• Economic and Environmental Geology
• /
• v.40 no.2 s.183
• /
• pp.141-151
• /
• 2007

This study was focused on iron removal from illite by L-ascorbic and oxalic acids. Iron has been shown as a secondary mineral such as iron oxides and hydroxides in illite ores. It is also known as a primary agent to degrade brightness index of the ores. Methods such as physical separation and chemical leaching with strong inorganic acids have been widely used to remove the iron from the ores. However, these methods are expensive and give rise to environmental problems. In this study, we examined an alternative method using solutions with different set of combination of sulfuric, hydrochloric, L-ascorbic, and oxalic acids. Compared to chemical treatments with only inorganic acids, our results demonstrate that an addition of L-ascorbic acid in inorganic acids results in decreasing both total concentrations of the inorganic acids and time for the treatments. The treatment with 0.15 M L-ascorbic acid and 0.25 M sulfuric acid in solution for 60 min significantly improved the brightness index from 42.4% to 74.4%. This improvement is similar to that of treatment with only 2.5 M sulfuric acid alone for 150 min. Mineralogical and chemical analyses were performed to compare the effect of acid leaching on illite powders. No obvious differences are observed in the mineralogical characteristics and particle size distributions of the samples. These results suggest that the treatment with the addition of L-ascorbic acid in sulfuric acid could effectively remove iron without modifying the physicochemical properties of illite under conditions used in this study.

• Korean Chemical Engineering Research
• /
• v.46 no.6
• /
• pp.1029-1038
• /
• 2008

Transition-metal-oxide-incorporated hydrotalcites were prepared by hydrothermal reaction of their synthetic mixtures containing precursors of transition metal oxides and their properties of nitrogen dioxide adsorption was investigated. The dispersion of transition metal oxides on the hydrotalcites and the amount and the state of nitrogen dioxide adsorbed on them were examined by using XRD, SEM, XPS, nitrogen adsorption, a gravimetric adsorption system, FT-IR spectroscopy and temperature programmed desorption techniques. Transition metal oxides were mainly incorporated on their surface and the incorporation of iron and nickel oxides to the hydrotalcites increased their adsorption amounts of nitrogen dioxide. The dispersion of iron oxide on the hydrotalcites was effective in increasing the amount of nitrogen dioxide adsorption, while too much amount of iron oxide incorporation reduced the amount of nitrogen dioxide adsorption due to masking of surface basic sites by agglomerated iron oxide. Although the incorporation of iron oxide to the hydrotalcites lowered the adsorption strength of nitrogen dioxide, the incorporation of it with a proper amount enhanced the amount of nitrogen dioxide adsorption and the stability against the hydrothermal treatment.

• Clean Technology
• /
• v.16 no.3
• /
• pp.162-171
• /
• 2010

The objective of this study is to develop cleaning agents for the indoor water supply pipe which is environmentally friendly and suitable for removing scale by using various organic acids, inorganic acids, and some additives. Among various organic acids, oxalic acid, citric acid, and malic acid showed good cleaning efficiency of iron oxides which were main components of the indoor water supply pipe scale. Several cleaning agents were formulated by adding chemical additives into these organic acids and evaluated for removal of iron oxides. In this study, it was found that nonionic surfactants were excellent for the removal of iron oxide scale among various additives. Two types of cleaning agents($F_1$, $F_2$) with comparatively high solvent power for iron oxides were formulated in this study. The cleaning agents $F_1$ made by organic acids and some additives were formulated to be safe and environmentally friendly, but seemed to have disadvantage due to their comparatively low cleaning efficiency of iron oxide than $F_2$. But, the cleaning agents $F_2$ prepared by adding inorganic acid a little to $F_1$ showed comparatively good cleaning efficiency of iron oxide and could be recommended for removing hard scale of iron oxides in the indoor water supply pipe. Thus, it is considered that the formulated cleaning agents should be selected based on the extent of scale in the indoor water supply pipe.

• Applied Chemistry for Engineering
• /
• v.29 no.1
• /
• pp.117-121
• /
• 2018

A stainless steel mesh was applied to the cathode of an electro-Fenton system. Methylene blue (MB) solution was chosen as the model waste water with non-biodegradable pollutants. For the model waste water, the degradation efficiency was compared among various SUS mesh cathodes with different surface treatments and magnetite coatings on them. With increasing amount of the magnetite coating on SUS mesh, the degradation efficiency also increased. The improved electro-catalytic characteristic was explained by the increased amount of in situ generated hydrogen peroxide near the cathode surface. Cyclic voltammetry data also showed improved electro-catalytic performance for SUS mesh with more magnetite coatings on them.

