Korean Journal of Chemical Engineering (v.27, #3)
Polymeric nanoparticles, micelles and polymersomes from amphiphilic block copolymer by Heui Kyoung Cho; In Woo Cheong; Jung Min Lee; Jung Hyun Kim (731-740).
Block copolymers are made up of blocks of different polymerized monomers. Among the block copolymers, amphiphilic block copolymers can self-assemble to form nano-sized vehicles, such as micelles, nanoparticles, polymersomes, in aqueous or non-aqueous media. This review describes the synthesis, formation, and major applications of amphiphilic block copolymer and corresponding vehicles in order to provide an overview of the current features of functionalized block copolymers for drug delivery applications.
Keywords: Amphiphilic; Block Copolymers; Stimuli-responsive; Drug Delivery; Controlled Radical Polymerizations
Onset of buoyancy-driven convection in isotropic porous media heated from below by Min Chan Kim (741-747).
A theoretical analysis of buoyancy-driven instability under transient basic fields is conducted in an initially quiescent, fluid-saturated, horizontal, isotropic porous layer. Darcy’s law is employed to explain characteristics of fluid motion, and Boussinesq approximation is used to consider the density variation. Under the principle of exchange of stabilities, a stability analysis is conducted based on the linear stability analysis and energy method and their modifications. The critical condition of onset of buoyancy-driven convection is obtained as a function of the Darcy-Rayleigh number. The propagation theory and the modified energy method under the self-similar coordinate suggest reasonable stability criteria and support each other. The former one based on the linear stability theory predicts more stable results than the latter based on the energy method. The growth period for disturbances to grow seems to be required until the instabilities are detected experimentally.
Keywords: Buoyancy-driven Convection; Porous Media; Propagation Theory; Energy Method
Parylene-C thin films deposited on polymer substrates using a modified chemical vapor condensation method by Hong Tak Kim; Taewook Koo; Chinho Park (748-751).
The properties of parylene-C thin films deposited on polymer substrates using a modified chemical vapor condensation technique were investigated. The configuration of the polymerization chamber was altered from horizontal to vertical and designed with a circular symmetry in the z-direction to improve the deposition rate. The growth rate of the thin films was improved 2–5 times in a vertical configuration compared to a horizontal configuration. Potential factors responsible for such an improvement include the effect of coincidence between the flow direction of the gases and the direction of the convection in the reaction tube due to buoyancy. The synthesized films have a high transparency (>90%) in the visible region, a smooth surface morphology (Rs<5.0 nm), and amorphous phase structures with the presence of some crystalline domains.
Keywords: Parylene; Chemical Vapor Condensation; CVC; Vertical Configuration; Polymer Substrate
Prediction of breakthrough curves for light hydrocarbons adsorption on 4A molecular sieve zeolite by Muthanna Jabbar Ahmed; Abdul Halim Abdul Karim Mohammed; Abdul Amir Hassan Kadhum (752-758).
Breakthrough curves for the adsorption of methane, ethane, and propane mixture on 4A molecular sieve zeolite were obtained experimentally and theoretically at a constant temperature of 301 K. The equilibrium model and linear driving force model were used to predict the experimental breakthrough curves for this multi component mixture. The equilibrium model gave a satisfactory fit for experimental data. The model equations were solved by a numerical method based on backward finite difference with a fixed griding technique. The effect of feed flow rate (0.385–3.465 l/min), feed concentration (60.72–182.16 mmole/l), and adsorbates composition (11.73–20.11%) on the breakthrough curves were examined.
Keywords: Breakthrough Curves; 4A Molecular Sieve Zeolite; Light Hydrocarbons; Equilibrium Model; Multi Component Adsorption
A numerical study on unsteady natural convection of air with variable viscosity over an isothermal vertical cylinder by Hari Ponnamma Rani; Chang Nyung Kim (759-765).
The present study deals with the boundary layer flow and heat transfer of unsteady laminar free convection flow past a semi-infinite isothermal vertical cylinder immersed in air. The fluid viscosity is assumed to vary with the temperature. An implicit finite-difference method has been employed to solve the governing non-dimensional boundary layer equations. A parametric study is performed to illustrate the influence of variable viscosity on the velocity and temperature profiles. The numerical results reveal that the viscosity has significant influences on the transient velocity and temperature profiles, average skin-friction coefficient and the average heat transfer rate. The results indicate that as the viscosity parameter increases, the temperature and the skin-friction coefficient increase, while the velocity near the wall and the Nusselt number decrease.
Keywords: Transient; Natural Convection; Vertical Cylinder; Variable Viscosity; Finite Difference Method
Mathematical modeling of CO2 removal using carbonation with CaO: The grain model by Behnam Khoshandam; Ramachandran Vasant Kumar; Leila Allahgholi (766-776).
CaO carbonation with CO2 is potentially a very important reaction for CO2 removal from exhaust gas produced in power plants and other metallurgical plants and for hydrogen production by promoting water gas shift reaction in fossil fuel gasification. A mathematical model based on the grain model was applied for modeling of this reaction. Diffusion of gaseous phase through the product layer and structural change of the grains were considered in the model. The modeling results show that ignoring the reaction kinetics controlling regime in the early stage of the reaction and replacing it with a regime considering both the reaction kinetics and diffusion can generate good simulation results. The frequency factor of the reaction rate equation and the diffusivity of CO2 through the CaCO3 layer were justified to get the best fit at different temperature range from 400 to 750 °C with respect to experimental data in the literature. The mathematical model switches to a pure diffusion controlling regime at final stage of reaction.
Keywords: CaO Carbonation; CO2 Removal; Mathematical Modeling; Porous Media; Diffusion
Effect of cobalt catalyst type and reaction medium on Fischer-Tropsch synthesis by Chul-Ung Kim; You-Sung Kim; Ho-Jeong Chae; Kwang-Eun Jeong; Soon-Yong Jeong; Ki-Won Jun; Kwan-Young Lee (777-784).
