• 한국지하수토양환경학회지:지하수토양환경
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• 제11권6호
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• pp.76-82
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• 2006

일반적으로 Fenton 반응 공정을 실제 오염토양에 적용하기에는 다소 무리가 있다. 그 이유로 대표적인 Fenton 반응공정인 고전적인 Fenton 반응은 낮은 pH에서 우수한 처리효율을 보이고 있기 때문이다. 또한, 철이온의 투입을 대신하여 철광석을 이용하는 Fenton-like 반응도 철광석 표면에서 hydroxyl radical을 생성하나 높은 pH에서는 다량의 수산화물과의 경쟁반응으로 인하여 그 활성이 상당히 감소되어진다. 이러한 단점을 보완하기 위하여 중성영역의 pH에서 철이온-chelating agent의 복합체를 촉매로 사용하는 modified Fenton 반응이 제시 되어지고 있다. 이 처리방식의 경우에는 다량의 철이온의 투입이 요구되어진다. 따라서, 본 실험에서는 Fenton-like 반응과 modified Fenton 반응의 효율적인 접목으로 중성영역에서의 chelating agent의 투입으로 철광석으로부터 철이온을 용출하여 복합체를 형성함으로 혼합 Fenton 공정에서 부가적인 촉매로 사용되어짐으로 오염물 처리효율을 크게 향상시킨 기법 개발을 진행하였다. 2,4,6-Trinitrotoluene은 본 실험에서 오염원으로 사용하였으며, chelating agent에 의해 용출된 철이온이 약 0.1 mM 이상일 경우 Fenton-like 반응에 비하여 상당히 좋은 제거효율을 보였다. 혼합 Fenton 공정의 최대제거효율은 magnetite-NTA 시스템으로써 약 76%의 제거효율과 magnetite-EDTA의 경우 약 56%로서 이는 Fenton-like 반응에 비하여 약 40-60% 정도의 제거효율이 향상된 결과이다.

• 대한화학회지
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• 제56권6호
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• pp.673-678
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• 2012

변전위법과 선형분극법을 이용하여 Borate 완충용액에서 철의 부식에 대한 대기의 영향을 조사하였다. 철의 부식은 용액 속에 녹아있는 산소의 양에 크게 영향을 받았다. 용액에 녹아 있는 산소의 환원반응으로 환원전류가 증가하여 부식전위가 양의 방향으로 이동하였다. 물 또는 산소의 환원 반응에 의하여 생성된 $OH^-$ 이온은 철 전극의 전기이중층에 $OH^-$ 이온의 농도를 증가시켜 철 전극에 $OH^-$ 이온의 흡착을 용이하게 하였다. 철 전극 표면에 $OH^-$ 이온의 흡착은 Langmuir isotherm 또는 Temkin logarithmic isotherm을 이용하여 설명할 수 있었다.

• Environmental Engineering Research
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• 제20권3호
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• pp.205-211
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• 2015

Reduced forms of iron, such as zero-valent ion (ZVI) and ferrous ion (Fe[II]), can activate dissolved oxygen in water into reactive oxidants capable of oxidative water treatment. The corrosion of ZVI (or the oxidation of (Fe[II]) forms a hydrogen peroxide ($H_2O_2$) intermediate and the subsequent Fenton reaction generates reactive oxidants such as hydroxyl radical ($^{\bullet}OH$) and ferryl ion (Fe[IV]). However, the production of reactive oxidants is limited by multiple factors that restrict the electron transfer from iron to oxygen or that lead the reaction of $H_2O_2$ to undesired pathways. Several efforts have been made to enhance the production of reactive oxidants by iron-induced oxygen activation, such as the use of iron-chelating agents, electron-shuttles, and surface modification on ZVI. This article reviews the chemistry of oxygen activation by ZVI and Fe(II) and its application in oxidative degradation of organic contaminants. Also discussed are the issues which require further investigation to better understand the chemistry and develop practical environmental technologies.

• 한국대기환경학회지
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• 제7권2호
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• pp.137-142
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• 1991

A method is developed for the simultaneous determination of dissolved iron, copper, and zinc in rainwater. The method involves 25-fold evaporative concentration, ion chromatographic separation and subsequent spectrophotometric detection after post-column reaction with 4-(2-pyridylazo) resorcinol. Analytical sensitivities, being defined by the slopes of calibration curves, are 0.93, 0.54, and 0.11 Abs/ $\mu$g/ml for iron, copper, zinc, respectively. Detection limits render around a few tenth of one ng/ml. Precisions evaluated by replicate analysis of real sample are better than 10% RSD. Due to the lack of certified standards for rainwater, the accuracy of the method could not be assessed directly. However, the results of this method agree well with those by inductively coupled plasma mass spectrometry. Analytical results for a suite of Seoul rainwaters are presented herein.

• 산업기술연구
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• 제32권A호
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• pp.21-27
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• 2012

The characteristics of floc formation of the iron(Fe) ions contained in the acid mine drainage was studied for developing the process treating the acid mine drainage. The iron(Fe) ions were formed into flocs by the acid-base reaction with the added $Ca(OH)_2$. The molal ratio of iron(Fe) vs $Ca(OH)_2$ was one of major control variables in treatment; pH change, iron(Fe) ions concentration in treated drainage, DO (dissolved oxygen content). In addition, the air gave much effect on the color of the $iron(Fe)-Ca(OH)_2$ flocs and the attachment to magnet. The attaching to the magnet of the flocs formed in the air was much less than the case without air.

