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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Chemical Engineering Research
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Journal DOI :
The Korean Institute of Chemical Engineers
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Volume & Issues
Volume 37, Issue 6 - 00 1999
Volume 37, Issue 5 - 00 1999
Volume 37, Issue 4 - 00 1999
Volume 37, Issue 3 - 00 1999
Volume 37, Issue 2 - 00 1999
Volume 37, Issue 1 - 00 1999
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Selective Catalytic Reduction of NO by NH₃ over Chromia Catalysts Supported on Al₂O₃-TiO₂
Chae, Ho-Jeong ; So, Byeong-Hwan ; Choe, Jae-Ho ; Lee, Jae-Seong ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 623~623
the NO removal activity and sulfur tolerance of chromia catalyst supported on Al2O3-TiO2 with respect to the contents of TiO2 were examined in a fixed bed flow reactor for the selective reduction of NO by NH3. By XPS analysis, it was observed that the content of Cr6+ on the catalyst surface, a known active reaction site for the catalyst surface examined by NH3 TPD may play an important role for this reaction system. The chromia catalyst on the mixed supports developed in the present study showed a slight improvement for its sulfur tolerance by SO2 compared to the catalyst supported on Al2O3 alone.
Synthesis of MMA-FA Polymeric Membrane and its Gas Permeation Properties
Kim, Min-Su ; Lee, Yong-Taek ; Lee, Dong-Jin ; Choe, Yeong-Guk ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 628~628
The gas permeation was experimentally carried out for the various gases with menbranes made out of methyl methacrylate(MMA) and fluoro acrylate(FA) copolymer. Particularly the effect of fluoro functional group on the gas permeability of the membrane was investigated with various FA contents. It turned out that the surface free energy of the membrane was significantly decreased as the FA content increased, resulting in very unique properties with respect to the permeability and the selectivity of gas. P(MMA-FA) membranes showed that its permeability was 2 to 20 times higher than that of the PMMA membrane for the typical gases of H2, CO2, O2, N2 and CH4 while its selectivity was kept to be almost comparable to those of the PMMA membrane. The optimum content of FA was found to be in the range of 1 to 5 wt%.
Improvement of Thermal Stability of Pd Catalyst upon Incorporation of TiO₂
Jo, Seong-Jun ; Gang, Seong-Gyu ; Park, Il-Nam ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 634~634
Improvement of thermal stability of the surpported Pd catalyst has been achieved with the incorporation of TiO2 onto the catalyst. The catalyst was characterizes with X-ray diffraction, thermo-gravimetric analysis, temperature programmed desorption and X ray absorption fine structure. The activity of methane combustion of the presence of TiO2. The interaction between the Pd catalyst and TiO2 at 1,473K suppressed the transformation of PdO into Pd, thereby improving the thermal stability of palladium catalyst.
Phthalocyanine Organic Semiconductor for NO₂ Gas Sensor
Jeong, Seok-Bong ; Jeon, Hui-Gwon ; Lee, Deok-Dong ; Choe, Dong-Han ; Ji, Jong-Gi ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 639~639
NO2 gas sensors using various metal phthalocyanines were prepared by vacuum sublimation method at 390oC to test the electrical properties of the sensors in the presence of NO2 gas. Among the sensors prepared in the present study, a lead phthalocyanine(PbPc) thin film showed the best performance and its sensitivity was over 80% at 5 ppm of NO2 gas. The structure of PbPc thin film was a mixture of tri and mono-clinic crystal phases. Optimal operating conditions including response time, cyclic treatment of NO2 gas, and selectivity of various reduction and oxidation gases were developed and examined.
