• 한국지하수토양환경학회지:지하수토양환경
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• 제14권6호
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• pp.19-28
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• 2009

폐금속광산과 비위생매립지로 인하여 중금속으로 오염된 지하수를 처리하기 위해 FeS를 이용한 투과성반응벽체(Permeable Reactive Barriers; PRBs)를 이용한다면 효과적인 결과를 보일 것으로 예상되어 FeS를 PRB 매질로 사용하기 위한 연구를 수행하였다. 컬럼 실험에 앞서 반응 매질들의 중금속 제거 특성을 알바보고자 합성 나노 FeS, 원석 FeS, 경량기포콘크리트에 대하여 96시간까지 인공중금속오염지하수와 반응을 시키는 회분식 실험을 수행하였다. 3가지 매질 모두 pH 6 이상에서 평형을 이뤘으며, 합성 나노 FeS는 반응 1시간 이후부터 평형상태에 가까워졌다. 중금속 제거효율은 합성 나노 FeS가 반응 1시간에 As와 Ni를 제외한 모든 중금속 제거율이 99% 이상으로 다른 매질에 비하여 상대적으로 빠른 제거 속도와 높은 효율을 나타내었다. 컬럼실험 결과 합성 나노 FeS로 피복된 경량기포콘크리트로 충진된 컬럼은 회분식 실험과 같은 결과로 나타났으며, 원석 FeS로 충진된 컬럼에서는 초반에 Ni을 제외한 모든 중금속이 99%이상 제거되었으나 pH는 약 9.20에서 평형을 이루었다. 본 연구에서 나타난 결과를 종합하였을 때 다양한 중금속으로 오염되어 있는 지하수를 처리하기 위한 방법으로 별도의 pH 조절이 필요 없는 합성 나노 FeS로 피복된 경량기포콘크리트를 이용한 투과성반응벽체의 적용은 매우 효과적인 것으로 판단된다.

• 한국물환경학회지
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• 제30권2호
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• pp.175-183
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• 2014

The influence of temperature on the treatment efficiency of chlorinated organic substances contained in groundwater by permeable reactive barrier which is composed of $Fe^{\circ}$ has been investigated by constructing the Pourbaix diagrams for Fe-$H_2O$ system at different temperatures based on thermodynamic estimation. In aerobic condition, the equilibrium potentials for $Fe^{\circ}/Fe^{2+}$ and $Fe^{2+}/Fe^{3+}$ were observed to increase, therefore, the dechlorination reaction for organic pollutants by $Fe^{\circ}$ was considered to decline with temperature due to the diminished oxidation of reactive barrier. The result for the variations of the ionization fraction of $Fe^{2+}$ and $Fe^{3+}$ ion in the pH range of 0 ~ 2.5 obtained by employing Visual MINTEQ program showed that the ionization fraction of $Fe^{2+}$ increased with pH, however, that of $Fe^{3+}$ decreased symmetrically and the extent of the variation of ionization fraction for both ions was raised as temperature rises. The equilibrium pH for $Fe^{3+}/Fe(OH)_3$ was examined to decrease with temperature so that the treatment efficiency of chlorinated organic substance was expected to decrease with temperature due to the enhanced formation of passivating film in aerobic condition. The change of the reactivity of a specific chemical species with temperature was defined quantitatively based on the area of its stable region in Pourbaix diagram and depending on this the reactivity of $Fe^{3+}$ was shown to decrease with temperature, however, that of $Fe(OH)_3$ was decreased monotonously as temperature is raised for $Fe^{3+}/Fe(OH)_3$ equilibrium system. In anaerobic condition, the equilibrium potential for $Fe^{\circ}/Fe^{2+}$ was observed to rise and the equilibrium pH for $Fe^{2+}/Fe(OH)_2$ were examined to decrease as temperature increases, therefore, similar to that for aerobic condition the efficiency of the dechlorination reaction for organic substances was considered to be diminished when temperature rises because of the reduced oxidation of $Fe^{\circ}$ and increased formation of $Fe(OH)_2$ passivating film.