Korean Journal of Chemical Engineering (v.26, #4)
A multi-phase model for VOC emission from single-layer dry building materials by Baoqing Deng; Ru Li; Chang Nyung Kim (919-924).
A multi-phase model for the emission of VOC from dry building materials is developed. Dry building materials are viewed as porous media. A general adsorption isotherm is used to construct the concentration equation in the porous media. The boundary conditions at the material-air interface are presented for both CFD model and one compartment model. With the use of Henry’s law for the adsorption isotherm, an analytical solution is obtained and further is validated with the comparison of the experiment performed by Yang et al. , yielding a relatively good agreement. The effects of the model parameters on the emission are investigated in detail. Increasing the effective diffusion coefficient and the partition coefficient tends to promote the emission and increase the peak value of the concentration in the air. The effect of the porosity depends on the degree of the dependence of the effective diffusion coefficient on the porosity. When a weak dependence exists, the increase of the porosity tends to suppress the emission and decrease the peak value of the concentration in the air. However, when a strong dependence exists, the increase of the porosity tends to promote the emission and increase the peak value of the concentration in the air.
Keywords: VOC Emission; Multi-phase Model; Porosity; Adsorption Isotherm
Improved fourier transform to estimate frequency responses by Yu Jin Cheon; Chun Ho Jeon; Jietae Lee; Su Whan Sung (925-929).
For the automatic tuning of PID controllers, a new identification method is proposed to estimate the frequency responses of the process from the activated process input and output. It can extract many more frequency responses as well as guarantee better accuracy compared with the previous describing function analysis algorithm. Also, the proposed method can be applied to the case that the initial part of the activated process input and output is periodic (cyclic-steady-state), whereas the previous method using the modified Fourier transform cannot incorporate the case.
Keywords: Frequency Response; Identification; Autotuning; PID
Stability of buoyancy-driven convection in directional solidification of a binary melt by In Gook Hwang; Chang Kyun Choi (930-934).
In directional solidification, compositional convection can be driven by an unstable density gradient in the melt. In this paper convective instabilities in liquid and mushy layers during solidification of a horizontal binary melt are analyzed by using the propagation theory. The self-similar stability equations are used to examine the boundary-mode and mushy-layer-mode of convection. The effects of velocity conditions at the liquid-mush interface on the onset of convection are discussed. The critical Darcy-Rayleigh number for the convection in the mushy layer decreases with increasing the temperature of a cooled boundary.
Keywords: Directional Solidification; Buoyancy-driven Convection; Propagation Theory; Self-similar Stability Analysis
Development of MBPLS based control for serial operation processes by Junghui Chen; Ren-Kai Tsai (935-945).
A control scheme based on the multiblock PLS (MBPLS) model for multi-stage processes (or serially connected processes) is developed. MBPLS arranges a large number of variables into meaningful blocks for each stage of the large-scale system. Two control design strategies, course-to-course (CtC) and within-stage (WS) controls, are proposed for the re-optimization design in the whole multistage course. In CtC, MBPLS control and optimization are done by applying feedback from the finished output quality when one course for all stages is done. It utilizes the information from the current course to improve quality of the next one. In WS, the MBPLS-based re-optimization strategy is developed to explore the possible adjustments of the future inputs at the rest of the stages in order to fix up the disturbances just in time and to maintain the product specification when the current course is finished. The proposed technique is successfully applied to two simulated industrial problems, including a photolithography sequences and a reverse osmosis desalination process, and the advantages of the proposed method are demonstrated.
Keywords: Iterative Learning Control; Multistage Process; Partial Least Squares
A numerical study of the Dufour and Soret effects on unsteady natural convection flow past an isothermal vertical cylinder by Hari Ponnamma Rani; Chang Nyung Kim (946-954).
The Dufour and Soret effects on the unsteady laminar free convective flow with mass transfer flow past a semi-infinite isothermal vertical cylinder were studied numerically. The governing partial differential equations were converted into a non-dimensional form and solved numerically by applying a Crank-Nicolson type of implicit finite-difference method with a tri-diagonal matrix manipulation and an iterative procedure. For the hydrogen-air mixture, which is a non-chemical reacting fluid, the profiles of the unsteady dimensionless velocity, temperature and concentration are shown graphically for the different values of thermal and mass Grashof numbers, thermal diffusion parameters (Soret numbers) and diffusion-thermo parameters (Dufour numbers). Finally, the simulated values of the average skin-friction coefficient, the average Nusselt number and the average Sherwood number are presented. The numerical results reveal that for an increasing Soret number or decreasing Dufour number, the time to reach the temporal maximum and the steady-state decreases for the flow variables. As the Soret number increases or the Dufour number decreases, both the skin friction and the Sherwood number increase, whereas the Nusselt number decreases.
Keywords: Dufour Effect; Soret Effect; Transient; Natural Convection; Vertical Cylinder
Optimization of the heat plant of district energy systems by Ui Sik Kim; Tae Chang Park; Lae-Hyun Kim; Weon Ho Kim; Yeong Koo Yeo (955-962).
This paper presents a scheme to achieve structural and operational optimization for the heat plant in a district energy system. A district energy system consists of energy suppliers and consumers, district heating pipelines and heat storage facilities in a region. Production and consumption of energy and transport of energy as well as storage of heat are taken into account in the model. The problem is formulated as a mixed integer linear programming (MILP) problem where the objective is to minimize the overall cost of the district energy system. Evaluation of the energy production cost is based on the daily operation for every season at the plant located at Suseo in Seoul, Korea. From the results of numerical simulations we can see that the district energy system is well approximated by the proposed model, and that the energy efficiency is improved by the application of the optimal operation conditions provided by the proposed model.