Synthesis of HCFC-123 by Isomerization and Hydrogenation of CFC-113
Ha, Baek-Hyeon ; Baek, Seong-Yeop ; Park, Tae-Jin ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 646~646
CFC-113(CF2Cl-CfCl2) was isomerized to CFC-113a(CF3-CCl3) over aluminum chloride catalyst with the addition of manganese and chromium metal powder. Then the product CFC-113a was hydrodehalogenated to HCFC-123(CF3-CCl2H) over Pt or Pd catalysts supported on activated carbon. The life of aluminum chloride catalyst was extended by the addition of manganese and chromium, and a synergic effect was observed when the two were added simultaneously. The conversion of CFC-113a over Pt/carbon catalyst was higher than that over Pd/carbon and reached up to 95%. The activity of the catalyst was found to be dependent on the property of the active carbon support. The conversion and the yield of CFC-123 increased as the reaction temperatues was elevated and reached the maximum at 120oC, However, the yield of HCFC-123 starts decreasing rapidly at the temperature higher than 120oC due to the formation of HCFC-133a(CF3-CClH2).
A Study on the Kinetics of Thermal Degradation of Poly(vinyl chloride) using Dynamic Model
O, Se-Cheon ; Lee, Hae-Pyeong ; Kim, Hui-Taek ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 652~652
The kinetic analysis of the thermal degradation of poly(vinyl chloride)(PVC) has been studied by a conventional thermogravitric technique using dynamic model method. The thermal degradation was found to be a complex process composed of at least two steps for which kinetic values can be calculated. The kinetic analysis of PVC gave apparent activation energy of 159.7 kJ/mol for the first step with a value of 189.6 kJ/mol for the second step. To verify the effectiveness of the kinetic analysis method proposed in this work, the results based on dynamic model method were compared to those of analytical methods reported in the literature.
Specific Surface Area Measurement by Air Adsorption Method
Lee, Gwang-Bok ; Lee, Yeong-U ; Yu, Min-Ung ; Jo, Seong-Jun ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 659~659
Specific surface area has been obtained by using air adsorption method which is simpler than other conventional method. Physical constants are obtained from standard materials having known specific surface area, and specific surface areas of unknown samples are calculated by using the physical constants. It has been observed that the larger surface area difference between standard and unknown samples resulted in the lower measurements accuracy. Since the measurements accuracy decreased linearly with the specific surface area difference between unknown and standard samples, a correction curve could be obtained. Reliability of specific surface area investigated in this study stringly depended on the physical constants. If the surface structure of unknown material is different from that of standard material, new physical constant should be recalculated. The air adsorption method was, however, effective for the material that has same or similar surface structure as that of standard material.
Data Reconciliation and Gross Error Detection Using Chemical Process Models
Eo, Su-Yeong ; Jang, Tae-Seok ; Sin, Dong-Il ; Jang, Gwang-Sik ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 663~663
In this paper an intergrated system for data reconcilation and gross error detection of the measurements in chemical processes is suggested. With unit process models and physical property routines, the proposed system itself works as an independent system. The proposed algorithm of data reconcilation is appropriate for the chemical processes that are consisted of the set of nonlinear equations. Since this method takes advantage of the repeated calculations of the constraint equations acquired by linear approximation, it improves the overall efficiency of the calculation. Also, the Point of the constraint equations better than the Measurements Test in co-linearity, for gross error detection is also suggested. The performance of the proposal system has been tested through a case study.
Preliminary Design and Cost Estimation of New MeOH Synthesis Process using Water Shift Reaction
Kim, Jin-Gyeong ; Mun, Il ; Ju, O-Sim ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 670~670
Removing CO2, which is the major cause of the global warming, and recycling it to the energy source are very important socially and environmentally. For those, we developed a new process that synthesizes methanol by reacting CO2 and H2. First, this process converts CO2 to CO and H2O by the water-gas shift reaction. Then, it produces methanol by the methanol-synthesizing reaction. The main purpose of this study is to develop a new process of reducing CO2 coming from various plants and of producing methanol. This study focuses on designing and cost estimating of the two-step process, using the experimental data of reaction condition and catalyst. The experiments and simulation are done simultaneously to minimize the number of experiments. This study also adopts design hierarchy(Douglas) to find the best flowsheet systematically. By choosing the best one among numerous alternative processes and operating condition, an optimal flowsheet is designed. This new process is also proved to be economically sound compared with conventional methanol systhesis processes.
