• Environmental Engineering Research
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• v.17 no.2
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• pp.111-116
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• 2012

This study investigates the complete removal of nitrate and the recovery of valuable ammonium salt by the combination of nanoscale zero-valent iron (NZVI) and a membrane contactor system. The NZVI used for the experiments was prepared by chemical reduction without a stabilizing agent. The main end-product of nitrate reduction by NZVI was ammonia, and the solution pH was stably maintained around 10.5. Effective removal of ammonia was possible with the polytetrafluoroethylene membrane contactor system in all tested conditions. Among the various operation parameters including influent pH, concentration, temperature, and contact time, contact time and solution pH showed significant effects on the ammonia removal mechanism. Also, the osmotic distillation phenomena that deteriorate the mass transfer efficiency could be minimized by pre-heating the influent wastewater. The ammonia removal rate could be maximized by optimizing operation conditions and changing the membrane configuration. The combination of NZVI and the membrane contactor system could be a solution for nitrate removal and the recovery of valuable products.

• Journal of Conservation Science
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• v.29 no.2
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• pp.103-110
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• 2013

Since its development in the United Kingdom, the stapler has been used extensively to bind books. Staples comprising almost entirely of iron, first made in the early 1900s, are used to staple the cores of books. These staples change the colour of paper to brown and this browned paper ultimately crumbles. Basic research is being performed on solutions to prevent the deterioration in the quality of paper in the area around the staples. In this study, the cause of this browning of paper in the area was investigated. SEM-EDS, optical microscopy and FT-IR were used to analyze a browned area of three paper samples. It was found that the browned area had shortened fibres. In addition, iron was detected in this area. The corrosion of this iron led to this area of the paper being partially covered by iron(III) oxide, the product of the corrosion, as determined by FT-IR spectroscopy.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.4_1
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• pp.797-803
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• 2024

In this study, a device was used to conduct heat to the riser by combining a cylindrical heater with the riser to maintain the molten metal above a certain temperature while continuously compensating for the shrinkage phenomenon that occurs as the molten metal solidifies in the product area. A cylindrical heater is coupled to the riser portion of the upper part of the upper mold, and a heater portion mold is formed between the riser and the cylindrical heater. The cylindrical heater is connected to a controller to control the temperature and a power supply. The cylindrical heater conducts a heat source to the molten metal located on the riser and can continuously compensate for the shrinkage of the cast product by heating the molten metal located on the riser or maintaining it at a constant temperature. The block without a riser had a large shrinkage cavity at the top, and the top became concave due to shrinkage. There is no shrinkage in the block with the Ø100 mm riser. Blocks that did not apply heaters to the Ø50 mm riser experienced shrinkage around the riser and also at the bottom. There is no shrinkage in the block with the Ø50 mm riser to which the heater was applied.

• Food Science of Animal Resources
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• v.37 no.2
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• pp.228-241
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• 2017

Hematological, chemical and functional characteristics of porcine, chicken and duck blood were evaluated. A porcine blood sample showed the most abundant red blood cell, hemoglobin concentration, packed cell volume and plasma protein content as well as its freeze-dried blood possessed the highest contents of protein, fat, Cu and Cr with the highest percentage of heme iron (p<0.05). Unlike porcine blood, chicken blood showed a well balance in some essential amino acids, specifically for a higher isoleucine content (p<0.05). Furthermore, it possessed the highest contents of carbohydrate, Zn and non-heme iron (p<0.05). The most rapid response to form a strong gel, especially at $70^{\circ}C$ and $80^{\circ}C$, was found in chicken blood, followed by duck and porcine blood, respectively. The result of emulsion activity index (EAI) and emulsion stability index (ESI) at the low protein concentration indicated that chicken blood had the most superior emulsion properties (p<0.05). Regarding duck blood, it exhibited the highest content of Mg and Mn (p<0.05). Moreover, duck blood had similar foaming properties to porcine blood in which they showed higher values than chicken blood (p<0.05). Specific characteristics of blood were therefore diminished by animal species in which this information could be used as food supplementation or product development based on their potential applications.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.1
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• pp.27-35
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• 2006

The aim of this study was to identify the sources of benzene detected in airborne of casting workplace where benzene was not used as raw material. We have identified benzene by GC/FID and GC/MSD. In this pilot test, small size iron chamber(diameter 30 cm, height 20 cm) was used. As the raw materials, new sand, recovered sand, and mixed casting sand(new sand + solidifying agent + organic resin + coating material) was tested, respectively. In the new sand benzene was not detected, but in the recovered sand and the mixed casting sand was detected. Xylenesulfonic acid(solidifying agent), one of the mixed casting sand ingredients was thought to product benzene by thermal decomposition above $400^{\circ}$..., but the other raw materials(organic resin and coating material) were thought not to product benzene. In this experiment, the most of benzene by thermal decomposition was produced within 1 hour after pouring the iron solution($1560^{\circ}$...) in small size iron chamber. When the mixed casting sand with coating material was used, the concentration of the produced benzene was average 2.91 ppm(range 1.98~3.72 ppm), and without coating material, benzene concentration was average 0.11 ppm(range 0.08~0.14 ppm).