This study covers the performance of five cobalt-based catalytic systems with different support characteristics in Fisher-Tropsch synthesis (FTS) under conventional gas-phase using syngas, and the manner in which the reaction medium is influenced by the addition of solvents such as n-hexane and squalane has been also investigated. The reaction was conducted in a fixed bed high-pressure FTS reactor setup at a reaction temperature of 220 °C to 260 °C. In terms of the effect of the reaction medium, higher CO conversion was obtained in gas phase reaction, whereas the olefin selectivity was higher in n-hexane medium than in gas phase and squalane medium. In addition, the undesired production of CH4 and CO2 was relatively reduced in solvent addition compared to the gas phase FTS. The reaction performance was also compared according to the type of catalyst. CO conversion by type of catalyst decreased in the following order: 20% Co/SiO2>20% Co/Al2O3>20% Co/HAS>20% Co/Si-MMS>20% Co/TiO2. However, the C5+ content of products was little affected by catalyst supports.
Keywords: Cobalt Catalyst; Fischer-Tropsch; Gas Phase; Reaction Medium; n-Hexane; Squalane
Kinetic model of glycerol chlorination with hydrochloric acid by Jong Hun Lim; Won Seob Song; Sung Yul Woo; Dong Hyun Lee (785-790).
A new reaction model for dichloropropanol (DCP) synthesis from glycerol chlorination is proposed based on the models reported by Tesser et al. (2007) and Luo et al. (2009). Two reaction steps, glycerol to glycerol-1-acetate and α-MCP to 3-chloropropandiol-1-acetate, were defined as reversible reactions and other reaction steps were defined as irreversible processes. Using the experimental data reported by Luo et al. (2009), the values predicted in this study were compared with the previous model reported by Luo et al. (2009) using both the average absolute deviation (AAD) and root mean square deviation (RMSD). The AAD and RMSD of the new model were 31% and 33% lower than that of the existing one, respectively. Overall, the proposed model for glycerol chlorination is superior to the previous model.
Keywords: Kinetic Model; Glycerol; Chlorination; Dichloropropanol; Hydrochloric Acid
Thermogravimetric analysis of longan seed biomass with a two-parallel reactions model by Supunnee Junpirom; Chaiyot Tangsathitkulchai; Malee Tangsathitkulchai (791-801).
The kinetic analysis of pyrolysis process of longan seed was performed in a thermogravimetric analyzer. All experimental runs were carried out by using an initial sample mass of 15 mg and final temperature of 650 °C under the inert atmosphere of nitrogen. Particle sizes in the range from 0.05–2.1 mm and the heating rates from 5–100 °C/min were employed to investigate their effects on the thermogram and the kinetic parameters. The TG curves generally showed sigmoid shape and displayed one major peak in DTG curve. The main devolatilization of longan seed occurred over the temperature range of 210–330 °C. It was found that heat transfer resistance in a particle could be reduced either by decreasing the size of particle or increasing the heating rate. The thermal decomposition of longan seed could be well described by the two-parallel reactions kinetic model. This analysis of reaction kinetic gave the values of activation energy for the decomposition of the two fractions in the model corresponding closely to those of hemicellulose and lignin.
Keywords: Pyrolysis; Devolatilization; Two Parallel Reactions Model; Longan Seed
The effect of PtRuW ternary electrocatalysts on methanol oxidation reaction in direct methanol fuel cells by Dae Kyu Kang; Chang Soo Noh; Sang Tae Park; Jung Min Sohn; Seung Kon Kim; Young-Kwon Park (802-806).
PtRu and PtRuW ternary electrocatalysts were synthesized using an NaBH4 reduction method. A uniform distribution of particles, with average particle size of 3–3.5 nm was indentified from X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemically active surface area was slightly decreased after the addition of W into PtRu. When W was added to PtRu, the specific and mass activity of methanol electro-oxidation was increased. The most active catalyst was Pt5Ru4W, of which specific and mass activities were 265.38 mA/m2 and 6.21 A/g·catal, respectively. The specific and mass activity was 390 and 320% higher than that of PtRu.
Keywords: Direct Methanol Fuel Cell; Methanol Oxidation Reaction (MOR); PtRuW; CO Stripping
Production of middle distillate through hydrocracking of paraffin wax over Pd0.15Cs x H2.7−x PW12O40 catalysts: Effect of cesium content and surface acidity by Joongwon Lee; Sunhwan Hwang; Dong Ryul Park; Jeong Gil Seo; Min Hye Youn; Ji Chul Jung; Sang-Bong Lee; Jin Suk Chung; In Kyu Song (807-811).
Palladium-exchanged heteropolyacid (Pd0.15Cs x H2.7−x PW12O40) catalysts were prepared by an ion-exchange method with a variation of cesium content (x=2.0, 2.2, 2.5, and 2.7) for use in the production of middle distillate through hydrocracking of paraffin wax. Surface acidity of Pd0.15Cs x H2.7−x PW12O40 catalysts determined by NH3-TPD experiments showed a volcano-shaped trend with respect to cesium content. Surface acidity of the catalysts played an important role in determining the catalytic performance in the hydrocracking of paraffin wax. Conversion of paraffin wax increased with increasing surface acidity of the catalyst, while yield for middle distillate showed a volcano-shaped curve with respect to surface acidity of the catalyst. Among the catalysts tested, Pd0.15Cs2.7PW12O40 catalyst with moderate surface acidity showed the best catalytic performance.
Keywords: Hydrocracking; Middle Distillate; Paraffin Wax; Heteropolyacid; Surface Acidity
High performance phosphorus-modified ZSM-5 zeolite for butene catalytic cracking by Xionghou Gao; Zhicheng Tang; Haitao Zhang; Conghua Liu; Zhongdong Zhang; Gongxuan Lu; Dong Ji (812-815).
Phosphorus-modified ZSM-5 zeolites were prepared with a novel method, hydrothermal dispersion. XRD showed that the catalysts prepared by the hydrothermal dispersion had better hydrothermal stability than that by impregnation. At the same time, more pronounced cracking activity and higher yield of ethylene plus propylene were obtained on the phosphorus-modified ZSM-5 catalysts prepared by hydrothermal dispersion. Highest yield of ethylene plus propylene was obtained when the loading of phosphorus was 0.68%. The higher amount of phosphorus fixed on the pores of zeolite, higher hydrothermal stability and appropriate acid amount were the possible reasons for obtaining higher yield of ethylene plus propylene.
