• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.174-174
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• 2005

• Journal of Korean Society of Water and Wastewater
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• v.25 no.1
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• pp.1-5
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• 2011

Arsenic is one of the most abundant contaminant found in waste mine tailings and soil around refinery, Because of its carcinogenic property, the countries like United States of America and Europe have made stringent regulations which govern the concentration of arsenic in soil. The study focuses on solidification/stabilization for removal of arsenic from soil. Cement was used to solidify/stabilize the abandoned soil primarily contaminated with arsenic (up to 68.92 mg/kg) in and around refinery. Solidified/stabilized (s/s) forms in the range of cement contents 5-30 wt % were evaluated to determine the optimal binder content. Revised Korean standard leaching tests (KSLT), toxicity characteristic leaching procedures (TCLP), Old Korea standard leaching test and revised Korea standard leaching test were used for chemical characterization of the S/S forms. The addition of 10 % cement remarkably reduced the leachability of arsenic in contaminated soil. The concentration of As in leachate of TCLP, KSLT, and old KSLT for soil are below the standard. However that in leachate of revised KSLT is above the standard. Because of extraction fluid used in revised KSLT is very strong acid. It is arsenic in s/s with binder should be exhaustingly leached. Therefore S/S process would not be available for As treatment in soil in Korea.

• Membrane Journal
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• v.26 no.2
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• pp.116-125
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• 2016

This study described a synthesis of MF having a arsenic removal characteristics and the fundamental research was performed about the simultaneous removal system of both As(III) and As(V) ions with the composite nanofiber membrane (PMF) based on PVdF and MF materials for the water-treatment application. From the TEM analysis, the shape and structure of MF materials was investigated. The mechanical strength, pore-size, contact angle and water-flux analysis for the PMF was performed to investigate the possibility of utilizing as a water treatment membrane. From these results, the PMF11 showed the highest value of mechanical strength ($232.7kgf/cm^2$) and the pore-diameter of composite membrane was reduced by introducing the MF materials. In particular, their pore diameter decreased with an increase of iron oxide composition ratio. The water flux value of PMF was improved about 10 to 60% compared with that of neat PVdF nanofiber membranes. From the arsenic removal characterization of prepared MF materials and PMF, it was shown the simultaneous removal characteristics of both As(III) and (V) ions, and the MF01, in particular, showed the highest adsorption-removal rate of 93% As(III) and 68% As(V), respectively. From these results, prepared MF materials and PMF have shown a great potential to be utilized for the fundamental study to improve the functionality of water treatment membrane.

• Economic and Environmental Geology
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• v.44 no.3
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• pp.203-215
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• 2011

Geochemical and mineralogical properties of a contamited soil should be taken into account to decide a remediation strategy for a given contaminant because development and optimization of soil remedial technologies are based on geochemical and mineralogical separation techniques. The objective of this study was to investigate the geochemical and mineralogical characteristics of arsenic-contaminated soils. The arsenic-contaminated soil samples were obtained from Chonam gold mine, Gwangyang, Chonnam, Particle size analysis, sequential extraction, and mineralogical analyses were used to characterize geochemical and mineralogical characteristics of the As-contaminated soils. Particle size analyses of the As-contaminated soils showed the soils contained 17-36% sand, 25-54% silt, 9-28% clay and the soil texture were sandy loam, loam, and silt loam. The soil pH ranged from 4.5 to 6.6. The amount of arsenic concentrations from the sequential soil leaching is mainly associated with iron oxides (1 to 75%) and residuals (12 to 91%). Major minerals of sand and silt fractions in the soils were feldspar, kaolinite, mica, and quartz and minor mineral of which is an iron oxide. Major minerals of clay fraction were composed of illite, kaolinite, quartz, and vermiculite. And minor minerals are iron oxide and rutile. The geochemical and mineralogical analyses indicated the arsenic is adsorbed or coprecipitated with iron oxides or phyllosilicate minerals. The results may provide understanding of geochemical and mineralogical characteristics for the site remediation of arsenic-contaminated soils.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.137-148
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• 2010

