Korean Journal of Chemical Engineering (v.27, #4)

Recent advances in bioreactor engineering by Jian-Jiang Zhong (1035-1041).
A bioreactor is the core of biological processes. To design an appropriate bioreactor system for a particular bioprocess, intensive studies on the biological system, such as cell growth, metabolism, genetic manipulation, and protein or other product expression are needed to understand the cells’ requirement on their physical and chemical environments. It is also necessary to control and optimize the bioreactor environment via operating variables in order to favor the desired functions of cells and achieve cost-effective large-scale manufacture. This article briefly describes fundamental design principles and new types of bioreactors such as centrifugal impeller and wave bioreactors. Bioreactor operation factors and modes including mixing, oxygen supply, shear force, fed-batch, and perfusion cultures are discussed. The trends in bioreactor engineering are also briefly shown.
Keywords: Bioreactor Engineering; Bioprocess; Scale-up; Bioreactor Operation Strategy; Process Variables

The market for protein-drugs has steadily increased due their increased use as alternatives to traditional small molecule drugs. While some therapeutic proteins have been produced in microbial systems, mammalian cell systems such as Chinese hamster ovary (CHO) cells are widely used as the host cell system. To increase the efficiency of producing therapeutic proteins, many researchers have attempted to solve the critical problems that occur in mammalian cell systems. As a result, several serum-free media and advanced culture methods have been developed, and protein productivity has increased considerably through the development of efficient selection methods. However, the prevalence of apoptosis during mammalian cell culture still remains a significant problem. Based on the understanding of apoptotic mechanisms and related proteins, anti-apoptotic engineering has steadily progressed. In this study, we review the strategies that have been developed for high-level production of recombinant proteins in the CHO cell system via a selection of clones, target-gene amplification, optimization of culture systems and an inhibition of apoptosis through genetic modification.
Keywords: Mammalian Cell; Chinese Hamster Ovary Cell; Therapeutic Proteins; Apoptosis; Recombinant Proteins; Productivity

Numerical modeling of volatile organic compound emissions from multi-layer dry building materials by Baoqing Deng; Songming Tang; Jeong Tai Kim; Chang Nyung Kim (1049-1055).
This paper presents a mathematical model capable of simulating VOCs emission from a multi-layer material. The analytical solutions of the concentration in the air and the emission rate are obtained by Laplace transform and are validated through experiment. The influences of parameters of multi-layer material on the emission of VOCs are investigated in detail. Results show that the inner layer may act as a sink or a source of the top layer, depending on their initial concentrations and partition coefficients. For the case of the inner layer being a source of the top layer, the top layer becomes a barrier layer, reducing the emission rate of VOCs from the source. A low diffusion coefficient and a large thickness may promote the effect of the barrier on the emission rate, which helps to maintain better air quality in an indoor environment. The present solution is a longitudinal extension of a single layer problem, while the emission from multi-source is a transverse extension of a single layer problem.
Keywords: VOC Emission; Multi-layer; Dry Building Material; Exact Solution

Experimental evaluation of a modified fully thermally coupled distillation column by Kyu Suk Hwang; Byoung Chul Kim; Young Han Kim (1056-1062).
A modified fully thermally coupled distillation column replacing the conventional distillation system is introduced, and its performance is experimentally evaluated for the stable operation of the column. The existing distillation system is modified to an energy-efficient distillation column for the reduction of investment cost and energy requirement. The experiment is conducted for the separation of methanol, ethanol and n-propanol mixture using a 4-in sieve tray column. The temperatures at seven different locations of the column are measured to monitor the column operation, and the measurements indicate that the column is stably operable. The stable operation proves that neither compressor nor pump is necessary for the vapor or liquid flow between tray sections. The experimental result is compared with that of the HYSYS simulation to show how satisfactory the separation is. The modeling of temperature variation provides a successful prediction of the temperature variation.
Keywords: Thermally Coupled Distillation; Energy-efficient Distillation; Multi-component Distillation; Experimental Evaluation

Effective management of district heating networks depends upon the correct forecasting of heat consumption during a certain period. In this work short-term forecasting for the amount of heat consumption is performed first to validate the three forecasting methods: partial least squares (PLS) method, artificial neural network (ANN), and support vector regression (SVR) method. Based on the results of short-term forecasting, one-week ahead forecasting was performed for the Suseo district heating network. Data of heat consumption and ambient temperature during January and February in 2007 and 2008 were employed as training elements. The heat consumption estimated was compared with actual one in the Suseo area to validate the forecasting models.
Keywords: Partial Least Squares; Artificial Neural Network; Supporting Vector Regression; Heat Forecasting

Process characteristics of pretreatment system under H2S circumstance for bio-gas micro gas turbine power generation by Kwang-Beom Hur; Sang-Kyu Rhim; Jung-Keuk Park; Jae-Hoon Kim (1072-1075).
As distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation such as Micro Gas Turbine Power system would be interconnected to the existing grids. This paper describes the results for the mechanical and environmental tests of pretreatment system for Livestock bio-energy Micro Gas Turbine (MGT) Combined Heat & power. It is very important for bio-energy pretreatment system to design MGT power generation. Especially, mechanical and corrosion characteristics of H2S removal system make differences between parent and weldment material, notch existence/non-existence and air/H2S conditions. As a result, the life of pipelines needs to be maintained and fit for the operating period. Based on actual situations, the tension test of pipe welding-parts is carried out varying the exposure time to hydrogen sulfide and a fatigue resistance test is also performed inserting a notch into the pipe welding part, being exposed to the hydrogen sulfide environment for 180, 360, 540, 720 hours.
Keywords: Micro Gas Turbine (MGT); Bio-energy; Fatigue; H2S Removal System; Pretreatment System

