• 한국광물학회지
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• 제27권1호
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• pp.53-62
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• 2014

저 품위 엽납석 광석에 포함된 불순물 Fe를 제거하기 위하여 입도크기, 황산농도, 황산암모늄농도, 과산화수소농도 그리고 온도변화에 따른 제거 효율에 대하여 연구하였다. 저 품위 엽납석 광석에서 자형의 입방체 황철석이 포함된 것을 반사현미경으로 관찰할 수 있었으며, X-선 회절분석결과 주 구성광물은 석영과 딕카이트였다. 실험 결과 Fe 용출율이 최대로 나타나는 입도 -325 mesh에서, 황산농도는 2.0 M에서, 황산암모늄 농도는 10.0 g/l, 과산화수소 농도 3.0 M 그리고 최적의 용출 온도는 $70^{\circ}C$에서였다. 용해 동역학 분석에서, Fe 용해는 황철석 표면에서 일어나며 화학적 반응에 통제되는 것으로 그리고 0.066/R, $[H_2SO_4]^{1.156}$, $[(NH_4)_2SO_4]^{0.745}$, $[H_2O_2]^{0.428}$에 비례하는 것으로 나타났다.

• 한국환경보건학회지
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• 제35권3호
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• pp.201-208
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• 2009

Oxidation of phenol in aqueous media by electro-Fenton process using Ru-Sn-Sb/graphite electrode has been studied. Hydrogen peroxide was electrically generated by reaction of dissolved oxygen in acidic solutions containing supporting electrolyte and $Fe^{2+}$ was added in aqueous media. Phenol degradation experiments were performed in the presence of electrolyte media at pH 3. Effect of operating parameters such as current, electrolyte type (NaCl, KCl and $Na_2SO_4$) and concentration, $Fe^{2+}$ concentration, air flow rate and phenol concentration were investigated to find the best experimental conditions for achieving overall phenol removal. Results showed that current of 2 A, NaCl electrolyte concentration of 2g/l, 0.5M concentration of $Fe^{2+}$, air flow rate of 1l/min were the best conditions for mineralization of the phenol by electro-Fenton.

• Journal of Animal Science and Technology
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• 제61권4호
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• pp.216-224
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• 2019

This study was conducted to investigate the effects of hot melt extrusion (HME) nano-iron as an alternative for the common ferrous sulfate on iron (Fe) bioavailability, growth performance, nutrient digestibility, intestinal morphology, and intestinal microbiota of weanling pigs. A total of 200 piglets (Landrace ${\times}$ Yorkshire ${\times}$ Duroc) were randomly allotted to seven treatments on the basis of initial body weight (BW) and sex. Treatments were the INO100 (100 ppm Fe as $FeSO_4$), HME-Fe levels (50, 75, and 100 ppm nano-Fe as $FeSO_4$). ORG100 (100 ppm Fe as iron methionine). In phase 1, the HME50 pigs showed the lowest Fe content in feed and feces. Plasma Fe concentration was increased in HME100 and ORG100 pigs. In phase 2, there were significantly lower concentration of Fe in feed and feces of HME50 pigs (p < 0.01). A lower Fe concentration in the plasma and liver were observed in HME50 pigs compared with HME100 pigs. Concentration of red blood cell (RBC) was the lowest (p < 0.01) for HME50 pigs. During phase 2, the HME100, HME75, and ORG100 pigs showed a higher RBC and hemoglobin values compared with HME50 pigs. Digestibility of gross energy (GE) and crude protein (CP) were significantly higher in HME100 pigs compared with HME50 pigs. There was an increased (p < 0.01) villus height in the duodenum and jejunum of HME100 pigs compared with HME50 pigs. It is concluded that dietary Fe does not improve growth performance of weanling pigs; however, increasing the dietary iron concentration in weanling piglets increased the RBC and hemoglobin. In addition, the potential ability of HME to be used at a lower level (HME75) was observed.