Keywords: Butene Catalytic Cracking; Propylene; ZSM-5 Modification; Phosphorus; Hydrothermal Dispersion
A catalytic membrane reactor for water-gas shift reaction by Kyung-Ran Hwang; Son-Ki Ihm; Jong-soo Park (816-821).
We conducted the WGS reaction on a catalytic membrane reactor consisting of a WGS catalyst bed, Pt/CeO2 and thin, defect-free, Pd-Cu alloy membranes. The presence of CO and other gases with H2 reduced the H2 permeation through the membrane by more than 50% and the effect of the other gases on the permeation reduction decreased in the following order: CO>CO2>N2. In a catalytic membrane reactor with helium sweep gas, the CO conversion was improved by about 65% compared with the catalyst without any membrane, and the CH4 formed from an undesirable side reaction was significantly reduced. Although the H2 permeation was severely reduced by surface phenomena such as blocking of available H2 dissociation sites by CO, CO2 and steam, the CO conversion was notably improved by the membrane presence. Moreover, the CO conversion was maintained at 98% even after 60 h of reaction and our Pd-Cu-Ni alloy membrane withstood the exposure of CO and the other gases. However, for separation of pure H2, a newly designed, catalyst-membrane system is required with better sealing and the ability to withstand the high operating pressure that drives the H2 permeation.
Keywords: Water-gas Shift Reaction; Pd Membrane; Hydrogen; Catalytic Membrane Reactor; Permeation
The effect of cobalt precursors on NO oxidation over supported cobalt oxide catalysts by Dae Su Kim; Yun Ha Kim; Jae Eui Yie; Eun Duck Park (822-827).
The effect of cobalt precursors such as cobalt acetate and cobalt nitrate on NO oxidation was examined over cobalt oxides supported on various supports such as SiO2, ZrO2, and CeO2. The N2 physisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction with H2 (H2-TPR), NO chemisorptions, and temperature-programmed oxidation (TPO) with mass spectroscopy were conducted to characterize catalysts. The NO uptake as well as the catalytic activity for NO oxidation was dependent on the kinds of cobalt precursors and supports for supported cobalt oxides catalysts. Among tested catalysts, Co3O4/CeO2 prepared from cobalt acetate showed the highest catalytic activity. The catalytic activity generally increased with the amount of chemisorbed NO. Reversible deactivation was observed over Co3O4/CeO2 in the presence of H2O. On the other hand, irreversible deactivation occurred over the same catalyst even in the presence of 5 ppm SO2 in a feed. The strongly adsorbed SO2 can prohibit NO from adsorbing on the active sites and also can prevent formed NO2 from desorbing off the catalyst surface. The formation of SO3 cannot be observed from the chemisorbed SO2 on Co3O4/CeO2 during TPO.
Keywords: NO Oxidation; Co3O4 ; Precursors; SO2 ; H2O
Characterization of an open biocathode microbial fuel cell for electricity generation and effluent polish by Guo-Wei Chen; Jae-Hwan Cha; Soo-Jung Choi; Tae-Ho Lee; Chang-Won Kim (828-835).
The application of a biocathode in a microbial fuel cell (MFC) could be an alternative for the abiotic cathode MFCs that use noble metal catalysts and/or artificial mediators. An open biocathode MFC with oxygen reduction was investigated in this study and the roles of microbes in the cathode compartment were characterized. After 50-days operation, the MFC became stable and the power density of the MFC reached 2.55 W/m3 at an influent flowrate of 0.20 mL/min. The concentration of chemical oxygen demand (COD) was significantly reduced from 372 mg/L (in the influent) to 22 mg/L (in the final effluent) at an influent flowrate of 0.20 mL/min. Microbial community analysis demonstrated that four major groups of the clones were identified, where 28 clone types were derived from the cathode microorganisms, which included proteobacteria, Firmicutes, Bacteroidetes and unclassified bacteria. Among these phylatypes, Deltaproteobacteria was the most abundant division with 25.0% of total clones, which plays important roles in the cathodic electron transfer process. The presence of symmetric peaks could be detected in the effluent of the cathode compartment, which confirmed that the possible electron mediators were excreted by cathodic bacteria involved in the electron transfer process.
Keywords: Biocathode; Cathodic Microbe; Electrochemical Response; Microbial Fuel Cell
Evaluation of direct formic acid fuel cells with catalyst layers coated by electrospray by Yongchai Kwon; Seungmin Baek; Byungwan Kwon; Jinsoo Kim; Jonghee Han (836-842).
We investigated cell performance and performed phenomenological analyses of direct formic acid fuel cells (DFAFCs) incorporating anode (palladium) and cathode (platinum) catalysts prepared using a new electrospray coating technique. To optimize the design of the DFAFC, we examined the cell performance by the Pd catalyst loading and formic acid feed rate. Of Pd catalyst loaded samples, 3 mg/cm2 sample showed the highest electrical performance with formic acid feed rate of 5 ml/min. This behavior was caused by discrepancies in the mass transfer limitation. When the feed rate was greater than 10 mL/min, however, the 7 mg/cm2 sample provided the highest electrical performance, which was attributed to enhanced electrooxidation reactions. For comparison of the effect of the catalyst coating method on the cell performance of DFAFC, polarization curves of the DFAFC incorporating catalysts prepared using a conventional airspray coating method were also measured. As a result of the comparison, the electrospray coatingused DFAFC showed better cell performance. Based on these results, the cell performance of the DFAFCs was optimized when the catalysts using the electrospray catalyst coating were employed, the amount of Pd loaded on the anode electrode was 3 mg/cm2 (Pd thickness: ∼6 μm), and the formic acid feed rate was 10 mL/min.
Keywords: Direct Formic Acid Fuel Cell; Electrospray; Mass Transfer; Electrooxidation
Effect of hydrogen partial pressure on a polymer electrolyte fuel cell performance by Jae-Young Lee; Jiyong Joo; Jae Kwang Lee; Sunghyun Uhm; Eon Soo Lee; Jae Hyuk Jang; Nam-Ki Kim; Yong-Chul Lee; Jaeyoung Lee (843-847).
