Korean Journal of Chemical Engineering (v.26, #5)
Simultaneous optimal integration of water utilization and heat exchange networks using holistic mathematical programming by Wu Xiao; Rui-jie Zhou; Hong-Guang Dong; Nan Meng; Chih-Yao Lin; Vincentius Surya Kurnia Adi (1161-1174).
A systematic holistic mathematical programming (HMP) is proposed to formulate a mixed integer nonlinear programming (MINLP) model for one-step optimization of water-allocation and heat exchange network (WAHEN) designs with single- or multi-contaminant water streams. The proposed model formulation and solution strategy are believed to be superior to the available ones in the following aspects. First, a comprehensive representation combining two separate superstructures is adopted to capture the structural characteristics of the integrated WAHEN. Then, a hybrid optimization strategy integrating stochastic and deterministic components is developed for the resulting MINLP model and, also, an interactive iteration method is adopted based on sensitivity analysis to guide the search toward a potential global optimum. Finally, evolutionary strategies and manipulations are executed to enhance WAHEN configurations. Two illustrative examples are presented to demonstrate the validity and advantages of the proposed approach.
Keywords: Simultaneous Optimization; Water Utilization Network; Heat Exchange Network; Evolutionary Strategy
Support vector regression with parameter tuning assisted by differential evolution technique: Study on pressure drop of slurry flow in pipeline by Sandip Kumar Lahiri; Kartik Chandra Ghanta (1175-1185).
This paper describes a robust support vector regression (SVR) methodology that offers superior performance for important process engineering problems. The method incorporates hybrid support vector regression and differential evolution technique (SVR-DE) for efficient tuning of SVR meta parameters. The algorithm has been applied for prediction of pressure drop of solid liquid slurry flow. A comparison with selected correlations in the literature showed that the developed SVR correlation noticeably improved prediction of pressure drop over a wide range of operating conditions, physical properties, and pipe diameters.
Keywords: Support Vector Regression; Differential Evolution; Slurry Pressure Drop
Study on flow fields of centrally fuel rich swirl burner and its applications by Zhichao Chen; Zhengqi Li; Jianping Jing; Lizhe Chen; Shaohua Wu; Yang Yao (1186-1193).
Experiments on a single-phase test facility were done to optimize primary air outlet cones of a centrally fuel rich swirl coal combustion burner. On the basis of optimized results from the single-phase test, a three-component particle-dynamics anemometer was used to measure, in the near-burner region, the characteristics of gas/particle two-phase flows for the burner with two primary air outlet cones, on a gas/particle two-phase test facility. Velocities, RMS velocities and particle volume flux profiles were obtained. According to the results, the primary air outlet cone structure of the centrally fuel rich burner was matching a 670 ton per hour boiler. The performance of the burner on a 670 ton per hour boiler was studied.
Keywords: Burner; Flow Field; Coal Combustion; Utility Boiler; Gas/Particle Flow
A new predictive PID controller for the processes with time delay by Kyung Nam Lee; Yeong Koo Yeo (1194-1200).
A new proportional-integral-derivative (PID) controller is proposed based upon a simplified generalized predictive control (GPC) control law. The tuning parameters of the proposed predictive PID controller are obtained from the simplified GPC control law for the 1 st -order and 2 nd -order processes with time delays of integer and non-integer multiples of the sampling time. The internal model technique is employed to compensate the effect of time delay of the target process. The predictive PID controller is equivalent to the PI controller when the target process is 1 st -order and to the PID controller when the target process is an integrating process. The performance of the proposed predictive PID controller is almost the same as that of the simplified GPC. The main advantage of the proposed control scheme over other control methods is the ease of tuning and operation.
Keywords: Predictive PID; Simplified GPC; PID Tuning Method; Discrete PID Control Law
Application of experimental non-linear control based on generic algorithm to a polymerization reactor by Gülay Özkan; Öznur Tekin; Hale Hapoğlu (1201-1207).
The dynamics of free radical polymerization of styrene and on-line control of temperature in a cooling jacketed batch polymerization reactor is investigated. The benzoyl peroxide initiator is introduced into the reactor once at the beginning of the reaction to obtain the desired monomer conversion and the desired average chain length in a minimum reaction time. The optimal constant set temperature, which is generally realized in industrial applications, and the set profile are used as two different optimal operating conditions. The temperature control of the polymerization reactor is achieved experimentally and theoretically. The control of nonlinear systems has progressed considerably, and various nonlinear process model based control techniques have appeared in the literature. The problem is how to tune the controller in order to obtain comparable closed loop responses. Generic model control (GMC) is applied and the performance of the control results are compared with the previously published control results.
Keywords: Polystyrene; Non-linear Control; Generic Model Control
Developing a new model to predict mass transfer coefficient of salicylic acid adsorption onto IRA-93: Experimental and modeling by Somayeh Kananpanah; Nader Dizadji; Hossein Abolghasemi; Babak Salamatinia (1208-1212).
An experimental breakthrough curve for Salicylic acid in an adsorption recovery process was determined by an anion-exchange resin IRA-93. The volumetric mass transfer coefficients were calculated by employing constant wave propagation theory. Meanwhile, the effects of volumetric feed flow rates on this break through curve and mass transfer coefficients at different flow rates were also studied in order to develop three new models to predict mass transfer coefficient. The results demonstrated that by the increase in the feed flow rates, the amount of adsorption reduces. However, while the volumetric feed flow rates increase the overall volumetric mass transfer coefficients will increase. This grows the feeling that the feed flow rate should be optimized. The optimum flow rate for the adsorption was found to be 7 mg/l in this study. In addition, three new models to predict the mass transfer coefficient in respect of feed rates were developed in this research work which showed very high fittings with R2>0.99. These models could fully support the experimental data obtained.