• Resources Recycling
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• v.12 no.5
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• pp.36-41
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• 2003

Although slag has an enough potential as the secondary resources due to its high content of iron, quite a large amount of slags are simply landfilled when market prices of iron and steel are not so beneficial. The purpose of this study is to investigate the basic characteristics regarding the recovery of iron content from slag by magnetic separation method for the enhancement of its recycling rate. Three kinds of slags such as blast furnace slag, water-cooled converter slag, and air-cooled converter slag were tested taking the strength of magnetic field, revolving speed of drum, and feeding rate of slag as the influential factors on the magnetic separation. For blast furnace slag, the recovery of iron was observed to increase as drum speed and feeding rate were lowered. For water-cooled converter slag, iron recovery was raised as feeding rate was increased and drum speed was lowered. Also, finer slag particles were observed to be more favorable for the higher recovery of iron content. Regarding air-cooled converter slags, higher iron recovery was accomplished when both feeding rate and drum speed were increased or decreased. In addition, when the magnetic field strength was increased the iron recovery was raised, however, the iron grade of separated product was observed to diminish because of the co-separation of impurities.

• Journal of Korea Foundry Society
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• v.24 no.1
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• pp.52-59
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• 2004

Microstructure and mechanical properties of ductile cast iron were investigated in terms of diameter change of samples that gives rise to modify the microstructure due to different cooling rate in the continuous casting process. The chemical composition used in this study was GCD 400 grade. From the microstructural observation, we have found a large number of graphite with small size in diameter which is comparable to the microstructure of the sample produced by conventional sand casting. The major reason of this would he due to high cooling rate. In the sample with 26 mm in diameter, the microstructure was composed of pearlite, iron carbide, and graphite. In the samples with 60 and 100 mm in diameter, however, we have observed a dissimilar microstructure that consisting of ferrite and graphite. Concerning the mechanical property, the sample with 26 mm in diameter showed higher hardness and strength compared to those samples with 60 and 100 mm in diameter. The result obtained for ductility appeared a reversal. Much more works such as inoculation, process design and chemical composition would be required in order to have a sound product even in a small diameter of samples.

• Journal of Soil and Groundwater Environment
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• v.22 no.1
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• pp.41-48
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• 2017

Persulfate (PS) activated with nanosized zero-valent iron (NZVI) was tested as a reagent to remove phenol from groundwater. Batch degradation experiments indicated that NZVI/PS molar ratios between 1 : 2 and 1 : 5 were appropriate for complete removal of phenol, and that the time required for complete removal varied with different PS and NZVI dosages. Chloride ions up to 100 mM enhanced the phenol oxidation rate, and nitrate of any concentration up to 100 mM did not significantly affect the oxidation rate. NZVI showed greater performance than ferrous iron did as an activator for PS. A by-product was formed along with phenol degradation but subsequently was completely degraded, which showed the potential to attain mineralization with the NZVI/PS system. Tests with radical quenchers indicated that sulfate radicals were a predominant radical. The results of this study suggest that NZVI is a promising activator of PS for treating contaminated groundwater.

• Economic and Environmental Geology
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• v.41 no.5
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• pp.497-507
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• 2008

This study identified and quantified the hidden flows for steel and iron production in Korea using MIPS (Material Input per Service) methodology. In order to estimate the input orientated impact on the environment caused by the manufacture or services of a product, MIPS indicates the quantity of resources used for this product or service. In 2005, 71 million tons of raw materials were used to produce $17.6 million of added value and 4.8 thousand tons of finished steel. The amount of natural resources extracted from natural environments for the purpose of steel production was 245 million tons of TMR(Total Material Requirement), 1524 million tons of water, and 34 million tons of air. The material intensities for steel production by natural inputs (raw materials and energy) was 4.3 ton/ton of TMR, 28 ton/ton of water, and 0.5 ton/ton of air.

• Corrosion Science and Technology
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• v.3 no.6
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• pp.227-232
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• 2004

The carboxylates as a corrosion inhibitor has been studied by many researchers because of its environmental safety and low depletion rate. However, conventional test methods of inhibitor such as weight loss measurements, linear polarization resistance and corrosion potential monitoring etc., evaluate uniform corrosion of metals. These methods are unable to evaluate crevice-related corrosions, which are encountered in most of heat exchanging facilities. In order to choose the optimum corrosion inhibitor, the appropriate test methods are required to evaluate their performances in service environment. From this point of view, polarization technique was used to evaluate the characteristics of sodium heptanoate on corrosion behavior for carbon steel. Especially a thin film crevice sensor technique were applied to simulate the crevice corrosion in this study. From these experiments, we found that oxygen as an oxidizing agent was required to obtain stable passive film on the metal. Presence of oxygen, however, accelerated crevice corrosion. Potential shift by oxygen depletion and weakened inhibitive film inside the crevice were responsible for such accelerated feature. It is shown that film for corrosion inhibition is a mixture of sodium heptanoate and iron (II) heptanoate as reaction product of iron surface and sodium heptanoate. The iron (II) heptanoate which has been synthesized by reaction of heptanoic acid and ferrous chloride in methanol solution forms bidentate complex.