We first investigated the effect of partial pressure of hydrogen (H2) on the performance of polymer electrolyte fuel cells (PEFCs) by controlling the ratio of hydrogen and nitrogen (N2). The cell performance with Pt/C anode was significantly decreased with reduction of the partial pressure of H2 in the presence of carbon monoxide (CO), while the performance variation was negligible in the absence of CO. Severe CO poisoning on Pt/C electrode at low partial pressure of H2 might be attributed to the hindering effect by N2 and CO. On the other hand, PtRu/C anode showed consistent power performance even at low partial pressure of H2.
Keywords: PEM Fuel Cells; Reforming Gas; H2/N2 Ratio; CO; Recovery Test
Performance characteristics of NO removal by cobalt diethylenetriamine solution by Houzhang Tan; Jinchao Wei; Yunbai Luo; Ping Yu (848-853).
The cobalt(II) diethylenetriamine ([Co(dien)2]2+) complex is a newly developed metal thiochelate for the removal of NO from flue gas. The performance characteristics of NO absorption into [Co(dien)2]2+ solution were studied in a stirred reactor. The experimental results showed that this absorption could be regarded as fast pseudo-mth-order reaction and the reaction rate could be expressed as second-order with respect to NO concentration and first-order with respect to [Co(dien)2]2+ concentration. The enhancement factor was 1609.1 at the [Co(dien)2]2+ concentration of 0.01 mol/L. Its optimal absorption conditions were temperature 50 °C, NO concentration 540 ppm, [Co(dien)2]2+ concentration 0.02 mol/L and O2 concentration 6%, which were determined by orthogonal experiment.
Keywords: Nitric Oxide; Absorption; Cobalt Chelate; Diethylenetriamine
Application of the electrocoagulation technique for treating heavy metals containing wastewater from the pickling process of a billet plant by Chaloempan Petsriprasit; Jirachaya Namboonmee; Mali Hunsom (854-861).
This work was carried out to study the removal of various heavy metals, including Cu, Cr, Pb and Zn, from billet industry wastewater by the electrocoagulation process in both batch and continuous experiments at a laboratory scale and ambient temperature (30 °C). In the batch experiment, the effect of various parameters including the current density, initial wastewater pH and electrolysis time, on the metal removal efficiency was examined. Optimal metal ion depletion was attained with a current density of 98 A/m2, an initial wastewater pH of 5 and a 30 min electrolysis time. Under these conditions, greater than 99% of Cu, Cr and Zn was removed, whilst the outlet wastewater contained Cu, Cr, Pb and Zn at less than 0.02, 0.01, 0.07 and 0.05 mg/l, respectively. For the continuous process, the results indicated that the treatment system reached its steady state condition within 120 min, and the optimum condition for the continuous treatment was found at an initial wastewater pH of 3 and flow rate of 55 ml/min. At this condition, a complete removal of Cu and Pb and greater than 99% removal of Cr and Zn were achieved.
Keywords: Electrocoagulation; Metal Removal; Current Efficiency; Pickling Process
A study of the improvement in dewatering behavior of wastewater sludge through the addition of fly ash by Jung Eun Lee; Jae Keun Lee; Dong Soo Kim (862-867).
Wastewater sludge is classified as a difficult dewatering material (DDM) due to the high cake specific resistance (CSR). On the other hand, fly ash is classified as an easy dewatering material (EDM), which suggests that it might be able to improve the dewaterability of wastewater sludge. The water content and cake specific resistance of dewatered sludge without the addition of fly ash were 80% and 2.9×1014 kg/m, respectively. When 50% (by dry weight) fly ash was added to the sludge, the water content and cake specific resistance decreased to 29.4% and 2.9×1013 kg/m, respectively. The cake specific resistance and water content decreased with increasing fly ash additions. Therefore, the production of sludge cake can be reduced by adding fly ash, which can help minimize the social and environmental problems caused by the need to dispose of wastewater sludge.
Keywords: Dewatering; Wastewater Sludge; Fly Ash; Difficult Dewatering Material; Easy dewatering Material; Cake Specific Resistance
Characterization of molecular biological indicators to define stabilization of landfills by Ji-Sun Han; Chang-Gyun Kim (868-873).
This study was assessed such that a molecular biological investigation in uncontrolled landfills can be comparably used for characterizing its stability in association with the conventional water quality parameters. At first, the microbiological diversity in two landfill sites (Cheonan and Wonju landfills in Korea) was identified by 16s rDNA cloning. It was also quantitatively investigated for denitrification enzyme coding genes (nitrite reductase; nirS and nitric oxide reductase; cnorB) and methane producing enzyme coding gene (methyl coenzyme M reductase; MCR) by realtime polymerase chain reaction. The copy numbers of nirS and cnorB in Cheonan were higher than those in Wonju, which was well reflected from the time difference after site closure, respectively. The greatest number of MCR, nirS and cnorB genes of C1 spot (Cheonan) verified that it was immediately bordering the sources, which was steeply decreased toward the outer boundary landfill. Cheonan landfill is more rapidly stabilized based on molecular biological indicator even if the present state of Wonju landfill is more stable based on BOD and COD concentrations. However, the comparison between the copy number of these genes and the conventional water quality monitoring parameters addressed that those of parameters have similar patterns, especially for the source or the boundary. It was concluded that the molecular biological parameters could be used for determining microbial stability toward down-gradient around the uncontrolled sites.
Keywords: 16S rDNA; Landfill; Groundwater Monitoring; Real-time Polymerase Chain Reaction; Stabilization
Evaluation of the effect of baffle shape in flocculation basin on hydrodynamic behavior using computational fluid dynamics by Youngman Cho; Soojeon Yoo; Pyeongjong Yoo; Changweon Kim (874-880).
This study on the party wall of a flocculation basin provides important ground to facilitate the inducement of uniformity in the rectangular sedimentation basin and to achieve an improvement in sedimentation efficiency. In the water treatment plant used for this study, perforated baffle type, square type, pillar type and downward rectangular type partitions have been applied. We evaluated the hydrodynamic behavior of several types of party walls in the flocculation basin by using computational fluid dynamics (CFD). The perforated baffle type demonstrates more effective output for uniform flow than the square type, and the third party wall of the flocculation process has the most influence of the three party walls for water flow distribution. To prevent sinking of the flocs formed between the third party wall and the final outlet wall, it is necessary to develop the third party wall into an actual final outlet wall or to modify it into a pillar baffle type. In the case of a drinking water treatment system that treats low density water, a perforated baffle is more efficient as the final outlet wall because a downward rectangular type may form a bottom flow, which may cause a reduction in the efficiency of the volume capacity.