• Journal of the Korean Chemical Society
• /
• v.56 no.5
• /
• pp.542-547
• /
• 2012

We have investigated the electronic properties of the oxide film and anodic oxidation mechanism. Iron was oxidized by two reaction pathways depending on pH. The oxide film has showed the electronic properties of n-type semiconductor based on the Mott-Schottky equation.

• Journal of the Korean Magnetics Society
• /
• v.21 no.1
• /
• pp.37-41
• /
• 2011

Fe compounds of scoria samples distributed in Songdang-ri positioning north-eastern area of Jeju island were investigated by means of X-ray diffractometry (XRD) and $^{57}Fe$ M$\ddot{o}$ssbauer spectroscopy. The samples were prepared from six parasite. We found that the samples were composed of a typical olivine, pyroxene, ilmenite, $SiO_2$, anorite and anorthoclase, M$\ddot{o}$ssbauer spectrum of the most scoria samples are shown doublets and sextets of olivine, doublets of pyroxene, ilmenite and silicate minerals. And the valence states of Fe ion of the scoria samples in this area are chiefly 3+ charge state and a little 2+ charge state.

• Clean Technology
• /
• v.19 no.3
• /
• pp.233-242
• /
• 2013

The influences of Ca and Fe based oxides as dechlorination sorbents on the product distribution, boiling point distribution of liquid product, concentration of Cl of the products from the pyrolysis of PVC containing combustible wastes were investigated. With Fe based oxides as the sorbents, the yield of liquid product remarkably decreased whereas the decrease of the boiling point distribution of the liquid product was not noticeable. This phenomenon indicated that Fe based oxides worked as catalysts with weak catalytic activity. With Ca based oxides as the sorbents, the yield of liquid product did not decrease and the boiling point distribution of liquid product did not change significantly, but the dechlorination performance of these was much better than that with Fe based oxides.

• Journal of Nutrition and Health
• /
• v.44 no.1
• /
• pp.5-15
• /
• 2011

Although iron is an essential mineral, excess iron intake during pregnancy may increase oxidative stress in tissues. This study was conducted to investigate the effects of iron overload during pregnancy on iron status and oxidative stress in maternal rats. Ten week-old female Sprague-Dawley rats were mated with male rats. Non-pregnant (control) and pregnant rats were fed diets containing normal Fe (35 mg/kg diet), high Fe (350 mg/kg diet), or excess Fe (1,050 mg/kg diet) during pregnancy. Rats were sacrificed on pregnancy day 19. No significant difference in weight gain, diet intake, or litter size was observed according to iron intake levels. Furthermore, serum iron, hemoglobin, and hematocrit were not different among the rats administered the three levels of Fe both in the control and pregnant groups. However, the iron levels were lower in pregnant rats than those in the control. The liver and spleen iron contents increased significantly in the excess Fe group. An increase in liver ferritin levels with increasing iron intake was observed. Protein carbonyl content, as a marker of oxidative stress, increased significantly in liver with increasing iron intake but not malondialdehyde. Glutathione peroxidase activity in the liver of pregnant rats fed excess iron decreased significantly. Bcl-2 protein expression in the liver declined remarkably with increasing maternal iron intake in pregnant rats. Taken together, iron overload during pregnancy had little effect on hematology. However, the deposits of iron in the liver and the decline in antioxidant enzyme activity implied increased oxidative stress in tissues of the excess Fe group. These results suggest that excess iron intake during pregnancy increases oxidative stress in maternal tissues and may also affect fetal tissues.

• Proceedings of the KWS Conference
• /
• 2004.05a
• /
• pp.15-17
• /
• 2004

철강재의 산소절단은 연료가스의 연소열 및 철의 산화 반응열을 이용하여 강재를 절단하는 방법이다. 연료가스의 연소열을 이용하여 강재를 가열 및 용융시키고, 여기에 고순도의 산소를 취입하면 강재의 용융물질 중 철의 급격한 산화반응이 발생된다. (중략)

• Proceedings of the KSEEG Conference
• /
• 2007.04a
• /
• pp.346-348
• /
• 2007