중금속 오염 토양 복원에 사용되는 Chelating agent의 회수 및 재사용에 대한 연구

공성호; 박은경; Sung Ho Kong; Eun Kyung Bak

Journal of the Korean Industrial and Engineering Chemistry, Vol.12, No.6, 632-636, October, 2001

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중금속 오염 토양 복원에 사용되는 Chelating agent의 회수 및 재사용에 대한 연구

A Study on the Recovery and Reuse of Chelating Agent for Remediation of Heavy Metal-contaminated Soil

공성호 ^†, 박은경

한양대학교 화학공학과, 서울 133-791

Sung Ho Kong^†, and Eun Kyung Bak

Department of Chemical Engineering, Hanyang Univ., Seoul 133-791, Korea

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초록

중금속으로 오염된 토양으르 soil flushing 기술을 적용하여 처리한 후 회수된 용출액을 재사용하기 위해서 재생된 chelating agent의 중금속 처리효과를 평가하고자 하였다. pH 변화에 따른 중금속-유기산 복합체의 성상 변화가 조사되었다; 1) citric acid를 chelating agent로 사용한 경우 pH 변화에 따른 구리의 제거 효율은 전체적으로 낮았다. 납의 제거 효율은 pH 11.5에 이르는 동안 급격히 제거되다가 그 이후 다시 용해되는 결과를 보였으며, 아연의 경우는 pH 증가에 따라 비교적 꾸준한 비율로 제거되었다. 2) oxalic acid를 chelating agent로 사용한 경우 구리의 제거효율은 pH 11.5 이상에서 거의 전량이 Cu(OH)2로 제거되었으며, 납과 아연은 복합체의 낮은 용해도로 인해 알칼리 주입 전에 이미 많은 양이 침전되었다. 또한 구리로 오염된 자연토양을 사용한 실험에서 구리의 제거 효율은 유기산의 재사용 횟수가 증가할수록, 침전 pH가 낮아짐에 따라 감소함을 알 수 있었다. 이와 관련하여 회수한 용출액 내 oxalic acid 자유이온의 양 역시 재사용 횟수의 증가 및 pH 감소에 따라 감소하는 경향을 보였다.

The effectiveness of reapplying a recycled organic acid as the chelating agent following the treatment of contaminated soil was investigated. Following properties of the recycled metal-ligand complex were found under various pH regimes: 1) In citric acid, a small amount of copper was removed. The removal amount of lead increased until the solution's pH reached 11.5, and then it decreased as lead hydroxide formed. The precipitation of zinc increased at a constant rate as pH increased. 2) In oxalic acid, copper was removed completely as Cu(OH)2 at pH greater than 11.5. Lead and zinc precipitated readily due to the low solubility of the complexes even before the alkali solution was injected to the metal solution. The recovery and reuse of the organic acid in copper-contaminated soil was also investigated. As the frequency of reuse increased and as pH decreased, the removal efficiency of copper decreased, indicating that the amount of free ion of organic acid decreased in the recycled solution.

Keywords:chelating agent recovery;heavy metal;ligand exchange

[References]

Manahan SE, "Fundamentals of Environmental Chemistry", LEWIS PUBLISHERS (1993)
Elliott HA, Herzig LM, J. Soil Contamination, 8, 105 (1999)
Stumm WE, "Aquatic Chemical Kinetics; reaction rates of processes in natural waters", John Wiley and Sons (1990)
Mandal R, Salam MSA, Murimboh J, Hassan NM, Chakrabarti CL, Back MH, Gregoire DC, Environ. Sci. Technol., 34, 2201 (2000)
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Wolt JD, "Soil Solution Chemistry", John Wiley and Sons, Inc (1994)
Martell AE, Smith RM, "Critical Stability Constants : Vol. 4, Inorganic Complexes", Plenum Press (1974)

[Related Articles]

[1] Manahan SE, "Fundamentals of Environmental Chemistry", LEWIS PUBLISHERS (1993)

[2] Elliott HA, Herzig LM, J. Soil Contamination, 8, 105 (1999)

[3] Stumm WE, "Aquatic Chemical Kinetics; reaction rates of processes in natural waters", John Wiley and Sons (1990)

[4] Mandal R, Salam MSA, Murimboh J, Hassan NM, Chakrabarti CL, Back MH, Gregoire DC, Environ. Sci. Technol., 34, 2201 (2000)

[5] Crawford RJ, Mainwaring DE, Colloids Surf. A: Physicochem. Eng. Asp., 126, 167 (1997)

[6] Effluent Processing Club (EPC) : Manual of Effluent Process Technology, Vol. 5-PRECIPITATION PROCESSES

[7] Wolt JD, "Soil Solution Chemistry", John Wiley and Sons, Inc (1994)

[8] Martell AE, Smith RM, "Critical Stability Constants : Vol. 4, Inorganic Complexes", Plenum Press (1974)