• Applied Biological Chemistry
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• 제2권
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• pp.9-14
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• 1961

The formation of sulfide from sulfate has been discussed from the thermodynamic principles. No mechanism of the reaction has been presented. From the stoichiometric and Nernst equations for the conversion of sulfate into sulfide, it was concluded that the formation of sulfide from sulfate can take place more readily if pH of a medium is low. The difficulty of this conversion increases with increasing pH. As pH of a medium increases, the degree of dissociation of H₂S into S= increases and this, in turn, renders the chance of precipitation of sulfide as FeS easier. Higher the pH of a soil or medium, greater is the S= concentration. The concentration of ferrous ion required to remove dissolved sulfide in a medium by forming insoluble FeS decreases with increasing pH. From the theory it was pointed out that an application of lime and iron rich foreign substances to a soil may be effective in causing the removal of dissolved sulfide from solution.

• 상하수도학회지
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• 제32권2호
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• pp.145-152
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• 2018

This study is focused on manganese (Mn(II)) removal by ozonation in surface water. Instant ozone demand for the water was 0.5 mg/L in the study. When 0.5 mg/L of Mn(II) is existed in water, the optimum ozone concentration was 1.25 mg/L with reaction time 10 minutes to meet the drinking water regulation. The ozone concentration to meet the drinking water regulation was much higher than the stoichiometric concentration. The reaction of soluble manganese removal was so fast that the reaction time does not affect the removal dramatically. When Mn(II) is existed with Fe, the removal of Mn(II) was not affected by Fe ion. However As(V) is existed as co-ion the removal of Mn(II) was decreased by 10%. Adding ozone to surface water has limited effect to remove dissolved organic matter. When ozone is used as oxidant to remove Mn(II) in the water, the existing co-ion should be evaluated to determine optimum concentration.

• 공업화학
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• 제4권1호
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• pp.171-177
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• 1993

원자로 냉각계통의 방사성 오염물질을 제거하기 위한 제염공정에서 유기산에 용해된 금속이온들은 이온교환 수지를 통과하면서 제거된다. 그러나 제염용액내 유기산들은 용액내 금속이온과 착화합물을 형성하여 이온교환수지에 대한 친화도를 감소시킨다. 이같은 관점에서 착화합물 형성이 이온교환공정에 미치는 영향 해석을 위해 코발트와 철 이온을 대상으로 Amberlite IRN-77 양이온수지와의 이온교환실험을 수행하였다. 실험결과에서 화학제염제로 사용된 유기산 가운데 EDTA는 철 이온보다 코발트 이온과 강한 착화합물을 형성하여 코발트 이온의 수지에 대한 이온교환용량을 현저히 감소시켜 주는 성분으로 나타났다. 반면에, Oxalic Acide와 Citric Acide의 영향은 미미하였다. 또한, 실험결과로부터 이들 금속이온 들에 대한 단일 성분계 및 2성분계 비선형 평형식을 결정하였다.

• 자원리싸이클링
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• 제13권6호
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• pp.9-15
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• 2004

FeSO$_4$ 용액에 NaOH를 첨가하여 FeOOH를 제조하였으며, R(=2NaOH/FeSO$_4$), FeSO$_4$의 농도, 반응온도 및 산화용 가스인 air의 유량 변화에 따른 제조변수를 통해 투명산화철의 제조 조건을 연구하였다. 수용액 중에 FeSO$_4$의 농도가 증가할수록 Fe$_3O_4$를 석출하며 입자의 크기가 증가하였다. 생성된 FeOOH는 약 200$^{\circ}C$에서 탈수반응을 일으켜 약 320$^{\circ}C$부근에서 종료하였다. 반응온도가 낮을수록 Fe(OH)$_2$의 입자의 길이가 짧아졌으며, 산화제인 air의 공급량이 클수록 용액 중에 용존산소의 량이 증가하여 Fe(OH)$_2$의 입자길이가 감소하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권6호
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• pp.80-90
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• 2014

The laboratory and field studies were conducted to identify an optimal injection concentration of nanoscale zero-valent iron particles (NZVI) and to evaluate the applicability of NZVI-based reactive zone technology to the site contaminated with trichloroethylene (TCE) DNAPL (Dense Non-Aqueous Phase Liquid). The laboratory test found an optimal injection concentration of NZVI of 5 g/L that could remove more than 95% of 0.15 mM TCE within 20 days. Eleven test wells were installed at the aquifer that was mainly composed of alluvial and weathered soils at a strong oxic condition with dissolved oxygen concentration of 3.50 mg/L and oxidation-reduction potential of 301 mV. NZVI of total 30 kg were successfully injected using a centrifugal pump. After 60 days from the NZVI injection, 86.2% of the TCE initially present in the groundwater was removed and the mass of TCE removed was 405 g. Nonchlorinated products such as ethane and ethene were detected in the groundwater samples. Based on the increased chloride ion concentration at the site, the mass of TCE removed was estimated to be 1.52 kg. This implied the presence of DNAPL TCE which contributed to a higher estimate of TCE removal than that based on the TCE concentration change.