Safety Analysis of Boiler Process Operating Procedures using SMV
Lee, Seung-Hun ; Kim, Jin-Gyeong ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 679~679
This study developed an algirithm for analyzing the safety of the boiler system including equipments and operating procedures using SMV (Symbolic Model Verifier). The strength of this algorithm is to verify the interactions of various variables simultaneously, while conventional simulation technique verifies only a few variable at one time. A boiler model is developed using SMV, and it can specify failures of fans, detectors and pumps. This method tests numerous dangerous conditions occured by multiple variables and identifies potential in the boiler system.
Pervaporation Characteristics of Removal of Trace Phenol in Aqueous Phenol Solution Using Tubular Type PDMS/Ceramic Composite Membrane
Hong, Yeon-Gi ; Kim, Yong-Un ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 686~686
PDMS(Polydimethylsiloxane)/ceramic composite membrane was used in pervaporation process in order to enhance the flus with maintaining proper selectivity. In Pervaporation of trace phenol from aqueos phenol solution, selectivities of phenol decreased and fluxes increased with concentration of phenol in feed mixtures. And selectivities of phenol increased with operating temperature. This phenomenon could be explained by coupling of each components, plasticization of PDMS membrane, and capillary condensation of water in ceramic pores.
Separation of Naphthalene from Naphthalene-Benzothiophene-Methanol System by Solution Crystallization
Kim, Gwang-Ju ; Kim, Jeong-U ; Lee, Jeong-Min ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 692~692
Separation of naphthalene from naphthalene-benzothiophene mixture has been studied by crystallization using methanol as a solvent. The phenomena of inclusions trapped in naphthalene crystals were explored. The inclusion of impurity in crystals was investigated through process variables like the cooling rate, the subcooling degree and the ratio of solvent to organic mixtures. The purity of crystals was related to the crystal growth rate, mass transfer coefficient, residual concentration and feed concentration. The crystal growth rate of naphthalene from naphthalene-benzothiophene mixture with methanol as a solvent is proportional to the supersaturation to the 3.2 power. Morphological study proved that inclusion of impurity in crystals can be controlled by the cooling rate.
A Kinetic Study of Copper Adsorption with Polyacrylamidoxime
Lee, Sang-Hun ; Jeong, Gap-Seop ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 699~699
The kinetic characteristics of copper adsorption from an aqueous solution with PAO(polyacrylamidoxime) as a chelating adsorbent were investigated to determine the adsorption mechanism, adsorption rate and some thermodynamic constants. As a result the dissociation constant of PAO, the stability constant of chelate and the overall equilibrium constant were experimentally determined. The adsorption rate and the effective surface diffusivity were also determined. The mechanism of copper adsorption with PAO was found to be an endothermic reaction of 2HL+Cu2+ ⇔ CuL2+2H+. The dependence of the thermodynamic equilibrium constant on temperature was expressed as lnK = 24.31-5.11T-1. The adsorption rate of copper was directly proportional to the concentration of PAO, to half power of the copper concentration and inversly to half power of the concentration of hydrogen ion below pH 4, but was constant over pH 4. Based experimental results and theoretical consideration the rate controlling step was found to be the surface diffusion.
Dynamic Characteristics of Adsorption for H₂/CO and H₂/CH₄ Mixtures in Layered Bed
Ji, Jeong-Geun ; Lee, Jae-Uk ; Kim, Min-Bae ; Jo, Chan-Hwi ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 706~706
Dynamic characteristics of adsorption using a layered bed packed with activated carbon and zeolite 5A in ratio of 50:50 were studied through the breakthrough experiments of H2CO(70:30 vol%) and H2/CH4(70:30 vol%) mixtures. Effects of adsorption pressure and feed flow rate on the breakthrough curves in the layered bed were observed. The higher adsorption pressure or the lower feed flow rate, the longer the breakthrough time became. Since breakthrough curves in both binary systems had tail due to temperature variance in the bed by the heat of adsorption, the energy balance should be applied to the simulation of adsorption dynamics. In the layered bed, each bonary mixture showed the specific characteristics of concentration and temperature wave fronts in each layer. As a result, the configuration and ratio adsorbents in the layered bed will play an important role in obtaining the high purity product.
