 2011

차수 및 지반안정을 목적으로 규산나트륨을 사용한 기존의 알칼리성 물유리계 약액주입공법은 주입 후 시간경과에 따라 지하수에 의해 주입고결체로부터 알칼리성분의 용탈이 진행되어 내구성이 약해지고 지하수를 오염시키는 문제점이 있다. 따라서 본 연구에서는 규산나트륨 주입재의 문제점을 보완하기 위해 개발된 알칼리성 실리카졸 지반주입재의 효과를 규명하는 데에 그 목적이 있다. 연구비교대상으로는 규산나트륨 주입재와 알칼리성 실리카졸 주입재로 하였다. 규산나트륨과 알칼리성 실리카졸 용액에 대하여 보통 포틀랜트 시멘트와 고로 슬래그 시멘트를 각각 배합하여 총 4가지의 Case로 나누어 공시체를 제작하여 시험을 실시하였다. 재령에 따른 일축압축강도 시험을 실시하였고, 환경영향성평가를 위하여 어독성시험과 pH시험을 실시하여 비교 및 분석을 하였다. 본 연구를 통해 고로 슬래그 시멘트를 배합한 알칼리성 실리카졸 지반주입재가 우수한 강도와 친환경성을 가지고 있는 것으로 나타났다.

• 자원환경지질
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• 제12권1호
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• pp.41-49
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• 1979

본문은 광물학 및 습식야금법의 관점에서, 산성용액내의 점토 광물의 물리적 특성과 화학적 특성을 문헌에 의해 검토한 것이다. 점토광물의 몇가지 중요한 특성은 이들이 산성용액내에서 양이온을 교환하고 흡수팽창하며, 이질광물로 분해(incongruent dissolution)하는 능력을 갖는다는 것이다. 여러 점토광물들은 양이온 교환과정으로 금속 이온들을 용액으로부터 흡착할 수 있다. 일반적으로 이들의 양이온 교환능력은 다음 순서로 증가된다. 즉, kaolinite, halloysite, illite, vermiculite, montmorillonite 산성용액내에서는 점토광물들에 의하여 동과 같은 양이온 흡착은 수소와 알미늄에 의해 크게 방해를 받으므로, 우라늄 및 동 등의 금속을 회수하는데는 점토광물이 중용한 요소가 되지 않는다. 그러나, 염기성용액에서는 양이온 흡착(uptake)이 중요하다. 흡수 팽창성은 낮은 pH에서 최소가 된다. 이는 격자 파괴에 기인할 가능성이 많다. 흡수 팽창은 montmorillonite형 점토에서 조절이 되는데 그것은 내부층의 Na 이온이 리튬 과/또는 수산화된 알미늄 이온과 교환을 하기 때문이다. 점토광물에 대한 산의 효과는 다음과 같다. i) 면적 및 다공성이 증가됨에 따라 보다 작은 판상의 집합체로 분리됨 ii) 점토-산 반응은 다음 순서로 일어난다. (ㄱ) 내부층 양이온들의 $H^+$ 치환 (ㄴ) Al, Fe, Mg 등의 팔면체 양이온의 이동. (ㄷ) 사면체 Al 이온들의 이동. 산의 공격반응(attack)은 점토 입자의 가장자리에서부터 시작되어 내부로 계속되며, 수화된 규소겔을 가장 자리에 남긴다. iii) (ㄴ)과 (ㄷ)의 반응속도는 위-일급($pseudo-1^{st}$ order)이며, 이는 산의 농도에 비례한다. 그리고 그 속도는 온도 매 $10^{\circ}C$ 증가에 따라 배가된다. 산에 의한 동이나 우라늄을 제자리에서 용해시키는 경우 고찰할 문제는 다음과 같다. i) 1년 혹은 그 이상의 오랜 작용으로 산의 반응을 받은 점토광물은 규소겔을 남길 것이다. 그런데 이 겔이 용해(leaching)작용을 받고 있는 유용 광물 표면을 덮게 되면 용해에 의한 회수 속도는 실질적으로 감소된다. ii) 0.5% 점토광물과 동을 함유하는 회수 가능한 동광상에 대해 점토-산 반응에 사용될 값의 상승은 동 1파운드당 1.5c이다. (혹은 구리 1파운드당 $H_2SO_4$ 0.93Ibs) 점토광물에 의한 이러한 산의 소모량이 산화동광상에서 동을 추출하는데 경제적 평가의 한 요소가 될 것이다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.189-196
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• 2003

Soil-cement column is often used as a contaminant barrier. This study presents the results of experimental study performed to investigate the changes of properties of soil-cement column under the attack of acids. Sulfuric nitric, and ascetic acid were used as contaminants. Specimen were made of clayey and sandy soils with addition of cement and water Permeability of soil-cement decreased with time during permeability test. When significant amount of acid percolated the specimen, permeability increased and compressive strength decreased due to the dissolution and leaching of cement and its chemical reaction compounds. Sulfuric and nitric acid were more effective than ascetic acid in deteriorating soil-cement column. Amount of acid required to lower the pH of soil cement below 12 was calculated from the results of permeability tests. This leads to a conclusion that, under the conditions employed in this study, the chemical stability of soil-cement column could be maintained against acid attack for longer than generally accepted lifetime of contaminant barriers.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1593-1596
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• 2012

A new enzyme immobilization method based on hydrophobic interaction between supporting material and enzyme has been successfully developed. The efficacy of the new technique has been investigated by loading a horse radish peroxidase (HRP) enzyme on the surface of conducting polymer-silica composites and by measuring the enzyme activity and leaching property of HRP loaded within polymer-silica composites. The immobilized HRP enzyme showed activity profiles similar to that of free HRP in phosphate buffer (pH 6). Above all, HRP adsorbed on the polymer-silica composites has showed excellent stability over 10 days, compared to HRP adsorbed on the pristine silica. It is thought that with appropriate optimization works, the present method would be used as a cost-effective and facile route for the immobilization of biomolecules.