Keywords: Mixed Integer Linear Programming; District Energy System; Optimal Operation; Energy Efficiency
Modelling mass transfer coefficient for liquid-liquid extraction with the interface adsorption of hydroxyl ions by Javad Saien; Shabnam Daliri (963-968).
A combined model was used for prediction of overall mass transfer coefficient of drops in the liquid-liquid extraction process, prone to the deleterious effect of adsorbed hydroxyl ions onto the interface. The importance is due to the use of different pH waters as aqueous phase. The work is based on single drop experiments with a chemical system of toluene-acetone-water where the pH of the continuous aqueous phase was within the range 5.5–8, appropriate to most industrial waters, and can lead to rigid behavior of circulating drops. The combined model in conjunction with the correlation developed here for the ratio of interfacial velocity to drop terminal velocity that links the film mass transfer coefficients of both sides can be used satisfactorily for design purposes. This model gives a maximum relative deviation of less than ±10% for the mass transfer directions of dispersed to continuous phase and vice versa.
Keywords: Adsorption; Combined Model; Liquid-liquid Extraction; Mass Transfer Coefficient; Hydroxyl Ion
Mapping multi-class cancers and clinical outcomes prediction for multiple classifications of microarray gene expression data by Yong Su Kim; Sun Jin Hwang; Jong Min Oh; Gye Dae Whang; Chang Kyoo Yoo (969-979).
DNA microarray analysis of gene expression is useful for discriminating between the various subtypes of cancer, which is necessary for the accurate diagnosis and treatment of patients. Particularly, assigning biological samples into subclasses or obtaining detailed phenotypes is an important practical application for microarray gene expression profiles. In the present study, a hierarchical framework of a nonlinear mapping classification was developed for elucidating data and classifying multiclass cancers based on microarray data sets. This classification maps the gene expression profiles of multi-class cancers to the visualized latent space and predicts the clinical output through high-dimensional computational biology. The proposed method was used to interpret and analyze four leukemia subtypes from microarray data. The results demonstrate that, using a high-dimensional nonlinear mapping to extract biological insights from microarray data, the proposed method can identify leukemia subtypes on the basis of molecular-level monitoring and improve the interpretability of leukemia clinical outputs. Furthermore, this nonlinear mapping of cancer subtypes is used to establish a relationship between expression-based subclasses of leukemia tumors and leukemia patient treatment outcomes. The proposed method may be used to guide efficient and effective approaches for the treatment of leukemia subclasses.
Keywords: Bioinformatics; Cancer Classification; Clinical Outcome; Hierarchical Framework; Generative Topographic Mapping; Microarray Gene Expression
Physico-chemical variation in bentonite by sulfuric acid activation by Amin Salem; Leila Karimi (980-984).
The physico-chemical behavior of Iranian typical bentonite was characterized during the activation process by sulfuric acid. The main variations were studied by evaluating specific surface area, chemical and mineralogical composition, thermal gravimetric curves, Fourier transform infrared spectrometry pattern, and morphology of starting and activated samples. The effects of acid concentration, particle size distribution, activation temperature and time on specific surface area were discussed. It was found that the above parameters have significant role in the activation process. The optimum condition was also obtained for the activation of typical bentonite.
Keywords: Bentonite; Specific Surface Area; Activation Temperature and Time; Montmorillonite; Illite
Catalytic oxidation of 1,3-diisopropylbenzene using imidazolium ionic liquid as catalyst by Shuai Xu; Chongpin Huang; Jie Zhang; Jia Liu; Biaohua Chen (985-989).
Peroxidation of alkylaromatics is the key step in the synthesis of phenols. Different imidazolium ionic liquids were investigated for the oxidation of cumene. The selectivity of cumene hydroperoxide (CHP) increased with different ionic liquids in the order [C4mim]Cl<[C4mim]Br<[C4mim]BF4<[C4mim]OH. This finding could be interpreted as being due to the partial decomposition of CHP by the acidic proton of the imidazolium cation. Thus [C4mim]OH was chosen as the catalyst for the oxidation of 1,3-diisopropylbenzene to corresponding hydroperoxides and its derivatives. The catalytic performance of [C4mim]OH was also better than that of the traditional catalyst NaOH. Furthermore, the effects of the operating variables were investigated and the mechanism was discussed.
Keywords: Catalysis; Ionic Liquid; 1,3-Diisopropylbenzene; Hydroperoxide; Oxidation
Catalytic conversion of urea to biuret: A catalyst screening study by Dong Ryul Park; Heesoo Kim; Ji Chul Jung; Min Seung Shin; Sang Jin Han; In Kyu Song (990-993).
Biuret was synthesized from urea in a batch reactor using various homogeneous and heterogeneous catalysts, with the aim of searching for efficient catalyst in converting non-catalytic reaction to catalytic reaction. For this purpose, zeolite, heteropolyacid, organic acid and base, multicomponent bismuth molybdate, and multicomponent bismuth molybdate-alumina mixed catalysts were tested. It was revealed that the performance of catalytic reaction was better than that of non-catalytic reaction in the synthesis of biuret from urea. Among the homogeneous acid and base catalysts tested, thionyl chloride (SOCl2) showed the best catalytic performance. Among the heterogeneous catalysts tested, on the other hand, a mixed catalyst comprising multicomponent bismuth molybdate (Co8Fe3Bi1Mo12O50) and alumina showed the best catalytic performance.