A Study on the Characteristics of Ion Separation by Nanofiltration
Gang,Sang-Hyeon ; Lee,Eun-Gyo ; Jang,Yong-Geun ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 713~713
Study on Removal of Unburned Carbon from Fly Ash by Column Flotation
Gil, Jun-Ho ; Choe, Jeong-Wan ; No, Gap-Su ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 719~719
In this study, as a removal method of unburned carbon from fly ash for the purpose of recycling, the characteristics of separation and the effect parameters on separate efficiency were investigated by the flotation method, making use of the difference between the surface chemistry of carbon and that of ash. The separation charactieristics were investigated according to fly ash type, and then the flotation experiments were done to increase the separation efficiency by the pH adjustment of pulp, the addition of surfantants and the change of kerosene amount. As a result, the separation efficiency by the pH was highest ar neutral region, pH 7 and the addition of moderate amount of surfactant to kerosene was so effective to increase it. Moreover, the column flotation method produced the refined fly ash containing unburned carbon contents under 2% and yield over 80% at the optimum flotation condition made by a pH adjustment, the addition of moderate amount of surfactant etc. Therefore, it is expected that the recycling of the refined fly ash is possible.
Preparation of Microporous RuO₂-TiO₂ Electrodes by the Sol-Gel Process
Hwang, Gyu-Yeon ; Go, Hui-Chan ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 725~725
Microporous RuO2-TiO2 binary metal oxide electrodes with various compositions were prepared by the sol-gel process. Ruthenium chloride hydrate and titanium isopropoxide were used as precursors, and isopropyl alcohol was used as a solvent. Sol solutions were stable and uniform at room temperature. With increasing mole ratio of RuO2 in the metal oxide electrode, RuO2 particle grow on the electrode surface and specific surface area was decreased. From Tafel plots and anodic polarization curves, the binary metal oxide electrode with 40% RuO2 showed the highest exchange current density and the lowest overpotential for oxygen evolution.
Electrochemical Characterization of an Alkaline Battery with AC Impedance
Hwang, Gyu-Yeon ; Hwang, Seong-Min ; Go, Hui-Chan ; Jeon, Byeong-Uk ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 729~729
To understand the dynamic behavior of an alkaline zinc-manganese dioxide battery. AC impedence analysis was performed with pulse discharged and self-discharged cells. To observe the variations of open circuit voltages and internal resistances of both positive and negative electrodes, the Hg/HgO micro-reference electrode was inserted between a separator and a positive electrode. While the internal resistance increased at the positive electrode dominated cell performance during pulse discharge, the internal resistance increased mainly at the negative electrode due to the by zinc corrosion during self-discharge.
Performance of a 2 kW-Class Molten Carbonate Fuel Cell Stack
Im, Hui-Cheon ; An, Gyo-Sang ; Seol, Jin-Ho ; Nam, Seok-U ; Im, Tae-Hun ; O, In-Hwan ; Hong, Seong-An ; Mun, Gil-Ho ; Choe, Yeong-Tae ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 734~734
A 2 kW-class molten carbonate fuel cell(MCFC) stack consisting of 20 cells was fabricated and its performance was evaluated in a kW-class test facility. The electrode area of each cell was 1000 cm2. The initial performance of the stack was close to that of previous stacks, showing 0.826 V/cell at a current density of 150 mA/cm2(150A) and gas utilization of 40% using 72% H2/18% H2O and 70% Air 30% CO2 as fuel and oxidant, respectively, The initial output of the stack was 2.5 kW at 150A. the long-term performance of the stack was considerbly improved by using Al-coated separators. During 1,000 hour operation, the stack showed a stable performance with a degradation rate of 9-36 mV/1,000h/cell. The standard deviation of the voltage distribution in 20 cells was 35-43 mV. A thermal cycling of the stack did not lead to significant degradation of the stack performance. The life of the stack would be improved by constructing stable stack sub-system and by adopting creep-resistant anode as well as stable cathode.
