• Carbon letters
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• v.5 no.4
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• pp.186-190
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• 2004

In this work, a nickel metal (Ni) electroplating on the activated carbon fiber (Ni/ACFs) surfaces was carried out to remove the toxic hydrogen chloride (HCl) gas. The surface properties of the treated ACFs were determined by using nitrogen adsorption isotherms at 77 K, SEM, and X-ray diffraction (XRD) measurements. HCl removal efficiency was confirmed by a gas-detecting tube technique. As a result, the nickel metal contents on the ACF surfaces were increased with increasing the plating time. And, it was found that the specific surface area or the micropore volume of the ACFs studied was slightly decreased as increasing the plating time. Whereas, it was revealed that the HCl removal efficiency containing nickel metal showed higher efficiency values than that of untreated ACFs. These results indicated that the presence of nickel metal on the ACF surfaces played an important role in improving the HCl removal over the Ni/ACFs, due to the catalytic reactions between nickel and chlorine.

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.321-326
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• 2002

On this study, removal method for microcystin, toxic substance released from the blue-green algae, using chloride was investigated. 82 ~ 98% of Microsystin were removed within 1 hr when sample had microsystin only. However, if the sample had algae cell removal efficiency was decreased to 50%, except the concentration of chloride $10Cl-mg/{\ell}$. As a result, intermediate-chlorination which dose chloride after coagulation process is considered the optimum method for the removal of microcystin because most of algae cell could remove during the coagulation process.

• Textile Coloration and Finishing
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• v.12 no.3
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• pp.218-223
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• 2000

Color removal of dyeing wastewater is becoming more important due to intensive limitation on color unit of effluent water, so this study was to investigate an efficient color removal of dyeing wastewater. We found that bittern+iron chloride(II) inorganic coagulant developed by Kabool research center is much higher than any other inorganic coagulants for color removal. Optimum pH of this coagulant was 10.5 and removed more than 90% for color removal efficiency. The results showed that COD and color unit of effluent water was average 60mg/L and 200~250 units when continuous activated sludge test after coagulation with this coagulant has done. From the results of the experiments, the application of bittern+iron chloride(II) inorganic coagulant can save the operating cost of wastewater treatment plants.

• Analytical Science and Technology
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• v.19 no.4
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• pp.316-322
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• 2006

The removal efficiencies of silver-ACFs were associated with their surface properties such as surface area, porosity, and the electro-chemical reaction time for the silver treatments. X-ray diffraction patterns of fibers electrochemically treated with silver display diffraction peaks for metallic silver and kinds of silver chloride complexes on the fiber surface after electrochemical adsorption. The results of SEM and EDX indicate that surface reaction motive of silver-ACF prepared by electrochemical reaction are depend on time function for the chloride ion removal efficiency. Finally, Cl ion adsorbed by the silver-ACFs from the ICP analysis seems to show an excellent removal effect.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.1
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• pp.125-133
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• 1999

The objective of present work is to evaluate the optimum coagulation conditions in order to decrease dissolved organic carbon(DOC) and turbidity at different polyaluminum chloride dosage and pH from Nakdong River water. This studies were carried out to examine distribution on apparent molecular weight(AMW) of DOC in the Nakdong River water and its coagulation-sedimentation water. On the basis of jar tests, at the optimum coagulation pH in order to decrease DOC and turbidity were pH 5.0~6.0 and optimum dosage of polyaluminum chloride were 10~15mg $Al_2O_3/L$. The removal percentage of DOC and UV-254 absorbance were 35~40%, 45~60%, respectively. In pilot plant, at the optimum coagulation pH in order to decrease DOC and turbidity were 5.0-6.5, and the removal percentage of DOC were 30~45%. Distributions of AMW in the Nakdong River, less than 6,800dalton were 60.7% 6,800~11,000dalton were 32.8%, more than 11,000dalton were 6.4%. When the polyaluminum chloride dosage was 12~20mg/L, the removal percentages of each AMW for AMW of Nakdong River water, less than 6,800dalton were 25~28%, 6,800~11,000dalton were 65~68% more than 11,000dalton were 10~60%.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.5-17
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• 2012

The amount of snow due to global warming and climate change has recently increased. The effective management of snow removal materials will be required. First, on the basis of domestic winter temperature, it is not necessary to get a baseline to less than the freezing point of $-52^{\circ}C$ for the calcium chloride($CaCl_2$) of 30%.. In terms of cost comparison between calcium chloride($CaCl_2$) and sodium chloride($NaCl$), the calcium chloride($CaCl_2$) is 2 to 3 times more expensive, and the supply of the calcium chloride($CaCl_2$) is not produced in domestic country and is in the conditions that have to imports all needed. Accordingly, the effective use scheme of snow removal materials should be considered to multifaceted ways. Thus, the objective of this study is to develop effective method and to replace from calcium choride($CaCl_2$) to sodium chloride($NaCl$) solution in the current snow removal operating system that uses a pre-wetted salt spreading method. The effective method that equals to the quality of the existing snow removal materials was developed in this study through performance tests for deicing chemicals, corrosion test of steel and freezing and thawing tests of concrete.

