Effects of the Boundary Layer and Interfacial Reaction on the Time Lag in Supported Liquid Membranes

Yi, Jong Heop 한국화학공학회 1995 NICE Vol.13 No.6

A mathematical model is proposed to describe the effects of boundary layer resistance and interfacial reaction on the time lag in supported liquid membranes for metal ion separation. $quot;the model shows that the presence of boundary layer resistance and interfacial reaction delays the time-lag, compared with the limiting case that rapid equilibrium at the interfaces and negligible boundary layer resistance are assumed. Calculated result describes the expected trend and the model equation allows one to predict the lumped parameters which represent the ratios of the diffusion time in the membrane to the characteristic time for boundary layer transfer and interfacial reactions.

REGENERATION OF DEACTIVATED POROUS CERAMIC MEMBRANES

Jong Heop Yi,L L Tavlarides 한국화학공학회 1995 Korean Journal of Chemical Engineering Vol.12 No.1

Because of the pore structure change and blocking of the ceramic membrane pores, deactivation of ceramic membranes occurred after repeated use. A pore blocking mechanism has been observed from the SEM study that in the first stage of deactivation, the membrane pore sizes became smaller due to the accumulation of the unremoved chemicals, and the pore neck parts were closed and/or blocked. Finally, the pure structures changed to the broken piece of long and thin elliptical shapes. Two regeneration methods were explored and tested in attempts to recover useful activity for the deactivated membranes. Relatively fresh membranes, including intermediately used membranes, can recover fluxes as much as 70 percent of fresh membrane flux by chemical treatments such as acetoneacid treatment, while the severely deactivated membranes were partially regenerated by an oxidation method followed by the acetone and acid treatment.

EFFECTS OF THE BOUNDARY LAYER AND INTERFACIAL REACTION ON THE TIME LAG IN SUPPORTED LIQUID MEMBRANES

Yi, Jong Heop 한국화학공학회 1995 Korean Journal of Chemical Engineering Vol.12 No.3

A mathematical model is proposed to describe the effects of boundary layer resistance and interfacial reaction on the time lag in supported liquid membranes for metal ion separation. The model shows that the presence of boundary layer resistance and interfacial reaction delays the time-lag, compared with the limiting case that rapid equilibrium at the interfaces and negligible boundary layer resistance are assumed. Calculated result describes the expected trend and the model equation allows one to predict the lumped parameters which represent the ratios of the diffusion time in the membrane to the characteristic time for boundary layer transfer and interfacial reactions.

Regeneration of Deactivated Porous Ceramic Membranes

Yi, Jong Heop,Tavlarides, L L 한국화학공학회 1995 NICE Vol.13 No.2

Because of the pore structure change and blocking of the ceramic membrane pores, deactivation of ceramic membranes occurred after repeated use. A pore blocking mechanism has been observed from the SEM study that in the first stage of deactivation, the membrane pore sizes became smaller due to the accumulation of the unremoved chemicals, and the pore neck parts were closed and/or blocked. Finally, the pore structures changed to the broken piece of long and thin elliptical shapes. Two regeneration methods were explored and tested in attempts to recover useful activity for the deactivated membranes. Relatively fresh membrines, including intermediately used membranes, can recover fluxes as much as 70 percent of fresh membrane flux by chemical treatments such as acetone-acid treatment, while the severely deactivated membranes were partially regenerated by an oxidation method followed by the acetone and acid treatment. .

토양내 불포화지대 및 포화지대에서의 DNAPL 과 LNAPL 의 이동현상에 대한 모사

이종협,김주형 한국화학공학회 1998 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.36 No.6

본 연구에서는 비중이 서로 다른 고밀도비수상액체(Denser-than-water Non-Aqueous Phase Liquids ; DNAPLs) 또는 저밀도비수상액체(Lighter-than-water Non-Aqueous Phase Liquids ; LNAPLs)가 지하토양에 노출되었을 때 그 이동현상을 모사하였다. 대상 시스템으로 지하수의 흐름이 부분적으로 존재하는 임의의 불균일층을 가지는 토양구조를 가정하였고 DNAPL로 1,1-dichloroacetone, LNAPL로 n-hexane을 선정하여 지하토양을 따라 이동하는 오염물에 대한 형태학적 변화를 관찰하기 위하여 비정상상태에 대한 모사연구를 수행하였다. 연구결과 DNAPLs와 LNAPLs의 이동현상은 불포화지대 및 포화지대에서 중력, 지하수 유동 및 부력에 의하여 영향을 받음을 보여주었다. 또한, NAPLs의 토양의 특성에 따른 영향과 DNAPL과 LNAPL간의 지하수와의 경계면에서의 거동현상의 차이를 관찰하였다. 불포화지대에서는 중력의 영향으로 DNAPLs가 2배 이상 빠르게 수직으로 이동하였고, 이때 형태학적 관찰을 통하여 DNAPLs는 첫 번째 지층 경계면에서 유동 저항 효과가 더 적음을 확인하였다. 불포화지대에서는 LNAPLs의 경우 지하수면 위에 연속적 막을 형성하며 지하수 흐름을 따라 수평으로 퍼지는 반면, DNAPLs의 경우에는 불연속적 막을 이루며 퍼지다가 지하수면 아래 몇 개의 핵을 형성하며 수직으로 확산되어 가는 양상을 나타내었다. 이때, LNAPLs의 경우 연속막은 수평 방향뿐만 아니라 수직방향으로도 연속성을 가진다는 것이 본 연구를 통해 확인되었다. 현장에서 관찰하기 어려운 비정상상태에 대한 NAPLs 확산의 가시적인 모사결과는 복잡한 DNAPLs와 LNAPLs의 거동현상을 이해하고 오염정도를 예측하며, 오염된 토양의 정화기술을 선정하고 공정설계의 기초 자료를 제공하는데 도움이 될 것이다. This study is to simulate the transport phenomena of LNAPLs and DNAPls spilled in saturated and unsaturated zones. The model system consists of four heterogeneous layers with different permeabilities and goundwater flow at the bottom layer. In the study, LNAPL and DNAPL are assumed to be n-hexane and 1,1-dichloroacetone, respectively. Results show that the transport phenomena and morphology of the NAPLs change with the extent of water saturation, groundwater flow and buoyancy. In the unsaturated zone, the DNAPL migrates vertically two times faster than the LNAPL due to the gravity. Also, the lateral deformation of the DNAPL becomes smaller than that of the LNAPL in the interface between the layers. When the spilled NAPLs reach at the top of the water-table, the LNAPL forms the continuous film on the water table and spreads horizontally with water flow. In contrast, the DNAPL builds up the discontinuous plumes on the water-table and creates the several nuclears under the water table. Also, the profiles of volume fraction of DNAPL and LNAPL in vertical direction are estimated. Results would provide a tool to understand the transport phenomena of NAPLs spilled in the underground and provide a basis for the selection of the remediation technologies of both soils and groundwater polluted with NAPLs.

