• The Korean Journal of Food And Nutrition
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• v.9 no.3
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• pp.336-340
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• 1996

Rhizopus japonicus had the highest chitosan productivity compared with the chitosan productivity among Rhizopus sp. strains. To increase the productivity of microbial chitosan from Rhizopus faponicus, production medium and incubation conditions were optimized. The composition of the medium and the incubation conditions were as follows : starch 2%, yeast extract 2.5%, KH2PO4 0.05%, MgSO4 0.01%, FeSO4 0.002%, MnSO4 0.002%, ZnSO4 0.002%, CaC12 0.002%, PH 5.5, incubation temperature medium compared with chitosan productivity.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.297-302
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• 2011

Acid drainage generated by pyrite oxidation has caused the acidification of soil and surface water, the heavy metal contamination and the corrosion of structures in abandoned mine and construction sites. The applicability of Na-acetate (Na-OAc) buffer and/or Na-silicate solution was tested for suppressing pyrite oxidation by reacting pyrite containing rock and treating solution and by analyzing solution chemistry after the reaction. A finely ground Mesozoic andesite containing 10.99% of pyrite and four types of reacting solutions were used in the applicability test: 1) $H_2O_2$, 2) $H_2O_2$ and Na-silicate, 3) $H_2O_2$ and 0.01M Na-OAc buffer at pH 6.0, and 4) $H_2O_2$, Na-silicate and 0.01M Na-OAc buffer at pH 6.0. The pH in the solution after the reaction with the andesite sample and the solutions was decreased with increasing the initial $H_2O_2$ concentration but the concentrations of Fe and $SO_4^{2-}$ were increased 10 - 20 times. However, the pH of the solution after the reaction increased and the concentrations of Fe and $SO_4^{2-}$ decreased in the presence of Na-acetate buffer and with increasing Na-silicate concentration at the same $H_2O_2$ concentration. The solution chemistry indicates that Na-OAc buffer and Na-silicate suppress the oxidation of pyrite due to the formation of Fe-hydroxide and Fe-silicate complex and their coating on the pyrite surface. The effect of Na-OAc buffer and Na-silicate on reduction of pyrite oxidation was also confirmed with the surface examination of pyrite using scanning electron microscopy (SEM). The result of this study implies that the treatment of pyrite containing material with the Na-OAc buffer and Na-silicate solution reduces the generation of acid drainage.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.482-486
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• 2004

울산지역 수질특성에 관하여 연구하기 위해 228개 지점에서 수질성분 25개 항목을 분석하였다. 그 성분중 지하수 음용수 9개 수질성분(pH, EC, TDS, Cl, Mn, NO$_3$, SO$_4$, F, Fe)에 관해 수질분포특성 및 오염도를 나타내기 위해 모수적 통계기법인 정규크리깅과 비모수적 통계기법인 지시크리깅 기법을 적용하였다. OK와 IK의 성분별 베리오그램 분석한 결과 OK의 경우 모든 수질성분은 구상형모델(Spherical model)로 선정되었으며, IK의 경우 pH, TDS, SO$_4$, Cl, Mn, F, Fe 성분은 구상형모델로, EC는 지수형모델로, NO$_3$는 선형모델로 선정되었다. 그 결과 정규크리깅의 경우 연구지역의 수질특성을 정량적 분포특성이 잘 나타났다. 특히 태화강, 인접한 남구일원과 중구일원, 북구의 북서 일원 그리고 동구의 방어동일원에서 수질성분 9개 성분들이 다소 높게 나타났다. 특히 EC, TDS 그리고 Cl$^{-}$ NO$_3$ 성분이 높게 나타났다. 그리고 지시크리깅의 경우 정규크리깅과 비교하여 이상치가 크게 영향을 미칠 수 있는 통계학적인 오류를 보완하여 분석한 결과 울산지역 9개 성분 오염도는 EC>TDS>NO$_3$>pH>Fe>Mn>Cl>SO$_4$>F 순으로 오염특성이 나타났다.

