• Korean Journal of Materials Research
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• 제10권5호
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• pp.369-374
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• 2000

In order to investigate the effects of addition of 1M sulfuric acid to the etching solution or 1M hydrochloric acid on the etching behavior of aluminum foil for electrolytic capacitors, the changes in the density of etch pit, the length and diameter of etch tunnels and the capacitance were analyzed using SEM, TEM, LCR meter etc. Sulfate ion as a corrosion inhibitor was contributed to the increase of the surface area comparing with chloride ion. By adding sul-furic acid the density of etch pit and the length of etched tunnel increased and the diameter of the tunnel decreased, resulting in the increase of capacitance. It was also shown that the capacitance decreased when the current density was below $0.9A/\textrm{cm}^2$, while remarkably increased in the other case.

• Journal of Environmental Science International
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• 제19권8호
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• pp.931-940
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• 2010

The Raw water from Deer Creek (DC) reservoir and Little Cottonwood Creek (LCC) reservoir in the Utah, USA were collected for jar test experiments. This study examined the removal of arsenic and turbidity by means of coagulation and flocculation processes using of aluminum sulfate and ferric chloride as coagulants for 13 jar tests. The jar tests were performed to determine the optimal pH range, alum concentration, ferric chloride concentration and polymer concentration for arsenic and turbidity removal. The results showed that a comparison was made between alum and ferric chloride as coagulant. Removal efficiency of arsenic and turbidity for alum (16 mg/L) of up to 79.6% and 90.3% at pH 6.5 respectively were observed. Removal efficiency of arsenic and turbidity for ferric chloride (8 mg/L) of up to 59.5% at pH 8 and 90.6% at pH 8 respectively were observed. Optimum arsenic and turbidity removal for alum dosages were achieved with a 25 mg/L and 16 mg/L respectively. Optimum arsenic and turbidity removal for ferric chloride dosages were achieved with a 20 mg/Land 8 mg/L respectively. In terms of minimizing the arsenic and turbidity levels, the optimum pH ranges were 6.5 and 8for alum and ferric chloride respectively. When a dosage of 2 mg/L of potassium permanganate and 8 mg/L of ferric chloride were employed, potassium permanganate can improve arsenic removal, but not turbidity removal.

• Journal of Korean Society of Water and Wastewater
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• 제32권1호
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• pp.47-53
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• 2018

This study investigated phosphorus removal from secondary treated effluent using coagulation-membrane separation hybrid treatment to satisfy strict regulation in wastewater treatment. The membrane separation process was used to remove suspended phosphorus particles after coagulation/settlement. Membrane separation with $0.2{\mu}m$ pore size of micro filtration membrane could reduce phosphorus concentration to 0.02 mg P/L after coagulation with 1 mg Al/L dose of polyaluminum chloride (PACl). Regardless of coagulant, the residual concentration of phosphorus decreased as the dose increased from 1.5 to 3.5 mg Al/L, while the target concentration of 0.05 mg P/L or less was achieved at 2.5 mg Al/L for the aluminum sulfate (Alum) and 3.5 mg Al/L for PACl. Moreover, alum showed better membrane flux as make bigger particles than PACl. Alum showed a 40% of flux decrease at 2.5 mg Al/L dose, while PACl indicated a 50% decrease of membrane flux even with a higher dose of 3.5 mg Al/L. Thus, alum was more effective coagulant than PACl considering phosphorus removal and membrane flux as well as its dose. Consequently, the coagulation-membrane separation hybrid treatment could be mitigate regulation on phosphorus removal as unsettleable phosphorus particles were effectively removed by membrane after coagulation.