Cobalt Stearate 혼성막의 제조 및 후처리 과정에 관한 연구

이종협,배은주,차순우 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.3

코발트 이온과 stearic acid를 이용하여 랑뮤어-블라젯 혼성막(CoSt₂막)을 제조한 후, UV 및 골격화(skeletonization)의 후처리 과정을 거쳐 유기물을 제거함으로써 플라즈마 처리 방법 혹은 H₂S처리 방법과 같은 기존의 후처리 과정에 비해 조작이 용이하고 효율적인 후처리 방식을 제안하고자 하였다. 코발트 이온의 농도와 pH를 변화시키면서 상전이가 일어나지 않고 분자들이 고르게 배열하는 최적 조건을 찾아 CoSt₂ 막을 제조하였으며, 제조된 CoSt₂막을 UV 조사 및 골격화 과정을 통해 후처리하였다. UV처리를 위해 정제수를 CoSt₂막에 첨가한 후 UV 램프를 약 12시간 정도 조사하였고, 약하게 교반하고 있는 벤젠에 CoSt₂막을 약 30분 동안 담금으로써 골격화를 수행하였다. 표면 분석 결과, 골격화를 우선 수행하거나 대기중에서 UV램프를 조사한 경우에는 유기물이 코발트 이온과 상대적으로 큰 입자를 형성하고 서로 엉겨 있는 형태로 있어 유기물의 제거가 어려움을 알 수 있었다. 그에 비해 정제수를 CoSt₂막에 첨가하여 UV를 조사한 후 골격화한 경우에는 10 ㎚이하의 미세입자가 고르게 분산되는 것을 확인할 수 있었다. Langmuir-Blodgett hybrid films (CoSt₂) were prepared with cobalt ion and stearic acid. We proposed a new posttreatment process which is easier and more efficient than the commonly used mehtods such as plasma treatment or H₂S gas treatment. LB films were prepared depending on concentrations, pHs of subphase solution and the dipping number. In this study, UV treatment in the presence of H₂O molecules sequencing skeletonization was proposed as a post-treatment technique; LB film is irradiated by UV lamp with water for 12 hours, followed by immersion of LB film into benzene stirred for 30 minutes. Analysis results of morphology for either skeletonization only or UV treatment showed that relatively large size particles (∼50 ㎚) were formed, while UV treatment with water sequencing skeletonization showed that particle size formed on the substrate decreased up to 10 ㎚ and cobalt molecules had regular electron pattern.

Separation Technology, Thermodynamics : Adsorption of Acid Dyes Using Polyelectrolyte Impregnated Mesoporous Silica

( Jong Chul Park ),( Ji Bong Joo ),( Jong Heop Yi ) 한국화학공학회 2005 Korean Journal of Chemical Engineering Vol.22 No.2

노출평가를 위한 전국규모의 환경지리지형정보 시스템 개발

김종호(Jong Ho Kim),김미숙(Mi Sug Kim),곽병규(Byeong Kyu Kwak),유홍석(Hong Suk Yoo),신치범(Chi Bum Shin),이종협(Jong Heop Yi) 大韓環境工學會 2006 대한환경공학회지 Vol.28 No.10

배출량산정모델과 다중매질모델링을 이용한 환경오염물질의 노출평가 및 위해도 평가

김종호 ( Jong Ho Kim ),곽병규 ( Byoung Kyu Kwak ),신치범 ( Chee Burm Shin ),전원진 ( Won Jin Jeon ),이종협 ( Jong Heop Yi ) 한국화학공학회 2009 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.47 No.2

Preparation of Modified Silica for Heavy Metal Removal

Kim, Jong Sung,Chah, Soon Woo,Yi, Jong Heop 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.1

2-hydroxy-5-nonyl-acetophenoneoxime, di-2,4,4-trimethylpentyl phosphinie acid, and a tertiary amine were bound on the silica surface after surface modification. The adsorption of the metal chelating agents appears to be due to physical attraction such as van der Waals interactions and not covalent bonding. Stability tests show that the adsorbents are stable under acidic conditions. Batch tests were conducted for heavy metal ion adsorption and elution. Heavy metal ions which were adsorbed to the surface of the adsorbents could be recovered by elution with 0.1 M HCl.