• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 추계학술발표회
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• pp.40-43
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• 2002

Electrokinetic remediation was studied for the removal of toxic heavy metals from tailing soils. This study emphasized the dependency of removal efficiency upon heavy metal speciation, as demonstrated by different extraction methods (sequential extraction, total digestion, and 0.1 N HC1 extraction). The tailing soils examined showed different physicochemical characteristics, in view of initial pH, particle size distribution, and major mineral constituents, and contained high concentrations of target metal contaminants in various forms. The electrokinetic removal efficiency of heavy metals was significantly influenced by their partitioning prior to treatment, and by the pHs of the tailing soils. The mobile and weakly bound fractions of heavy metals, such as exchangeable fraction, were easily removed by electrokinetic treatment (more than 90% in removal efficiency), whereas immobile and strongly bound fractions, such as organically bound and residual fractions, were not effectively removed (less than 20% in removal efficiency).

• 한국환경농학회지
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• 제25권3호
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• pp.236-246
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• 2006

In this study, we give insight into questionable results that can be encountered in the conventional sequential extraction of heavy metals (Cd, Cu, and Zn) from soils. Objectives of this study were to determine the extraction variability of exchangeable (EXC)-metals as using six different EXC-extractants commonly accepted, and to investigate selectivity problems with carbonates bound (CAB)-metal fraction, a buffered acetate (1.0 M NaOAc; pH 5.0) extractable-metal fraction, leading to erratic results in especially non-calcareous soils. The contents of EXC-metals were markedly varied with the different extractability of various EXC-metal extractants used. The contents of EXC-Cd fraction were ranged from 2.0 to 74.3% of total Cd content in all of the metal spiked soils studied. The contents of EXC-Zn fraction extracted with the different EXC-extractants were varied with soil types, which were from 0.4 to 3.9% of total Zn in the calcareous soils, from 7.6 to 17.9% in the acidic soil, and from 13.6 to 56.8% in the peat soil. However, the contents of EXC-Cu fraction were relatively similar among the applications of different EXC-meal extractants, 0.2 to 2.1 % of total Cu, in all soils tested. Also, these varied amounts of EXC-metal fractions, especially Cd and Zn, seriously impacted the contents of subsequent metal fractions in the procedure. Furthermore, the CAB-Cd, -Cu, and -Zn fractions extracted by the buffered acetate solution were in critical problem. That is, the buffered acetate solution dissolved not only CAB-metals but also metals that bound or occupied to subsequent fractions, especially OXD-metal fraction, in both calcareous and non-calcareous soils. The erratic results of CAB-fraction also seriously impacted the amounts of subsequent metal fractions. Therefore, the conventional sequential extraction should be reconsidered theoretically and experimentally to quantify the target metal fractions or might be progressively discarded.

• 한국광물학회지
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• 제10권2호
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• pp.139-147
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• 1997

The Janghang smelter is the first lead, zinc and copper smelting facility in Korea which was operated for a half century from 1936 to 1989. The clay minerals and their heavy metal association in the soil profile around the smelter have been studied using XRD, EPMA, SEM-EDS, TEM, EPR and sequential extraction techniques. The soils in A horizon are highly acidic showing pH 4.45. The pH is going up with increasing depth. They have residual water contents of 1.18-1.51 wt%, loss on ignition of 6.32-7.79 wt%, and carbon contents of 0.08-0.88 wt%. Soils consist of quartz, feldspar, muscovite, kaolinite, vermiculite, biotite, chlorite, goethite and hematite in the decreasing abundance. The contents of clay minerals, especially vermiculite and chlorite, decrease with increasing depth. Sequential extraction experiments for the profile samples show that heavy metals (Zn, Cu, Pb, Cd) are highly concentrated in the A horizon of the soil profile as water-extractable (mostly amorphous), MgCl2-extractable (exchangeable in clay minerals), and organic phases. The heavy metal contents decrease with increasing depth. It suggests that the heavy metals are mainly associate with clay minerlas in an exchangeable state. It is also noted that heavy metals are highly concentrated in the manganese and iron oxide phases.