Keywords: Modeling; Predict Mass Transfer Coefficient Ion-exchange Resin; IRA-93; Salicylic Acid; Breakthrough Curve; Constant Wave Propagation Theory
Computational fluid dynamic simulation of MVG tray hydraulics by Taleb Zarei; Rahbar Rahimi; Mortaza Zivdar (1213-1219).
The flow pattern and hydraulics of a Mini V-Grid valve (MVG) tray is predicted by using computational fluid dynamics simulation. A 3-D CFD model in the Eulerian framework was used. The simulation results for MVG tray are compared with that of sieve tray. The sieve tray geometry and operating conditions are based on the Solari and Bell’s sieve tray . The MVG tray differs from that of Solari and Bell’s sieve tray solely by the difference in design of available openings for the flow of gas. The simulation results show that the clear liquid height and the pressure drop of MVG tray are lower than that of sieve tray whereas the liquid velocity is higher and contacts of phases are good. The simulation results of sieve tray are in agreement with the experimental data of Solari and Bell .
Keywords: MVG Tray; Sieve Tray; Distillation; Two Phase Flow; CFD
Modelling of crystallization process and optimization of the cooling strategy by Do Yeon Kim; Michaella Paul; Jens-Uwe Rapke; Günter Wozny; Dae Ryook Yang (1220-1225).
To obtain a uniform and large crystal in seeded batch cooling crystallization, the cooling strategy is very important. In this study, an optimal cooling strategy is obtained through simulation and compared to linear and natural cooling strategies. A model for a crystallization process in a batch reactor is constructed by using population balance equation and material balance for solution concentration, and a prediction model for meta-stable limit is formulated by the dynamic meta-stable limit approach. Based on this model, an optimal cooling strategy is obtained using genetic algorithm with the objective function of minimizing the unwanted nucleation and maximizing the crystal growth rate. From the simulation results, the product from the optimal cooling strategy showed uniform and large crystal size distribution while products from the other two strategies contained significant amount of fine particles.
Keywords: Optimal Cooling; Batch Crystallization; Meta-stable Zone; Genetic Algorithm
Network numerical simulation of two-dimensional nonlinear micropolar hydrodynamics in a Darcian porous medium by Joaquin Zueco; Osman Anwar Bég; Tong-Bou Chang (1226-1234).
The two-dimensional steady-state boundary layer flow of an incompressible micropolar fluid in a Darcian porous medium is studied theoretically and computationally. The governing parabolic partial differential equations are reduced to dimensionless form by using a set of transformations, under appropriate boundary conditions. A network simulation method (NSM) solution is presented. Translational velocities (U, V) are found to increase with a rise in Darcy number (Da) and to increase and decrease, respectively, with a rise in micropolar parameter (Er), i.e., Eringen number (ratio of micropolar vortex viscosity to Newtonian viscosity). Micro-rotation is increased with increasing Er and Da values. Translational velocity gradient, ∂U/∂Y and micro-rotation gradient, ∂Ω/∂Y both increase with Darcy number; however, they are both found to decrease with increasing micropolar parameter, Er. The present study finds applications in polymer flows in filtration systems, chemical engineering, biorheology of porous tissue and plastic sheet processing.
Keywords: Non-Newtonian; Micropolar Fluid; Porous Medium; Network Numerical Simulation (NSM); Eringen Number; Darcy Number; Angular Velocity; Rheology
Direct incorporation of vanadium into three-dimensional KIT-6: 1. Optimization of synthesis conditions by Balasamy Rabindran Jermy; Sang-Yun Kim; Kanattukara Vijayan Bineesh; Manickam Selvaraj; Dae-Won Park (1235-1240).
Three dimensional (3-D) cubic KIT-6 with directly incorporated vanadium was hydrothermally synthesized by using Pluronic P123 and n-butanol as the structure-directing mixture, tetraethyl orthosilicate (TEOS) as the silica source and NH4VO3 as the vanadium source. The molar composition was varied in the range of 0.017 P123/0.08–2.4 V/1.0–2.0 TEOS/1.31–1.70 BuOH/1.83–3.00 HCl/195 H2O. The orderness of mesopore structure was estimated by X-ray diffraction, N2 adsorption, and TEM analysis. The effects of the amount of HCl, TEOS and BuOH on the structure of KIT-6 were discussed. The time and temperature for the synthesis of KIT-6 were also optimized. The amount of vanadium content influenced the framework structure and crystallinity of the Ia3d phase significantly.
Keywords: KIT-6; Hydrothermal Synthesis; Vanadium Incorporation
Direct incorporation of vanadium into three-dimensional KIT-6: 2. Reactivity test for styrene oxidation by Balasamy Rabindran Jermy; Sang-Yun Kim; Kanattukara Vijayan Bineesh; Manickam Selvaraj; Seung-Kug Song; Jong-Woo Ryu; Dae-Won Park (1241-1245).
The direct incorporation of vanadium into the three-dimensional (3-D) cubic Ia3d mesostructure designated as V-KIT-6 was prepared, and the material obtained therein showed a very high specific surface area of ∼1,000 m2/g with tunable pore diameters in a narrow distribution of sizes, ∼5.7 to 6.0 nm. The coordination and nature of the V sites in V-KIT-6 were characterized by 51V-spin-echo NMR analysis. It shows that after calcination, the V4+ species are totally oxidized to the V5+ state with 4- and 6-coordinated V-O environments in a highly dispersed state with much less crystalline V2O5 formation. The calcined V-KIT-6 materials showed excellent catalytic activity in the direct oxidation of styrene using tert-butyl hydroperoxide (TBHP) as an oxidant.