Comparison of Operation Characteristics of Proton Exchange Membrane Fuel Cell with External and Internal Humidifier
Lee, Seung-Jae ; Park, Dae-Jin ; No, Yong-U ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 740~740
Proton exchange membrane fuel cell(PEMFC) stacks with external and internal humidifier were made, and those performance were measured and compared each other. After measuring temperatures of the individual cells in the both stacks, we examined the correlation with these performances. The decrease of performance caused by scale-up and stacking could be explained by higher contact resistance of membrane-electrode, higher contact resistance between one individual cell and another, hindrance to provision of reacting gas and to remove generated water. The performance of the external humidifier stack was greater than that of the internal humidifier stack. Humidification is important to the stack performance. Cell performance improved in the middle individual cell of the stack for the external humidifier stack and in the individual cell closed to internal humidifier for the internal humidifier stack. Temperature and performance distribution in the individual cells of the both PEMFC stacks have much correlations with humidifier type of stacks.
Removal of Anions by Precipitation using Alumina Cement and Lime from Polluted Water
Sim, Sang-Jun ; Lee, Gyeong-Hui ; Gang, Chang-Deok ; Jo, Yeong-Sang ; U, Gyeong-Ja ; Choe, Gwang-Jin ; Kim, Yeong-Dae ; Choe, Ui-So ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 746~746
The Removals of nitrate and other undesirable anions by adding alumina cement and lime from highly polluted water with various anions were studied in a batch reactor. By adding alumina cement and lime to the anion polluted water, various anions including nitrate, sulphate, phosphate, and chloride were precipitated, formed to hydrates of anoin aluminate complex. The precipitation conditions of anoin removal in batch reactor was optimized. To determine the influence of specific anions in nitrate precipitation, a series of tests were performed with nitrate and various specific anions. As the result, the removal rate and yield of nitrate were found to be affected by the existence of other specific anion. After the precipitation reaction, the characteristics of hydrated alumina cement including specific anions were investigated by scanning electron microscopy, thermogravimetric analysis, and X-ray diffractometry. Post-treatments including sodium carbonate addition and neutralization with sulfuric acud alleviated the levels of aluminium and calcium ion concentrations dissolved in treated water.
Exergy Analysis of a Coal Fired Power Plant by ASPEN PLUS
Kim, Jong-Jin ; Park, Myeong-Ho ; Yanzi-Chen ; Kim, Cheol ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 752~752
In this study, a performance analysis for a 500 MW class coal fired power plant was carried out using ASPEN PLUS, a chemical process simulation code. Exergy analysis and steam turbine user models were developed to perform the analysis for the steam cycle which was not available by the existing ASPEN PLUS. Also, the cause of inefficiency in coal fired power plant was defined through the exergy analysis. From the analysis, the exergy destruction and loss in the boiler were found to be approximately 76% of total exergy and 43% of chemical exergy input, respectively. Energy losses by combustion, in the evaporator and the reheated showed about 250, 130 and 50 MW, respectively.
Removal of Nitric Oxide Using Non-Thermal Plasma Technology
Ham, Seong-Won ; Park, Heon-Hwi ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 759~759
The removal of nitric oxide by a pulsed corona discharge process was investigated. As an energy saving technique, the addition of hydrocarbons such as ethylene and propylene to flue gas was examined, and the scheme for the oxidation of NO facilitated by hydrocarbon was discussed. Compared to ethylene known asn the most powerful additive, propylene gave much better performance in the conversion of NO. From the theoretical and experimental analyses performed to find out active component dominantly affecting the oxidation of NO, ozone was found to play a major role in the oxidation of NO. It indicates that the removal of NO is also possible by injecting ozone to flue gas as well as by inducing corona discharge. The possibility for the removal of NO using ozone was experimentally proved. Maximum energy utilization efficiency for the removal of nitric oxide was obtained when the pulse-forming capacitance in the pulse voltage generator was five times larger than the geometirc capacitance of the corona reactor.