• Corrosion Science and Technology
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• v.2 no.6
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• pp.260-265
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• 2003

The experimental methods to rapidly and stably reproduce Microbially Influenced Corrosion (MIC) of stainless steel by sulfate-reducing bacteria such as Desulfovibrio vulgaris were developed. In this study, using two types of stainless steel, 304 and 444, obtained from Pohang Steel & Iron Co., Ltd. (POSCO)., three major factors were tested; overall medium composition, dilution ratio, and chloride concentration. In the overall medium tests, three different media were prepared according to $FeSO_4$ concentration; PM (original Postgate's medium No. 2), MPM 1 (modified PM, no $FeSO_4$, MPM 2 (modified PM, 1/10 $FeSO_4$). The effects of various dilution ratios (3, 1, 1/3, 1/10, 1/30, and 1/100 times) and chloride concentrations (0.0067M, 0.01M, 0.05M, and 0.1M) were examined during 2 months cultivation. Through SEM (Scanning Electron Microscopy) observation, the diluted and modified media, particularly the $1/3{\times}MPM$ I medium, showed more micro-pitting points on surfaces compared to the original PM medium. High concentrations of chloride ions (above 0.05M) were not adequate for observation of MIC since those brought about non-microbiologically induced corrosion. From this study, the optimization of medium composition was very effective to routinely observe MIC in a laboratory system.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.201-206
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• 1997

본 연구에서는 Ni-기 합금인 합금 600과 합금 690, Fe-기 합금인 합금 800 및 초내식성 오스테나이트계 스테인리스강인 SR-50A에 대하여 부식 환경의 변화에 따른 특성 평가를 행하였다. 전기화학적 부식 평가는 양극 분극 시험을 통하여 행하였으며 부식 환경은 NaCl, HCI, NaOH(+$Na_2$SO$_4$) 액이었다. 응력 부식 균열 시험으로는 CERT(Constant Extension Rate Test)를 행하였으며 부식환경은 40%NaOH, 40%OH+12%$Na_2$SO$_4$ 용액이었다. CERT시험 후 그 파면을 SEM관찰하여 파괴 양상을 관찰하였다. 각 합금의 양극 분극 특성을 부식 환경에 따라 평가한 결과, 부식 용액의 증류에 따라 서로 다른 분극 거동을 보이고 있는데 산성과 중성 용액에서는 SR-50A가 가장 큰 저항성을 보이는 반면, 강 알카리용액인 NaOH용액에서는 Ni-기 합금의 저항성이 Fe-기 합금의 저항성보다 우수하게 나타났다. 응력 부식 균열 저항성은 전반적으로 Fe-기 합금보다 Ni-기 합금이 우수하게 나타났다. 파단면을 SEM관찰한 결과 합금 800과 SR-50A(tube)는 용액에 관계없이 입내 파괴 모드를 나타내고 있으며, 합금 600과 SR-50A판재는 입계 파괴 양상을 보이고 있다. 또한 가성 용액 중에 $Na_2$SO$_4$를 첨가할 경우, 부식 속도를 가속화시키고 응력 부식 균열 저항성을 감소시키고 있다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.346-349
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• 2004

국내에 자연 방치된 폐광산에 대한 문제가 대두되면서 폐광산 주변지역에 대한 산성광산폐수와 중금속 광산폐기물의 오염실태조사가 활발히 진행되고 있다. 본 연구는 폐광산의 유출수와 광산폐기물에 주변 오염지하수 내의 중금속 As, Cd, Pb, Fe, Mn, Zn, Cu에 대하여 무기 응집제의 첨가와 pH의 조절에 의한 제거효율을 .실내 배치실험을 통하여 규명하였다. 본 실험을 통하여 황산알루미늄(Al$_2$(SO$_4$)$_3$ㆍ13～14$H_2O$), 염화 제2철(FeCl$_3$ㆍ6$H_2O$), 황산 제2철(Fe$_2$(SO$_4$)$_3$ㆍ n$H_2O$)을 이용하여 오염수내 중금속을 90%이상 제거할 수 있었으며, 폐광산 침출수나 오염 지하수의 중금속 제거에 0.1 wt%의 응집제 첨가만으로 응집제를 이용한 화학적 처리 방법이 효과적으로 사용될 수 있을 것으로 판단되었다.