Keywords: KIT-6; Vanadium; Styrene; Oxidation
Optimization of the process parameters for an electrochemical preparation of strontium perchlorate by Subramanyan Vasudevan (1246-1251).
The electrochemical preparation of strontium perchlorate, Sr(ClO4)2, from strontium chlorate employing platinum anode and a rotating stainless steel cathode is described. The effect of electrolyte concentration, current density, pH and temperature of the electrolyte and cathode rotation on current efficiency for the preparation of strontium perchlorate was studied. A maximum current efficiency of 42% was achieved corresponding to an energy consumption of 6.1 kWh. kg−1.
Keywords: Electorchemical; Oxidation; Strontium Perchlorate; Rotating Cathode
Effect of CeO2-addition sequence on the performance of CeO2-modified Ni/Al2O3 catalyst in autothermal reforming of iso-octane by Sang Ok Choi; In Young Ahn; Sang Heup Moon (1252-1258).
Two types of CeO2-modified Ni/Al2O3 catalysts were prepared by a consecutive impregnation method with different sequences in the impregnation of Ni and CeO2, and their performance in autothermal reforming (ATR) of isooctane was investigated. Catalysts prepared by adding CeO2 prior to the addition of Ni, Ni/CeO2-Al2O3, produced larger amounts of hydrogen than those obtained using catalysts prepared by adding the two components in an opposite sequence, Ni-CeO2/Al2O3. The results of H2 chemisorption and temperature-programmed reduction revealed that added CeO2 increased the dispersion of the Ni species on Al2O3 and suppressed the formation of NiAl2O4 in the catalyst such that large amounts of Ni species were present as NiO, the active species for the ATR. The elemental and thermogravimetric analyses of deactivated catalysts indicated that Ni/CeO2-Al2O3, which showed a longer lifetime than Ni-CeO2/Al2O3, contained lesser amounts and different types of coke on the surface.
Keywords: Autothermal Reforming; Steam Reforming; Hydrogen Production; CeO2 ; Iso-octane
The effect of additive chemicals on the viscosity of coal-petroleum coke-water slurry fuel for a gasification process by Sang Jun Yoon; Young-Chan Choi; Jae-Goo Lee (1259-1264).
As a preliminary study for the gasification of an anthracite and petroleum coke mixture, viscosity was measured at various temperatures (20–50 °C), slurry concentrations (60–70 wt%) and additive amounts (0–0.8 wt%) by using an LV-II type viscometer. In addition, four types of different additives, sodium naphthalene sulfonate, poly(methyl methacrylate), polypropylene and a polypropylene glycol based additive, were applied to Korean anthracite, petroleum coke and mixtures of these materials, and the viscosity data were compared. Viscosity dependency values for coal, anthracite, bituminous and sub-bituminous coal, were compared, and it was found that a high content of moisture and particularly ash increases CWS viscosity. The four types of additives tested in this research can effectively diminish the viscosity of coal and especially petroleum coke-water slurry by more than 70% to 95%, respectively. Moreover, the sodium naphthalene sulfonate-based additive reduced the viscosity of coal and petroleum coke-water slurry best, especially at concentrations in excess of 65 wt%. Based on these results, highly loaded slurry created by mixing anthracite and petroleum coke with additives was achieved.
Keywords: Coal; Petroleum Coke; Slurry; Viscosity; Gasification
Degradation of proton exchange membrane by Pt dissolved/deposited in fuel cells by Taehee Kim; Ho Lee; Woojong Sim; Jonghyun Lee; Saehoon Kim; Taewon Lim; Kwonpil Park (1265-1271).
An accelerated single cell test and single electrode cell test were carried out to investigate membrane degradation by Pt dissolved/deposited on the membrane. For a cell operating under accelerated conditions (OCV, 90°C, anode RH 0%, cathode O2 supply), MEA analyses revealed that Pt particles were deposited in the membrane at the anode side, with a decrease in F, O, and C content near the anode side of the membrane. Dissolved Pt from the cathode showed that Pt existed mainly in the form of Pt2+ ionic species. Oxygen and hydrogen helped Pt dissolution from the cathode and Pt deposition in the membrane, respectively. Radical formation on deposited Pt in the membrane was detected by electron spin resonance (ESR). Fluoride emission rate (FER, an indicator of membrane degradation rate) increased with an increase in the amount of Pt in the membrane.
Keywords: PEMFC; Membrane Degradation; FER; Pt Dissolution; Oxygen Radical
CFD study on hydraulic performance of subsurface flow constructed wetland: Effect of distribution and catchment area by Liwei Fan; Reti Hai; Zexiang Lu (1272-1278).
A subsurface flow constructed wetland (SSFW) was simulated by using a commercial computational fluid dynamic (CFD) code (Fluent 6.22, Fluent Inc.). The liquid residence time distribution in the SSFW was obtained by the particle trajectory model. The simulation confirmed that the effect of the distribution and/or catchment area on the hydraulic efficiency is significant. An inappropriate horizontal distribution and/or catchment area can result in poor hydraulic efficiency. The hydraulic efficiency of the SSFW with the vertical distribution and/or catchment area can be kept at a high level (above 0.898). The design of the vertical distribution and/or catchment area in the SSFW is better than that of the horizontal. From the point of view of the engineering design, a small dimension distribution and/or catchment area in the SSFW is advisable, which maintains a considerable hydraulic efficiency of the SSFW (above 0.840), but also benefits the increase of the purge area.