• KSBB Journal
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• v.13 no.4
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• pp.404-410
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• 1998

Three types of adsorbents were developed by immobilizing synthetic zeolite, Philipsite-Gismonine, in alginate, cellulose acetate and dialysis membrane for the in situ removal of ammonium ion which inhibits growth and productivity of animal cells such as CHO cells producing tPA. Ammonium ion removal efficiency and cell growth promoting effect with various immobilized adsorbents were evaluated and the membrane type was selected as an optimal immobilized adsorbent. The experiments were then simulated by adding 8mM ammonium chloride and immobilized adsorbent in order to validate the removal effect under high density cell cultures. The results showed increase in maximum cell density by three times, in cell viability, and in tPA productivity by 40%. And it was found that the promoting effects were more significant in case of high ammonium ion concentration system. It was also found that the optimum addition time for immobilized adsorbents was 48 hr in the absence of ammonium chloride addition and 72 hr in the presence of ammonium chloride addition.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.77-85
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• 2012

The present study investigates treatment methods for removal of arsenic from wastewater. The granular activated carbon (GAC) with the coating of iron chloride ($FeCl_3$) was used for the treatment of a low concentration of arsenic from wastewater. Batch experiments were performed to investigate the synthesis of Fe-GAC (Iron coated granular activated carbon), effects of pH, adsorption kinetics and the Langmuir model. The synthesized Fe-GAC with 0.1 M $FeCl_3$ shows best removal efficiency. Adsorption studies were carried out in the optimum pH range of 4-6 for arsenic removal. The Fe-GAC showed promising results by removing 99.4% of arsenic. In the adsorption isotherm studies, the observed data fitted well with the Langmuir models. In continuous column study showed that As(V) could be removed to below 0.25 mg/L within 1,020 pore volume. Our results suggest that the surface modified granular activated carbon treated with $FeCl_3$ for effective removal of arsenic from wastewater.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.244-250
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• 2007

This study was carried out to obtain the optimum design factors for an eletrolytric flotation reactor. When the effluent of the leachate treatment facility was treated under the condition of 10 volts, 30 minutes, at the Al-Al electrode system; COD removal efficiency was 45%, and total phosphorus removal efficiency was 98%. The high removal efficiency was caused by the fact that phosphate was removed by leaching $Al^{3+}$ from two electrodes. The leachate containing high ammonium nitrogen concentration was treated by a batch test under the condition of 60 minutes reaction time and added chloride ion; ammonium nitrogen removal efficiency was 89%. This high efficiency was affected by added chloride ion to wastewater. To find the optimum current density and voltage of the leachate containing chloride ion (ratio of $Cl^-/NH_4-N$ is 11) a electrochemical polarization curve was used. These values were found to be $4.5mA/cm^2$ and about 2.1 V, respectively. When C-Al electrode system was used at a batch test, the total nitrogen removal efficiency was increased by 1.8 to 3.3 times, compared to Al-Al electrode system due to high $Cl_2$ gas production.

• Environmental Engineering Research
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• v.10 no.3
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• pp.105-111
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• 2005

The applicability of the USEPA's (United States Environmental Protection Agency) three criteria of enhanced coagulation (criterion 1-TOC level less than 2 mg/l. before chlorination; criterion II-% requirement of TOC removal; criterion III-point of diminishing return) for Korean waters was evaluated in this study. This study also investigated an effect of enhanced coagulation on turbidity removal, and attempted to identify the best coagulant for enhanced coagulation. Three different waters were used in this study: one river water and two lake waters. five different coagulants were used: alum, liquid alum, PACl, ferric chloride with and without water. Results of this study showed that all three criteria were achievable for the tested waters. For these waters, controlling criterion was found to be different depending upon raw water characteristics. When initial Toe level was low(< 4 mg/L), criterion I (< 2 mg/L) could be the controlling criterion. As TOC level increased, criterion II (% TOC removal) became the controlling criteria. It was possible to achieve different goals of turbidity and TOC removals. Although the optimum region of TOC removal was more acidic than that of turbidity removal, there was no conflict between these two removals. The best coagulant was found to be different depending upon the evaluation tool: maximum and optimum removal. ferric chloride was more effective than alum in terms of the maximum TOC removal, while Al-based coagulant such as alum or PACl was the best coagulant in terms of the optimum TOC removal.