• Journal of Environmental Science International
• /
• v.9 no.1
• /
• pp.43-47
• /
• 2000

A study on the remediation of heavily for ion contaminated soils from abandoned iron mine was carried out, using ex-situ extraction process. Also, oxalic acid as a complex agent was evaluated as a function of concentration, reaction time and mixing ratio of washing agent in order to evaluate Fe removability of the soil contaminated from the abandoned iron mine. Oxalic acid showed a better extraction performance than 0.1N-HCl, i.e., the concentrations of Fe ion extracted from the abandoned mine for the former at uncontrolled pH and the latter were 1,750 ppm and 1,079 ppm, respectively. The optimum washing condition of oxalic acid was in the ratio of 1:5 and 1:10 between soil and acid solution during l hr reaction. The total concentrations of Fe ion by oxalic acid and EDTA at three repeated extraction, were 4,554 ppm and 864 ppm, respectively. The recovery of Fe ions from washing solution was achieved, forming hydroxide precipitation and metal sulfide under excess of calcium hydroxide and sodium sulfide. In addition, the amounted of sodium sulfide and calcium hydroxide for the optimal revovery of Fe were 15g/$\ell$ and 5g/$\ell$ from the oxalic acid complexes, respectively.

• 한국생물공학회:학술대회논문집
• /
• 2000.04a
• /
• pp.109-112
• /
• 2000

Long chain fatty acids (LCFA) are potential inhibitors of bacteria involved in anaerobic digestion because of their surface activity. Precipitation of long-chain fatty acids with iron can improve the anaerobic degradation due to their precipitation and reducing surface properties. Degradation of stearic acid was improved in the presence of iron (II). The methane production was increased 1.6 times as compared to control. Iron-containing soil was applied for degradation of vegetable oil as model case. The methane production was increased 1.5 times as compared to control. Yield of methane production was 0.09 and 0.06L/g COD in experiment and control respectively. Optimum COD/Fe ratio was found 20 mg/mg. Iron (II) can be produced in the treatment system from iron (III) hydroxide or iron containing minerals.

• Korean Journal of Materials Research
• /
• v.33 no.10
• /
• pp.377-384
• /
• 2023

Exploring earth-abundant, highly effective and stable electrocatalysts for electrochemical water splitting is urgent and essential to the development of hydrogen (H₂) energy technology. Iron-cobalt layered double hydroxide (FeCo-LDH) has been widely used as an electrocatalystfor OER due to its facile synthesis, tunable components, and low cost. However, LDH synthesized by the traditional hydrothermal method tends to easily agglomerate, resulting in an unstable structure that can change or dissolve in an alkaline solution. Therefore, studying the real active phase is highly significant in the design of electrochemical electrode materials. Here, metal-organic frameworks (MOFs) are used as template precursors to derive FeCo-LDH from different iron sources. Iron salts with different anions have a significant impact on the morphology and charge transfer properties of the resulting materials. FeCo-LDH synthesized from iron sulfate solution (FeCo-LDH-SO₄) exhibits a hybrid structure of nanosheets and nanowires, quite different from other electrocatalysts that were synthesized from iron chloride and iron nitrate solutions. The final FeCo-LDH-SO₄ had an overpotential of 247 mV with a low Tafel-slope of 60.6 mV dec^-1 at a current density of 10 mA cm^-2 and delivered a long-term stability of 40 h for the OER. This work provides an innovative and feasible strategy to construct efficient electrocatalysts.

• Journal of the Korean Ceramic Society
• /
• v.22 no.5
• /
• pp.61-65
• /
• 1985

This stud deals with the conditions for the Formation of Ba-Ferrite by Hydrothemal synthesis Suspensions Containing either iron(III) hydroxide or hydroxide oxide and barium ians were subjected to autoclavings at various temperatures from 150 to 30$0^{\circ}C$. A ferromagnetic precipitate BaO.$6Fe_2O_3$ consisting of hexagonal plate-like particle was obtained by suitable combination of temperature and concentration of KOH

• Resources Recycling
• /
• v.2 no.2
• /
• pp.16-21
• /
• 1993

This study was carried out to investigate the settling characteristics of Fe(II) and Fe(III) hydroxide precipitates formed by pH adjustment of aqueous solution to remove ferrous and ferric ion in waste water. The results obstained in this study are as fellows : The settling rate was effectively increased with increasing the pH values of aqueous solution regulated by CaO and with increasing the amount of flocculant, on the other hand, application of excess flocculants decreased the settling rate. It is desirable that the concentration of iron ion is kept under $10^{-2}$ mol/ㅣ because the settling rate was decreased with increasing the concentration of iron hydroxide precipitates.

