• Title/Summary/Keyword: Stripping efficiency

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Electrochemical Determination of As(III) at Nanoporous Gold Electrodes with Controlled Surface Area

  • Seo, Min Ji;Kastro, Kanido Camerun;Kim, Jongwon
    • Journal of the Korean Chemical Society
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    • v.63 no.1
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    • pp.45-50
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    • 2019
  • Because arsenic (As) is a chemical substance toxic to humans, there have been extensive investigations on the development of As detection methods. In this study, the electrochemical determination of As on nanoporous gold (NPG) electrodes was investigated using anodic stripping voltammetry. The electrochemical surface area of the NPG electrodes was controlled by changing the reaction times during the anodization of Au for NPG preparation, and its effect on the electrochemical behavior during As detection was examined. The detection efficiency of the NPG electrodes improved as the roughness factor of the NPG electrodes increased up to around 100. A further increase in the surface area of the NPG electrodes resulted in a decrease of the detection efficiency due to high background current levels. The most efficient As detection efficiency was obtained on the NPG electrodes prepared with an anodization time of 50 s. The effects of the detection parameters and of the Cu interference in As detection were investigated and the NPG electrode was compared to flat Au electrodes.

Study on Tourism Carbon Emissions and Distribution Efficiency of Tourism Economics

  • Cheng, Xiaoyu;Jiang, Keshen
    • Asian Journal of Business Environment
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    • v.8 no.2
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    • pp.15-22
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    • 2018
  • Purpose - It is important to figure out the relationship between tourism carbon emissions and tourism economics for a healthy tourism development. Research design, data, and methodology - Data of this study are collected from 27 provinces (cities) of China. Tourist consumption stripping coefficient is used to calculate tourism carbon emissions. SBM-Undesirable model is used to measure the efficiency of tourism economics under the constraint of tourism carbon emissions. Results - The results show that: during the year of 2005-2015, there are obvious differences in totals and intensities of tourism carbon emissions among 27 provinces and cities which can be divided into three areas. There is a high possibility of underestimating the actual efficiency of tourism economics by leaving tourism carbon emissions out of account, and a high inefficiency caused by tourism carbon emissions will lead a low efficiency of tourism economics. Conclusions - The development of tourism should give consideration to both economic and environmental benefits, and reduce the inefficiency caused by tourism carbon emissions to improve efficiency of tourism economics by improving the level of technical efficiency and promoting technological progress.

The Optimization of Solvent Extraction Process of Iron Chloride Etching Waste Solution (염화철 에칭폐액의 용매추출공정 최적화에 관한 연구)

  • Park, Il-Jeong;Kim, Dae-Weon;Kim, Geon-Hong;Chae, Hong-jun;Lee, Sang-Woo;Jung, Hang-Chul
    • Clean Technology
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    • v.23 no.3
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    • pp.279-285
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    • 2017
  • In this study, a new organophosphorus acid-based solvent (KMC-P) from KMC Co., Ltd. was used for the recovery of the iron chloride etching waste solution. In order to increase the extraction efficiency for the new solvent in the solvent extraction process, we selected the process variables and conducted the optimization experiment according to the DOE to investigate the correlation between the variables. Solvent concentration, pH, and O/A ratio were found to be factors affecting extraction and stripping efficiency. The optimum stripping efficiency was 69.7% when the solvent concentration was 29.4 wt%, the HCl addition amount was 0 mL, and the O/A ratio was 7, and the reliability was more than 86%.

A Separation of manganese (II) and cobalt (II) ions by D2EHPA/TBP-immobilized PolyHIPE membrane

  • Chen, Jyh-Herng;Mai, Le Thi Tuyet
    • Membrane and Water Treatment
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    • v.10 no.2
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    • pp.127-137
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    • 2019
  • The D2EHPA/TBP co-extractants immobilized PolyHIPE membrane can be used for the selective separation of Mn (II) from Co (II). By solvent-nonsolvent method, D2EHPA/TBP co-extractants can be effectively immobilized into PolyHIPE membrane. The pore structure of PolyHIPE membrane and the presence of TBP enhance the stability of immobilized co-extractants. The optimal operating conditions for the separation of Mn (II) and Co (II) are feeding phase at pH 5.5, sulfuric acid concentration in the stripping phase of about 50 g/L and stirring speed at 400 rpm. The D2EHPA/TBP co-extractants ratio of 5:1 shows synergetic effect on Mn/Co separation factor about 22.74. The removal rate and recovery rate of Mn (II) is about 98.4 and 97.1%, respectively, while for Co (II) the transport efficiency is insignificant. The kinetic study of Mn (II) transport shows that high initial flux, $J_f^o=80.1({\mu}mol/m^2s)$, and maxima stripping flux, $J_s^{max}=20.8({\mu}mol/m^2s)$, can be achieved with D2EHPA/TBP co-extractants immobilized PolyHIPE membrane. The stability and reusability study shows that the membrane can maintain a long term performance with high efficiency. High purity of Co (II) and Mn (II) can be recovered from the feeding phase and stripping phase, respectively.