• 한국환경과학회지
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• 제17권2호
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• pp.185-193
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• 2008

This study has been carried out to examine the feasibility of soil washing process for reducing arsenic contamination level of soil around $Dalch\hat{e}n$ Mine. The results of physicochemical tests of the target soil showed that pH was weak alkalic ($pH{\simeq}7.8$), soil texture was coarse sand, and organic contents (5.7%) and CEC (Cation exchange capacity; 21.5 meq/100 g) were similar with those of soils generally found in Korea. Contamination levels of arsenic were found to over 201 mg/kg which exceed the Korea standard levels of countermeasure and concern. To investigate chemical partitioning of heavy metals, sequential extraction procedures were adopted and it was found that arsenic was predominantly associated with the residual fraction among five fractional forms as much as over 85%, which is demonstrating that only less than 15% of all might be vulnerable to a selected washing agents. Among 6 kinds of washing agents applied on the screening for arsenic-contaminated soil, HCl and $H_3PO_4$ solution were selected as promising washing agents. In comparison with HCl and $H_3PO_4$ solutions for arsenic washing by kinetic experiment in the change of pH, soil-solution ratio, temperature, and washing solution concentration, $H_3PO_4$ solution was determined to best one of agents tested, which showed faster washing rate than HCl to accomplish regulatory goal.

• 자원환경지질
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• 제27권5호
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• pp.469-477
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• 1994

Many researchers have investigated most representative sequential extraction method using various reagents for determining the chemical forms of metals in soils and sediments. In this paper, a newly modified method for sequential extraction scheme based on Tessier's method by Environmental Geochemistry Research, Centre for Environmental Technology, Imperial College, was introduced and examined. In comparison with Tessier's method, originally designed for sediment analysis by Atomic Absorption Spectrophotometry (AAS), the sequential extraction scheme has been developed for the multi-element analysis by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The partitioning of particulate trace elements was classified into five fractions: (i) exchangeable, (ii) bound to carbonates or specially adsorbed, (iii) bound to Fe and Mn oxides, (iv) bound to organic matter and sulphides and (v) residuals. The experimental results of the pilot study for in-house reference material (HRM2) and certified international standard reference material (SRM2711) using the modified method showed not only reasonable precision and accuracy but also acceptable overall recovery rates. In addition, mine dump soils sampled in the Dalsung Cu-W mine, Korea were prepared and sequentially extracted using the method. Most of Cu was bound to organic matter/sulphides and residual fractions. The dominant fraction of soil Pb and Zn in the study area was found in the residuals. The fraction of Cd showed a wide variation between samples and could be found bound to the carbonates or specially adsorbed, oxides, organic fraction and residuals. The recovery rates of Cd, however, were poor due to relatively low Cd concentrations in soils. The heavy metals in these mine dumps appear to be in the more inert forms and should not be readily bioavailable. The soils, however, had very low pH values (average 4.1) and had sandy textures; consequently, rapid infiltration of rainfall may increase leaching of Zn and Cd which were found to be around 5 to 10% of the exchangeable fraction. As a result of the investigation of this study, it has been strongly recommended that these mine waste materials should still be considered a significant contaminant source and will need environmental remediation to prevent pollutants from being released into the environment.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1998년도 Advances in Ginseng Research - Proceedings of the 7th International Symposium on Ginseng -
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• pp.160-167
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• 1998

Chemical studies of nitrogen compounds of Panax ginseng seem relatively rare, Probably due to the isolation difficulties, subsequently the investigations of biological activities are little. The experimental conditions were established for highly complete extraction of peptides (basic, acidic and neutral) from Panax ginseng. This task was achieved by applying the follow isolation procedure: 1 , the sequential extraction with water, 0.1% TFA in 20% acetonitril and buffer pH 6.5 (water-pyridine-acetic acid 100:3:900) : 2, fractionation by ultrafiltration : 3, n-butanol extraction 4, cation- and anion-exchange chromatography : 5, chromato-electrophoresis. The comparison of red ginseng (xylem Sl pith part) and red ginseng inside white (xylem Sc pith part) was also provided. To analyze the peptide mixture the chromato-electrophoresis method of separation was applied. Optimal conditions for peptides mapping of sample were explored. Our experiments revealed the quantitative difference of peptide between xylem & pith and phloem & cortex part. We have also found the qualitative difference in the composition of polypeptides between normal red ginseng (xylem Sc pith part) and red ginseng inside-white (xylem St pith part)

• 자원환경지질
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• 제36권3호
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• pp.159-170
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• 2003