Keywords: Flocculation; Party Walls; Perforated Baffle; Computational Fluid Dynamics (CFD)
A study on submerged rotating MBR for wastewater treatment and membrane cleaning by Dan-Ying Zuo; Hong-Jun Li; Hong-Tao Liu; Gui-Ping Wu (881-885).
A submerged rotating membrane bioreactor (SRMBR), with a rotatable, rounded, flat-sheet Poly(vinyldiene fluoride) (PVDF) membrane module fixed on hollow axes and moved by an electromotor, was used for wastewater reclamation. It was found that the effluent COD became stable and lower than 20 mg/L after one day running. The equilibrium permeate flux increased from 42.5 to 47.5 L/m2·h with the rotation speed increasing from 15 r/min to 25 r/min. Prolonging relaxation time could alleviate membrane fouling and enhance the flux. Finally, membrane cleaning was studied. The results showed that flushing the membrane surface with water, water/NaOH and water/NaOH/HCl recovered permeate flux to 48.4%, 83.5% and 90.2% of that of the initial operation, respectively.
Keywords: Submerged Rotating MBR; Rotation Speed; Permeate Flux; Membrane Cleaning; PVDF Flat-sheet Composite Membrane
Sludge settleability detection using automated SV30 measurement and comparisons of feature extraction methods by Yejin Kim; Hoonsik Yeom; Soojung Choi; Hyeon Bae; Changwon Kim (886-892).
The need for automation and measurement technologies to detect the process state has been a driving force in the development of various measurements at wastewater treatment plants. While the number of applications of automation & measurement technologies to the field is increasing, there have only been a few cases where they have been applied to the area of sludge settling. It is not easy to develop an automated operation support system for the detection of sludge settleability due to its site-specific characteristics. To automate the human operator’s daily test and diagnosis work on sludge settling, an on-line SV30 measurement was developed and an automated detection algorithm on settleability was developed that imitated heuristics to detect settleability faults. The automated SV30 measurement is based on automatic pumping with a predefined schedule, the image capture of the settling test with a digital camera, and an analysis of the images to detect the settled sludge height. To detect settleability faults such as deflocculation and bulking from these images, two feature extraction methods were used and their performance was evaluated.
Keywords: Detection; Diagnosis; Dynamic Time Warping; Discriminant Analysis; Settling; Sludge Volume Index
Application of A2O moving-bed biofilm reactors for textile dyeing wastewater treatment by Hye Ok Park; Sanghwa Oh; Rabindra Bade; Won Sik Shin (893-899).
A three-stage pilot-scale moving-bed biofilm reactor (MBBRs, anaerobic-anaerobic-aerobic in series) was investigated to treat textile dyeing wastewater. Each reactor was filled with 20% (v/v) of polyurethane-activated carbon (PU-AC) carrier for biological treatment. To determine the optimum operating conditions of MBBRs, the effect of PUAC carrier, its packing percentage (v/v%) and pH control on COD removal were analyzed by batch experiments. The MBBRs were inoculated with activated sludge obtained from a local dyeing wastewater treatment plant. The MBBR process removed 86% of COD and 50% of color (influent COD=608 mg/L and color=553 PtCo unit) using relatively low MLSS concentration (average 3,000 mg/L in biomass attached to PU-AC carrier) and hydraulic retention time (HRT=44 hr). The MBBR process showed a promising potential for dyeing wastewater treatment.
Keywords: Moving-bed Biofilm Reactor (MBBR); Carrier; Decolorization; Dyeing Wastewater; Extracellular Polymeric Substances (EPS)
Removal of neurotoxic ethyl parathion pesticide by two-stage chemical/enzymatic treatment system using Fenton’s reagent and organophosphorous hydrolase by Suk Soon Choi; Sang Hwan Seo; Dong Gyun Kang; Jeong Hyub Ha; Hyung Joon Cha (900-904).
Organophosphate compounds, which are essential ingredients of pesticide, plasticizer, air fuel, and chemical warfare agents, are serious neurotoxic hazardous materials. Therefore, diverse physical-chemical treatments have been attempted to degrade organophosphate compounds. In the present work, we propose a two-stage chemical and enzymatic treatment system. As a first stage, pretreatment of oxidation and coagulation using Fenton’s reagent utilizing iron and hydrogen peroxide was employed. Preferentially, 1 mM ethyl parathion (EP) pesticide was largely (∼80%) removed by Fenton’s reagent reaction within 15 min. To remove residual EP, enzymatic treatment with organophosphorous hydrolase (OPH) from recombinant Escherichia coli was employed as a second stage. We successfully demonstrated that the proposed two-stage hybrid treatment process removed 1mM environmental toxic EP efficiently (∼98%) within 30 min.
Keywords: Organophosphate Compound; Ethyl Parathion Pesticide; Two-stage Treatment; Fenton’s Reagent; Organophosphorous Hydrolase
Biotransformation of medium-chain alkanes using recombinant P450 monooxygenase from Alcanivorax borkumensis SK2 expressed in Escherichia coli by Sang-Ho Baik (905-909).
A bioconversion system for medium-chain alkanes was constructed by using a recombinant Escherichia coli whole-cell biocatalyst expressing P450 monooxygenase genes, ferredoxin, and ferredoxin reductase cloned from Alcanivorax borkumensis as an operon. The recombinant E. coli harboring the P450 gene and two related expression component enzymes, ferredoxin and ferredoxin reductase, was constructed in a single vector pET21(a) and successfully expressed in E. coli BL21(DE3) as a soluble form, showing a molecular weight of 53 kDa on 10% SDS-PAGE. When the cell-free extract of E. coli BL21 expressing p450 monooxygenase was subjected to reduced CO difference spectral analysis, a soret band near 450 nm appeared indicating that the cloned P450 was expressed as a functionally active enzyme. The E. coli cells harboring the expressed P450 gene were able to convert n-octane and 1-decene, producing approximately 450 μg/ml of n-octanol and 290 μg/ml of 1,2-epoxydecane, respectively, at pH 7.0 and 30 °C. However, the recombinant E. coli cells were not able to convert the branched alkane, 2,6,10,14-tetramethylpentadecane (C19).