Keywords: Biuret; Catalytic Conversion of Urea; Catalyst Screening
Effect of Cs x H3−x PW12O40 addition on the catalytic performance of ZnFe2O4 in the oxidative dehydrogenation of n-butene to 1,3-butadiene by Howon Lee; Ji Chul Jung; Heesoo Kim; Young-Min Chung; Tae Jin Kim; Seong Jun Lee; Seung-Hoon Oh; Yong Seung Kim; In Kyu Song (994-998).
Oxidative dehydrogenation of n-butene to 1,3-butadiene over ZnFe2O4 catalyst mixed with Cs x H3−x PW12O40 heteropolyacid (HPA) was performed in a continuous flow fixed-bed reactor. The effect of Cs x H3−x PW12O40 addition on the catalytic performance of ZnFe2O4 was investigated. Cs x H3−x PW12O40 itself showed very low catalytic performance in the oxidative dehydrogenation of n-butene. However, addition of small amount of Cs x H3−x PW12O40 into ZnFe2O4 enhanced the catalytic performance of ZnFe2O4 catalyst. The catalytic performance of ZnFe2O4-Cs x H3−x PW12O40 mixed catalysts was closely related to the surface acidity of Cs x H3−x PW12O40. Among the catalysts tested, ZnFe2O4-Cs2.5H0.5 PW12O40 mixed catalyst showed the best catalytic performance. Strong acid strength and large surface acidity of Cs2.5H0.5PW12O40 was responsible for high catalytic performance of ZnFe2O4-Cs2.5H0.5PW12O40 mixed catalyst. Thus, Cs2.5H0.5PW12O40 could be utilized as an efficient promoter and diluent in formulating ZnFe2O4 catalyst for the oxidative dehydrogenation of n-butene.
Keywords: Zinc Ferrite; n-Butene; 1,3-Butadiene; Oxidative Dehydrogenation; Cesium-exchanged Heteropolyacid
Properties of unsupported MoS2 species produced in the preparation of MoS2/Al2O3 using a sonochemical method by Jae Hyun Koh; Ara Cho; Sang-il Lee; Sang Heup Moon (999-1003).
Unsupported MoS2 particles, which were produced in the preparation of MoS2/Al2O3 using a sonochemical method, were successfully separated from the prepared sample catalyst by adding oleylamine as an agent for dispersing the unsupported particles. The fraction of the unsupported MoS2, which was estimated based on Mo balance, varied between 0.03 and 0.4, independent of the Mo loading levels investigated (6–54 wt% of Mo). The activity of the unsupported MoS2 for the hydrodesulfurization of dibenzothiophene was nearly the same as that of the Al2O3-supported MoS2, indicating that the activity of the prepared catalyst was not affected by the presence of the unsupported MoS2 particles.
Keywords: Hydrodesulfurization; Dibenzothiophene; Sonochemistry; MoS2 ; Oleylamine
Analysis of micro-leak sodium-water reaction phenomena in a sodium-cooled fast reactor steam generator by Ji-Young Jeong; Tae-Joon Kim; Jong-Man Kim; Byoung-Ho Kim; Nam-Cook Park (1004-1008).
The effects of the sodium-water reaction by small water/steam leaks on 2.25Cr-1Mo and Mod.9Cr-1Mo steels have been studied. Test specimens were exposed to small leaks of water/steam in 300°C stagnant sodium. The phenomenon where the size of the nozzle hole became larger with time was observed for the two types of material. Enlargement rate was slightly faster in the 2.25Cr-1Mo steel than in the Mod.9Cr-1Mo steel. Test results of the enlargement rate of the nozzle hole itself with an increasing duration of the steam injection were analyzed by using SEM and CAMSCOPE images. The maximum reaction temperature appeared at a 17 mm point from the measuring tool, which agrees with the maximum distance that was affected by a jet flame.
Keywords: Sodium-water Reaction; Small Leak; Sodium-cooled Fast Reactor; Steam Generator; Wastage; Self-wastage
CO2 gasification of Thai coal chars: Kinetics and reactivity studies by Supaporn Sawettaporn; Kunchana Bunyakiat; Boonyarach Kitiyanan (1009-1015).
Two sized fractions (<75 μm and 150–250 μm) of Ban Pu lignite A and Lampang subbituminous B coals were pyrolyzed in a drop tube fixed bed reactor under nitrogen atmosphere at 500–900 °C. Gasification of coal chars with excess carbon dioxide was then performed at 900–1,100 °C. The result was analyzed in terms of reactivity index, reaction rate and activation energy. It was found that chars at lower pyrolysis temperature had highest carbon conversion, and for chars of the same sized fraction and at the same pyrolysis temperature, reactivity indices increased with gasification temperature. The lower rank Ban Pu lignite A had higher R s values than higher rank Lampang subbituminous B coals. Smaller chars from both coals had higher R s values, due to the higher ash content. At present, it can be concluded that, within the gasification temperature range studied, gasification rates of chars obtained at various pyrolysis temperatures showed a linear correlation with temperature. However, additional experiment is needed to verify the correlation.
Keywords: Coal Chars; Reactivity; Kinetics; Gasification
Preparation of silica-based proton conductors for intermediate temperature fuel cells by Dongho Seo; Sangsun Park; Yong-Gun Shul (1016-1021).
The ternary system SiO2-P2O5-ZrO2 electrolyte and phosphotungstic acid (PWA) doped SiO2-P2O5-ZrO2 electrolyte were prepared for intermediate temperature fuel cell by using sol-gel technique. These silica-based proton conductors were confirmed to be non-crystalline structure without phase separation and good thermal stability by XRD and TG/DTA analysis. The doped PWA was found to be stabilized within the silica matrix and to enhance the proton conductivity. The proton conductivities of SiO2-P2O5-ZrO2 and SiO2-P2O5-ZrO2-PWA electrolytes showed 3.3×10−5 and 1.8×10−3 S/cm at 90 °C, respectively, and the cell performance of SiO2-P2O5-ZrO2-PWA electrolyte was obtained as 0.02–0.25 mA/cm2 at 300 °C under humid condition.
