• Journal of the Korean Chemical Society
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• v.19 no.2
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• pp.142-146
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• 1975

The formation of iron oxide hydroxide in a ferrous sulfate was studied in different contents of iron in the solution at a temperature range of 90 to $100^{\circ}C$ under 1${\sim}$3 atmospheres. The Mohr's salt thus formed was hydrolyzed under 1 to 3 atmospheres, in 14 to 72 g/l of iron content in the solution pH 3 or 6 for two hours at 90 to $100^{\circ}C$. The results obtained was as follows; 1) In Mohr's salt solution, as the iron content was increased, with decreasing the concentration of hydrogen ion, the yield of iron oxide hydroxide was gradually increased. 2) When iron content in Mohr's salt solution was 42.81 g/l, 91.5% of iron was recovered in the form of $\alpha$-goethite similar to yellow grade of natural goethite. 3) When $\alpha$-goethite obtained was calcined of $500^{\circ}C$, it was turned into ${\alpha}$-ferric oxide with a redish brown colour.

• Journal of the Korean institute of surface engineering
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• v.15 no.4
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• pp.218-225
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• 1982

The effects of ferrous ion on the properties of bright nickel electrodeposit were exa-mined. Iron exists as ferrous ion (Fe+2) and ferric ion (Fe+3) in the bath, a portion of the former tend to be oxidized to the somewhat harmful ferric ion. Iron was added to bath as the ferrous sulfate, ferrous ion prevented from the oxidation with citric acid. It was found that the hardness was increased as the concentration of ferrous ion, the ductility was slightly increased too. The appearance can obtain the wide bright deposits within 4g/$\ell$. The corrosion resistance drastically dropped from 5g/$\ell$ In the case of considering the effect of ferrous ion on the corrosion resistance and the appearance, the allowable limits is 4g/$\ell$, if the reductant is used.

• Journal of Environmental Health Sciences
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• v.23 no.1
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• pp.34-42
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• 1997

A laboratory experiments were performed to investigate the treatment of photographic processing wastewater by chemical oxidation and biological treatment system. The effect of reaction conditions such as hydrogen peroxide dosage, ferrous sulfate dosage and pH on the COD removal in Fenton oxidation were investigated. The optimal dosage of hydrogen peroxide was 2.58 M and 3.87 M for the developing and fixing process wastewater, respectively. The Fenton oxidation was most efficient in the pH range of 3-5 and the optimal condition for initial reaction pH was 5 for a developing process wastewater. With iron powder catalyst, the COD for a developing process wastewater was removed in lower pH than with ferrous sulfate catalyst. The removal efficiency of COD for refractory compounds such as Diethyleneglycol, Benzylalcohol, Hydroxylamine Sulfate, Ammonium Thiosulfate, Ammonium Ferric EDTA and Disodium EDTA in the photogaphic wastewater was found than 90% except Potassium Carbonate. When the photographic processing wastewater after pretreatment by Fenton oxidation was treated with batch activated sludge process, the addition of $KH_2PO_4$ as a phosphorous compound improved the removal efficiency of COD. During the continuous biological treatment of developing and fixing process wastewater after pretreatment by Fenton oxidation, the effluent COD concentration less than 100 mg/l was obtained at 0.425 and 0.25 kgCOD/m$^3$.d, respectively.

• Elastomers and Composites
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• v.30 no.3
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• pp.229-234
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• 1995

Membrane process has been applied widely to petroleum chemistry, fine chemistry, polymer, electronics, food, bioprocessing, and wastewater treatment process. Membrane process has advantage that there's no phase change through separation, energy consumption is smaller than other separation processes. And equipment investment and operation cost are inxpensive too. We prepared the silicone rubber membrane and then separated the heavy metal ion from wastewater. Silicone rubber membrane was prepared using a superitical fluid process and heavy metal ions were separated from the chromium nitrate, ferric sulfate, cupric sulfate, nickel sulfate aqueous solution. The pressure difference between top and bottom of separation apparatus was preserved by vacuum pump, and the removal amount of heavy metal at each separation step were analyzed by instrumental analysis, AAS. The surface and pore of silicone rubber membrane was investigated using SEM, and the capability of wastewater treatment using a silicone rubber membrane was proposed as calculated removal rate of heavy metal after comparing removal amount of heavy metal to amount of heavy metal in mother solution by AAS analysis.

• Journal of the Mineralogical Society of Korea
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• v.26 no.1
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• pp.1-8
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• 2013

This study was carried out to test the possibility of using an environmentally friendly method of leaching silver concentrate from the Samjo mine. The Samjo mine ore contained minerals such as pyrite, chalcopyrite, galena, arsenopyrite, and sphalerite. The concentrate samples tested with the thiourea solution were roasted at $750^{\circ}C$. The results of different experimental conditions showed that the highest silver leaching rate was obtained when the concentration of thiourea was at 0.8 g with ferric sulfate at 0.425 g and the leaching temperature at $60^{\circ}C$. The Ag leaching rate obtained was 91.5% at a pulp density of 10%. However, in the XRD analysis, peaks of pyrite, galena, and hematite were still found in the leached solid residues in which the Ag leaching rate was the highest. it is expected that the unrecovered silver in the solid residue can be lost.