Effects of Pulverized Coal Injection on Fines Behaviors in Blast Furnace
Jeong, Jin-Gyeong ; Heo, Wan-Uk ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 767~767
To investigated on the reasons for the fines increase with PCR, several analyses such as TGA, SEM and separation by heavy medium are carried out for blast furnace wet dust and fines obtained by coke sampling. The results show that the fines are composed of unburned pulverized coal and coke. The contribution of char and carbon contents in char and coke fines changes with coal combustibility. It is concluded that the origin of carbon source, coke or coal, can be discriminated by the relative intensity of graphite peak in XRD carbon analysis.
Performance Evaluation of Heavy Residual Oils in the 500 MW IGCC Plant
Lee, Seung-Jong ; Yun, Yong-Seung ; Yu, Jin-Yeol ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 775~775
As a way to evaluate the performance of the IGCC process with fuels from petroleum refineries, heating values of the raw gas as well as the plant efficiency were simulated by employing the static process simulation technique. Fuels chosen were visbreaker residue, butane asphalt and a asphalt from one Korea Refinery. In order to verify the simulation technique, simulated results of a visbreaker residue were compared first with actual demonstration plant data published from Shell Co. and then the simulation technique was applied to the cases of other fuels, butane asphalt and a Korean refinery asphalt. At the gasifier temperature of 1300℃, simulation results showed that heating value of raw gas produced from residual oils was in the range of 2,750-2,800 kcal/m3 with the plant efficiency over 43%. The results exhibit the technical and economical viability of using heavy residual oils from petroleum refineries as successful fuels in IGCC power plants.
Activation of Petroleum Coke by Alkali Metal Compounds and SO₂ Adsorption Characteristics: Moisture Effect
Lee, Si-Hun ; Im, Yeong-Jun ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 782~782
Activation of petroleum cokes by alkali metal compounds and SO2 adsorption characteristics were investigated. Near complete removal(>95%) of sulfur and ash, hydrogen evolution of purity more than 95%, and reductions of particle size were major features of alkali activation. Adsorption capacities of activated carbons at low temperatures (30℃) were not increased with moisture contents, and this is opposites results reported with the activaed carbon fiber. It was found that the moisture contents above saturation level cause condensation on pore surfaces of activated carbons due to the smaller number of free sites and lower adsorption/desorption rates than the activated carbon fiber, and also found that the optimum adsorption temperatures must be selected with moisture contents. Typical results showed that 100℃ for the 10% moisture, and 30℃ for the 4% moisture were optimum conditions respectively. Alkali activated carbon from petroleum cokes showed larger SO2 adsorption capacity than the conventional activated carbon due to its wide ranges of pore size and its hydrophilic surface functional groups. SO2 adsorption capacity was about 200 mgSO2/gAC/6 hr without pretreatment such as oxidation and thermal treatment.
Drug Release Characterization and Preparation of Ca-Alginate Microparticle Drug Carrier using Membrane Emulsification Method
Yu, Jin-O ; Park, Seong-Bae ; Park, Ham-Yong ; Ham, Seung-Ju ; Kim, Jung-Hyeon ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 789~789
Conventional alginate bead has been limited to be used as a drug carrier because of its large size. To overcome the disadvantages of conventional large-size alginate drug beads, Ca-alginate microparticles were prepared using membrane emulsification method controlled with the sodium alginate concentration and the pressure of reactor. The optimal monodispersed microparticles were obtained with the concentration of 2 wt% alginate solution and the pressure of 0.4×105 Pa. The mean size of our prepared microparticles was about 4 ㎛. As the drug solutions, lidocaine·HCl(cationic), sodium salicylate(anionic) and 4-acetamidophenol(nonionic) were selected. These three different drugs were loaded in the drug carrier of prepared alginate microparticles. Drug releases were performed in the siduim phosphate buffers of pH 2 and pH 7 and ionic strength of 0.2. The release behavior with the variation of drug charge showed that of the cationic drug release was retarded more than anionic one due to the ionic interaction between carboxyl group of alginates and positive charge of cationic drug. From the comparison experiments of the buffers of pH 2 and pH 7, the release was much retarded at pH 2 buffer due to ionic repulsivw force or ionic attractive force between the carboxyl group and the hydroxy or sodium ion in the buffer. Conclusively, the usage of small-size pH sensitive microparticles as a drug carrier has a high potential for the application of drug delivery systems.