• 대한화학회지
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• 제56권4호
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• pp.448-458
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• 2012

In order to develop alloy resistance in aggressive sulphat ion, the corrosion behavior of metallic glasses $Ni_{92{\cdot}3}Si_{4.5}B_{32}$, $Ni_{82,3}Cr_7Fe_3Si_{4.5}B_{3.2}$ and $Ni_{75.5}Cr_{13}Fe_{4.2}Si_{4.5}B_{2.8}$ (at %) at different concentrations of $H_2SO_4$ solutions was examined by electrochemical methods and Scanning Electron Microscope (SEM) and X-ray Photoelectron Microscopy (XPS) analyses. The corrosion kinetics and passivation behavior was studied. A direct proportion was observed between the corrosion rate and acid concentration in the case of $Ni_{92{\cdot}3}Si_{4.5}B_{32}$ and $Ni_{75.5}Cr_{13}Fe_{4.2}Si_{4.5}B_{2.8}$ alloys. Critical concentration was observed in the case of $Ni_{82,3}Cr_7Fe_3Si_{4.5}B_{3.2}$ alloy. The influence of the alloying element is reflected in the increasing resistance of the protective film. XPS analysis confirms that the protection film on the $Ni_{92{\cdot}3}Si_{4.5}B_{32}$ alloy was NiS which is less protective than that formed on Cr containing alloys. The corrosion rate of $Ni_{82,3}Cr_7Fe_3Si_{4.5}B_{3.2}$ and $Ni_{75.5}Cr_{13}Fe_{4.2}Si_{4.5}B_{2.8}$. alloys containing 7% and 13% Cr are $7.90-26.1{\times}10^{-3}$ mm/y which is lower about 43-54 times of the alloy $Ni_{92{\cdot}3}Si_{4.5}B_{32}$ (free of Cr). The high resistance of $Ni_{75.5}Cr_{13}Fe_{4.2}Si_{4.5}B_{2.8}$ alloy at the very aggressive media may due to thicker passive film of $Cr_2O_3$ which hydrated to hydrated chromium oxyhydroxide.

• 한국토양비료학회지
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• 제44권2호
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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.

• Advances in environmental research
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• 제5권3호
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• pp.189-200
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• 2016

This study aimed at advanced oxidation of hetero tri-functional reactive dye Acid orange 7 using photo-Fenton conditions in a lab-scale experiment. Decolourisation of Acid Orange 7 dye by Fenton's process was dependent on concentration of Hydrogen peroxide, Ferrous sulphate, pH, and contact time. A $2^3$ factorial design was used to evaluate the effects of these key factors: pH, Fe(II), and $H_2O_2$ concentration, for a dye concentration of 50 mg/L with COD of 340 mg/L at pH 3.0. The response function was removal of colour under optimised conditions; pH 3.0, [Fe(II)] 40.83 mg/L, [$H_2O_2$] 4.97 mmol/L; 13.6 min. of treatment resulting in 100% colour removal. The final COD of treated wastewater was nil suggesting that AOP is a potentially useful process of color removal and dye degradation/mineralisation of effluent having AO7. Minimum contact time for complete decolourisation was at 5 mmol/l $H_2O_2$ concentration. Increase in $FeSO_4$ (mg/l) concentration resulted in decrease of time for complete decolourisation. Box-Behnken Design was used to optimize the process variables. Maximum and minimum levels of pH (3-5), $H_2O_2$ (4-6 mmol/l), $FeSO_4$ (30-46 mg/l) and contact time (5-15 minutes) were used. The statistical analysis revealed a value of 0.88 for coefficient of regression ($R^2$) indicating a good fit of model. Calculated F-value was found higher than the tabulated value confirming to significance of the model. Based on student's t-test, Ferrous sulphate, pH, and contact time have a positive effect on the percent decolourisation of Acid Orange 7.

• 한국세라믹학회지
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• 제38권12호
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• pp.1115-1122
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• 2001

