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Regeneration of Deactivated Porous Ceramic Membranes
Jong Heop Yi,L . L . Tavlarides 한국화학공학회 1995 화학공업과 기술 Vol.13 No.2
N/A 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. .
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. .
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.
Effects of the Boundary Layer and Interfacial Reaction on the Time Lag in Supported Liquid Membranes
Jong Heop Yi 한국화학공학회 1995 화학공업과 기술 Vol.13 No.6
N/A 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.
Modeling Human Exposure Levels to Airborne Volatile Organic Compounds by the Hebei Spirit Oil Spill
Kim, Jong-Ho,Kwak, Byoung-Kyu,Ha, Min-A,Cheong, Hae-Kwan,Yi, Jong-Heop The Korean Society of Environmental Toxicology 2012 환경독성보건학회지 Vol.27 No.-
Objectives: The goal was to model and quantify the atmospheric concentrations of volatile organic compounds (VOCs) as the result of the Hebei Spirit oil spill, and to predict whether the exposure levels were abnormally high or not. Methods: We developed a model for calculating the airborne concentration of VOCs that are produced in an oil spill accident. The model was applied to a practical situation, namely the Hebei Spirit oil spill. The accuracy of the model was verified by comparing the results with previous observation data. The concentrations were compared with the currently used air quality standards. Results: Evaporation was found to be 10- to 1,000-fold higher than the emissions produced from a surrounding industrial complex. The modeled concentrations for benzene failed to meet current labor environmental standards, and the concentration of benzene, toluene, orthometa- para-xylene were higher than the values specified by air quality standards and guideline values on the ocean. The concentrations of total VOCs were much higher than indoor environmental criteria for the entire Taean area for a few days. Conclusions: The extent of airborne exposure was clearly not the same as that for normal conditions.