Keywords: Subsurface Flow Constructed Wetland; Computational Fluid Dynamics; Distribution Area; Catchment Area; Hydraulic Efficiency
Diffusion of some chemical species through a granite considering their geochemical properties by Chung-Kyun Park; Min-Hoon Baik (1279-1285).
Through-diffusion experiments for some chemical species onto granite have been carried out to understand their diffusion characteristics according to their geochemical properties. The chemical species used in the experiment were classified into three groups as a nonsorbing tracer, simple cation and multivalent species. The difference in the diffusion process among the nonsorbing tracers was evaluated and discussed in terms of their interactions with the rock’s pore surface. The extent of surface diffusion was examined from the view of sorption reversibility for the sorbing cations. For the multivalent species, two kinds of experiments were performed to study the effects of geochemical conditions in acidic and alkaline solutions. Chemical species and sorption properties were also investigated as a function of the pH and carbonates in order to examine the effects of the carbonates on diffusion in alkaline conditions.
Keywords: Diffusivity; Surface Diffusion; Carbonate Complex; Granite; Uranium; Thorium; Europium
Improving the SO2 absorption rate of CeFeMg-based sorbent promoted with titanium promoter by Soo Jae Lee; Soo Chool Lee; Suk Yong Jung; Chong Kul Ryu; Jae Chang Kim (1286-1290).
To improve the poor SO2 absorption rate of CeFeMgTi sorbent with high sulfur removal capacity and fast regeneration, a new sorbent, CeFeMgTi-sol was prepared by the modified co-precipitation method and tested in a packed bed reactor at RFCC conditions (sulfation of MgO to MgSO4 in the presence of low concentration of SO2 at 973 K, regeneration of MgSO4 to MgO and H2S in the presence of H2 at 803 K). The CeFeMgTi-sol sorbent showed excellent SO2 absorption and sulfur removal capacity (46.2 sulfur g/g absorbent×100). It was found that the SO2 absorption rates were related to the structure of the Mg and Ti and the textural properties such as surface area and pore volume. In the case of the fresh state of CeFeMgTi sorbent, CeO2, MgO and MgTiO3 structures were observed. But the new CeFeMgTisol sorbent before SO2 absorption, showed a separated MgO and TiO2 peak only. These differences in the sorption rates were discussed by the difference in the XRD pattern, surface area and pore volume.
Keywords: SO2 ; Sorbent; Ce; MgTiO3 ; MgO; TiO2
The effect of metal ions in MNaY-zeolites for the adsorptive removal of tetrahydrothiophene by Yun Ha Kim; Hee Chul Woo; Doohwan Lee; Hyun Chul Lee; Eun Duck Park (1291-1295).
The adsorptive removal of tetrahydrothiophene (THT) was carried out over transition metal ion-exchanged Na-Y zeolites. CuNa-Y, CoNa-Y, NiNa-Y and FeNa-Y were prepared by a conventional ion exchange method from Na-Y using the nitrate solutions of corresponding metals. N2 physisorption, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and X-ray diffraction were conducted to characterize adsorbents. The temperature programmed desorption (TPD) of THT was also perfomed to probe the interaction between the adsorbent and the THT. The crystal structure of Y-zeolite was completely destroyed in FeNa-Y, which resulted in a insignificant amount of adsorbed THT. The breakthrough capacity, which is defined as the amount of sulfur adsorbed on the adsorbent before detecting sulfur species by PFPD, decreased in the following order CuNa-Y>CoNa-Y>NiNa-Y>>FeNa-Y. For interaction between THT and adsorbent, a TPD peak appeared over CoNa-Y at the highest temperature, which implies that the strongest interaction can be made between THT and Co2+ in CoNa-Y.
Keywords: Adsorption; Tetrahydrothiophene; Zeolite; Ion-exchange; Fuel Cell
Photocatalytic reduction of hexavalent chromium (Cr(VI)) using rotating TiO2 mesh by Jaekyung Yoon; Eunjung Shim; Hyunku Joo (1296-1300).
An immobilized TiO2 electrode for photocatalytic hydrogen production is applied to reduce toxic Cr(VI) to non toxic Cr(III) in aqueous solution under UV irradiation. To overcome the limitation of powder TiO2, a novel technique of immobilization based on anodization was applied and investigated under various experimental conditions. The anodization was performed with three different electrolytes (single or mixed), and then the anodized samples were annealed under an oxygen stream. Among the three kinds of anodized/annealed TiO2 on Ti foil, Sample II (anodized at 20 V in 0.5% HF for 45 min at 5 °C, and annealed at 450 °C for 5 hr in ambient oxygen at a flow rate of 400 mL/min) was more effective for both Cr(VI) reduction than the other samples. Based on the electrolyte compositions, nanotubular TiO2 grown on Ti meshes was fabricated for the purpose of its light-harvesting ability and efficiency, where the anodized/annealed TiO2 on meshes were rotated in the center of the reactor and Cr(VI) could be effectively reduced at rotation speeds ranging from 0 to 64 rpm. In case of Sample II, it was found that up to 98 % of the Cr(VI) was reduced in 30 min at 64 rpm.
Keywords: Cr(VI) Reduction; Immobilized TiO2 ; Anodization; Rotating Mesh Type Reactor
Influences of humic acids and photoreactivation on the disinfection of Escherichia coli by a high-power pulsed UV irradiation by Eunyoung Lee; Hyejung Lee; Wonyoung Jung; Soonho Park; Dongjin Yang; Kisay Lee (1301-1307).