Performance Evaluation of the MAC Protocols for WDM Metro Ring with Wavelength-Shared Nodes Connecting Broadband Access Networks (대역 액세스 망을 연결하는 파장 공유 노드 기반 WDM 메트로 링의 MAC 프로토콜 성능 평가)

  • So Won-Ho
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.1 s.343
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    • pp.111-120
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    • 2006
  • In this paper, a node architecture of WDM metro network for connecting broadband access networks to converge wire/wireless networks. In consideration of the proposed node architecture and network requirements we proposed and evaluated medium access control protocols. We review WDM related technologies of sub-carrier multiplexing and optical components in order to resolve the bottleneck between optical backbone networks md access networks, and a access node architecture sharing common wavelength is introduced. Source-stripping (SS) MAC protocol Is evaluated under the proposed functional node architecture. DS+IS (Destination-Stripping and Source-Stripping) and DS+IS (Destination-Stripping and Intermediate-Stripping) MAC protocols are described to increase the slot-reuse factor which is low on SS MAC protocol. The key function of new MAC protocols regards the optical switch module of proposed node architecture and helps intermediate or source access nodes for dropping slots to destinations of different wavelength group. Thus, slot-reuse factor increases as the MAC protocols reduce the unnecessary ring-rotation of transferred slots. We use a numerical analysis to expect bandwidth efficiency and maximum throughput by slot-reuse factor Throughput network simulation, the verification of throughput, queuing delay, and transmission fairness are compared among MAC protocols.

Methane Recovery and Carbon Dioxide Stripping by MEA Solution the Autocirculation Bubble Lift Column Reactor (내부순환식 기포탑 반응기 상에서 MEA (monoethanolamine) 용액에 의한 이산화탄소 분리 및 메탄회수)

  • Lee, In-Hwa;Kim, Sun-Yil;Park, Ju-Young
    • Applied Chemistry for Engineering
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    • v.18 no.3
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    • pp.239-244
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    • 2007
  • For the simultaneous methane recovery and $CO_2$-stripping, we have been developed dual vent auto circulation bubble lift column reactor, and evaluate optimum conditions for monoethanolamine (MEA) solutions as a $CO_2$ absorbent. At the 5 wt% MEA solution, we investigated the pH change during $CO_2$-stripping and absorption reaction, $CO_2$-stripping rate with reaction time, methane recovery efficiency for various inflow rates of air, $CO_2$-stripping rate for flow liquid over flow height, and $CO_2$-stripping dependency on the temperature of absolvent solutions. The suggested optimum conditions for $CO_2$ recovery with MEA in the dual vent auto circulation bubble lift column reactor were 40 mm over flow liquid height, 1.5 L/min of air inflow rate, and $25^{\circ}C$ of absorbent solution temperature.

Formation of Furans during the Acid Hydrolysis of Agar and Their Removal by Treatments of Lime, Steam-stripping and Hydrophobic Resins (한천의 산 당화에 의한 Furan화합물의 생성 및 제거)

  • Kim, Na-Hyun;Lee, Jae-Won;Seo, Yung-Bum;Yoon, Min-Ho
    • Korean Journal of Agricultural Science
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    • v.36 no.2
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    • pp.225-232
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    • 2009
  • The ratio of saccharification and formation of furans during the acid hydrolysis of agar with oxalic acid and sulfuric acid were examined base on the contents of the agar and acids. The ratio of saccharification in oxalic acid appeared to be 51~59% somewhat higher than 49~61% of sulfuric acid. Formation of the furans during the acid hydrolysis increased proportional to the contents of agar and acid. The relative formation ratio was high 10~47% for furfural (FUR) and 15~29% for hydroxy-methyl furfural (HMF) in 0.5~1.25% sulfuric acid rather than those of oxalic acid. When comparing the removal efficiency of the furans using an alkali treatment, steam stripping and hydrophobic resins, FUR was eliminated 60% by the alkali treatment, 62~90% by steam stripping and 71~75% by Amberlite XAD4 and 7HP, while HMF was removed to low levels of 10.5%, 4~17% and 13~25%, respectively. The loss of reducing sugar was also observed in process of the removal of furans, and the loss rate was the level of 2~4% in alkali treatment, 11~16% in steam stripping and 7~9% in Amberlite resins.