전주시 하천 퇴적물시료, 호남고속도로 주변의 토양과 퇴적물 시료, 광산주변 광미 및 토양시료를 대상으로 토양오염 공정시험방법상의 용출법, 0.1N 유지용출법, Tessir et al.(1979)의 연속추출방법을 적용하여 중금속을 추출하고 그 결과를 비교하였다. 공정시험방법상의 용출법 사용시 산에 대한 완충능력이 있는 시료는 용출액의 pH 1(0.1N HCl)이 유지되지 못했고 용출액의 pH가 최고 8.0까지 증가하였다. 또한, 토양오염 공정시험방법상의 용출법 사용시 중금속 추출량(HPE)/0.1 N 유지용출법 사용시 중금속 추출량(HPEM) 값의 평균치와 범위는 Cd의 경우 0.479와 0.145~0.929, Zn의 경우 0.534와 0.078~0.928, Mn의 경우 0.432와 0.041~0.992, Cu의 경우 0,359와 0.011~0.874, Cr의 경우 0.150과 0.018~0.530, Pb의 경우 0.219와 0.003~0.853, 그리고 Fe의 경우 0.088과 1.73${\times}$$10^{-5}$~0.303이다. 이는 두 전처리 방법에 의해 추출된 중금속량의 차이가 Fe>Cr>Pb>Cu〉Mn>Cd>Zn 순임을 지시한다. HPE, HPEM과 연속추출법 비교시 Zn, Cd, Mn의 경우 추출량은 대체적으로 연속추출 3단계까지의 합$\geq$0.1N 유지용출법>연속추출 2단계까지의 합$\geq$용출법 순이었으며, Cr과 Fe의 경우 연속추출 3단계까지 합》0.1N 유지용출법>용출법 순이었으며 연속추출 2단계 까지 합은 Cr의 경우 0.1N 유지용출법의 추출량보다 낮았고 용출법의 추출량보다 높았다. Cu의 경우 연속추출 4단계까지의 합$\geq$0.1N 유지용출법>3단계까지의 합 용출법으로 나타났다. 0.1N유지위해 첨가된 염산의 양이 증가할수록, 즉 시료내의 산에 대한 완충능력이 증가할수록 HPE/HPEM 값이 감소하며, 완충능력이 큰 시료의 경우 모든 원소에서 HPE/HPEM이 0.2보다 낮다. 완충능력이 낮은 시료의 경우 Zn, Cd, Mn, Cu는 연속추출 1,2단계의 합과 연속추출 3단계의 중금속 추출함량간의 차이가 적고, 다른 원소에 비해서 상대적인 유동도가 높기 때문에 HPE/HPEM이 대채적으로 0.2보다 높으며 0.6이상의 값을 갖는 시료가 많다. 그러나, Fe, Cr의 경우는 상대적으로 Zn, Cd, Mn, Cu에 비해 유동도가 낮고, 연속추출 3단계의 함량이 1+2단계의 함량과 차이가 커 완충능력이 낮은 시료의 HPE/HPEM값도 전반적으로 0.2보다 낮다. 이러한 연구결과는 국내 토양오염 공정시험방법상의 전처리 방법인 용출법이 장래에 장기적으로 산성비와 같은 환경피해에 노출되어 토양의 완충능력이 감소하거나 상실될 수 있는 지역의 오염평가에 적합치 않을 가능성을 제시한다.

• Journal of Microbiology and Biotechnology
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• 제24권12호
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• pp.1690-1698
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• 2014

Partial purification of glucoamylase from solid-state fermentation culture was, firstly, investigated by reverse micellar extraction (RME). To avoid back extraction problems, the glucoamylase was kept in the original aqueous phase, while the other undesired proteins/enzymes were moved to the reverse micellar organic phase. The individual and interaction effects of main factors (i.e., pH and NaCl concentration in the aqueous phase, and concentration of sodium bis-2-ethyl-hexyl-sulfosuccinate (AOT) in the organic phase) were studied using response surface methodology. The optimum conditions for the maximum recovery of the enzyme were pH 2.75, 100 mM NaCl, and 200 mM AOT. Furthermore, the optimum organic to aqueous volume ratio ($V_{org}/V_{aq}$) and appropriate number of sequential extraction stages were 2 and 3, respectively. Finally, 60% of the undesired enzymes including proteases and xylanases were removed from the aqueous phase, while 140% of glucoamylase activity was recovered in the aqueous phase and the purification factor of glucoamylase was found to be 3.0-fold.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.372-378
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• 2003

This study investigates the fractional composition and the leaching characteristics of heavy metals in polluted soils due to mining activities. The fractionated composition of heavy metals is classified into five fractions, adsorbed, carbonate, reducible, organic and residual fraction. The status of humic substances in mine wastes of most sites are polyhumic except tailing from Sangdong mine. According to the sequential extraction procedures (SEPs), leaching probabilities of Cd in coal wastes and tailing are relatively low due to high percentage of residual fraction. 46.4% of Ni in tailings from Sangdong mine is probably leached under oxidized environment, and 39.4% of Cu in these tailings is readily extracted under strongly oxidized environment by organic fraction. According to leaching condition of pH 3.0 and pH 5.6, the amount of heavy metals leached out of coal wastes and tailing increases to 1/2 hours. At pH 3.0 and pH 5.6, concentration of Ni in tailing increases up three times of the initial value. Heavy metals released from coal wastes and tailing were not influenced significantly by leaching time.

• 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.