The radial migration of a single neutrally buoyant particle in Poiseuille flow is numerically investigated by direct numerical simulations. The simulation results show that the Segré and Silberberg equilibrium position moves towards the wall as the Reynolds number increases and as the particle size decreases. At high Reynolds numbers, inner equilibrium positions are found at positions closer to the centerline and move towards the centerline as the Reynolds number increases. At higher Reynolds numbers, the Segré and Silberberg equilibrium position disappears and only the inner equilibrium position exists. We prove that the inner annuluses in the measurements of Matas, Morris & Guazzelli (J. Fluid Mech. 515, 171–195, 2004) are not transient radial positions, but are real equilibrium positions. The results on the inner equilibrium positions and unstable equilibrium positions are new and convince us of the existence of multiple equilibrium radial positions for neutrally buoyant particles.
Keywords: Segré and Silberberg Effect; Particle Migration; Suspensions; Multiple Equilibrium Positions; Fluid-particle Interaction

Surface functionalization of SBA-15 particles for ibuprofen delivery by Dae Hyun Hwang; Deokkyu Lee; Hosub Lee; Dongcheol Choe; Sang Hoon Lee; Kangtaek Lee (1087-1092).
We have synthesized SBA-15 particles and functionalized their surface with different functional groups (amine, diamine, and sulfonic acid groups) to use them as carrier materials in drug delivery. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption, and zeta potential measurements were used to characterize the synthesized particles. After surface functionalization, the surface of the sulfonic acid-functionalized particles was more acidic than that of the other particles. Using ibuprofen as a model drug, we found that the release rate increased at higher pH. Furthermore, the particles with the sulfonic acid groups exhibited higher release rate than those with the amine and diamine groups. We explained the difference in the release rate using different electrostatic interaction between drug and particle surface that was caused by the surface functionalization. These results should enable design of drug carrier materials based on the SBA-15 particles with the desired release rate.
Keywords: SBA-15 Particles; Mesoporous; Surface Functionalization; Ibuprofen; Release

Methanol synthesis from CO/H2 and CO2/H2 was carried out at atmospheric pressure over Cu/ZnO/Al2O3 catalyst. The formation and variation of surface species were recorded by in situ FT-IR spectroscopy. The result revealed that both CO and CO2 can serve as the primary carbon source for methanol synthesis. For CO/H2 feed gas, only HCOO-Zn was detected; however, for CO2/H2, both HCOO-Zn and HCOO-Cu were observed, and without CH3O-Cu. HCOO-Zn was the key intermediate. A scheme of methanol synthesis and reverse water-gas shift (RGWS) reaction was proposed.
Keywords: Methanol Synthesis; Mechanism; In Situ; FT-IR

4-Lump kinetic model for vacuum gas oil hydrocracker involving hydrogen consumption by Sepehr Sadighi; Arshad Ahmad; Mehdi Rashidzadeh (1099-1108).
A 4-lump kinetic model including hydrogen consumption for hydrocracking of vacuum gas oil in a pilot scale reactor is proposed. The advantage of this work over the previous ones is consideration of hydrogen consumption, imposed by converting vacuum gas oil to light products, which is implemented in the kinetic model by a quadratic expression as similar as response surface modeling. This approach considers vacuum gas oil (VGO) and unconverted oil as one lump whilst others are distillate, naphtha and gas. The pilot reactor bed is divided into hydrotreating and hydrocracking sections which are loaded with different types of catalysts. The aim of this paper is modeling the hydrocracking section, but the effect of hydrotreating is considered on the boundary condition of the hydrocracking part. The hydrocracking bed is considered as a plug flow reactor and it is modeled by the cellular network approach. Initially, a kinetic network with twelve coefficients and six paths is considered. But following evaluation using measured data and order of magnitude analysis, the three route passes and one activation energy coefficient are omitted; thus the number of coefficients is reduced to five. This approach improves the average absolute deviation of prediction from 7.2% to 5.92%. Furthermore, the model can predict the hydrogen consumption for hydrocracking with average absolute deviation about 8.59% in comparison to those calculated from experimental data.
Keywords: Vacuum Gas Oil; Hydrotreating; Hydrocracking; Lump Kinetic Model; Hydrogen Consumption

Parameter effect on photocatalytic degradation of phenol using TiO2-P25/activated carbon (AC) by Sze-Mun Lam; Jin-Chung Sin; Abdul Rahman Mohamed (1109-1116).
P25 powder embedded and TiO2 immobilized on activated carbon (TiO2-P25/AC) was prepared by P25 powder modified sol-gel and dip-coated method. The photocatalysts were characterized by XRD, BET, SEM and their photocatalytic activities were evaluated through phenol degradation in a fluidized bed photoreactor. The addition of P25 in the photocatalysts could significantly enhance the photocatalytic activity, and the optimum loading of P25 was 3 g L−1. The operating parameter results indicated that the optimum pH for phenol degradation was 5.2; the effect of air flow rate gave an optimal value of 2 L min−1; the increasing of UV light intensity led to an increase of degradation efficiency due to more photons absorbed on the surface of the photocatalyst. The kinetics of the phenol degradation fitted well with the Langmuir-Hinshelwood kinetics model. Finally, the photocatalytic ability of TiO2-P25/AC was reduced only 10% after five cycles for phenol degradation.
Keywords: TiO2-P25/AC; Phenol; Modified Sol-gel; Photocatalytic Degradation; Langmuir-Hinshelwood Model

The performance of V2O5/TiO2-based commercial SCR catalyst for the oxidation of gaseous elemental mercury (Hg0) with respect to reaction conditions was examined to understand the mechanism of Hg0 oxidation on SCR catalyst. It was observed that a much larger amount of Hg0 adsorbed on the catalyst surface under oxidation condition than under SCR condition. The activity of commercial SCR catalyst for Hg0 oxidation was negligible in the absence of HCl, regardless of reaction conditions. The presence of HCl in the reactant gases greatly increased the activity of SCR catalyst for the oxidation of Hg0 to oxidized mercury (Hg2+) such as HgCl2 under oxidation condition. However, the effect of HCl on the oxidation of Hg0 was much less under SCR condition than oxidation condition. The activity for Hg0 oxidation increased with the decrease of NH3/NO ratio under SCR condition. This might be attributed to the strong adsorption of NH3 prohibiting the adsorption of HCl which was vital species promoting the oxidation of Hg0 on the catalyst surface under SCR condition.
Keywords: Mercury Oxidation; Selective Catalytic Reduction; Hydrogen Chloride; Elemental and Oxidized Mercury