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Effect of Operating Condition of Stripping Process on Ammonia Removal for Pre-treatment of Swine Wastewater (축산폐수 전처리를 위한 암모니아 탈기공정의 운전조건이 암모니아 제거에 미치는 영향)

  • Whang, Gye-Dae;Cho, Young-Moo
    • Journal of Korean Society on Water Environment
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    • v.20 no.1
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    • pp.86-92
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    • 2004
  • Lab-scale experiments have been carried out to investigate ammonia stripping with a modified spray tower for removing ammonia nitrogen from swine wastewater. The operating conditions such as initial pH, temperature, air flow, hole size of distributor determining the diameter of water drops, and influent solids concentration were closely examined focusing on removal efficiency of ammonia. As a result of the experiment, in order to achieve high rate of ammonia removal by the air stripping system, the air flow rate must be supplied at high rate with sufficiently high initial pH, temperature. The optimum operating condition to meet the residual ammonia concentration of 300 mg/L was the initial pH of 11.0 at $35^{\circ}C$ with the air flow rate of 20 L/min. It also showed that the smaller hole size is, the higher removal rate of ammonia is expected. However, when used a small sized distributor (2 mm), the flooding problem at the upper column occurred due to clogging of the hole. With regard to the influent solids concentration, it was showed that the lower concentration of solids, the higher removal rate of ammonia. The removal of particulate materials in influent led to improve the removal efficiency of ammonia, rather than to control the operating condition including initial pH, temperature, and air flow. The empirical correlation between KLa and operating parameters would be driven as, $K_{La}=(0.0003T-0.0047){\cdot}G^{0.3926}{\cdot}L^{-0.5169}{\cdot}C^{-0. 1849}$. The calculated $K_{La}$ from proposed formula can be used effectively to estimate the optimum reaction time and to calculate the volume of modified spray tower system.

Efficient Stripping of High-dose Ion-implanted Photoresist in Supercritical Carbon Dioxide (초임계 이산화탄소를 이용한 고농도이온주입 포토레지스트의 효율적인 제거)

  • Kim, Do-Hoon;Lim, Eu-Sang;Lim, Kwon-Taek
    • Clean Technology
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    • v.17 no.4
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    • pp.300-305
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    • 2011
  • A mixture of supercritical carbon dioxide and a co-solvent was employed to strip a high-dose ion-implanted photoresist (HDIPR) from the surface of semiconductor wafers. The stripping efficiency was highly improved by the physical force generated from a ultrasonication tip inside the reactor. In addition, helium gas was injected in the reactor as a barrier gas before the introduction of pure supercritical $CO_2$ ($scCO_2$), which reduced the rinsing time significantly. The effect of co-solvents on the stripping efficiency was investigated. The wafer surfaces were analyzed by scanning electron microscopy and by an energy dispersive X-ray spectrometer.

A Study of Biological Hydrolysis Efficiency for Methane Digestion with Municipal Solid Waste (메탄발효를 위한 도시쓰레기 초고온 가용화 방법의 효율성 검토)

  • Cheon, Ji-Hoon;Hiroshi, Tsuno
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.5
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    • pp.561-572
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    • 2010
  • The efficiency of biological hydrolysis at $80^{\circ}C$ on municipal solid waste mixed with anaerobic digestion sludge was investigated in 100L batch reactors. The hydrolysis effect was observed within a day, when the hydrolysis reactor used for a pre-treatment reactor for methanogenesis, and the effect was observed during two days, When the reactor used for post-treatment reactor. For both configurations, methane production rate decreased, when hydrolysis was carried out more than a day. Gaseous ammonia in the hydrolysis reactors was successtully removed by the ammonia stripping system. Microbial diversity analysis on the hydrolysis reactors indicated dependency of microbial diversity on the configuration of the hydrolysis reactors. Carbohydrate and lactate degrading microbes dominated in the hydrolysis reactor, when the hydrolysis reactor used for a pre-treatment reactor for methanogenesis, while protein degrading microbes dominated in the post-treatment reactor.