Headspace Solid-Phase Microextraction for Determination of Micellar Solubilization of methyl tert-butyl ether (MTBE)

Baek, Kitae,Lee, Hyun-Ho,Cho, Hyun-Jeong,Yang, Ji-Won 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.4

Headspace analysis using solid-phase microextraction (SPME) was tested as a rapid method to evaluate micellar solubilization of methyl tert-butyl ether (MTBE) with sodium dodecyl sulfate (SDS) and cetylpyridinium chloride (CPC). At equilibrium between aqueous phase and vapor phase, free MTBE in vapor phase (i.e., not solubilized MTBE by SDS or CPC) was analyzed by GC-FID (Hewlett Packard 5890 series II) equipped with a capillary HP1 column (30 m×0.25 mm). This method showed a good analytical performance such as linearity of calibration curve and precision (RSD less than 5%). Extent of MTBE solubilization was expressed as a function of molar ratio of SDS to MTBE and CPC to MTBE, and was saturated at about 57% and 37% with over the value of ratio 13 for SDS and CPC, respectively. This technique can be applied to analyze micellar solubilization potential of various surfactants on volatile and semi-volatile compounds.

Humic‐Substance‐Enhanced Ultrafiltration for Removal of Heavy Metals

Baek, Kitae,Yang, Ji‐,Won Taylor Francis 2005 Separation science and technology Vol.40 No.1

<P>The feasibility of a separation technique using ultrafiltration in connection with humic substances—humic-substance-enhanced ultrafiltration (HSEUF)—was investigated for the removal of the toxic heavy metals copper and cadmium. HSEUF is based on the high molecular weight of humic substances, as well as the binding of multivalent metals such as copper and cadmium to these materials. As the humic acid concentration increased, the removal of copper and cadmium was enhanced because of the increase in binding sites. As the pH of the solution increased, the removal of copper and cadmium was further improved because the solubility of the humic substances increased. In the simultaneous removal of copper and cadmium, the binding of cadmium to humic substances was inhibited significantly by the presence of copper at the low concentration of humic acid. However, copper binding was not affected by the presence of cadmium, because the affinity of copper to humic substances was greater than that of cadmium.</P>

Abstract : Electrokinetic remediation of metalcontaminated paddy rice field

( Kitae Baek ) 한국환경농학회 2012 한국환경농학회 워크샵자료 Vol.2012 No.2

We evaluated the influence of electrode configuration on in situ electrokinetic remediation of As-, Cu-, and Pb-contaminated soil in a pilot-scale field application. Dense electrode configurations resulted in high current under a constant voltage gradient, the high current raised soil temperature, and it caused unnecessary electrical energy consumption. Additionally, temperature increase in soil transported pore water from bottom to top layer, which accumulated contaminants in the top soil layer because the mobilized contaminants was co-transported by the water flow. On the other hand, the groundwater flow, gravitational force, and electro-osmotic flow were combined together and affected complexly the transport of mobilized contaminants. Sequential extraction showed that electrokinetic treatment increased the residual fraction of As, the fraction of Cu bound to organic matter, and the fraction of Pb bound to organic matter and residual portion. This result implies that the groundwater flow and soil temperature should be monitored during the remediation and the configuration should be considered to minimized unnecessary transport of contaminants. Additionally, the effectiveness of ex situ electrokinetic remediation (EKR) in treating actual As-contaminated soil was evaluated at a pilot scale (1 m [W] × 1 m [L] × 1.5 m [H]). Ethylenediamine tetraacetic acid (EDTA) and sodium hydroxide as the catholyte and anolyte, respectively, were circulated to enhance the desorption of As. Two types of soil were collected from a real contaminated agricultural area: silty loam from a rice paddy and sandy clay loam from dry land. An average of 78% of the As was removed from the two types of soil after 8 weeks, and the residual As concentration met the level set by Korean legal regulations. The average removal rates were 1.06 and 1.55 mg/kg/day, respectively, for the paddy and dry field soil samples. In addition, fractionation analysis showed that most other fractions and even a large portion of the residual fraction were removed after EKR. The ex situ application provided electrolyte more uniformly to the entire soil sample; therefore, there was no significant variation in As removal depending on the depth of the soil. These results indicated that ex situ EKR is an effective technique for the remediation of As-contaminated sites. EKR could be an excellent technology to remove metals from rice field with fine grained soil such as silt and clays, and it is possible to apply this technique to real field as in-situ and/or ex-situ. Acknowledgement This work was supported by KEITI through GAIA project.

Solubilization Isotherms of Chlorinated Aromatic Hydrocarbons in Ionic Surfactant Solutions

( Kitae Baek ),( Hyuo Jae Shin ) 조선대학교 공학기술연구원 2011 공학기술논문지 Vol.4 No.1

The solubilization characteristic of 1-chlorobenzene and 1,2-dichlorobenzene in ionic surfactant were investigated. The solubilization extent of 1,2-dichlorobezne was greater than that of 1-chlorobenzene because 1,2-dichlorobenzene was more hydrophobic than 1-chlorobenzene. Solubilization capacity of surfactant increased with the hydrophobic core volume of surfactant micelles. Solubilization of 1-chlorobenzene decreased slightly by the presence of I 2-dichlorobenzene however, that of 1,2-dichlorobenzne by the presence of 1­chlorobenzene was negligible. The decrease resulted in solubilization of 1-chlorobenzene is related to hydrophobic interior of micelles, because the major driving force of solubilization is hydrophobic interactions in the hydrophobic interior of the micelles.