Water-gas shift reaction over supported Pt and Pt-CeOx catalysts by Yong Tae Kim; Eun Duck Park (1123-1131).
A comparison study was performed of the water-gas shift (WGS) reaction over Pt and ceria-promoted Pt catalysts supported on CeO2, ZrO2, and TiO2 under rather severe reaction conditions: 6.7 mol% CO, 6.7 mol% CO2, and 33.2 mol% H2O in H2. Several techniques—CO chemisorption, temperature-programmed reduction (TPR), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES)—were employed to characterize the catalysts. The WGS reaction rate increased with increasing amount of chemisorbed CO over Pt/ZrO2, Pt/TiO2, and Pt-CeO x /ZrO2, whereas no such correlation was found over Pt/CeO2, Pt-CeO x /CeO2, and Pt-CeO x /TiO2. For these catalysts in the absence of any impurities such as Na+, the WGS activity increased with increasing surface area of the support, showed a maximum value, and then decreased as the surface area of the support was further increased. An adverse effect of Na+ on the amount of chemisorbed CO and the WGS activity was observed over Pt/CeO2. Pt-CeO x /TiO2 (51) showed the highest WGS activity among the tested supported Pt and Pt-CeOx catalysts. The close contact between Pt and the support or between Pt and CeO x , as monitored by H2-TPR, is closely related to the WGS activity. The catalytic stability at 583K improved with increasing surface area of the support over the CeO2- and ZrO2-supported Pt and Pt-CeO x catalysts.
Keywords: Water-gas Shift; Pt; Ceria; Support; Fuel Cell

Steam reforming of liquid petroleum gas over Mn-promoted Ni/γ-Al2O3 catalysts by Jae Hyun Park; Doohwan Lee; Hyun Chul Lee; Eun Duck Park (1132-1138).
Three different Mn-promoted Ni/γ-Al2O3 catalysts, Mn/Ni/γ-Al2O3, Mn-Ni/γ-Al2O3 and Ni/Mn/γ-Al2O3, were prepared and applied to the steam reforming of liquid petroleum gas (LPG) mainly composed of propane and butane. For comparison, Ni/γ-Al2O3 catalysts containing different amount of Ni were also examined. In the case of the Ni/γ-Al2O3 catalysts, 4.1 wt% Ni/γ-Al2O3 showed the stable catalytic activity with the least amount of coke formation. Among the various Mn-promoted Ni/γ-Al2O3 catalysts, Mn/Ni/γ-Al2O3 showed the stable catalytic activity with the least amount of coke formation. It also exhibited a similar H2 formation rate compared with Ni/γ-Al2O3. Several characterization techniques—N2 adsorption/desorption, X-ray diffraction (XRD), CO chemisorptions, temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and CHNS analysis—were employed to characterize the catalysts. The catalytic activity increased with increasing amount of chemisorbed CO for the Mn-promoted Ni/γ-Al2O3 catalysts. The highest proportion of Mn4+ species was observed for the most stable catalyst.
Keywords: Steam Reforming; Nickel; Manganese Oxides; Hydrogen; LPG

Micronization and characterization of drug substances by RESS with supercritical CO2 by Jung-Teag Kim; Hong-Lyong Kim; Chang-Sik Ju (1139-1144).
A RESS (rapid expansion of supercritical solution) process for the preparation of ultra-fine drug particles with no organic solvent has been developed with supercritical CO2. Three drug substances with different solubility in supercritical CO2 were used, and orifice disks and capillary tubes were adapted as an expansion device. The solubilities of drug substances in supercritical CO2 and the effects of various operating parameters on the characteristics of the particles prepared by RESS process were experimentally investigated. The solubility of the drug substance in supercritical CO2 had a major effect on the average diameter of the particle prepared by RESS process, and the particle diameter decreased with the solubility for all the drugs and operating conditions. The particle diameter also decreased with preexpansion temperature and increased with the hole diameter of the orifice nozzle and aspect ratio (L/D) of the capillary tube.
Keywords: RESS; Drug Substances; Micronization; Solubility; Supercritical

The electroless plating of Cu-Ni-P alloy onto cotton fabrics by Arezoo Afzali; Vahid Mottaghitalab; Mahmood Saberi Motlagh; Akbar Khodaparast Haghi (1145-1149).
The objective of this study is to apply the electroless plating of Cu-Ni-P alloy on cotton fabrics to the preparation of conductive fabrics. The alloy composed of infinit small amount of nickel and phosphorus particle originated from sodium hypophosphite and nickel sulphate respectively as reducing agent and hypophosphite oxidation accelerator. Electroless plating of Cu-Ni-P alloy on cotton fabrics and effect of plating on the physical and mechanical properties of alloy coated fabrics as well as electromagnetic interference (EMI) shielding effectiveness were reported in detail. In this research highly washing and abrasion durable conductive fabrics obtained with supreme shielding effectiveness.
Keywords: Electroless Plating of Cu-Ni-P Alloy; Cotton Fabric; Surface Morphology

Experimental and computational fluid dynamic (CFD) modeling studies have been performed on mixing characteristics of a new modified helical ribbon impeller in a viscous medium. A novel arrangement for the multiple reference frame (MRF) technique was proposed and the modeling results were compared with those of conventional MRF selecting method. Calculations were performed to study the effects of several parameters: axial flow number, axial circulation time, impeller clearance, and power consumption. The higher performance of the modified impeller has been proven in terms of axial flow number and axial circulation time. The results showed that significant improvement in mixing performance can be obtained at a higher impeller clearance with the modified impeller employed. In addition, the power consumption by the new impeller has been compared with that of the classic one. The CFD-predicted flow patterns generated by the impellers were used to explain the higher performance of the modified impeller. In addition, the results reveal that the CFD-predicted particle volume fractions at various axial distances from the tank bottom are reasonably in agreement with the experimental observations.
Keywords: CFD; Helical Ribbon; Hydrodynamics; Mixing; Visualization Mathematical Modeling