Low-Temperature Desulfurizing Reaction with Cu-Containing Sorbents
Lee, Gwang-Bok ; Choe, Eun-Mi ; Song, Ui-Geun ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 795~795
The sorbents containing CuO as an active material were prepared and their effectiveness in desulfurization was investigated at low temperatures(350-550℃). MoO3 and MnO2 were chosen as additives and SiO2 was chosen as support material. In the low temperature regeneration reaction, sulfate was formed, which could not be decomposed until regeneration temperature reached 650℃. Sulfidation reaction rate decreased as calcination temperature increased. Promoting effect of MoO3 was not observed throughout the sulfidation/regeneration reaction. When SiO2 content was below 25% of sorbents cimposition, silfur loading of above 25% could be obtained. Mass transfer inhibition by sulfiding gas was observed for the sorbents containing no SiO2.
Dependence of Carbon Dioxide Concentration on Microalgal Carbon Dioxide Fixation
Yun, Yeong-Sang ; Park, Jong-Mun ; Bohumil-Volesky ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 800~800
Batch cultivation of Chlorella vulgaris was carried out under various CO2 concentrations in order to understand and describe mathmatically the CO2 inhibition of microalgal CO2 fixation. The volumetric CO
2 transfer coefficient from mixture gas to culture medium was estimated from the volumetric O2 transfer coefficient obtained experimentally. Using this transfer coefficient and aquatic equilibrium relationship between dissolved inorganic carbons, the behavior of dissolved CO2 was calculated during microalgal culture. When air containing 0.035%(v/v) CO2 was supplied into microalgal culture, the fixation rate was limited by CO2 transfer rate. However, the limitation was disppeared by supplying mixture gas containing above 2%(v/v) CO2 and the dissolved CO2 concentration was maintained at the saturated value. In the range of CO2 partial pressure in the flue gases from thermal power stations and steel-making plants, the microalgal CO2 fixation rate was inhibited. The CO2 fixation rate was succesfully formulated by a new empirical equation as a function of dissolved CO2 concentration, which could be useful for modeling and simulating performance of photobioreaction with enriched CO2. Also, it was found that the CO2 inhibition of microalgal CO2 fixation was reversible and that microalgal CO2 fixation process could be stable against a shock of unusually high CO2 concentration.
A Study on Optimization of a Particulate Removal Facility with Ceramic Filter
Seo, Yang-Gon ;
Korean Chemical Engineering Research, volume 37, issue 5, 1999, Pages 807~807
To optimize the pulse-jet cleaning system of porous ceramic filters applied to IGCC and PFBC, the effects of factors on the cleaning performance were invsetigated at a temperature of 298.15K and pressure of 1 atm and 723.15K and 20 atm, respectively. The diameter of nozzle, the size of diffusor throat and pulse-jet pressure were the main factors of pulse-jet system. In case of 298.15K and 1 atm, the effective diffusor throat size was 2 to 3 cm which depended on pulse-jet pressure, the diameter of nozzle 0.4 to 0.6 cm and pulse-jet pressure 4 to 5 atm, respectively. In case of 723.15 K, 20 atm and the diameter of diffusor throat was 2.5 cm, the optimum diameter of nozzle was about 0.4 cm and pulse-jet pressure 50 to 60 atm, respectively.