Keywords: Proton Conductor; Intermediate Temperature Fuel Cell; Sol-gel; PWA
Production of synthesis gas from methane using compression ignition reformer by Mun Sup Lim; Myung Seok Hong; Young Nam Chun (1022-1027).
A new form for a partial oxidation compression ignition reformer, which is different from existing methods of reformation, is suggested to which the concept of super-adiabatic combustion is applied. In addition, experiments are conducted on variables such as the oxygen/methane ratio, the total flow rate, the intake preheating temperature, and the oxygen enrichment ratio, all of which affect the production of hydrogen, in order to understand the optimal features of the movement of the reformer. Results showed that the concentration of hydrogen and carbon monoxide was 20.84% and 13.36%, respectively, under the optimal standard conditions of an oxygen/methane ratio of 0.26, a total flow rate of 106.5 L/min, and an intake preheating temperature of 355 oC. Under the same conditions, the concentration of hydrogen decreased to 20.31% when the oxygen enrichment ratio was 55.6%, while that of carbon monoxide increased to 20.85% when the oxygen enrichment ratio was 50.33%.
Keywords: Synthesis Gas; Hydrogen Production; Reforming; Biogas; Compression Ignition Engine
Ternary Pt45Ru45M10/C (M=Mn, Mo and W) catalysts for methanol and ethanol electro-oxidation by Min Ku Jeon; Ki Rak Lee; Seong Ihl Woo (1028-1033).
Ternary Pt45Ru45Mn10/C, Pt45Ru45Mo10/C and Pt45Ru45W10/C catalysts were synthesized and physical and electrochemical properties were characterized. Particle sizes of the catalysts were determined by X-ray diffraction to be 3.9, 4.8 and 4.6 nm for the Mn, Mo and W incorporated catalysts, respectively. Electrochemically active surface areas were calculated from CO stripping results, which were 17.7, 17.2 and 15.7 m2/g catal for the Pt45Ru45Mn10/C, Pt45Ru45Mo10/C and Pt45Ru45W10/C catalysts, respectively. In methanol electro-oxidation, the Pt45Ru45W10/C catalyst showed highest mass and specific activities of 2.78 A/g cat. and 177 mA/m2, respectively, which were 22 and 100% higher than those of commercial PtRu/C. In the case of ethanol electro-oxidation, the Pt45Ru45Mo10/C catalyst exhibited highest mass and specific activities of 4.8 A/g catal and 280 mA/m2, respectively. Specific activity of the Pt45Ru45Mo10/C catalyst was 56% higher than that of the commercial PtRu/C.
Keywords: Electrocatalyst; Direct Alcohol Fuel Cell; Methanol Electro-oxidation; Ethanol Electro-oxidation; CO Stripping
Electrochemical characteristics of amophous carbon coated silicon electrodes by Oleg Mikhalovich Vovk; Byung-Ki Na; Byung Won Cho; Joong Kee Lee (1034-1039).
The properties of carbon films deposited by the radio frequency plasma sputtering of a fullerene C60 target were investigated to elucidate the dependence on the plasma power. A radio frequency argon plasma power ranging from 50 to 300W at a pressure of 1.3 Pa was applied for sputtering. This corresponds to a self-bias potential on the target ranging from −95 to −250 V and a maximum argon ion energy ranging from 240 to 575 eV. The analysis of the G and D peaks in the Raman spectra shows that the films are similar to tetragonal hydrogenated amorphous carbon annealed at 600–1,000 °C. The electron band structure of the carbon films deposited by the sputtering of C60 depends on the plasma power. The coating effect of these carbon films on the capacity performance of the silicon film electrode of lithium secondary batteries was significant in our experimental range. An electrochemical test revealed that such carbon thin film on the silicon electrode plays an important role in mitigating the capacity fading during the charge and discharge processes. The test revealed that the film formed at a plasma power of 300 W is the most effective.
Keywords: Fullerene C60 ; Carbon Film; r.f. Plasma Sputtering; UV-Vis Spectra; Raman Spectra; Anode of Lithium Secondary Batteries
Performance characterization of direct formic acid fuel cell using porous carbon-supported palladium anode catalysts by Sam Duck Han; Jae Ho Choi; Soon Young Noh; Kunyik Park; Soo Kyung Yoon; Young Woo Rhee (1040-1046).
Palladium particles supported on porous carbon of 20 and 50 nm pore diameters were prepared and applied to the direct formic acid fuel cell (DFAFC). Four different anode catalysts with Pd loading of 30 and 50 wt% were synthesized by using impregnation method and the cell performance was investigated with changing experimental variables such as anode catalyst loading, formic acid concentration, operating temperature and oxidation gas. The BET surface areas of 20 nm, 30 wt% and 20 nm, 50 wt% Pd/porous carbon anode catalysts were 135 and 90 m2/g, respectively. The electro-oxidation of formic acid was examined in terms of cell power density. Based on the same amount of palladium loading with 1.2 or 2 mg/cm2, the porous carbon-supported palladium catalysts showed higher cell performance than unsupported palladium catalysts. The 20 nm, 50 wt% Pd/porous carbon anode catalyst generated the highest maximum power density of 75.8 mW/cm2 at 25 °C. Also, the Pd/porous carbon anode catalyst showed less deactivation at the high formic acid concentrations. When the formic acid concentration was increased from 3 to 9 M, the maximum power density was decreased from 75.8 to 40.7 mW/cm2 at 25 °C. Due to the high activity of Pd/porous carbon catalyst, the cell operating temperature has less effect on DFAFC performance.