• Journal of Information Display
• /
• v.6 no.2
• /
• pp.19-24
• /
• 2005

The density controlled carbon nanotubes (CNTs) are grown on the iron acetate nanoparticles by using the freeze-dry method. The iron-acetate [Fe(II)$(CH_3COO)_2$] solution is used to prepare the catalytic iron nanoparticles. The density of CNTs is controlled in order to enhance the field emission process. Furthermore, the patterning of the iron nanoparticle catalyst-layer for the fabrication of electronic devices is simply achieved by using alkaline solution, TMAH (tetramethylammonium hydroxide). We applied this patterning process of catalyst layer to form the electron emitter with under-gate type triode structure.

• Environmental Engineering Research
• /
• v.24 no.3
• /
• pp.434-442
• /
• 2019

The present study investigated a novel calcium hydroxide-coated dairy manure-derived biochar (Ca-BC) for adsorption of phosphate from water and dairy wastewater. The Ca-BC showed much higher adsorption of phosphate than that of dairy manure-derived biochar. The Ca-BC possessed mainly the calcium hydroxide and various functional groups resulting in high reactivity between phosphate and calcium hydroxide in the Ca-BC. The adsorption of phosphate onto Ca-BC followed pseudo-second order kinetic and Freundlich isotherm models indicating chemisorptive interaction occurred on energetically heterogeneous surface of Ca-BC. The maximum adsorption capacity of the Ca-BC was higher than those of iron oxide and zinc oxide-coated biochars, but lower than those of CaO- and MgO-coated biochars. However, the Ca-BC showed high reactivity per surface area for adsorption of phosphate indicating importance of surface functionalization of biochar. On the other hand, the adsorption of phosphate in dairy wastewater on Ca-BC was lower than that in water owing to competition between other anions in wastewater and phosphate. Overall, the Ca-BC would be a low cost and effective adsorbent for recovery of phosphate from water and wastewater.

• Korean Journal of Medicinal Crop Science
• /
• v.23 no.2
• /
• pp.150-154
• /
• 2015

Physiological disorders such as symptoms in leaf colored with brown spots are so many occurred in ginseng garden cultivated with paddy soil. This study was carried out to inhibit the symptoms of brown-colored leaf in 3-year-old ginseng by fertilizing calcium hydroxide [$Ca(OH)_2$] of 100 ~ 400 kg per 10a on paddy soil before transplant of seedling. Soil pH was rapidly increased, while Fe was decreased in soil by the increase of application level of calcium hydroxide. Soil pH was increased from 4.53 to 6.18 when calcium hydroxide was fertilized at level of 100kg per 10a. The content of Fe in ginseng leaf was decreased more than the control by fertilizing calcium hydroxide in soil. Ratio of brown-colored leaf and plant height and leaf area were decreased by the increase of calcium hydroxide. Ratio of survived root and yield of root showed the peak at the application level of 100 kg per 10a, and both of them were gradually decreased by the increase of calcium hydroxide. The decrease of missing plant rate above the application level of 200 kg per 10a had a negative effect on the decrease of yield of root.

• Journal of the Korean Chemical Society
• /
• v.6 no.2
• /
• pp.117-121
• /
• 1962

The waters throughout Taegu area for 87 points were analysed and according to the analytical data, following unfavorable characteristics for industrial uses were given: (1)Shows strong hardness, (2)Has high ratio of ignition residue to evaporation residue, (3) pH value is over 7, (4) Contains considerable quntities of iron.And then investigated the exchange rate and regeneration level of iron ion using cation exchange resin, Lewatit KS.When the hard water containing 2.2 ppm of iron with 18.4 ppm of calcium and 6.2 ppm of magnesium was passed through the ion exchange resin under $3cc/cm^2/min$ in exhaustant flow rate, exchange rate of iron reached to 42% after 300 hours flow. The exchange efficiency shows abrupt decreasing in initial stage of flow up to 100 hours flow. The exchanger which contains iron was regenerated with 10% sodium hydroxide aqua solution under SV (space velocity) 4. By this method, 57% of iron was eliminated from exchanger while calcium and magnesium are removed as much as 85% and 87% respectively.

• Resources Recycling
• /
• v.21 no.4
• /
• pp.35-43
• /
• 2012

This study was carried out for the purpose of obtaining basic data to utilize the AMD sludge as sorbent for heavy metal ions. The sludge from the treatment process of Acid Mine Drainage mainly consists of fine iron hydroxide or iron oxide hydrate and calcite, and the fine iron hydroxide or iron oxide hydrate has a property of adsorbing heavy metal ions. In this study, we investigated the physical property of the AMD sludge like as mineral composition, particle size and shape and chemical composition and also investigated the influence of dosage of sludge, adsorbing time, pH, initial concentration and sintering temperature on the adsorption of heavy metal ions.