The characteristics of inactivation and photoreactivation of Escherichia coli by a high-power pulsed ultraviolet (PUV) irradiation and the influence of the humic acids on disinfection performance were investigated. The pulsed power source was operated at 2,400 V, with 200 J of energy being stored in a 100-μF capacitor. This energy dissipated in the xenon-filled flashlamp within 150 μs, generating a megawatt-level peak power per pulse. The light source was operated at 12 pulses per second (12 Hz). More than a 6-log reduction was achieved via 5 sec of irradiation at a distance of 20 cm, which corresponds approximately to a UV dose of 23 mJ/cm2. The inactivation efficiency decreased with increasing concentrations of humic acids (HA). At the distance of 20 cm, 10 ppm HA reduced the inactivation efficiency to 50%. UV absorption by HA and, in part, the growth-promoting effect of humic acids were implicated in reductions of inactivation performance in the presence of HA. After a disinfection procedure with PUV, the possibility of photoreactivation was greatly reduced and an additional reduction of approximately 1-log was also achieved during 8 h under visible light after inactivation with a UV dosage of 9.0 mJ/cm2 (3 sec at 30 cm). The extent of additional inactivation under visible light was reduced with increasing concentrations of humic acids in water.
Keywords: Disinfection; Pulsed-UV Irradiation; Xenon Flashlamp; Photoreactivation; Humic Acids
Production of dehydrated fuel ethanol by pressure swing adsorption process in the pilot plant by Jun-Seong Jeong; Byung-Uk Jang; Young-Ran Kim; Bong-Woo Chung; Gi-Wook Choi (1308-1312).
Fermented ethanol is gaining wide popularity as a car fuel additive. The pressure swing adsorption (PSA) process is attractive for the dehydration of bioethanol on the industrial scale, since its energy consumption is low and it is capable of producing a very pure product. 3 Å zeolite possesses micro-pores which, due to their small size, adsorb water molecules but not ethanol molecules. In this work, up to 2 kL/day of dehydrated ethanol (99.5% by weight) was successfully produced with 3 Å zeolite by the pressure swing adsorption process. The cycles of the PSA process were operated under the following variables: feed flow rate (27–62 Nm3/hr of 93.2% by weight), purge/feed ratio (30–24%), adsorption temperature (130–140 °C) and adsorption pressure (1.2 atm).
Keywords: Pressure Swing Adsorption; Fuel Ethanol; 3 Å Zeolite
Purification and partial characterization of milk-clotting enzyme extracted from glutinous rice wine mash liquor by Yanping Wang; Qiaoling Cheng; Zaheer Ahmed; Xiaoxue Jiang; Xiaojia Bai (1313-1318).
Glutinous rice wine mash liquor is a traditional food of south of China and its ability to coagulate the milk has been proved. The aim of this work was to extract milk-clotting enzyme from glutinous rice wine mash liquor. A partial purified extract of enzyme was obtained by fractional precipitation with (NH4)2SO4. The fractions obtained by precipitation, 40–90% possessed the milk-clotting activity (MCA) (145.72 U/mg). The 40–90% (NH4)2SO4 fraction was further purified by sephadex G-100 and DEAE-sephadex A-50 with MCA (4,360±50 U/mg), which was confirmed by SDS-PAGE that showed only one band with a molecular mass of 36.0 kDa. Highest MCA was attained at 36 °C. The enzyme was completely inactivated by heating for 20 min at 60 °C. The MCA increased with the decreasing of milk pH from 8.0 to 5.5, and it was active at the wide range of pH 1 to 7. The metal ions Mg2+, Ca2+, Ba2+, Mn2+, Al3+, Fe2+ had a very clear function to accelerate milk coagulation whereas Na+ and K+ decelerated the activity slightly. The curd effect of the milk-clotting enzyme has primarily been studied.
Keywords: Milk-clotting Enzyme; Activity; Purification; Glutinous Rice Wine Mash Liquor; Enzyme Properties
Analysis of methane production inhibition for treatment of sewage sludge containing sulfate using an anaerobic continuous degradation process by Tae-Young Jeong; Hyung-Keun Chung; Sung Ho Yeom; Suk Soon Choi (1319-1322).
The inhibition of methane production in the continuous anaerobic degradation process for the treatment of sewage sludge containing sulfate was investigated. Also, the competition between sulfate-reducing bacteria (SRB) and methane-producing bacteria (MPB) with COD/sulfate ratio was explained in terms of electron flow. The methane production rate was 0.07, 0.13, 0.24, 0.31 and 0.33 l-CH4 g-COD−1 when the initial COD/sulfate ratio was 3.3, 5.0, 6.7, 10 and 20, respectively. The numbers of SRB and MPB were counted after the continuous reactor reached steady state and the two bacteria showed opposite growth behaviors with COD/sulfate ratio. The inhibition by sulfate compounds was found to follow the uncompetitive model and inhibition constants were 24.57 and 87.99 mg l −1 for SRB and MPB, respectively. These results can be useful data for the efficient treatment of sewage sludge in a continuous anaerobic degradation process.
Keywords: Continuous Anaerobic Degradation; Inhibition of Methane Production; Uncompetitive Model
A bioreactor with an internal contactor for primary recovery of bovine serum albumin from yeast suspension by Sejoon Yoon; Huijun Sim; Jun Seok Kim; Suk-In Hong (1323-1327).