• Applied Biological Chemistry
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• v.37 no.6
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• pp.472-479
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• 1994

This study was conducted to determine the effective removal method of THMs and humic material in drinking water when the doses of oxidants, coagulants, and activated carbon, and the points of oxidants treatment were changed in the drinking water treatment process. The inhibition of THMs formation and the removal of humic matter were more effectively achieved by $ClO_2$ than by other oxidants, $Cl_2,\;NH_2Cl,\;KMnO_4\;and\;O_3$. By changing the point of oxidant treatment, the formation of THMs was reduced by about 36.7 to 8.2% on treatment after coagulation, but the content of humic matter was not affected. The coagulation efficiency of alum and ferric sulfate to coagulate organic materials in water was affected by the molecular weight of humic matter in drinking water. The treatment of activated carbon after filtration was found to be more effective than that before oxidation in inhibiting THMs formation and removing THMs.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.775-780
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• 2008

Sludge conditioning is widely used to improve aggregation and dewaterability of waste sludge in sludge treatment processes. The study aims to examine quantitative correlations between coagulant dosage and sludge cake dewaterability using three kinds of coagulants, such as an aluminum sulfate, a ferric chloride, and a poly aluminum chloride(PAC). When an aluminum sulfate, a ferric chloride, and a PAC were injected with 0.79$\sim$1.19 mmol/g, 0.61$\sim$1.25 mmol/g TSS, and 0.21$\sim$0.39 mmol/g TSS, respectively, specific resistances to filtration of the sludge were decreased at 95.0% or more. This study shows that the correlation between coagulant dosage per g sludge(D) and normalized specific resistance to filtration(R) could be expressed by the exponential functions.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.477-483
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• 2007

A coagulation process for RO (reverse osmosis) membrane pretreatment system was an effective technology to remove colloidal and particulate matters. However, coagulant residuals from the pretreatment process may negatively affect RO membrane performance. The bench-scale coagulant exposure study was performed to investigate the effect of their residual on adsorbed mass which related to the membrane performance. Coagulant addition in this study ranged from 0 to 5mg/L ferric chloride, alum, and 2mg/L cationic polymer(poly-di-methyldiallyl ammonium chloride) as coagulant aids. This results showed that adsorbed mass is not significantly increased during short-time period, however, accumulated mass of coagulants on the membrane surface is significantly increased during long-time experimental period. The effect of pH on coagulants adsorption characteristics was significantly differed due to the electrostatic repulsive interactions between soluble coagulants and membrane surface charge. This data suggest that the RO membrane performance of drinking water treatment plant could be decreased by adsorption of residual coagulants when applied for the coagulant pretreatment process.

• KSBB Journal
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• v.26 no.5
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• pp.443-452
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• 2011

In this study, inorganic flocculant with biodegradable polymer flocculant was usedfor microalgae harvest. The aim of this study was to optimize the concentration of inorganic flocculant, the concentration of biodegradable polymer flocculant and reaction volume for decreasing the amounts of flocculant and obtaining the suitable pH range for seawater by response surface methodology. The flocculation of three marine microalgae, Chlorella ellipsoidea, Dunaliella bardawil, and Dunaliella tertiolecta, using inorganic flocculants and biodegradable polymer flocculants was investigated. The results indicated that the optimal flocculant quantity showed 0.1 g/L of ferric chloride, 7.5 g/L of chitosan on Chlorella ellipsoidea. In the case of Dunaliella bardawil, the optimal flocculant quantity showed amount of ferric sulfate more than 0.12 g/L and chitosan more than 0.75 g/L. In the case of Dunaliella tertiolecta, the optimal flocculant quantity showed 1.0 g/L of sodium aluminate, 0.75 g/L of chitosan.

• Journal of Environmental Science International
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• v.4 no.4
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• pp.367-377
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• 1995

The study of flocculation kinetics is of fundamental interest in the field of water treatment, because rational study of the factors affecting the coagulation process should be based on the rate of particle growth. The effect of sulfate on flocculation kinetics were examined using ferric nitrate as a coagulant to coagulate kaolin clay in water under several experimental conditions. Both the particle size distribution data obtained from the AIA and the on-line measurement of turbidity fluctuation by the PDA were used to measure flocculation kinetics. Results show that sulfate ion added to the kaolin suspension played an important role in the flocculation process, not only improving flocculation kinetics at more acidic pH levels but also changing surface charge of particles. The kinetics of flocculation were improved mainly by the enhanced rate and extent of Fe(III) precipitation attributed to the addition of sulfate, and thereby, better interparticle collision frequency, but little by the charge reductions resulting from the sulfate addition. The increase in sulfate concentration beyond $3\times10^{-4}M (up to 2\times10^{-3}M)$ did not induce further improvement in flocculation kinetics, although the higher concentrations of sulfate ion substantially increased the negative ZP value of particles. Key Words : Flocculation Kinetics, Fe(III) Coagulant, Sulfate ion, Turbidity Fluctuation.