Keywords: P450 Monooxygenase; Medium-chain Alkane; Esheriachia coli
Regulation of meilingmycin in Streptomyces nanchangensis: Effect of ammonium ion by Yong Wang; Ying-ping Zhuang; Ping Wang; Ju Chu; Si-liang Zhang (910-914).
Effects of different ammonium sulfate concentrations on meilingmycin biosynthesis were studied in this research. The results show that a lower concentration of ammonium ions stimulates the biosynthesis of meilingmycin, while a concentration higher than 5 mmol/L inhibits the mycelial growth and the biosynthesis of the products. However, increased sugar consumption rate with the elevated concentration of ammonium sulfate was observed during the fermentation process. On this basis, six enzymes, which are responsible for the meilingmycin biosynthesis and the glucose metabolism, were measured and analyzed during the bioprocess. The results suggest that glucose-6-phosphate dehydrogenase, citrate synthase, succinate dehydrogenase and fatty acid synthase are stimulated by higher concentration of ammonium ions, while valine dehydrogenase and methylmalonyl-CoA carboxyltransferase are inhibited. From the results it follows that the precursor supply was restricted with the higher concentration of ammonium ions, which results in the lower production of meilingmycin. Thus, the strategy of maintaining a low level of FAS activity is a critical factor for high yield of meilingmycin.
Keywords: Meilingmycin; Streptomyces nanchangensis ; Ammonium Ion
Melanogenesis inhibitory effect of dehydroevodiamine isolated from fruits of Evodia rutaecarpa by Lian Hua Luo; Jeong-Woo Seo; Dung Hoang Nguyen; Eun-Ki Kim; Soon Ah Kang; Dae-Hyuk Kim; Chul Ho Kim (915-918).
Dehydroevodiamine, an alkaloid, was isolated from the fruit of Evodia rutaecarpa and melanin production, and tyrosinase inhibition in B16F10 melanoma cells treated with the isolated dehydroevodiamine was investigated. The compound decreased melanin synthesis significantly without promoting cytotoxicity. The IC50 value of dehydroevodiamine for melanogenesis and cell viability were 59.8 μM and 90.0 μM, respectively. The L-dopa oxidase activity of mushroom tyrosinase was reduced after dehydroevodiamine treatment by about 22.4% at a concentration of 33.2 μM. However, there was no effect on cellular tyrosinase activity. These results indicate that the observed decrease in melanin content after treatment with dehydroevodiamine was attributed to the direct inhibition of tyrosinase activity, rather than the suppression of tyrosinase gene expression. Dehydroevodiamine may be a promising new agent for use in cosmeceutical application.
Keywords: Melanogenesis; Evodia rutaecarpa ; Dehydroevodiamine; Skin Whitening; Cosmeceutical
Optimization of the fermentation conditions and partial characterization for acido-thermophilic α-amylase from Aspergillus niger NCIM 548 by Pouya Sirous Rezaei; Ghasem Najafpour Darzi; Hoda Shafaghat (919-924).
A high performance thermostable α-amylase at low pH values has been synthesized. Sugarcane bagasse was hydrolyzed in a dilute acid solution and utilized as carbon source for the growth of Aspergillus niger strain NCIM 548. Glucose, xylose and arabinose with the ratio of 1.0: 0.9: 0.3 (w/w/w) were detected in the hydrolyzate by HPLC analysis. Optimization of the fermentation conditions for α-amylase production was performed by varying four influential parameters such as Sugarcane bagasse hydrolyzate (SBH), NH4Cl, pH and incubation time using a central composite design (CCD) under response surface methodology (RSM). The optimum values of SBH, NH4Cl, pH and incubation time were 20.49, 2.34 g/l, 5.65 and 76.67 h, respectively. The acido-thermophilic enzyme showed maximum stability at 70°C and pH value of 4. The rate constant, K m and maximum reaction rate, V max were 18.79 g/l and 15.85 g/l·min, respectively.
Keywords: α-Amylase; Aspergillus niger ; Response Surface Methodology; Sugarcane Bagasse Hydrolyzate; Optimization
Optimal strategies of fill and aeration in a sequencing batch reactor for biological nitrogen and carbon removal by Moo Hwan Cho; Jintae Lee; Joon Ha Kim; Henry C. Lim (925-929).
A modified version of the IAWQ activated sludge model No. 1 (ASM 1) is adopted for the simulation of a sequencing batch reactor (SBR) to optimize the removal of nitrogen (T-N) and organic matters (COD) from wastewater. Since the removal of nitrogen requires both aerobic nitrification and anaerobic denitrification, we seek to find the optimal strategies of substrate fill and aeration. Substrate filling strategy critically influences the removal efficiency of T-N and COD; one fast discrete fill in the beginning of a cycle leads to the best result, while a slow continuous fill results in poor nitrification. In addition, the total aeration time is more important for the removal efficiency than the aeration frequency. A short aeration is beneficial for T-N removal, while a long aeration is beneficial for COD removal as expected. As a result, there is an optimal condition of aeration for the simultaneous removal of T-N and COD.
Keywords: Wastewater Treatment; Nitrogen Removal; Sequential Batch Reactor; Optimization Strategy
Catalytic production of hydroxymethylfurfural from sucrose using 1-methyl-3-octylimidazolium chloride ionic liquid by Jae-An Chun; Jin-Woo Lee; Young-Byung Yi; Seong-Sig Hong; Chung-Han Chung (930-935).
Hydroxymethylfurfural (HMF) is an important chemical intermediate, but it has not been widely used because of low yields and high production costs. Sucrose is available at lower costs than other sugars and thus could be a biomass-derived abundant source for HMF production. In this study, a catalytic process for efficiently producing HMF from sucrose was scrutinized using 1-methyl-3-octylimidazolium chloride ([MOIM]Cl) as a reaction solvent, and HCl and metal chlorides (CrCl2 and Zncl2) as a catalyst. The rate of sucrose hydrolysis was relatively much faster in the reactions with HCl than without it. The hydrolysis of sucrose to fructose and glucose was affected by its reaction time. The mixed solvent of 50% [MOIM]Cl and 50% sucrose solution with HCl was more effective in HMF synthesis than single solvent alone. The addition of ZnCl2 and CrCl2 increased HMF yields by approximately 1.2–1.8-fold and its higher yield was found in the latter. The highest yield (82.0±3.9 wt%) in HMF production was achieved in the reaction mixture containing 5 g [MOIM]Cl and 5 mL of 20% sucrose solution with 0.5M HCl plus CrCl2 at 30 min reaction time. However, 0.3 M HCl was more effective for the HMF productivity than 0.5 M HCl.