윤활유 유래 철도오염 토양의 정화 타당성 연구

백기태(Kitae Baek),신민철(Min-Chul Shin),박성우(Sung-Woo Park),류병곤(Byung-Gon Ryu),이재영(Jae-Young Lee) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-

Railway-contaminated soil is categorized by total petroleum hydrocarbon(TPH)-related contamination and heavy-metal contamination. The sources of TPH are diesel and lubricant. In this study, the feasibility of soil washing, chemical oxidation and ultra-sonication were investigated to treat lubricant-contaminated railway soil. tergitol, a non-ionic surfactant, was investigated as a washing agent. However, it is not effective to remove lubricant from soil even though tergitol is most effective washing agent for diesel-contaminated soil. Addition of alcohols with surfactant enhanced slightly washing efficiency of the lubricant-contaminated soil. To remediate railway-contaminated soil, source of pollution should be considered.

중금속 오염 철도 토양의 세척에 의한 정화 타당성 연구

백기태(Kitae Baek),신민철(Min-Chul Shin),현충호(Chung-Ho Hyun),이재영(Jae-Young Lee),강해숙(Hae-Sook Kang) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-

The feasibility of soil washing was investigated in the laboratory to treat heavy metals-contaminated railway soil. Various organic acids including ethylene diamine tetraacetic acid (EDTA) and citric acid as well as inorganic acids such as hydrochloric acid (HCl) and phosphoric acid were tested to evaluate washing efficiency. Generally, inorganic acid showed higher removal efficiency compared to organic acids. Specially, EDTA, which are well known as most effective washing agent to remove heavy metals from soil, was not efficient to remove heavy metals in this study. Among washing agents tested in this study, HCl was most effective. The removal of Cd, Cu, and Pb was high, however, that for Zn and Ni was less than 30% with 0.5 M HCl. This difference comes from analytical methods (Korean Standard Test Method for Soil). Aqua regia was used to extract Zn and Ni, however 0.1 N HCl was used for other metals. As a result, simple washing technology is not effective, to treat railway contaminated soil with heavy metals.

How to Protect ADS-B: Confidentiality Framework and Efficient Realization Based on Staged Identity-Based Encryption

Baek, Joonsang,Hableel, Eman,Byon, Young-Ji,Wong, Duncan S.,Jang, Kitae,Yeo, Hwasoo IEEE 2017 IEEE transactions on intelligent transportation sy Vol.18 No.3

<P>Automatic Dependent Surveillance-Broadcast (ADS-B) is one of the key technologies for future 'e-Enabled' air crafts. ADS-B uses avionics in the e-Enabled aircrafts to broadcast essential flight data such as call sign, altitude, heading, and other extra positioning information. On the one hand, ADS-B brings significant benefits to the aviation industry, but, on the other hand, it could pose security concerns as channels between ground controllers and aircrafts for the ADS-B communication are not secured, and ADS-B messages could be captured by random individuals who own ADS-B receivers. In certain situations, ADS-B messages contain sensitive information, particularly when communications occur among mission-critical civil airplanes. These messages need to be protected from any interruption and eavesdropping. The challenge here is to construct an encryption scheme that is fast enough for very frequent encryption and that is flexible enough for effective key management. In this paper, we propose a Staged Identity-Based Encryption (SIBE) scheme, which modifies Boneh and Franklin's original IBE scheme to address those challenges, that is, to construct an efficient and functional encryption scheme for ADS-B system. Based on the proposed SIBE scheme, we provide a confidentiality framework for future e-Enabled aircraft with ADS-B capability.</P>

DME 예혼합 압축착화 엔진에서 수소의 영향

백철우(Cheulwoo Baek),염기태(Kitae Yeom),장진영(Jinyoung Jang),배충식(Choongsik Bae) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1

Homogeneous charge compression ignition combustion (HCCI) is an advanced combustion technology that makes higher thermal efficiency and lower NO" emissions than that of conventional combustion system. Dimethyl ether (DME) which has been researched for the most attractive alternative fuel of diesel is more suitable for HCCI combustion because of the higher evaporation property. In this study. The single cylinder DME engine operated with a direct injection spark ignition (DISI) injection system has been made to investigate combustion processes and emissions of DME HCCI and to find the effects of premixed hydrogen in internal combustion. The experiment was carried by varying the engine speed and fraction rates of hydrogen. The dual fuel is mixed at the early time with changing the proportion. As a result, the increase of fraction rates of hydrogen had the effect to retard the DME ignition timing and to eliminate the knocking effect during high load condition. IMEP was increased until 30% fraction rates of hydrogen. There was almost misfiring that the fraction rates of hydrogen is more than 40%. NOx emission was reduced by increasing the fraction rates of hydrogen, but HC emission was increased.

Adsorption characteristics of alginate bead for the various heavy metals

Hojeong Kim,Kitae Baek,Jae-Young Lee,Jiyeon Park,Ji-Won Yang 한국생물공학회 2005 한국생물공학회 학술대회 Vol.2005 No.4

DME 예혼합 압축착화 엔진에서 수소의 영향

백철우(Cheulwoo Baek),윤현숙(Hyeonsook Yoon),염기태(Kitae Yeom),장진영(Jinyoung Jang),배충식(Choongsik Bae) 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.2