In this paper the internal contactor is a newly developed device for the primary recovery of protein from crude feedstock. Ion exchanges (DEAE-Streamline) are confined inside the internal contactor in a stirred tank. Interactions between the ion exchange in the internal contactor and protein (BSA) in yeast suspension have been studied. For better performance, two strategies are considered: to determine the ion conductivity of a simulated yeast suspension, and to select the optimum process time for adsorption. In this system, advantages of both batch adsorption and expanded bed adsorption were obtained. Furthermore, in denser cell concentration (50 g/L) where EBA cannot be operated, the primary recovery was carried out in 1–2 hr. The efficiency of yield is higher than 80% in this condition.
Keywords: Protein Recovery; Adsorption; BSA; Internal Contactor; Yeast Suspension
Effect of hydrotropes on solubility and mass transfer coefficient of lauric acid by Saghadevan Thenesh Kumar; Dhakshina Gnana Prakash; Nagaraja Nagendra Gandhi (1328-1333).
A comprehensive investigation on the solubility and mass transfer coefficient enhancement of lauric acid through hydrotropy has been undertaken. The solubility and mass transfer studies were carried out using hydrotropes such as sodium cumene sulfonate, sodium p-xylene sulfonate and sodium p-toluene sulfonate under a wide range of hydrotrope concentrations (0 to 3.0 mol/L) and different system temperatures (303 to 333 K). The effectiveness of hydrotropes was measured in terms of Setschnew constant K s and reported for all hydrotropes used in this study. The solubility data are also fitted in a polynomial equation as the function of hydrotrope concentration.
Keywords: Hydrotropy; Solubilization; Mass Transfer Coefficient; Separation
Application of [hmim][BF4] ionic liquid in reversed-phase simulated moving bed for the separation of 3- and 4-hydroxybenzoic acid by Thai-Hoang Le; Ju Weon Lee; Jeung Kun Kim; Yoon-Mo Koo (1334-1340).
In reversed-phase liquid chromatography (RP-LC), the separation of ionized compounds at neutral pH of the mobile phase is ineffective because these compounds easily become ionized and too hydrophilic to adsorb on the hydrophobic C18 stationary phase. The common method to separate ionized compounds in RP-LC is the usage of the ion pairing agent and the control of pH in the mobile phase. In this work, [hmim][BF4] ionic liquid was adopted as a mobile phase additive in reversed-phase simulated moving bed chromatography (RP-SMB) to overcome the problem mentioned above. The results showed that when 1.5 ml/l [hmim][BF4] was added to mobile phase, 3-hydroxy benzoic acid (3-HBA) and 4-hydroxy benzoic acid (4-HBA) were separated at neutral pH in the RP-SMB. In particular, purities of 3-HBA and 4-HBA products were 97.62% and 100%, respectively, and had a good agreement with simulation results.
Keywords: Ionic Liquid; Ionized Compounds; Mobile Phase Additive; Reversed-phase; Simulated Moving Bed; Continuous Chromatography
Surface modification and adsorption of eucalyptus wood-based activated carbons: Effects of oxidation treatment, carbon porous structure and activation method by Chaiyot Tangsathitkulchai; Yuvarat Ngernyen; Malee Tangsathitkulchai (1341-1352).
The incorporation of oxygen functional groups onto the surface of eucalyptus activated carbon and its surface chemistry were investigated as a function of oxidation conditions, carbon porous properties and carbon preparation method. Under all treatment conditions of increasing time, temperature and oxidant concentration, liquid oxidation with HNO3, H2O2 and (NH4)2S2O8 and air oxidation led to the increase of acidic group concentration, with carboxylic acid showing the largest percentage increase and air oxidation at the maximum allowable temperature of 350 °C produced the maximum content of both carboxylic acid and total acidic group. Nitric acid oxidation of chemically activated carbon produced higher total acidic content but a lower amount of carboxylic acid compared to the oxidized carbon from physical activation. The increased contents of acidic groups on oxidized carbons greatly enhanced the adsorption capacity of water vapor and heavy metal ions.
Keywords: Activated Carbon; Adsorption; Oxygen Functional Groups; Surface Modification; Carbon Porous Structure
Application of ionic liquids as mobile phase additives and surface-bonded stationary phase in liquid chromatography by Dandan Han; Minglei Tian; Dong Wha Park; Dae Ki Choi; Kyung Ho Row (1353-1358).
Ionic liquids (ILs) have gained wide recognition as novel solvents in chemistry. Their application in analytical chemistry, especially in separating analytes, is warranted due to their unique properties such as negligible vapor pressure, good thermal stability, tunable viscosity and miscibility with water and organic solvents, as well as good extractability for various organic compounds and metal ions. Recently, some new chromatographic separation media, formed by combining ILs on silica and polymer surface using covalently or non-covalently interaction, have been developed and applied to biological separation and environment analysis. This review will focus on some of the properties of ILs and their potential application as mobile phase modifier and surface-bonded stationary phase in high-performance liquid chromatography (HPLC) separation.
Keywords: Ionic Liquids; Modifier; Surface Bonded Stationary Phase; Chromatographic Separation
Absorption of carbon dioxide into glycidyl methacrylate solution with quaternary onium salts by Young-Sik Son; Sang-Wook Park; Dae-Won Park; Kwang-Joong Oh; Seong-Soo Kim (1359-1364).
Carbon dioxide was absorbed into organic solutions of glycidyl methacrylate (GMA) in a semi-batch stirred tank with a plane gas-liquid interface at 101.3 kPa to measure absorption rates of carbon dioxide, from which the reaction kinetics between carbon dioxide and GMA with quaternary onium salts as catalysts was obtained. The reaction rate constants were estimated by the mass transfer mechanism accompanied by the pseudo-first-order reaction method. An empirical correlation formula between the reaction rate constants and the solubility parameters of solvents such as toluene, N-methyl-2-pirrolidinone, and dimethyl sulfoxide was presented.