Keywords: Pd/porous Carbon Catalyst; DFAFC; Anode Catalyst; Formic Acid
Applying spray pyrolysis to synthesize MnO x for decomposing isopropyl alcohol in ozone- and thermal-catalytic oxidation by Chung-Liang Chang; Yu-Chih Lin; Hsunling Bai; Yu-Huei Liu (1047-1052).
Manganese oxides (MnO x ) were prepared by spray pyrolysis methods (Mn S ) and calcination at 600 and 1,000 °C (Mn600 and Mn1000) in this study. Further, the efficiencies of oxidizing isopropanol (IPA) by these MnO x utilizing ozone (OZCO) and thermal catalytic oxidation (TCO) were compared. The results indicated that Mn S , which are characterized by larger surface areas, processed gas hourly space velocity of 42,000 h−1 and inlet IPA concentration of 400 ppm performing IPA decomposition efficiencies approaching 100%, and the reaction temperature was operated at only 85 °C for OZCO. The reaction temperature of TCO operated above 270 °C decomposed IPA at the same efficiency.
Keywords: Manganese (Mn); Ozone; Volatile Organic Compounds (VOCs); Catalytic Oxidation
Electrochemical recovery of silver from waste aqueous Ag(I)/Ag(II) redox mediator solution used in mediated electro oxidation process by Thasan Raju; Sang Joon Chung; Il Shik Moon (1053-1057).
The paper presents a process for the electrochemical recovery of silver(Ag) by electro deposition on the electrode surface from the waste solutions of Ag(I)/Ag(II) redox system in nitric acid medium used for the mediated electrochemical process. Electrochemical recovery was carried out in an undivided cell with DSA-O2 electrodes at room temperature condition. At an optimized current density of 12 A/dm2, 99% of Ag recovery efficiency was achieved with high yield and low energy consumption. Experimental runs were made in order to observe the performance of the Ag recovery process. The operating conditions like current density, temperature and Ag(I) concentration of the electrolyte, the acid concentrations, agitation rate and inter-electrode distance were optimized.
Keywords: Electrochemical; Mediated Electro Oxidation; Electro Deposition; Recovery; Undivided Cell
Removal of iron from drinking water by electrocoagulation: Adsorption and kinetics studies by Subramanyan Vasudevan; Jeganathan Jayaraj; Jothinathan Lakshmi; Ganapathy Sozhan (1058-1064).
The present study provides an electrocoagulation process for the removal of iron from drinking water with aluminum alloy as the anode and stainless steel as the cathode. The studies were carried out as a function of pH, temperature and current density. The adsorption capacity was evaluated with both the Langmuir and the Freundlich isotherm models. The results showed that the maximum removal efficiency of 98.8% was achieved at a current density of 0.06 A dm−2, at a pH of 6.5. The adsorption of iron preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. The adsorption process follows second-order kinetics. Temperature studies showed that adsorption was endothermic and spontaneous in nature.
Keywords: Iron; Removal; Electrocoagulation; Adsorption; Kinetics
Improvement of the catalytic performance of immobilized penicillin acylase through assembly of macromolecular reagents in nanopore to create a crowding environment by Cheng Zhou; Anming Wang; Zhiqiang Du; Shemin Zhu; Shubao Shen (1065-1069).
Macromolecular reagents were co-assembled with penicillin acylase (PA) and immobilized in mesocellular siliceous foams (MCFs) to resemble living cells. Types and concentrations of macromolecules were studied. The catalytic characteristic and stability of PA preparations were also investigated. PA assembled with dextran 10 k in MCFs showed maximum specific activity, 1.32-fold of that of the solely immobilized PA. The optimum pH of dextran and BSA derivatives shifted to neutrality, and the optimum temperature increased by 10 °C. Also, Km of BSA derivative of PA declined 56.7% compared to solely immobilized PA, while the Kcat/Km of PA assembled with BSA was enhanced to 147%. After incubation at 50 °C for 6 h, residual activity of PA assembled with BSA exhibited 53.0%. The ficoll derivative showed 82.8% of its initial activity at 4 °C after 8-week storage. The results indicated that macromolecular reagents assembled with PA in MCFs could dramatically improve the catalytic performance and stability of immobilized enzyme.
Keywords: Penicillin Acylase; Immobilization; Covalent; Mesocellular Siliceous Foams; Macromolecular Crowding
Cost-cutting of nitrogen source for economical production of cellulolytic enzymes by Trichoderma inhamatum KSJ1 by Hongxian Li; Myong-Jun Kim; Seong-Jun Kim (1070-1074).
For saccharifying food wastes, cellulolytic enzymes were produced using Trichoderma inhamatum KSJ1 in modified Mandel’s medium. In a previous study, 0.1% bacto peptone in Mandel’s medium was established as the best organic nitrogen source for the production of cellulolytic enzymes using strain KSJ1. However, economically, peptone was too expensive. Therefore, soybean, yeast and Chunggookjang (fermented soybean paste) were substituted for peptone in this research. Also, yeast or ground soybean hydrolyzed by sulfuric acid or from a culture broth of Bacillus alcalophilus, a strain producing protease, was added to the medium as the nitrogen source to the production of cellulolytic enzyme. In the cultivation using 0.5% yeast hydrolyzed with a culture solution of B. alcalophilus as the nitrogen source, the activities of FPase and amylase were 0.20 and 2.17 U/mL in a 100 mL flask, compared to 0.35 and 1.24 U/mL with the 0.1% peptone as control, respectively. In a 10 L jar fermenter, the activities of FPase and amylase were improved to 0.40 and 4.82 U/mL in the cultivation, respectively, using 0.5% yeast hydrolyzed with the culture broth, compared with 0.38 and 3.79 U/mL, respectively, for the 0.1% peptone as control. Therefore, hydrolyzed yeast was established as an available nitrogen source for the industrial scale production of cellulolytic enzymes by strain KSJ1, resulting in a 52.3% cost reduction in the production of cellulolytic enzyme by substitution of the expensive nitrogen sources.