여기에너지에 따라서 $Y_2$O$_3$:Eu 형광체의 활성제의 농도 변화 및 적색안료인 $\alpha$-Fe$_2$O$_3$ 미립자를 형광체 표면에 코팅함에 있어 표면처리 방법 변화에 따른 발광 특성의 변화를 연구하였다. 형광체 표면처리방법은 FeSO$_4$를 이용하여 에멀젼 드라이 방식으로 $\alpha$-Fe$_2$O$_3$미립자를 만들어 형광체 표면에 흡착법과 FeSO$_4$/에탄올을 이용하여 액상에서 생성된 침전물을 형광체 표면에 침전시킨 침전법을 사용하였다. 고상법으로 합성된 $Y_2$O$_3$:Eu 형광체의 경우 여기에너지에 따라서 최고 휘도를 나타내는 활성제의 첨가량이 다르게 나타났으며, 활성제의 함량이 진공자외선(147nm)과 저 전압 영역(400V)에서는 0.02mol이고 5kV에서는 0.03mol이었다. 색순도 향상을 위한 안료가 표면 처리되면 형광체의 발광 휘도가 감소한다. 표면처리는 여기에너지에 따라서 다른 방법을 사용해야한다. 진공자외선과 저 전압 영역에서는 불균일 한 막을 형성하는 흡착법으로 표면처리를 해야하고, 고전압영역에서는 침전법으로 표면 처리하는 것이 유리하다.

• 방사성폐기물학회지
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• 제5권1호
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• pp.85-90
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• 2007

양이온교환수지인 IRN-77을 직접 분해 처리하기 위하여 Fonton시약을 적용하였으며, 분해반응의 특징으로써 반응의 효율 및 안전을 위해 수지를 먼저 건조시키고 $FeSO_4$ 용액을 수지에 완전히 흡수시킨 후 $H_2O_2$를 첨가하는 방법을 적용하였다. 수지 분해반응의 특성은 반응이 개시되기까지 반응유도시간이 필요하였으며, 반응유도시간은 $FeSO_4$의 농도가 낮을수록 또한 $H_2O_2$의 초기 첨가량이 적을수록 길었다. 단위량의 수지를 분해하는데 적절한 반응조건으로서 $FeSO_4$의 농도는 0.9 M 및 15% $H_2O_2$의 용액의 첨가량은 수지량에 대해 6-7배 비율로 나타났으며, 반응유도시간을 포함하여 1.5시간 이내에 완전 분해가 가능하였다. $H_2O_2$의 첨가방법은 반응 초기 및 반응개시 후로 나누어 첨가하므로서 $H_2O_2$의 분해효율 및 첨가량을 최소화하였다. 가열효과로서 분해반응 개시 전에 비교적 낮은 온도인 $50^{\circ}C$ 정도로 가열하면 반응유도시간이 5분 이내로 단축되었으며, 수지의 양을 5g 및 10g 으로 증가시킨 결과, $H_2O_2$의 첨가비율을 9-10배 정도로 증가시키면 완전분해가 가능하였다.

• 환경위생공학
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• 제9권2호
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• pp.8-23
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• 1994

During the period from Mar., 1991 to Feb., 1992 66 tSP samples were collected by Hi volume air sampler at 1 sampling site in Seoul and the amount of concentration of 21 components(SO$_{4}$$^{2-}$, NO$_{3}$$^{-}$, NH$_{4}$$^{+}$, Cl$^{-}$, Al, Ba, Ca, Cd, Cr, Cu, Fe, It Mg, Mn, Na, Ni, Pt Si, Ti, Zn, Zr ) were measured. And monthly and seasonal variation were surveyed and the principal component analysis( PCA ) were carried out with respect to these amount of pollutants, minimum of visibility and radiation on a horizontal surface. The total amount of soluble ion in water was high in order o(SO$_{4}$$^{2-}$> NO$_{3}$$^{-}$> N%'>Cl$^{-}$ and metal ion was high in order of Na> Ca>Si> Fe> Al> K> Mg> Zn> Pb> Cu>Ti> Mn > Ba> Cr> Zr> Ni> Cd. There was Seasonal variation in concentration for SO$_{4}$$^{2-}$, NH$_{4}$$^{+}$, Cl$^{-}$, Na, Al, Ca, Bt Mg, Fe and Si. It was assumed that the components of the highest concentration on April were depend on yellow sand and the frequency of wind velocity and direction. As the results of PCA, the amount of pollution components was able to characterized with two principal components(Z$_{1}$, Z$_{2}$ ). The first principal components Z$_{1}$ was considered to be a factor indicating the pollutants originated from natural generation and The second principal components Z$_{2}$ was considered to be a factor indicating the pollutants originated from human work. The monthly concentration of pollutants in ISP, minimum of visibility and radiation on a horizontal surface was possible to evaluate by the use of these two principal components Z$_{1}$ and Z$_{2}$ .

• Corrosion Science and Technology
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• 제2권6호
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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.