• Textile Coloration and Finishing
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• v.12 no.6
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• pp.389-395
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• 2000

A natural colorants was extracted from cherry by 10wt% aqueous acetic acid solution as an extractant. Silk and cotton fabrics were dyed with the cherry extract in the temperature range of $40-80^\circ{C}$ and for the time range of 30-60min. by pre- and post-mordanting with various mordants, their dyeability and fastness were investigated. The natural cherry extract prepared in this study has a maximum absorbance at 520nm. It was found that the optimum dyeing temperature and time were $40^\circ{C}$ and 50min, respectively. The pre-mordanting method was more effective than post-mordanting. All mordants except $SnCl_2\cdot{2H}_2O\;and\;FeSO_4\cdot{7H}_2O$ were effective for silk fabrics. However, the dyeability on cotton fabrics increased in the order of $CrK(SO_4)_2\cdot{12H_2O>(CH_3COO)_2Cu\cdot{H}_2O>CuSO_4\cdot{5H}_2O>AlK(SO_4)_2\cdot{12H}_2O>FeSO_4\cdot{7H}_2O>SnCl_2\cdot{2H}_2O$ among the mordants used in this study Fastness(light, water, washing, perpspiration fastness) on the silk and cotton fabrics increased with using mordants. The post-mordanting using mordant$(CH_3COO)_2Cu\cdot{H}_2O$ among the various mordants in this study gave the best fastness.

• Clean Technology
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• v.15 no.1
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• pp.38-41
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• 2009

Red mud is generated as a waste byproduct during the production of aluminum hydroxide/alumina from bauxite ore in the Bayer process. In this study coagulants for wastewater treatment were prepared by leaching iron and aluminum from red mud with hydrochloric acid. The removal efficiency of heavy metal ions by the red mud coagulant increased with increasing the adjusted pH value of the synthetic wastewater. When the red mud coagulant was prepared, the leaching efficiency of Fe decreased with increasing the weight of red mud, while the pH value of the red mud coagulant increased. The solution of the red mud coagulant mixed with water was reacted again with red mud to produce the leached solution, which had higher concentrations of Fe and Al and a higher pH value than the red mud coagulant. Also, its pH value was comparable to that of other coagulants: $FeCl_3$ and $Fe_2(SO_4)_3$.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.651-655
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• 1999

Xylenol Orange was bonded on an anion-exchange resin (Amberlite lRA 400, in $Cl^-$form) by batch equilibration. The resin was proved to be stable in acidic solutions of about 0.1 M HCl, $HNO_3$ or $H_2SO_4$. Sorption capacities for the metal ions on the Amberlite IRA 400 bonded with xylenol orange have been measured by batch method. The result showed that Fe(III) is higher than any other metals for sorption capacity. The preconcentration and the separation of Fe(lll) from the mixture soIution, therefore, were carried out with the 0.1 M sulfosalicylic acid as an eluent.

• Journal of the Korean institute of surface engineering
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• v.21 no.2
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• pp.53-67
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• 1988

The high temperature corrosion of Fe-C alloys were studied at I atm SO gas in the temperature range 500~80$0^{\circ}C$ by means of a thermogravimetric analysis. The Na2SO4 induced high tempwrature corrosion rate was also measured at atm O2 gas under above the temperature renge. The reaction products were identified with the aid of X-ray diffraction technique, and micostruction of the alloy/scale interface was observed with a optical microscope and SEM. The experimental results were disussed by the themodeynamic calcutions. Under above the experimental condition. the reaction rates decrbon with increasing carbon content. The transfer of Fe ion was limited by a residue of carbon precipitated at alloy scale interface due to the oxidation of Fe-C alloys at alloy surface. The effect of cold working on reaction rate was different between the Fe containing low carbon and Fe-C Alloy containing carbon above 0,73 wt%. In a cold worked iron containing low carbon content, the crystallization of metal surface leads to the poor adherence between the alloy and the cavity formed between the alloy and scale. The outward diffusion of ion through the scale is estimated to be hindered by the cavity formed between the scale, consequently decreasing reaction rate. In the case Fe-C containing carbon above 0.73 Wt% alloy, the reaction rate was little affected by cold working, because the effect of content on reaction rats is greater than the effect of cold working.