The kinetic analysis of wood degradation in supercritical methanol has been studied by a nonisothermal weight loss technique. The weight loss data according to degradation temperature have been analyzed using two integral methods based on Arrhenius form to obtain the kinetic parameters, such as apparent activation energy and overall reaction order. The experiments were carried out for three heating rates of 5.2, 11.6 and 16.3 °C/min. It was found that there are the distinct mass changes over the temperature range of 260–370 °C for all three heating rates, and the weight loss curves were displaced to higher temperatures as increasing of heating rate. The activation energies of wood degradation in supercritical methanol were 73.5–74.5 kJ/mol and 45.2–48.8 kJ/mol, and the reaction orders were 0.59–0.64 and 0.25, depending on the mathematical approach taken in the analysis and the heating rate.
Keywords: Kinetic Analysis; Supercritical Methanol; Degradation; Wood

The influence of fast pyrolysis condition on biocrude-oil yield and homogeneity by Hang Seok Choi; Yeon Seok Choi; Hoon Che Park (1164-1169).
The characteristics of biocrude-oil yield and quality have been investigated by changing fast pyrolysis condition for woody biomass. For the fast pyrolysis of woody biomass, a bubbling fluidized bed reactor having cylindrical shape was devised and a commonly used spiral quenching system was applied to the condensation of volatile gases from the reactor. Biomass feeding rate, nitrogen flow rate, pyrolysis temperature and particle size of woody biomass were changed to study the characteristics of volatile generation, its condensation and the homogeneity of the condensed biocrude-oil. In particular, the microscopic visualization of the collected biocrude-oil and its evaluation method by image processing technique were made for quantifying the homogeneity of the oil. From the results, the effects of heating and fluidization condition on the biocrude-oil yield and the homogeneity were fully scrutinized in a bubbling fluidized bed reactor. Also, the physical and chemical characteristics of the collected biocrude-oil were determined through various analysis techniques.
Keywords: Biocrude-oil; Biomass; Fast Pyrolysis; Fluidized Bed; Heat Transfer

Response surface methodology coupled with central composite design (CCD) was used to investigate the effects of operating variables, namely, coil outlet temperature (COT), flow rate and steam ratio, on the yield of light olefins (ethylene and propylene) in thermal cracking of heavy liquid hydrocarbon. From the CCD studies the effects of COT and flow rate were concluded to be the key factors influencing the yield of light olefins. Based on this experimental design, two empirical models, representing the dependence of ethylene and propylene yields on operating conditions, were developed. The single maximum response of ethylene and propylene yields and simultaneous maximization of both responses have also been obtained at the corresponding optimal independent variables. The results of the multi-response optimization could be used to find the suitable operating conditions.
Keywords: Thermal Cracking; Response Surface Methodology; Heavy Liquid Hydrocarbon

Thiosalicylic acid as a devulcanizing agent for mechano-chemical devulcanization by Pipat Thaicharoen; Patchanita Thamyongkit; Sirilux Poompradub (1177-1183).
A mechano-chemical devulcanization process for vulcanized natural rubber (NV) was investigated. Thiosalicylic acid was used as a test devulcanizing agent in comparison to diphenyl disulfide as the reference. The optimum condition for devulcanization of NR vulcanizates (NVs) was found to be grinding of the NV and subsequent mixing with a selected devulcanizing agent at 140°C for 30 min. The degree of devulcanization was indicated by using sol-gel fractions of the devulcanized rubber (DVR). Revulcanized rubber was made by using virgin natural rubber (NR) containing DVR at different ratios. The tensile strength of the DVR/NV composite, after revulcanization, decreased by 5–10%, while the elongation at brake was improved by 5–10% at a DVR content of 5–15%. Devulcanization of industrial truck tires, as a typical sample of industrial products, was also demonstrated for the practical application of this technique.
Keywords: Devulcanized Rubber; Devulcanization; Devulcanizing Agent; Vulcanization; Mechano-chemical Devulcanization

Mesoporous MCM-41 was synthesized at room temperature using tetraethoxysilane (TEOS) with cetyltrimethylammonium bromide (CTAB) and employed as an effective adsorbent for the adsorption of methylene blue dye from aqueous solution. The as-synthesized MCM-41 was calcined at 250 and 550°C to study the relation between the surface area and pore volume with surfactant removal. The synthesized MCM-41 was characterized using thermo gravimetric analysis (TGA), X-ray diffraction (XRD) patterns, nitrogen adsorption/desorption isotherms and Fourier transform infrared (FT-IR) spectroscopy. The MCM-41 calcined at 550°C showed higher surface area (1,059 m2 g−1) with pore volume of 0.89 ml g−1 and was used for the investigation of adsorption isotherms and kinetics. The experimental results indicated that the Freundlich and Redlich-Peterson models expressed the adsorption isotherm better than the Langmuir model. In addition, the influence of temperature and pH on adsorption was also investigated. The decrease in temperature or the increase in pH enhanced the adsorption of dye onto MCM-41. A maximum adsorption capacity of 1.5×10−4 mol g−1 was obtained at 30°C. The kinetic studies showed that the adsorption of dye on MCM-41 follows the pseudo-second-order kinetics.
Keywords: Adsorption; Methylene Blue; MCM-41; Isotherm; Kinetic

A computational fluid dynamics model that predicts the sedimentation of activated sludge in a circular secondary clarifier with activated sludge is developed. The axisymmetric single-phase flow is simulated by using a CFD code that has been written with Intel Visual Fortran. First, sludge withdrawing by suction-lift in the near-bottom region of the clarifier is simulated using suction at the bottom of clarifier. The flow and settling processes are simulated using k-e turbulence model on a two-dimensional and orthogonal grid. A convection-dispersion equation that is extended to incorporate the sedimentation of activated sludge in the field of gravity is used. The computational domain includes the sludge blanket where the viscosity is affected by the rheological behavior of the sludge. Experimental data provided by Weiss et al. show that the relationship between shear stress and shear rate follows the Casson law for the shear rates lower than 50 s-1. Plastic viscosity of activated sludge is not removed from the concentration diffusion, so using regular non-Newtonian models leads to overestimation of blanket height. Modified Casson model is introduced to overcome the blanket height overestimation problem. Results show that the local sludge distribution in the clarifier has excellent agreement with concentration profile measurements of Weiss et al., for different treatment plant loadings. Alternative sludge withdrawing methods include withdrawing from pipes position at the bottom of clarifier and withdrawing by using sink terms in governing equations are used. Results show that the first withdrawing method gives less error comparing to these withdrawing methods.
Keywords: Turbulence; Secondary Clarifier; Concentration; Activated Sludge; Modified Casson Model