Keywords: Nitrogen Sources; Cellulolytic Enzymes; Cost-cutting; Trichoderma inhamatum
Production of polysaccharides by submerged mycelial culture of entomopathogenic fungus Cordyceps takaomontana and their apoptotic effects on human neuroblastoma cells by Sung Hak Lee; Hee Sun Hwang; Jong Won Yun (1075-1083).
The effect of medium components and environmental factors on the production of mycelial biomass for the preparation of intracellular polysaccharides (IPS) and exopolysaccharides (EPS) by Cordyceps takaomontan was investigated in submerged cultures. The optimal culture condition was as follows (g/l): glucose 30, yeast extract 4, KH2PO4 0.46, K2HPO4 1, and MgSO4 0.5, and 28 °C and pH 8. When the fungus was cultivated under various agitation and aeration conditions in a 5-l stirred-tank fermenter, the maximum mycelial biomass (10.7 g/l) and EPS production (1.9 g/l) was obtained at 300 rpm and 2 vvm, respectively. The inhibitory effect of both IPS and EPS on the growth of SK-N-SH cells was studied by treating the cells with crude IPS and EPS at concentrations of 0.5, 1, and 2 mg/ml for 24, 48, 72 h, respectively. The maximum inhibitory effect on apoptosis of SK-N-SH cells (64.6%) was observed when IPS was treated at a concentration of 2 mg/ml, for 72 h. The apoptosis of SK-N-SH cells induced by IPS was evidenced by comet assay, where the number of the comet cells increased by the IPS treated. These findings suggest that IPS may therefore have therapeutic potential against neuroblastoma cells.
Keywords: Apoptosis; Cordyceps takaomontana ; Entomopathogenic Fungus; Polysaccharide; Submerged Culture
Production of hydrocortisone by Absidia coerulea in moderate pressure bioconversion system by Shi Ru Jia; Jian Dong Cui (1084-1089).
The effects of moderate pressure (0.1–2.5 MPa) on viability, cell membrane permeability and catalyzing activity of Absidia coerulea for RSA were investigated. A new method for improving the production of Hydrocortisone (HC) from 17α-hydroxypregn-4-en-3, 20-dione-21-acetate by Absidia coerulea in moderate pressure was developed. The results showed that the morphology of Abasidia coerulea mycelium was changed in moderate pressure, Absidia coerulea mycelium seemed to be loosed, and cell membrane permeability of Abasidia coerulea mycelium was improved. However, the viability of Abasidia coerulea mycelium could keep high level. Moreover, the yield of HC was improved over 1.25-fold as compared with that of the control (untreated cells), to give the yield of HC as 350 mg/l, when the Abasidia coerulea mycelium was treated with 0.5 Mpa the atmosphere as the pressure media. Especially, the production of HC with atmosphere as the pressure media (0.5 MPa) could be increased by the addition of H2O2 (60 mmol/l); the relative yield of HC in moderate pressure was enriched by over 4.5% in comparison with the control. The major composition of bioconverted mixture was reduced. It was indicated that the new approach (moderate pressure) obtained in this work possessed a high potential for the industrial production of HC.
Keywords: Abasidia coerulea ; Hydrocortisone; Permeability; Viability; Moderate Pressure; Biotransformation
Characterization of solvent induced crystalline and amorphous homoharringtonine by Byung-Sik Kim; Jin-Hyun Kim (1090-1093).
The morphologies of homoharringtonine were conveniently controlled by solvent treatment and the morphologies of homoharringtonine were characterized by XRD and SEM. Crystalline homoharringtonine was simply made by dissolving homoharringtonine in a special polar solvent containing a small amount of water (methanol/water= 98/2, v/v). On the other hand, amorphous homoharringtonine was made by dissolving homoharringtonine in relatively non-polar solvent (methylene chloride/methanol=98/2, v/v). Amorphous homoharringtonine, with a fine particle size, was obtained by dissolving in methylene chloride/methanol (98/2, v/v), following by spray drying. Also, residual solvents, methanol and methylene chloride, were easily removed to less than concentration limit in ICH (International Conference on Harmonisation) guidance by spray drying and successive drying in a vacuum oven. Amorphous homoharringtonine was more soluble in water than crystalline homoharringtonine, and the water content of amorphous homoharringtonine was less changeable than crystalline homoharringtonine at given humidity (95 RH%) during storage. This information is very useful for production and quality control of pharmaceuticals in the commercialization step.
Keywords: Crystalline and Amorphous Homoharringtonine; Solubility; Water Content; Residual Solvent; Spray Drying
An alternative sequential extraction process for maximal utilization of bioactive components from Korean red ginseng by Guijae Yoo; Sung Dong Lee; Man-Jin In; Woo Ik Hwang; Kwang Seung Lee; Eun Sil Lee; Dong Chung Kim; Hee Jeong Chae (1094-1097).