Keywords: Absorption; Carbon Dioxide; Gglycidyl Methacrylate; Quaternary Onium Salt
Salt-induced protein separation in an aqueous electrolyte solution by Sang Ha Choi; Young Chan Bae (1365-1372).
Liquid-liquid phase separations of aqueous ovalbumin and bovine serum albumin (BSA) solutions are reported experimentally for a wide range of solution conditions. The temperature-induced clouding of protein solutions, which signals the onset of liquid-liquid phase separation, provides a simple means of assessing the effect of solution conditions on the strength of protein interaction. Our results show that the effect of salts on protein interactions depends sensitively on the ionic composition of solution and the identities of both the cation and the anion of the added salts. The results are used to test and refine theoretical models for the interaction energy between macromolecules. A modified perturbed hard-sphere chain (MPHSC) model is employed to determine the interaction energy for solvation forces playing an important role in protein interactions and to predict the osmotic pressures of protein solutions.
Keywords: BSA; Ovalbumin; Liquid-liquid Phase Separation; Cloud-point Temperature (CPT); MPHSC
Vapor-liquid equilibrium in low pressure water+congener mixtures by Claudio Alonso Faúndez; Felipe Andrés Urbina; José Omar Valderrama (1373-1378).
Vapor-liquid equilibrium in binary water+congeners mixtures found in alcoholic distillation has been analyzed using the Peng-Robinson equation of state and one of the most popular modern mixing rules, the Wong-Sandler model. Accurate modeling of the concentration of congeners (substances different from ethanol and water) in the vapor phase is of special importance because these substances give some special characteristics of flavor and aroma to the final distilled spirit and also because their concentrations are regulated by law. In the Wong-Sandler mixing rules the van Laar model for the Gibbs excess energy has been used. The type of model used in this work is commonly used to correlate high pressure phase equilibrium and has not yet been used to treat complex low pressure water+congener mixtures as done in this work. Eight binary water+congeners mixtures have been considered for analysis. Comparison with available literature data is done and the accuracy of the model to correlate the pressure and the vapor phase concentration of the congeners is discussed. It is concluded that the model used is accurate enough for distillation analysis, modeling and simulation.
Keywords: Vapor-liquid Equilibrium; Alcoholic Mixtures; Equations of State; Wong-Sandler Mixing Rule
Adsorption of 2,4-dichlorophenol on metal-nitrate modified activated carbon by Kanagasabai Muruganandam Ponvel; Dhamodaran Kavitha; Kyung-Min Kim; Chang-Ha Lee (1379-1382).
To remove 2,4-dichlorophenol (2,4-DCP) from aqueous solution, the surface of the activated carbon was first treated with HCl and then the surface was modified by using various metal ions (Cu, Co, Fe, Ni, Zn, and Mg). Metal doping significantly enhanced the adsorption efficiency of activated carbon, an effect that was further increased by HCl treatment of the modified activated carbons. Of all the preparations, the zinc(II)-modified activated carbon with HCl treatment showed the highest adsorption capacity for 2,4-DCP. Analysis of the zinc(II)-modified activated carbon by SEM and BET showed a surface area and micropore volume of around 1,154.69 m2/g and 0.291 cm3/g, respectively, values about 20% higher than in the starting material. In the pH range of 2.0–11.0, the maximum uptake of 2,4-DCP from an initial concentration of 1,000 mg/L was 508 mg/g at pH 4.0.
Keywords: Activated Carbon Modification; 2,4-Dichlorophenol; Adsorption; Metal Ions; Metal-doped Activated Carbon
Sorption kinetics of carbon dioxide onto rubidium carbonate by Kyu-Suk Hwang; Sang-Wook Park; Dae-Won Park; Kwang-Joong Oh; Seong-Soo Kim (1383-1388).
Rubidium carbonate was used as an adsorbent to capture carbon dioxide from gaseous stream of carbon dioxide, nitrogen, and moisture in a fixed-bed to obtain the breakthrough data of CO2. Experiments were carried out at flow rates of carbon dioxide and nitrogen (5×10−6–35×10−6 m3/min), moisture (0.5×10−6–3.0×10−6 m3/h), amount of adsorbent (0.5×10−3–1.8×10−3 kg), mole fraction of carbon dioxide (0.03–0.22), and different sorption temperatures (323–353 K) at atmospheric pressure. The deactivation model in the non-catalytic heterogeneous reaction systems was used to analyze the sorption kinetics among carbon dioxide, carbonate, and moisture, employing the experimental breakthrough data that fit the deactivation model better than the adsorption isotherm models in the literature.
Keywords: Carbon Dioxide; Sorption; Breakthrough Curve; Deactivation Model; Rubidium Carbonate
Synthesis of hexagonal mesoporous aluminophosphate using Al dross by Govindasamy Chandrasekar; Jun Kim; Kwang-Seok You; Ji-Whan Ahn; Ki-Won Jun; Wha-Seung Ahn (1389-1394).