Drag reduction in co-current down flow packed column using xanthan gum by Iyyaswami Regupathi; Ponnan Ettiyappan JagadeeshBabu; M. Chitra; Thanapalan Murugesan (1205-1212).
Drag reduction is one of the most important techniques for reducing energy consumption in a packed bed contactor. The present work involves an experimental investigation on flow regime transition for air-water system with and without drag reducing agent (DRA), two-phase pressure drop, friction factor and drag reduction using xanthan gum as DRA. Drag reduction was quantified from the two-phase pressure drop data. Based on the present observations it was found that the percentage drag reduction increases with an increase in the concentration of DRA and it is only effective in the range of 300 ppm to 800 ppm. The experimental results indicate that a maximum of 80% drag reduction was achievable using xanthan gum (800 ppm) as DRA. Furthermore, the experimental data were validated with the available literature correlations.
Keywords: Drag Reduction; Packed Bed Down Flow; Two-phase Friction Factor and Xanthan Gum

The effect of an ion-exchange membrane combined with a dimensionally stable anode on the oxidation rate of organic brightener and electroplating performance was investigated. The oxidation rate of the brightener was measured by analyzing the total organic carbon content in the plating solution. The oxidation rate increased rapidly as the current density increased when there was no ion-exchange membrane. However, when an ion-exchange membrane was present, the oxidation rate of the brightener was significantly reduced by Neosepta CMX and CMS cation-exchange membranes. The CMS monovalent selective cation-exchange membrane in particular was the most effective in reducing organic brightener oxidation, regardless of the current density. Through-hole printed circuit board electroplating was more precise with an ion-exchange membrane than with no membrane. These results confirmed that the electroplating performance was improved by the presence of an ion-exchange membrane on the anode, effectively inhibiting the oxidation of organic brightener.
Keywords: Printed Circuit Board; Electroplating; Brightener; Oxidation; Ion-exchange Membrane

Experiments were conducted to evaluate the effect of adding ethanol amine during the preparation of a V/TiO2 catalyst to remove nitrogen oxide (NO x ) by selective catalytic reduction (SCR). The catalyst added monoethanolamine (MEA) had the highest NO x conversion among all the neutralization reagents tested, and the optimum MEA concentration was determined to be 10%. The catalyst-added MEA had a large amount of lattice oxygen, which was determined in the O2 on/off experiment. In addition, it also displayed a high reoxidation rate in the O2 reoxidation experiment. In the XPS analysis, the superior redox properties of the catalyst-added MEA were shown to be caused by the presence of Ti+3, a non-stoichiometric species.
Keywords: SCR; Monoethanolamine; Non-stoichiometric; V/TiO2 ; Redox

The effect of mode of sparging gas on the mixing parameters of an internal loop airlift bioreactor was investigated. Two bioreactors of identical volume of 14×103 cm3 and the optimum riser to downcomer cross sectional area ratio of 0.6 were studied. In one bioreactor a gas sparger was located in the draft tube and in the annulus in another. Liquid mixing characteristics, i.e., mixing time and circulation time, were employed to describe the performance of the bioreactors. The tracer injection method was used to determine the mixing parameters. A mathematical modeling based on the tanks-in-series model was employed to characterize the hydrodynamics behavior of the bioreactors. Matlab 7.1 software was used to solve the model equations in the Laplace domain and determine the model parameter, the number of stages. A comparison between the simulation results and experimental data showed that the applied model can accurately describe the behavior of the bioreactors. The results showed that when the gas sparger was located in the draft tube, the liquid mixing time, circulation time, and the number of stage were less than while the gas sparger was located in annulus. This is due to more wall effects, more energy losses and pressure drop in the case of gas injection in the annulus.
Keywords: Airlift Bioreactor; Circulation Time; Gas Sparger; Liquid Mixing Time; Mathematical Modeling; Tank-in-series Model

Modeling and optimization of cutinase production by recombinant Escherichia coli based on statistical experimental designs by Jianghua Li; Long Liu; Jing Wu; Jun Sun; Guocheng Du; Jian Chen; Wenyi Tao (1233-1238).
Statistics-based experiment designs were used to optimize the culture medium (glucose, yeast extract, IPTG, tween-60, and CaCl2) for cutinase production by recombinant Escherichia coli. A 25-1 fractional factorial design augmented with center points revealed that glucose, yeast extract, and IPTG were the most significant factors, whereas the other factors were not important within the levels tested. The method of steepest ascent was used to approach the proximity of optimum, followed by a central composite design to develop a response surface for culture condition optimization. The optimum culture medium for cutinase production was found to be: glucose 33. 92 g/L, yeast extract 30.92 g/L, and IPTG 0.76 g/L. A cutinase production of 145.27±1.5 U/mL, which was in agreement with the prediction, was observed in triplicate verification experiments. The results obtained here verified the effectiveness of the applied methodology and may be helpful for cutinase production on an industrial scale.
Keywords: Cutinase; Recombinant Escherichia coli ; Optimization; Statistical-based Experimental Design

Copper biosorption by Myriophyllum spicatum: Effects of temperature and pH by Guoxin Li; Peiying Xue; Changzhou Yan; Qingzhao Li (1239-1245).
Using submerged aquatic plants is a cheap and clean technique to remediate heavy metal water pollution at low concentrations. Biosorption of Cu(II) ions by fresh tissues of Myriophyllum spicatum, a submerged aquatic plant, was characterized in an artificial solution system under different values of contact time, temperature and pH in this paper. Cu(II) biosorption was fast and equilibrium was attained within 20 min. The equilibrium biosorption data were analyzed using three widely applied isotherm models: Langmuir, Freundlich and Redlich-Peterson isotherm. Langmuir isotherm parameters obtained from the three Langmuir linear equations by using linear method were dissimilar, except when the non-linear method was used. Best fits were yielded with Langmuir and Redlich-Peterson isotherms (R2=0.961–0.992 and 0.990–0.998, respectively). The saturated monolayer biosorption capacity of M. spicatum for Cu(II) at 298 K was calculated to be 0.19 mmol/g. The biosorption capacity of M. spicatum for Cu(II) increased with increasing pH, and the resulting isotherms were well described by Langmuir and extended Langmuir models (R2=0.931–0.993 and 0.961, respectively). The comparison of calculated q e and experimental q e values showed that the extended Langmuir model had a better simulation for Cu(II) biosorption by M. spicatum than the Langmuir isotherm model. FT-IR was used to characterize the interaction between M. spicatum and Cu(II), with the results indicating that carboxyl groups played an important role in Cu(II) binding.
Keywords: Aquatic Plant; Copper; Biosorption; Langmuir Isotherm Forms; pH