Two types of sequential extraction process (SEP) for the recovery of bioactive components from Korean red ginseng were examined. As a SEP (normal SEP, nSEP), Korean red ginseng was sequentially treated using hot water and n-hexane for the successive extraction of water-soluble and lipid-soluble components. Also by changing the sequential order of solvents, an alternative SEP (reverse SEP, rSEP) in which n-hexane extraction was followed by hot water extraction, was proposed. Regardless of the sequential order of solvents, the recovery yield of acidic polysaccharide (AP) and crude saponin (CS) showed no significant change. On the other hand, in the rSEP, the lipid-soluble fraction was obtained from red ginseng with an enhanced recovery yield, four times higher than that in nSEP. Additionally, from dose-response assays to assess the effects of lipid-soluble components on the proliferation of human hepatoma (HepG2) and breast (MCF-7) cancer cell lines, it was found that hexane extract of red ginseng (HER) in rSEP has higher efficacy than the hexane extract of red ginseng marc (HERM) obtained in nSEP. This strongly suggested that rSEP would be a more attractive industrial process in terms of the efficacy of lipid-soluble extract as well as the recovery yield.
Keywords: Sequential Extraction Process; Red Ginseng; Normal SEP; Reverse SEP
Monte Carlo simulation on the adsorption properties of carbon tetrachloride, neopentane, and cyclohexane in MCM-41 by Sung Doo Moon; Dae Woong Choi (1098-1105).
The adsorption properties of carbon tetrachloride, neopentane, and cyclohexane in MCM-41 with heterogeneous and cylindrical pores have been studied by using grand canonical ensemble Monte Carlo simulation. The adsorption isotherm, average potential of adsorbate, isosteric heat of adsorption, and number density of molecules in MCM-41 were calculated. The simulated isotherms were compared with experimental ones. Also, different adsorption behaviors in MCM-41 with pore diameter of 2.2 and 3.2 nm were discussed. The capillary-condensation pressure increased for a given adsorbate with an increase in pore diameter. The average densities of carbon tetrachloride, neopentane, and cyclohexane in the two different pores above the capillary-condensation pressure were smaller than the corresponding liquid densities by about 12%. The adsorbate molecules did not form the multilayer in pore below the capillary-condensation pressure. The number of adsorption layers of molecules was constant in a given pore for the three adsorbates above the capillary-condensation pressure. Carbon tetrachloride molecules in pore were also ordered along the pore axis.
Keywords: Adsorption; MCM-41; Monte Carlo; Carbon Tetrachloride; Neopentane; Cyclohexane
Production of pure ethanol from azeotropic solution by pressure swing adsorption by Pit Pruksathorn; Tharapong Vitidsant (1106-1111).
Pressure swing adsorption (PSA) is attractive for final separation in the process of water removal especially for fuel ethanol production. Despite many researches on simulation and experimental works on adsorption of water on 3A zeolite in a fixed bed, none have studied a process with the actual PSA system. The purpose of this research was to study the PSA process with two adsorbers and effects of several parameters. The research also included analysis of kinetic and thermodynamic data of ethanol-water adsorption on commercial 3A zeolites in a single fixed bed. A two-level factorial design experiment was used in this research work to preliminarily screen the influence and interaction among the factors. Effects of important parameters such as initial temperature, feed concentration and feed rate were investigated. It was proven that the Langmuir isotherm could best predict the experimental results. In the PSA pilot test, the principal factors, which had effects on the performance, were feed rate, feed concentration, adsorption pressure and the cycle time. Prediction of the process efficiency in terms of ethanol recovery and enrichment was proposed in the form of regression models. The results of the study in a fixed bed adsorber could help designing a pilot-scale PSA unit. The experiments proved to be successful in terms of producing high concentration ethanol with high percentage of ethanol recovery. With further simulation work the process could be scaled up for an industrial use.
Keywords: PSA; Adsorption; Separation; 3A Zeolites
Measurement and modeling of solubility of H2S in aqueous diisopropanolamine solution by Hassan Pahlavanzadeh; Masoumeh Farazar (1112-1118).
Modeling of solubility of acid gases in aqueous alkanolamine solutions is essential for design of an absorber for natural gas sweetening. In this work an apparatus similar to the device of Hayduk and Chen (1970), which was improved by Pahlavanzadeh and Motahhari (1997), for the measurement of gas solubility data by the synthetic method was used. The solubility of hydrogen sulfide in aqueous diisopropanolamine (DIPA) solution in mass concentration range of 30–40% for 101,325 Pa pressure and for temperature ranging from 313–343 K was reported. The obtained experimental solubility data of H2S in aqueous solutions of DIPA was used to predict the different interaction parameters of modified UNIQUAC-NRF model for calculating the activity coefficients. For nonideality of species in liquid phase, the UNIQUAC-NRF equation with ion-pair approach was applied. For long range interaction, the Pitzer-Debye-Huckel term was used.
Keywords: Diisopropanolamine; Hydrogen Sulfide; Modeling; Solubility; Data
Recrystallization of tetracycline hydrochloride using supercritical anti-solvent process by Junho Chu; Hanho Lee; Hwayong Kim; Youn-Woo Lee (1119-1124).
Tetracycline hydrochloride (TTC) was micronized by an Aerosol Solvent Extraction System (ASES) using supercritical CO2. The effects of solvent, pressure and temperature of CO2, solution concentration, and solution feed rate on particle size were investigated. Mean particle sizes of processed TTC were 0.16–0.31 μm, but the morphologies of processed particles were affected by agglomeration between the primary particles. Mean particle sizes of unprocessed TTC were ca. 200 μm and the shapes were irregular with rough surfaces. Especially, particle sizes increased from 0.18 to 0.31 μm as CO2 temperature increased. In addition, particle sizes increased from 0.18 to 0.23 μm as TTC concentration increased. Powder X-Ray diffractometry revealed that processed particles were amorphous whereas unprocessed particles showed strong crystallinity.