• 한국환경농학회지
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• 제16권1호
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• pp.80-93
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• 1997

Pesticide residues in soil could be affected to the growth of micro organisms and the activity of enzymes directly, and successively to the soil properties as pH, Eh and nitrogen metabolism. However, residues are diminished by degradation of soil microorganisms, run-off, leaching, volatilization, photodecomposition and uptake through crops. In this paper research results published in Korea were summarized about translocation of soil residues into crops, fates of residues in soil, effects to the activity of soil microorganisms and metabolic pathways of some pesticides. Generally speaking, pesticide residues in soil were not much affected to the agro-ecosystem except few chemicals. So it should be needed more further researches in this field, continuously.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.649-654
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• 2002

In order to suggest recyling and handling method of a tailing, observe it's physical and chemical properties, make an quality test of aggregates which are used a tailing and then examine a applied possibility in architectural materials. Tailing has a ununiform and many-side shape and it is organized quartz, muscovite, calcite, montmorillonite. pH is 6.86-7.28 and the result of leaching test is that Hg and Pb exceed of a standard. The specific gravity of aggregates which are used tailing is 1.95-2.23 and the absorption factor is 9-14.67%. The result of test for abrasion and crushing of aggregates which are used BFS is very excellent. The heavy metal is stabilized but a eruption property of Hg is similar to original sample.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.869-872
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• 2004

A study on the solidification of sludge by reactive amendment agent was carried out in this paper. The reactive amendment agent used in this study is mainly composed of inorganic solidification agent and reactive adsorptive material. The reactive agent has a function of soil-cement-agent solidification and harmlessness of contaminant in waste. The reactive agent is environmentally friendly material to the surrounding environment. In this study, a series of tests and experiments including unconfined compressive strength, permeability, pH test, constituent analysis, leaching test were carried out to analyse engineering and environmental characteristics of solidified sludge treated reactive agent. The result of this research shows that the solidified sludge treated reactive agent is increased in strength and decreased in contaminant concentration.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.73-77
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• 2003

Red mud is a waste material formed during the production of alumina when the bauxite ore is subjected to caustic leaching. It is a brick-red colored highly alkaline (pH 10-12) sludge containing mostly oxides of iron, aluminum, titanium, and silica. Red mud, due to its high aluminum, iron, and calcium contents, has been suggested as a cheap adsorbent for removal of toxic metals (e.g., As, Cr, Pb, Cd) as well as for water or wastewater treatment. The basic advantage of red mud is its versatility in application. This study was conducted to evaluate the effect of red mud on stabilization and fixation of heavy metals (such as Pb, Cu, C $r^{6+}$, Cd, Zn) contained in the Al-coating sludge and soil. The results showed that the concentration of heavy metals leached from the treated sludge and soil was low, meeting the regulatory permit level.

• 한국재료학회지
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• 제22권9호
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• pp.445-449
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• 2012

We investigate the effects of redox reaction on preparation of high purity ${\alpha}$-alumina from selectively ground aluminum dross. Preparation procedure of the ${\alpha}$-alumina from the aluminum dross has four steps: i) selective crushing and grinding, ii) leaching process, iii) redox reaction, and iv) precipitation reaction under controlled pH. Aluminum dross supplied from a smelter was ground to separate metallic aluminum. After the separation, the recovered particles were treated with hydrochloric acid(HCl) to leach aluminum as aluminum chloride solution. Then, the aluminum chloride solution was applied to a redox reaction with hydrogen peroxide($H_2O_2$). The pH value of the solution was controlled by addition of ammonia to obtain aluminum hydroxide and to remove other impurities. Then, the obtained aluminum hydroxide was dried at $60^{\circ}C$ and heat-treated at $1300^{\circ}C$ to form ${\alpha}$-alumina. Aluminum dross was found to contain a complex mixture of aluminum metal, aluminum oxide, aluminum nitride, and spinel compounds. Regardless of introduction of the redox reaction, both of the sintered products are composed mainly of ${\alpha}$-alumina. There were fewer impurities in the solution subject to the redox reaction than there were in the solution that was not subject to the redox reaction. The impurities were precipitated by pH control with ammonia solution, and then removed. We can obtain aluminum hydroxide with high purity through control of pH after the redox reaction. Thus, pH control brings a synthesis of ${\alpha}$-alumina with fewer impurities after the redox reaction. Consequently, high purity ${\alpha}$-alumina from aluminum dross can be fabricated through the process by redox reaction.