Efficient glutathione production by high-cell-density cultivation of Candida utilis was investigated. A series of batch glutathione fermentations were carried out and the optimal initial glucose concentration was found to be about 26 g/L. Then, fed-batch fermentation under diverse feeding strategies was used to enhance glutathione production with a total glucose concentration of 150 g/L. Constant glucose feeding strategy cannot meet the requirement of cells at the late period of feeding, while exponential glucose feeding strategy cannot satisfy the needs of cells at the beginning of feeding. Based on the results above, a polynomial glucose feeding strategy was developed to provide enough glucose for cells along with the cultivation, under which both the cell and glutathione productivity were satisfactorily improved. Furthermore, fed-batch fermentation under this strategy with a total glucose concentration of 200 g/L was successfully performed, the dry cell weight and glutathione concentration reached 91.2 g/L and 825 mg/L, respectively.
Keywords: Glutathione; Candida utilis ; Fed-batch Fermentation; High-cell-density Cultivation

Early withering and premature flower fall are a growing menace to the cut flower industry, the reasons of which were considered to be varied from loss of water uptake, bacterial proliferation, decay in tap water etc. In the present study, we identified the bacterial biofilm formation by Enterobacter sp. and subsequent water uptake blockage as the root cause of early withering in cut flowers using Chrysanthemum, Yellow Daisy and Maroon Rose as model plants. The biofilm-forming Enterobacter sp was identified by 16 S rDNA sequencing data. Studies on biofilm were conducted by using field emission scanning electron microscope electron back scattering diffraction (FE-SEM-EBSD), Atomic force microscopy (AFM) and fluorescence microscopy. In vitro and in vivo studies were conducted with different antimicrobials to prevent biofilm formation in both conditions. Most antimicrobials were toxic to plants, but we found citric acid 1,000 μg/ml and calcium hypochlorite 50 μg/ml to be most effective in preventing biofilm formation and extending the vase life of cut flowers. We studied the synergistic action of different combinations in vivo and suggest citric acid 1,000 μg/mL, Ca hypochlorite 50 μg/mL and glucose 1,000 μg/mL as the best combination to be used for prolonging vase life of cut flowers from 10 days (non-treated) to 30 days (treated).
Keywords: Water Uptake; Cut Flower; Withering; Enterobacter sp.; Biofilm

Extraction of rare earths using mixtures of sec-octylphenoxy acetic acid and organophosphorus acids by Naizhong Song; Xiaowei Zhao; Qiong Jia; Weihong Zhou; Wuping Liao (1258-1261).
The extraction of rare earths from nitrate medium using three organophosphorus acids, 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEHEHP), di-(2-ethylhexyl) phosphoric acid (D2EHPA), bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272), and their mixtures with sec-octylphenoxy acetic acid (CA12) has been studied in detail. The mixtures have different extraction effects on various rare earths. Synergistic extraction effects are only found when light rare earths and yttrium (III) are extracted with mixtures of D2EHPA and CA12. The possibilities of separating the rare earths with these mixtures are investigated according to the extractabilities. It is feasible and advantageous to separate yttrium (III) from the lanthanoids (III) with HEHEHP + CA12 and D2EHPA+CA12 mixtures at proper extractant ratios. The separation of yttrium (III) from heavy rare earths is also possible with mixtures of Cyanex272 and CA12.
Keywords: Extraction; Rare Earths; Organophosphorus Acids; sec-Octylphenoxy Acetic Acid; Separation

To determine the volatile compounds in Rhodiola sachalinensis, hydro-distillation (HD) and headspace liquid-phase micro-extraction (HS-LPME) were used to extract 75 and 68 volatiles, respectively. Geraniol (24.73%), n-octanol (15.56%), and linalool (14.51%) were the most abundant essential oils detected in the HD samples, while geraniol (24.17%) and n-octanol (15.81%) were also detected at high levels in the HS-LPME samples. The main chemical classes of the essential oils were monoterpene alcohols in both the HD and HS-LPME samples at 59.02% and 37.64%, respectively. The O-heterocyclic (8.52%) and aromatic (5.92%) compounds were more abundant in the HS-LPME samples than in the HD samples.
Keywords: Volatiles; HD; HS-LPME; Rhodiola sachalinensis ; GC/MS

Synthesis, characterization and application of allyl phenol modified amberlite XAD-4 resin for preconcentration and determination of copper in water samples by Mahshid Nikpour Nezhati; Homayon Ahmad Panahi; Elham Moniri; Somayeh Rangbar Kelahrodi; Farah Assadian; Meghdad Karimi (1269-1274).
A new chelating resin was prepared by coupling Amberlite XAD-4 with phenol through an azo spacer, then modified by allyl bromide and characterized (by elemental analysis and IR) and studied for preconcentration of Cu(II) using flame atomic absorption spectrometry (FAAS) for metal monitoring. The optimum pH value for sorption of the above mentioned metal ion was 4.5. The resin was subjected to chemical evaluation through batch binding and column chromatography of Cu(II). The chelating resin can be reused for 15 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 98% was obtained for the metal ion with 0.5 M HNO3 as eluting agent. The equilibrium adsorption data of Cu(II) on modified resin were analyzed by Langmuir, Freundlich and Temkin models. Based on equilibrium adsorption data the Langmuir, Freundlich and Temkin constants were determined to be 0.061, 0.193 and 0.045 at pH 4.5 and 25 °C. The method was applied for the copper determination from industrial waste water sample.
Keywords: Solid Phase Extraction; Amberlite XAD-4; Immobilization; Trace Element; Water Samples