The Myoungbong mine located in Boseong-gun, Jellanamdo consists of Au-Ag bearing quartz veins which filled the fissures of Bulguksa granitic rocks of Cretaceous. The tailings obtained from the Myungbong mine were used to investigate the effects of various processes, such as oxidation of primary sulfides and formation(alteration) of secondary and/or tertiary minerals, on arsenic immobilization in tailings. This study was conducted via both mineralogical and chemical methods. Mineralogical methods used included gravity and magnetic separation, ultrasonic cleaning, and instrumental analyses(X-ray diffractometry, energy-dispersive spectroscopy, and electron probe microanalyzer) and aqua regia extraction technique for soils was applied to determine the elemental concentrations in the tailings. Iron (oxy)hydroxides formed as a result of oxidation of tailings were identified as three specific forms. The first form filled in rims and fissures of primary pyrites. The second one precipitated and coated the surfaces of gangue minerals and the final form was altered into yukonites. Initially, large amounts of acid-generating minerals, such as pyrite and arsenopyrite, might make the rapid progress of oxidation reactions, and lots of secondary minerals including iron (oxy)hydroxides and scorodite were formed. The rate of pH decrease in tailings diminished, in addition, as the exposure time of tailings to oxidation environments was prolonged and the acid-generating minerals were depleted. Rather, it is speculated that the pH of tailings increased, as the contribution of pH neutralization reactions by calcite contained in surrounding parental rocks became larger. The stability of secondary minerals, such as scorodite, were deteriorated due to the increase in pH, and finally arsenic might be leached out. Subsequently, calcimn and arsenic ions dissociated from calcites and scorodites were locally concentrated, and yukonite could be grown tertiarily. It is confirmed that this tertiary yukonite which is one of arsenate minerals and contains arsenic in high level plays a crucial role in immobilizing arsenic in tailings. In addition to immobilization of arsenic in yukonites, the results indicate that a huge amount of iron (oxy)hydroxides formed by weathering of pyrite which is one of typical primary minerals in tailings can strongly control arsenic behavior as well. Consequently, this study elucidates that through a sequence of various processes, arsenic which was leached out as a result of weathering of primary minerals, such as arsenopyrite, and/or redissolved from secondary minerals, such as scorodite, might be immobilized by various sorption reactions including adsorption, coprecipiation, and absorption.

• Journal of the Mineralogical Society of Korea
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• v.26 no.4
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• pp.229-244
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• 2013

Arsenic contamination may be brought about by a variety of natural and anthropogenic causes. Among diverse naturally-occurring chemical speciations of arsenic, trivalent (As(III), arsenite) and pentavalent (As(V), arsenate) forms have been reported to be the most predominant ones. It has been well known that the behavior of arsenic is chiefly affected by aluminum, iron, and manganese oxides. For this reason, this study was initiated to evaluate the applicability of manganese slag (Mn-slag) containing high level of Mn, Si, and Ca as an efficient sorbent of arsenic. The main properties of Mn-slag as a sorbent were investigated and the sorption of each arsenic species onto Mn-slag was characterized from the aspects of equilibrium as well as kinetics. The specific surface area and point of zero salt effect (PZSE) of Mn-slag were measured to be $4.04m^2/g$ and 7.73, respectively. The results of equilibrium experiments conducted at pH 4, 7 and 10 suggest that the sorbed amount of As(V) was relatively higher than that of As(III), indicating the higher affinity of As(V) onto Mn-slag. As a result of combined effect of pH-dependent chemical speciations of arsenic as well as charge characteristics of Mn-slag surface, the sorption maxima were observed at pH 4 for As(V) and pH 7 for As(III). The sorption of both arsenic species reached equilibrium within 3 h and fitting of the experimental results to various kinetic models shows that the pseudo-second-order and parabolic models are most appropriate to simulate the system of this study.

• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.30-32
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• 1989

Traces of nine elements, gold, arsenic, cobalt, chromium, copper, europium, hafnium, sodium and antimony in commercially available silicon crystals were determined by the instrumental neutron activation analysis using the single comparator method. The values of the concentrations of these elements in both single and polycrystals were found to decrease significantly to a low limiting level by simply washing and etching surface contaminants having been introduced during various steps of sample preparation and irradiation. However, the chromium levels in polycrystals were not easily decreased, these depending upon the cutting tools employed. The Sb-doped content in each semiconductor has been compared with the associated quantities such as the concentration and the conductivity range given by the sample donor. Uncertainty in the sodium analysis due to the fission neutron reaction by silicon itself was discussed.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.593-598
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• 2004

The arsenical resistance (ars) operon was cloned from a 67-kilobase pair (kb) plasmid, which was previously shown to be responsible for arsenic salts resistance in K. oxytoca D12. When plasmid pAE48, carrying the ars operon, was transformed into E. coli, transformed cells displayed enhanced survival in the presence of 4 mM arsenite, 50 mM arsenate, or 0.4 mM antimonite. The nucleotide sequence of the 5.6-kb fragment encoding arsenical resistance revealed five open reading frames (ORFs), which were predicted to encode polypeptides of 12.8 (arsR), 13.4 (arsD), 62.6 (arsA), 45 (arsB), and 16.7 (arse) kilodaltons (kDa). Each ORF was preceded by a ribosome binding site. A putative promoter-like sequence was identified upstream of arsR, and a possible termination site was found downstream of arsC. When the deduced amino acid sequences of the K. oxytoca Dl2 Ars proteins were compared with the amino acid sequences of the E. coli R773 Ars proteins, a significant amino acid similarity was observed (87.9％ for ArsR, 89.2％ for ArsD, 83.2％ for ArsA, 92.6％ for ArsB, and 91.3％ for ArsC), suggesting an evolutionary relationship of the ars genes of E. coli plasmid R773 and K. oxytoca Dl2.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.521-533
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• 2013

This study was initiated to evaluate the applicability of Si slag as an adsorbent via investigation of the main properties of Si slag as an adsorbent aw well as characterization of adsorption features between aqueous arsenic and Si slag. The specific surface area of Si slag was measured to be 6.71 $m^2/g$ which seems to be slightly higher than those of other slags, but relatively lower than those of iron (oxyhydr)oxides extensively used for arsenic controlling processes. The point of zero salt effect (PZSE) of Si slag determined by potentiometric titration appeared to be comparatively high (7.3), indicating the Si slag may be favorably used for adsorption of arsenic which predominantly exists as an oxy-anions. The results of adsorption isotherm indicate that regardless of arsenic species, Langmuir-type isotherm is the most suitable to simulate the adsorption of arsenic onto Si slag. With regard to pH-dependence of arsenic adsorption, the adsorption maxima of arsenite was centered at pH 7, and the adsorption was remarkably decreased in the other pH conditions. In the case of arsenate, on the other hand, the adsorption was highest at the lowest pH (4.0) and then gradually decreased with the increase of pH. Based on the results of kinetic experiments, it is likely that the adsorption of arsenite approached equilibrium within 2 hr, but it took about 8 hr for arsenate adsorption to be equilibrated. In addition, the Pseudo second order was evaluated to be most consistent with the empirical data of arsenic adsorption onto Si slag in this study. Under identical conditions, the affinity of arsenate onto Si slag was estimated to be nearly 6 times higher than that of arsenite.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.197-210
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• 2012

Hematite has been known to be the most stable form of various iron (oxyhydr)oxides in the surface environments. In this study, its properties as an adsorbent were examined and also adsorption of arsenic onto hematite was characterized as well. The specific surface area of hematite synthesized in our laboratory appeared to be $31.8g\;m^2/g$ and its point of zero salt effect, (PZSE) determined by potentiometric titration was observed 8.5. These features of hematite may contribute to high capacity of arsenic adsorption. From several adsorption experiments undertaken at the identical solution concentrations over pH 2~12, the adsorption of As(III) (arsenite) was greater than that of As(V) (arsenate). As of pH-dependent adsorption patterns, in addition, arsenite adsorption gradually increased until pH 9.2 and then sharply decreased with pH, whereas adsorption of arsenate was greatest at pH 2.0 and steadily decreased with the increasing pH from 2 to 12. The characteristics of these pH-dependent adsorption patterns might be caused by combined effects of the variation in the chemical speciation of arsenic and the surface charge of hematite. The experimental results on adsorption kinetics show that adsorption of both arsenic species onto hematite approached equilibrium within 20 h. Additionally, the pseudo-second-order model was evaluated to be the best fit for the adsorption kinetics of arsenic onto hematite, regardless of arsenic species, and the rate constant of As(V) adsorption was investigated to be larger than that of As(III).