Keywords: Hydroxymethylfurfural; Ionic Liquid; Metal Chloride Catalyst; Sucrose Hydrolysis
Solubility of D(−)-p-hydroxyphenylglycine dane salt in binary methanol+isopropanol solvent mixtures by Qun-Sheng Li; Zheng-Ming Yi; Wei-Zhong Liu; Xu-Feng Sun (936-938).
The solubility of D(−)-p-Hydroxyphenylglycine Dane Salt (HPGDane Salt) in binary methanol and isopropanol solvent mixtures was measured using a laser technique with the temperature range from 283.15 K to 323.15 K and mole fraction (x2) range from 0.0000 to 1.0000. The results were correlated with a semi-empirical equation.
Keywords: D(−)-p-Hydroxyphenylglycine Dane Salt; Solubility; Laser Technique
Control of oxygen concentration in water using a hollow fiber membrane contactor by Dongjae Jeong; Mihye Yun; Jeongsik Oh; Ina Yum; Yongtaek Lee (939-943).
A novel theoretical analysis was performed to regulate the oxygen concentration in water using a membrane contactor composed of nonporous hollow fibers. The governing ordinary differential equations were derived for the countercurrent flow of the feed water and the feed gas in a membrane contactor. The governing equations were regarded as a two point boundary value problem. The nonlinear ordinary differential equations were simultaneously solved using a finite difference method. The computer program was coded in Fortran language using the Compaq Visual Fortran Software. It was found that the concentration of oxygen dissolved in water increases from 28.9 to 64.3 ppm as the area of the membrane increases from 1.24 to 3.73 m2 at the given typical operating condition: the flow rate of the feed gas is kept to be 1.0 L/min; its pressure is maintained to be 4 atm; the flow rate of the water is 15 L/min. It is observed that the concentration of oxygen increases from 48.2 to 56.2 ppm as the concentration of the feed gas increases from 0.75 to 0.95 mole fraction. As the flow rate of the water increases from 15 to 25 L/min, the concentration of oxygen decreases from 56.2 to 38.6 ppm with a constant membrane area of 3.11 m2.
Keywords: Membrane Contactor; Numerical Analysis; Oxygenated Water; Hollow Fiber
Purification of crude glycerol derived from waste used-oil methyl ester plant by Sangkorn Kongjao; Somsak Damronglerd; Mali Hunsom (944-949).
The purification of crude glycerol from a biodiesel plant using waste used-oil as a raw material was carried out on a laboratory scale by using the combined chemical and physical treatments based upon repeated cycles of acidification to the desired pH within the range of 1–6 using 1.19 M H2SO4, allowing phase separation and harvesting of the glycerol-rich middle phase followed by neutralization of the harvested glycerol phase with 12.5M NaOH. Subsequently, the glycerol-enriched fraction was extracted by ethanol. The results indicated that increasing the pH of the acidification step led to an increased yield of the glycerol-rich layer and decreased amount of inorganic salt and free fatty acids phase. Under strong acid conditions, large quantities of fatty acid and salt in the glycerol-enriched fraction were eliminated and, at pH 1, high purity glycerol (∼93.34%) with relatively low contaminant levels (0.00045% (w/w) ash and 5.16% (w/w) MONG) was obtained.
Keywords: Crude Glycerol; Purification; Biodiesel; Glycerol-rich Layer; Waste
Application of gas anti-solvent process to the recovery of andrographolide from Andrographis paniculatanees by Manop Charoenchaitrakool; Wuttichai Trisilanun; Penjit Srinopakhun (950-954).
The gas anti-solvent (GAS) process was employed to extract andrographolide, which is the active ingredient found in Andrographis Paniculatanees, using carbon dioxide as an anti-solvent. The effects of temperature, flow rate and solvent type on the extraction recovery, particle size and morphology were investigated in this study. The experiments were conducted at the temperature ranging from 25–45 °C, carbon dioxide flow rate of 1–15 mL/min, and various types of organic solvents (methanol, ethanol, acetone and N,N-dimethylformamide). The extracted product was analyzed using high performance liquid chromatography (HPLC). The highest extraction yield was found to be 1.24 g andrographolide per 100 g of A. paniculata when using acetone as a solvent, carbon dioxide flow rate of 5 mL/min and the temperature of 35 °C. It was also found that no significant change in size or morphology of the precipitates was observed when changing temperature, carbon dioxide flow rate and solvents.
Keywords: Dense Gas; GAS Process; Andrographolide; Andrographis paniculatanees ; Carbon Dioxide
Frequency response analysis of the constant molar flow semi-batch adsorption vessel containing core-shell composites by In-Soo Park (955-961).
Frequency response behavior of the constant molar flow semi-batch adsorption vessel containing core-shell composites is theoretically investigated. The periodic modulation of the inlet molar flow-rate into the vessel is considered as the forcing function to the response. Under the interaction between the core-phase and the shell-phase of the composite, both the response of the core-phase and the response of the shell-phase subject to the forcing function exhibit their own peaks on the out-of-phase characteristic curve and their own plateaus on the in-phase characteristic curve, respectively. The model to be developed will include the local linear equilibriums at the fluid-particle interface and at the intraparticle core-shell interface, the external diffusion, the intraparticle diffusion in the outer shell-phase, and the intraparticle diffusion in the inner core-phase.
Keywords: Frequency Response; Core-shell Composite; Adsorption Vessel; Transfer Function; Characteristic Function
Adsorption of carbon dioxide onto BDA-CP-MS41 by Youngson Choe; Kwang-Joong Oh; Seong-Soo Kim; Sang-Wook Park (962-969).