Keywords: Tetracycline Hydrochloride; Supercritical Carbon Dioxide; ASES; Recrystallization
Solvent effect on particle morphology in recrystallization of HMX (cyclotetramethylenetetranitramine) using supercritical carbon dioxide as antisolvent by Chang-Ki Kim; Byung-Chul Lee; Youn-Woo Lee; Hyoun Soo Kim (1125-1129).
Supercritical fluid processes have gained great attention as a new and environmentally benign method of preparing the microparticles of energetic materials like explosives and propellants. In this work, HMX (cyclotetramethylenetetranitramine) was selected as a target explosive. The microparticle formation of HMX using supercritical antisolvent (SAS) recrystallization process was performed and the effect of organic solvent on the size and morphology of prepared particles was observed. The organic solvents used in this work were dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), cyclohexanone, acetone, and N-methyl pyrrolidone (NMP).
Keywords: High Energy Material; Explosive; Supercritical Fluid; Recrystallization; Microparticle Formation; HMX; Morphology
High-pressure solubility of carbon dioxide in imidazolium-based ionic liquids with anions [PF6] and [BF4] by Bang-Hyun Lim; Woo-Hyuk Choe; Jae-Jin Shim; Choon Sup Ra; Dirk Tuma; Heun Lee; Chul Soo Lee (1130-1136).
The solubility of carbon dioxide in three ionic liquids (ILs) under supercritical fluid condition was measured at pressures up to 32 MPa and at temperatures of 313.15, 323.15, and 333.15 K in a high-pressure view cell. The imidazolium-derivative ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), and 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF4]) were employed in this research. The effects of pressure, temperature, nature of anion and cation as well as the water content on the solubility of CO2 in the ILs were investigated experimentally. The solubility of CO2 in the IL was higher for the ILs with longer cationic alkyl group and for the ILs with lower anion polarity. The lower the water content or the lower the temperature as well as the higher the pressure, the higher was the solubility of CO2.
Keywords: Solubility; Carbon Dioxide; Ionic Liquid; Water Content; Anion; Cation
Numerical simulation of the influence of over fire air position on the combustion in a single furnace boiler with dual circle firing by Hiu Liu; Nana Xin; Qingxi Cao; Long Sha; Dezhi Sun; Shaohua Wu (1137-1143).
The Computational fluid dynamics (CFD) code PHOENICS is applied to simulate and evaluate the combustion process within the furnace of a 1,000 MW dual circle tangential firing single furnace lignite-fired ultra supercritical (USC) boiler. The dependence on overfire air (OFA) positioning on the combustion process is studied. The results show that the highest temperature appears on the upside of the burner zone close to the front wall, and the high temperature zone rises with elevated OFA positions. However, the temperature field distributions are similar despite differing OFA positions. The char content near the rear wall is higher than that near the front wall, and below the furnace arch, coal particles concentrate towards the front wall. Also with elevated OFA positions, nitrogen oxide (NO x ) concentrations at the outlet fall, but char content increases. In regard to NO x emission and char burnout, the suggested optimal distance from the OFA center to the center of the uppermost primary air nozzle should be 6 meters.
Keywords: OFA; Combustion; NO x ; Numerical Simulation; Dual Circle Tangential Firing
CFD simulation of coal-water slurry flowing in horizontal pipelines by Liangyong Chen; Yufeng Duan; Wenhao Pu; Changsui Zhao (1144-1154).
An Eulerian multiphase approach based on kinetic theory of granular flow was used to simulate flow of coal-water slurries (CWS) in horizontal pipelines. The RNG k-ɛ turbulent model was incorporated in the governing equation to model turbulent two-phase flow with strong particle-particle interactions. In this model, the coal particles with bimodal distribution were considered as two solid-phase components, and the moment exchange between solid and liquid as well as that between solid and solid were accounted for. The model was firstly validated with pressure gradient and concentration profile data from the open literature, and then validated with pressure gradient data of the authors’ experiments. The effects of influx velocity, total influx concentration and grain composition were numerically investigated, and the results have displayed some important slurry flow characteristics, such as constituent particle concentration distribution and velocity distribution as well as pressure gradients, which are very difficult to display in the experiments. The results suggest that both gravity difference between large and small particles and strong particle-particle interaction had significant effects on concentration distribution as well as velocity distribution.
Keywords: Coal-water Slurry; High Concentration; Multi-fluid Model; Kinetic Theory of Granular Flow
Sulfation diffusion model for SO2 capture on the T-T sorbent at moderate temperatures by Yuran Li; Lizhai Yang; Changfu You; Haiying Qi (1155-1159).
A sulfation model was developed for dry flue gas desulfurization (FGD) at moderate temperatures to describe the reaction characteristics of the T-T sorbent clusters and the fine CaO particles that fall off the sorbent grains in a circulating fluidized bed (CFB) reactor. The cluster model describes the calcium conversion and reaction rate for various size sorbent clusters. The sulfation reaction is first order with respect to the SO2 concentration above 973 K. The calcium conversion and reaction rate for the CaO particles were obtained by extrapolation. In the model for CaO particle, the reaction rate is linearly related to the calcium conversion and the SO2 concentration in the rapid reaction stage and linearly related only with the calcium conversion after the product layer forms. The sulfation model accurately describes the sulfation of the T-T sorbent flowing through a CFB reactor.
Keywords: Sulfation Model; CaO Particle; Sorbent Cluster; Diffusion; Rreaction Rate