Recovery of [BMIM]FeCl4 from homogeneous mixture using a simple chemical method by Meng Wang; Bing Li; Chongjun Zhao; Xiuzhen Qian; Yunlong Xu; Guorong Chen (1275-1277).
[BMIM]FeCl4 (1-butyl-3-methylimidazolium tetrachloroferrate) was successfully separated from a homogeneous mixture of [BMIM]FeCl4 and H2O via a simple two-step method of phase-division by adding inorganic salt plus chemical extraction, or alternatively, ultracentrifugation, or ultrastrong magnetic field. NaCl showed excellent and effective phase-dividing performance combined with chemical extraction method from the homogeneous mixture of [BMIM]FeCl4 and H2O lower to 1 v%.
Keywords: Recovery; [BMIM]FeCl4 ; Homogeneous Mixture; Chemical Method

The electrochemical reduction process for spent oxide fuel is operated in a molten salt bath and adopts an integrated cathode in which the oxides to be reduced act as a reactive cathode in the molten salt electrolyte cell. Heat-generating radioisotopes in the spent oxide fuel such as cesium and strontium are dissolved in the molten salt and diffuse from the integrated cathode. However, the behavior of the dissolved cations has not been clarified under an electrochemical reduction condition. In this work, the reduction potentials of cesium, strontium, and barium were measured in a molten LiCl-3 wt% Li2O salt and their mass transfer behavior was compared with two current conditions on the cell. The concentration changes of the cations in the molten salt phase were measured and no significant differences on the dissolution behavior were found with respect to the current. However, under a continued current condition, the removal of the high heat-generating elements requires more time than the complete reduction of metal oxide due to the slow rate of diffusion.
Keywords: Pyroprocessing; Alkali Metal; Alkaline Earth Metal; Reduction Potential; Diffusion

On an old basic form for vapor pressure equations by Kyoung Kuhn Park (1284-1285).

A random lattice fluid model with finite coordination number is a versatile molecular-based lattice fluid equation of state, but this model fails to reproduce the non-analytical, singular behavior of fluids in the critical region. In this work, a method of obtaining the classical critical properties is presented in the random lattice fluid model. This model is combined with the crossover theory to obtain the crossover random lattice fluid model and to calculate the thermodynamic properties of hydrocarbons and carbon dioxide. This crossover random lattice fluid model presents much better agreement with experimental data near to and far from the critical region than the classical random lattice fluid model.
Keywords: Crossover; Random; Lattice Model; Hydrocarbons; Carbon Dioxide

High pressure experimental data are presented on the phase equilibrium of ethylene glycol dimethacrylate in supercritical carbon dioxide. Pressure-composition (P-x) isotherms were measured in static method at five temperatures of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 22.0MPa. This (carbon dioxide+ethylene glycol dimethacrylate) system has continuous critical mixture curves that exhibit maximums in pressure at temperatures between the critical temperatures of carbon dioxide and ethylene glycol dimethacrylate. At a fixed pressure, the solubility of ethylene glycol dimethacrylate for the (carbon dioxide+ethylene glycol dimethacrylate) system increases with increasing temperature. The (carbon dioxide+ethylene glycol dimethacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide+ethylene glycol dimethacrylate) system is correlated with Peng-Robinson equation of state using mixing rule including two adjustable parameters. The critical property of ethylene glycol dimethacrylate is predicted with Joback and Lee-Kesler method.
Keywords: Carbon Dioxide; Ethylene Glycol Dimethacrylate; Phase Behavior

Physical and thermal properties of acid-graphite/styrene-butadiene-rubber nanocomposites by Sung Ho Song; Ho Kyun Jeong; Yong Gu Kang; Chun Taek Cho (1296-1300).
In general, carbon-based materials play a major role in today’s science and technology and are required to advance with better properties to meet new requirements or to replace existing materials. We fabricated rubber composites reinforced with 5-weight% acid-graphite. The structural, mechanical and thermal properties of these composites were studied and compared. XRD studies indicated that the structure of the acid treated pristine-graphite (acid-graphite) did not change that of pristine graphite. Tensile properties of the composites indicated higher modulus, tensile strength and elongation in comparison with composites of pristine graphite, carbon black. Also, the composites were found to be in improving tendency with thermal properties and fatigue properties. The acid-graphite was investigated for surface morphology by scanning electron microscopy (SEM) and defects or purity by Raman spectroscopy. In this article, we discuss the influence of acid-graphite on rubber with high mechanical and thermal properties.
Keywords: Acid Graphite; Styrene-butadiene-rubber

Influence of aging conditions on textural properties of water-glass-based silica aerogels prepared at ambient pressure by Pradip Bhikaji Sarawade; Jong-Kil Kim; Askwar Hilonga; Hee Taik Kim (1301-1309).
The experimental results of aging time and temperature on the textural properties of water-glass (sodium silicate)-based silica aerogels are reported and discussed. Aging of the hydrogel for different times and temperatures led to an ability to increase the stiffness and strength of the networks. These improvements enabled the gel to withstand ambient pressure drying (APD) and, consequently, preserve the highly porous silica network without collapse. The pore size and volume increased with increasing aging temperature and time, while the specific surface area decreased. Monolithic aerogels with extremely low bulk density (∼0.069 g/cm3), high specific surface area (820 m2g−1), large cumulative pore volume (3.8 cm3g−1), and high porosity (∼96%) were obtained by aging at 60 °C for 18 hours. Therefore, easy synthesis of monolithic silica aerogels at ambient pressure is achievable using a relatively inexpensive silica precursor (sodium silicate).
Keywords: Silica Aerogels; Sodium Silicate; Ambient Pressure; Monolithic

