• Title/Summary/Keyword: KOH treatment

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Influence of pH on Mn Concentration of Effluent from Sludge Thickener of Water Treatment Plant (정수장 슬러지 농축조 배출수의 망간 농도에 미치는 pH의 영향)

  • Kim, Younjung;Lee, Seungeun;Baek, Seungcheol;Kim, Taeheui
    • Journal of the Korean GEO-environmental Society
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    • v.16 no.5
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    • pp.27-33
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    • 2015

  • Manganese in sludge precipitated during water treatment might be soluble again in effluent from sludge thickener. If that happens, the manganese concentration of effluent from water treatment plant will exceed the limit for clean reservation. In this study the influence of pH on Mn concentration of effluent from sludge thickener of water treatment plant was investigated. When the pHs of sludge solutions increased with alkaline materials such as NaOH, KOH, CaO, $Ca(OH)_2$, $CaCO_3$, the Mn concentrations of sludge solutions decreased under the limit. The Mn concentration of effluent from sludge thickener could be controlled with waste limestones from beneficiation process at limestone mine as an alkaline material.

  • https://doi.org/10.14481/jkges.2015.16.5.27 인용 PDF KSCI

A Study on Development of Activated Carbons from Waste Timbers (폐벌목(廢伐木)을 이용(利用)한 활성탄(活性炭) 개발(開發)에 관(關)한 연구(硏究))

  • Kim, Jong-Moon;Chung, Chan-Kyo;Min, Byong-Hoon
    • Resources Recycling
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    • v.17 no.6
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    • pp.68-78
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    • 2008

  • Using a Pinus koraiensis and Pinus rigida which are normally being discarded in South Korea, optimal conditions of producing activated carbons have been studied to recycle as a higher value-added product. This study consists of two processes, the production process of charcoals from waste timbers by low temperature pyrolysis and the production process of activated carbons from the charcoals by chemical activation reaction. This paper deals with the production process of activated carbons from the charcoals by chemical activation reaction. As an alkali has been generally used as an activating agent, KOH and NaOH which react well with a carbon were used in this study. As a result of the experiments, it is confirmed that activated carbons made with KOH treatment had superior values in physicochemical properties to NaOH, showing that there was no remain of KOH at the surface of the charcoals while there was $3{\sim}4%$ of NaOH remaining after the experiments. Thus, it is concluded that KOH reacted more actively with a charcoal than NaOH. Moreover, it was also found that values in physicochemical properties when using a Pinus koraiensis are superior to the ones when using a Pinus rigida. The optimal mixing ratio of an activating agent to a charcoal was 400 wt.%. To improve the physicochemical properties, activated carbons were washed out by distilled water after neutralization with SM hydrochloric acid solution. When activated carbons were produced from a Pinus koraiensis in this optimal conditions, value of BET surface area was found to be approx. $2400\;m^2/g$.

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Structures and Double Layer Performances of Carbons Pyrolized from Carbon Oxides (산화탄소로부터 열분해한 탄소의 구조 및 전기이중층 거동)

  • Kim, Ick-Jun;Yang, Sunhye;Jeon, Min-Je;Moon, Seong-In;Kim, Hyun-Soo;An, Kye-Hyeok
    • Applied Chemistry for Engineering
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    • v.18 no.5
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    • pp.522-526
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    • 2007

  • Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.

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