• YAKHAK HOEJI
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• 제21권4호
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• pp.200-210
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• 1977

This investigation was undertaken from February 1976 to September 1976. The detergents in municipal sewages from the Chung Kae Stream, Ahn Yang Stream, and Bong Won Stream were determined at 1.5ppm, 0.93ppm, and 3.36ppm in average respectively. The concentrations of detergents determined in the Han river were 0.013ppm of Kwang Na Ru, 0.11ppm of Duk Do, 0.370ppm of Bo Kwang Dong, and 0.285ppm of Ka Yang Dong basin respectively. And the potable waters of Sung Book Ku and Sung Dong Ku from Ku Eu water pumping station located up-stream of the Han river were less polluted at 0.045ppm and 0.037ppm in average. Young Deung Po Ku and Su Dae Moon Ku had been relatively polluted at 0.181ppm and 0.133ppm. The coagulant, alum [$Al_{2}(SO_{4})_{3}$] could eliminated the small amount of detergent by coagulation. The eliminated rates were about 13% by 5ppm and 22.7% by 20ppm of aluminum sulfate in sewage contained 10ppm of turbidity. The sand and the charcoal adsorbed some detergent as the following Langmuir's equations: For the charcoal, m/x=0.029.$\times$1/Ce-11.43 For the charcoal, m/x=2.705log1/Ce-5.46 Where m: amount of snad and active carbon used(g) x: amount of detergent adsorbed from liquid(g) Ce:concentration in the liquid at equilibrium(miles) The adsorption effect of sand would be neglected. In the low concentration of detergent solution, one gram of active carbon adsorbed 0.263g of detergent. It was determined that one gram of chlorine reduced 5.5g pf DBS om keeping up 0.2ppm of residual chlorine by disinfection process with chlorine compound.

• Journal of Korea Soil Environment Society
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• 제2권3호
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• pp.31-38
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• 1997

Temporal and spatial comparisons of acid mine drainage contaminated waters are difficult because of the complex physico-chemical nature of the pollutant. In the present study, an acid mine drainage index has been developed and evaluated for the assessment of surface waters. AMD index is calculated using a modified arithmetic weighted index using seven parameters which are most indicative of AMD contamination, i. e. pH value, sulphate, iron, zinc, aluminum, copper and manganese. Weighting is used to express the relative indicator value of each parameter. The proposed AMD index is used to quantify contamination from acid mine drainage over ten different old mine sites and assess the degree of impact on surface on surface waters. As a result of AMD evaluation, the Sukbong Mine located near the Moonkyung province showed lowest AMD value indicating the worst acid mine drainage quality. In overall, Youngdong mine sites showed higher contaimination compared to the other mine sites including Youngsuh, Choongbu, Suhbu and Nambu area.

• Korean Journal of Materials Research
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• 제5권7호
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• pp.794-801
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• 1995

To connect the driver IC and Al coated glass, a method has been developed to plate electrolessly Ni on Al/PR system. It Is necessary to pretreat Al to remove oxide film before plating. In order to find pretreatment process which does not damage photoresist or glass, alkaline and fluoride zincate process have been investigated. Because photoresist and aluminum thin film can easily dissolve in alkaline solution, it is considered that the fluoride zincate process was a suitable one. After immersion in the zincate solution containing 1.5 g/$\ell$ ammonium bifluoride and 100 g/$\ell$ zinc sulfate, electroless nickel plating could be performed. The additive in the zincate solution and thiourea in the plating solution increased smoothness of the plated surface. Acld dip could improve the uniformit of the surface.

• Environmental Engineering Research
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• 제18권2호
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• pp.95-101
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• 2013

Alternative sources of water are sought in some water stressed communities in the study area. The study focuses on the Aguata-Awka area of southeastern Nigeria. Aquifers occur at great depths, and surface waters may be far from homesteads. The scarcity of water has necessitated the people to adopt various local technologies for harvesting rainfall. The local technology includes collecting rainwater from roofs and channeling the water into large underground tanks, shallow wells and surface reservoirs. Large concrete tanks of $6m{\times}6m{\times}4m$ dimensions are often built underground and can store $144m^3$ of water. Surface reservoirs built on 4 m concrete pillar supports having dimensions of $10m{\times}10m{\times}4m$ and have a storage capacity of $400m^3$. Water samples were collected at 3 different locations of Agulu, Ekwulobia, and Awka and were analyzed for their physical, chemical, and bacteriological parameters. Results indicate a range of values for pH, 5.9 to 7.1; turbidity, 0.9 to 2.7; total dissolved solids, 80 to 170 mg/L; total hardness, 4.5 to 6.4 mg/L; magnesium, 1.2 to 1.4 mg/L; bicarbonate, 19.4 to 83.6 mg/L; and sulfate, 3.6 to 6.4 mg/L. Bacteriological analysis results were negative for fecal and total coliform counts. All parameters, with the exception of pH where aluminum and galvanized iron roofs are used for collection, fall within the recommended guidelines for drinking water quality of the World Health Organization, and the Standard Organization of Nigeria, new Nigerian standards for drinking water quality. Magnesium is above the maximum permitted level for consumer acceptability of the Nigerian standards for drinking water quality. The water can be classified as fresh moderately hard and soft. The water can be described as a calcium and bicarbonate type.