Hexagonal mesoporous aluminophosphate (HMA) materials were synthesized using cetyltrimethylammonium bromide as a structure directing agent and industrial aluminum dross powder or Al(OH)3 extracted from Al dross as an aluminum source at room temperature. XRD confirmed the presence of ordered mesostructures in all of the prepared HMA samples, and textural properties of the prepared samples were close to those of HMA prepared using pure chemicals. Uniform pore structure of the materials prepared using the industrial Al dross was confirmed by TEM, and N2 adsorption-desorption isotherms of the HMA samples showed type IV isotherms with surface area in the range of 410–560 m2/g. Cr-containing HMA (CrHMA) samples were also prepared using industrial aluminum dross as an aluminum source, which demonstrated virtually identical catalytic performances in liquid phase tetralin oxidation reaction to those obtained over a CrHMA catalyst prepared using pure chemicals.
Keywords: Aluminum Dross; Extraction; Hexagonal Mesoporous Aluminophosphate; Chromium
Measurement of radiative heat transfer coefficient in a high temperature circulating fluidized beds by Seung Chul Lee; Gui Young Han (1395-1398).
Experimental measurements of the radiative heat flux were made, and radiative heat transfer coefficients were determined for a circulating fluidized bed of sand particles of mean diameters of 137 and 264 microns. The bed used in this study measured 0.05 m in diameter. The heat transfer test section was 0.9 m long and located in the middle of CFB riser. Operating temperature was varied from 200–600 °C, and the gas velocity in the CFB riser varied from 6 m/s to 11 m/s. The suspension densities covered a range from 3 to 35 kg/m3. Time-averaged radiative heat flux was directly measured with a radiometer. Radiative heat flux and suspension emissivity showed strong dependence on the suspension density. Particle size effect on suspension emissivity was observed. Experimentally determined suspension emissivities, which ranged from 0.3 to 0.85, were in good agreement with the predicted suspension emissivity based on independent scattering theory. The radiative heat transfer coefficients were determined from the measured radiative heat fluxes and were found to be well predicted by the Stefan-Boltzmann law. It was also found that for a dilute system, the prediction of suspension emissivity by Hottel and Sarofim, in conjunction with independent scattering theory of Brewster and Tien, showed good agreement with experimentally determined suspension emissivity.
Keywords: Radiative Heat Transfer; Circulating Fluidized Bed; Emissivity
Prevention of bed agglomeration with iron oxide during fluidized bed incineration of refuse-derived fuels by Mi-Ran Kim; Jea-Keun Lee (1399-1404).
The present study was performed to evaluate the effect of iron oxide addition on the prevention of bed agglomeration during the fluidized bed incineration of refuse-derived fuels (RDFs) having different alkali contents. To investigate the extent of bed agglomeration as a function of the Fe2O3/(K2O+Na2O) molar ratio, a simulation was performed by using a thermodynamic equilibrium model. Based on this simulation, potassium (K) component exhibited a much higher affinity for iron (Fe) component than for silicon (Si) component, and the extent of agglomeration was remarkably reduced. Therefore, a small amount of iron oxide added to the bed effectively reduced the extent of bed agglomeration in the fluidized bed incineration process. Furthermore, the extent of agglomeration decreased as the molar ratio of Fe2O3/(K2O+Na2O) increased until unity was attained. In excess Fe2O3, no potassium silicate melts existed in the products, while the amount of sodium silicate melts remained constant.
Keywords: Fluidized Bed Incineration; Bed Agglomeration; Defluidization; Refuse-derived Fuels
CFD simulation of gas-solid bubbling fluidized bed containing FCC particles by Seyyed Hossein Hosseini; Rahbar Rahimi; Mortaza Zivdar; Abdolreza Samimi (1405-1413).
The hydrodynamics of a bubbling gas-solid fluidized bed of 57.4 μm FCC particles was simulated by using a state-of-the-art two-fluid model integrating the kinetic theory of granular flow for particulate phase stresses. The overestimation of the bed expansion was resolved by using a suitable scale factor in the drag model as suggested by McKeen and Pugsley (T.R. McKeen, T.S. Pugsley, Powder Technol., 129, 139 (2003)). This study showed that the method was appropriate in simulation of a gas-solid fluidized bed of Geldart A particles at high gas velocities (0.3 to 0.61 m/s). The reduction of computational time especially for simulation of large-scale systems was achieved. The time-averaged local voidage was compared with the experimental data and the trend of varying several parameters on the hydrodynamic of the bed was investigated. The simulation results showed both qualitative and quantitative agreement with the literature.
Keywords: Bubbling Fluidized Bed; FCC; CFD
CO2 capture from flue gases using a fluidized bed reactor with limestone by Fan Fang; Zhen-shan Li; Ning-sheng Cai (1414-1421).
The CO2 capture from flue gases by a small fluidized bed reactor was experimentally investigated with limestone. The results showed that CO2 in flue gases could be captured by limestone with high efficiency, but the CO2 capture capacity of limestone decayed with the increasing of carbonation/calcination cycles. From a practical point of view, coal may be required to provide the heat for CaCO3 calcination, resulting in some potential effect on the sorbent capacity of CO2 capture. Experiment results indicated that the variation in the capacity of CO2 capture by using a limestone/coal ash mixture with a cyclic number was qualitatively similar to the variation of the capacity of CO2 capture using limestone only. Cyclic stability of limestone only undergoing the kinetically controlled stage in the carbonation process had negligible difference with that of the limestone undergoing both the kinetically controlled stage and the product layer diffusion controlled stage. Based on the experimental data, a model for the high-velocity fluidized bed carbonator that consists of a dense bed zone and a riser zone was developed. The model predicted that high CO2 capture efficiencies (>80%) were achievable for a range of reasonable operating conditions by the high-velocity fluidized bed carbonator in a continuous carbonation and calcination system.
Keywords: CO2 Capture; Carbonation/Calcination Reactions; Fluidized Bed Reactor; Modeling; Sorbent