Characterization and synthesis of Ce-incorporated mesoporous molecular sieves under microwave irradiation condition by Qian Zhao; Qian Wang; Yajing Tang; Tingshun Jiang; Chang-sheng Li; Hengbo Yin (1310-1315).
Ce-incorporated MCM-41 mesoporous molecular sieves (CeMCM-41) were synthesized by microwave irradiation method from sodium silicate and ammonium cerium (IV) nitrate precursors and using cetyltrimethyl ammonium bromide (CTAB) as template. The resulting samples were characterized by means of XRD, TEM, FT-IR, UV-Vis, XPS and N2 physical adsorption, respectively. The effect of the Si/Ce molar ratio on the textural properties of CeMCM-41 was investigated. The results reveal that the CeMCM-41 was successfully synthesized. The resultant mesoporous materials have specific surface areas in the range of 602–1,216 m2/g and pore sizes in the range of ca. 2.6–2.9 nm. The structural properties are related to the amount of cerium incorporation. The surface area and pore volume of the resulting CeMCM-41 were gradually reduced as the cerium content in the sample increased, and the mesoporous ordering diminished.
Keywords: Ce-incorporated Mesoporous Molecular Sieve; Microwave Irradiation Method; Synthesis; Characterization; Textural Property

Spheres of mesoporous silica were prepared in aerosol phase of acidic TEOS sols having structure-directing agents (SDA) such as cetyltrimethylammonium bromide (CTAB) and Pluronic P-123. Their structural characteristics were investigated by systematically varying the chemical and thermal conditions of preparation with TEM, FT-IR, BET and SAXS. Both SDAs produced well-assembled 2-D hexagonal structures. Alcoholic solvent left better order with smaller d values than aqueous one. The upper SDA concentration for mesoporosity was much lower in the former than the latter. To get the highest order, it was important to obtain the complete self-assembly of SDA molecules without any deterioration prior to calcination. Well self-assembled mesophase appeared for the product spray dried at 100 °C and subsequently calcined at 400 °C. One-hour calcination yielded the best order. The number of domains increased with the calcination period up to 5 hrs and then decreased in further extended period. CTAB was bonded to silica surface to preserve the affinity to OH after it disappeared while P123 was not the case.
Keywords: Mesoporous Silica; Structure-directing Agent; Aerosols; Nanostructures; TEOS Sols

Physico-chemical changes in polymer impregnated mortars on exposure to sea water by Priya Nair; Jung Soon Park; Chul Woo Lee; Hun Young Park; Won Mook Lee (1323-1327).
This paper highlights the results and interpretations of experiments conducted to analyze the effect of sea water on conventional precast cement mortar (OPC) and polymer impregnated mortars (PIC). The precast cement mortars were impregnated with a mixture of methyl methacrylate and 2, 2′-Azobisisobutyronitrile (AIBN) initiator and polymerized using two different procedures: by microwaves and by conventional hot water method. The OPC and PIC specimens were immersed in sea water separately for 7, 14, 21 and 28 days and their strength parameters were calculated. The changes in the microstructure indicated movement of ions into the cement matrix and the presence of fan-like crystals on the surface of cement mortar. The protective polymer coating in the PIC prevented contact of sea water with cement concrete, thereby increasing the durability of the composite.
Keywords: Polymer; Cement Mortar; Strength; Microstructure; Interactions

Hydrodynamic characteristics of cold-bed circulating fluidized beds for the methanol to olefins process by Hyun Suk Lee; Yoong Lee; Sang-Soon Park; Ho-Jeong Chae; Soon-Yong Jeong; Dong Hyun Lee (1328-1332).
The effects of the riser inlet velocity (2.2–3.9 m/s), seal-pot inlet velocity (2.4–7.1 U mf ), aeration flow rate (2.5×10−7–3.7×10−6 m3/s) in seal-pot, and solid inventory (0.15–0.2 kg) on the hydrodynamic characteristics of a 9 mm-ID×1.9 m-high cold-bed circulating fluidized bed for methanol to olefins (MTO) process were investigated. FCC (Engelhard; 82.4 μm) particles were used as bed particles. Most of the experimental flow regimes were observed in fast fluidization and pneumatic transport regimes. The axial solid holdup in a riser increased with increasing solid mass flux and solid inventory. Solid mass flux increased proportionally until reaching a maximum value and then decreased with increasing seal-pot inlet velocity. The obtained hydrodynamic characteristics in the cold-bed circulating fluidized beds were compared with previous results.
Keywords: Circulating Fluidized Bed; Solid Holdup; Solid Mass Flux; Seal-pot

Comparison of amine-functionalized mesoporous silica particles for ibuprofen delivery by Kitae Lee; Deokkyu Lee; Hosub Lee; Chang-Koo Kim; Zhijian Wu; Kangtaek Lee (1333-1337).
We have prepared three different types of amine-functionalized silica particles: i) mesoporous silica (MESO1); ii) nonporous core-mesoporous shell silica (MESO2); iii) SBA-15 particles. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen sorption experiment were used to study the morphology of the synthesized particles. To investigate the drug loading and subsequent release of the particles, ibuprofen was used as a model drug for oral delivery. Loading capacity of the particles in this work was found to be higher than that in the previous studies, and followed the order of MESO1>MESO2>SBA-15 particles. Release experiments showed the similar release rate for MESO1 and MESO2 particles from which only <40% of ibuprofen was released after 5 h. From SBA-15 particles, however, more than 80% of ibuprofen was released in 5 h at pH 4 and 7.4. Ibuprofen release from SBA-15 was slowest at pH 2 (∼pH of stomach body) and fastest at pH 7.4 (∼pH of proximal intestine). Difference in release rates was ascribed to the different morphology and pore structure of the carrier particles.
Keywords: Mesoporous; Silica; Ibuprofen; Loading; Release

In-situ mechanical process for preparation of the polyvinyl alcohol (PVA) coated nano-B4C powder was investigated by using a high-energy ball mill. The produced PVA coat on the surface of nano-B4C particles was observed by x-ray diffraction (XRD) and confirmed by TEM images. The average particle size of the produced nano-B4C/PVA particles was in the range of several tens to hundreds of nanometers depending on the milling conditions. The polymer composites were fabricated by hot pressing ultra high molecular weight polyethylene (UHMWPE) powder mixed with nano-B4C/PAV and micro-B4C powders, respectively. Nano-B4C/PVA dispersed UHMWPE shows slightly lower crystallinity and stiffness than micro-B4C dispersed UHMWPE based on differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) evaluations.
Keywords: PVA; B4C; Ball Mill; Nano Powder; Polymer Nanocomposite