• Horticultural Science & Technology
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• 제31권5호
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• pp.573-579
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• 2013

This study was conducted to investigate optimal harvesting stage and the effects on cut roses of Korean cultivar harvested at different stages. Cut roses are harvested at three different flowering stages. The optimal harvesting stage of cut roses was different depending on varieties. The vase life of standard type 'Pink Song' and spray type 'Peace One' was extended when they were harvested in one and three stages, respectively. The vase life was generally increased when the cut roses were pretreated with a solution containing 2% sucrose + $200mg{\cdot}L^{-1}$ aluminum sulfate + $200mg{\cdot}L^{-1}$ $Mg(NO_3)_2$ + $50mg{\cdot}L^{-1}$ $CaCl_2$ as compared to the control regardless of the harvesting stage. And this pretreatment solution improved the flower quality of cut roses bred in Korea. But the effects of pretreatment were varied depending on the harvesting stage.

• Applied Chemistry for Engineering
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• 제19권3호
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• pp.264-269
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• 2008

For the synthesis of lead chromate pigments, we investigated the characteristics of particle growth with reacting conditions in the synthetic process, the effect of additives, and its micro-capsulation. The more tiny and uniform dispersion particles could be obtained at a lower pH and diluter intial concentration. The variation range of average pigment size was increased with the agitating speed. The pigment size could be controlled by adding aluminum sulfate as an additive, which maintained the optimum particle dispersion. It was found that the optimum micro-capsulation conditions were pH 9~10 and above $90^{\circ}C$ during the micro-capsulation of lead chromate pigment, and below 0.5% humidity after micro-capsulation.

• Journal of Korean Society for Atmospheric Environment
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• 제4권1호
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• pp.33-44
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• 1988

For the purpose of examining the effects of simulated acid rain on the chemical properties of the experimental soil in Pinus densiflora seedlings and Forsythia koreana rooted cuttings, the experimental design of randomized block arrangement with three replications was implemented in the experimental field of Yesan National Agricultural Junior College. One-year-old Pinus densiflora seedlings and Forsythia koreana cuttings were planted in the pots filled the mixed soils (nursery soil: forest soil of siliceous sandy loam = 1 : V/V)in the early spring of 1985. The regime of artificil acid rain, in terms of spray frequency per monthly and spray amount at single treatment per plot, was simulated on the basis of climatological data averaged from 30 years records. Simulated acid rain (pH 2.0, pH4.0, and pH 5.5 as control) containing sulfuric and nitric acid in the ratio of 3:2 (chemical equivalant basis) diluted ground water, were treated on the experimental plants under condition of cutting off the natural precipitation with vinyl tunnel, during the growing season (May 1 to August 31) in 1985. THe results obtained in this study were as follows; 1. Soil acidity was dropped, and exchangeable aluminum contents in the soil was dramatically increased in both species, with decreasing pH levels of acid rain. 2. Exchangeable potassium, clacium, magnesium contents, and base saturation degree of the soil were highly drcreased in two species as the pH levels of acid rain decreased. 3. In two species, sulfate concentrations in the soil were decreased of pH 4.0 treatment, and remarkably increased at pH 2.0 treatment of acid rain in comparison with control. 4. Total nitrogen and available phosphate contents of the soil were not affected by acid rain treatment in the both species, and Fe contents at pH 2.0 treatment were highest among three acid rain treatments.