Carbon dioxide was adsorbed onto mesoporous adsorbent of butylene diamine immobilized CP-MS41 (BDA-CP-MS41), which was synthesized by chloropropyl functionalized MCM-41 (CP-MS41) with butylene diamine in a laboratory-scale packed-bed. The adsorber was operated batchwise with the charge of adsorbent in the range of 1–3 g to obtain the breakthrough curves of CO2. Experiments were carried out at different adsorption temperatures (20–40 °C) and flow rates of nitrogen (10–20 cm3/min) to investigate the effects of these experimental variables on the breakthrough curves. The deactivation model was tested for these curves by combining the adsorption of CO2 and the deactivation of adsorbent particles. The observed values of the adsorption rate constant and the deactivation rate constant were evaluated through analysis of the experimental breakthrough data using a nonlinear least squares technique. The experimental breakthrough data fitted very well to the deactivation model than the adsorption isotherm models in the literature.
Keywords: Adsorption; Carbon Dioxide; Breakthrough Curve; Deactivation Model; Mesoporous Adsorbent
A comparative study on the recovery of 1,2-dichloroethane and the removal of benzene contained in the byproducts of VCM process by Dong Min Kim; Young Woo Kim; Jungho Cho (970-976).
A comparative study has been performed to compare initial investment costs and operation costs for two different process configurations. The two processes were used to recover 1,2-dichloroethane (EDC) and to remove benzene contained in the byproducts of the vinyl chloride monomer (VCM) process. The objectives of this process were to recover 70% of EDC contained in the byproducts and to reduce the benzene content below 0.7 wt%. The first process configuration for comparison is a conventional distillation column that consists of upper and lower columns. The other process configuration is an extractive distillation process that uses Normal Formyl Morpholine (NFM) as a solvent to remove benzene. The conventional distillation process which consists of upper and lower distillation columns was superior to the extractive distillation process, which used a solvent, in the aspects of the initial investment and annual operating cost.
Keywords: Simulation; Extractive Distillation; Process Comparison; 1,2-Dichloroethane Recovery; Benzene Removal
Hybrid supercapacitor based on poly(aniline-co-m-anilicacid) and activated carbon in non-aqueous electrolyte by Muthu Selvakumar; Sethuraman Pitchumani (977-982).
A hybrid asymmetrical super capacitor has been fabricated based on p-doped poly(aniline-co-m-anilicacid) and activated carbon coated on SS electrodes. The characterization of material, electrode and performance of the super capacitor has been studied by FTIR, Cyclic Voltammetry, TGA/DTA, AC Impedance spectroscopy, and galvanostatic charge-discharge tests. The super capacitor showed a maximum specific capacitance of 102 F/g at a scan rate of 10 mV/s. The normalized active-reactive power behavior of the capacitor has been determined. The time constant calculated for the super capacitor is 6 milliseconds, indicating the suitability of the system for efficient use at low frequency range.
Keywords: Supercapacitor; Hybrid Supercapacitor; Conducting Polymer; Activated Carbon; Doping; Capacitance; Poly (aniline-co-m-anilicacid)
Mesoporous silica synthesis in sub- and supercritical carbon dioxide by Byung-Soo Chun; Phillip Pendleton; Alexander Badalyan; Sun-Young Park (983-990).
Mesoporous silicas were synthesized from sodium silicate (Na2Si3O7) and tetraethylorthosilicate (TEOS) with Pluronic F127 (polyethylene oxide-polypropylene oxide-polyethylene oxide, EO106PO70EO106) triblock copolymer using sub- and supercritical carbon dioxide (SubCO2 and SCO2) respectively, as solvents. Templates were removed using liquid carbon dioxide (LCO2) and SCO2. The most efficient template removal was achieved by LCO2 − 92.7% (w/w), followed by LCO2 with ethanol entrainer − 85.6% (w/w), and by methanol − 78.8% (w/w). The best efficiency of template removal by SCO2 was 50.7%. Values of specific surface areas, ABET, were increased by 10% with the increase of an ageing time from 6 to 24 hours for Na2Si3O7-based silicas at aqueous synthesis conditions, whereas the use of SCO2 reduced this value by 19.4%. For TEOS-based silicas synthesized using SCO2, A BET values increased by 3.8 times. Application of SCO2 for synthesis of TEOS-based silicas resulted in higher mesopore volumes of 0.719 and 1.241 mL/g with an average mesopore width varying from 3.4 to 3.9 nm. Although Na2Si3O7-based silicas have almost similar mesopore width range, their mesopore volumes were 7 times less than those for TEOS-based silicas. Formation of mesopores in Na2Si3O7- and TEOS-based silicas was at the expense of micropores when synthesized in SCO2.
Keywords: Mesoporous Silica Synthesis; Mesopore Development; Pluronic F127 Triblock Copolymer; Liquid Carbon Dioxide Solvent; Supercritical Carbon Dioxide Solvent
Kinetics of graft copolymerization of acrylamide and 2-hydroxyethylmethacrylate monomer mixture onto poly(ethylene terephthalate) fibers by Metin Arslan (991-998).
Poly(ethylene terephthalate) (PET) fibers were grafted with acrylamide (AAm) and 2-hydroxyethylmethacrylate (HEMA) using benzoyl peroxide (Bz2O2) as initiator in aqueous media. PET fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of AAm/HEMA onto PET fibers. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 10 mmol/L. The maximum graft yield was obtained (prep.) 273%. The optimum temperature and polymerization time were found to be 85 °C and 120 min, respectively. The rate of grafting was found to be proportional of the 1.39 and 0.37 powers of AAm/HEMA and Bz2O2 concentrations, respectively. The grafted PET fibers were characterized by FTIR spectroscopy and scanning electron microscopy (SEM). Further changes in properties of grafted PET fibers such as water absorption capacity and diameter were determined. The dyeability of the PET fibers increased with an increase in grafting with acidic and basic dyes.
Keywords: Poly(Ethylene Terephthalate) Fibers; 2-Hydroxyethylmethacrylate; Acrylamide; Graft Copolymerization; Monomer Mixture
Optimization of inverted bulk heterojunction polymer solar cells by Bing Zhang; Dong-Hyun Lee; Heeyeop Chae; Chinho Park; Sung Min Cho (999-1002).
We have successively fabricated inverted bulk heterojunction polymer solar cells employing ZnO and MoO3 as electron and hole selective layers, respectively. The device structure is ITO/ZnO/P3HT: PCBM/MoO3/Al. Differently from conventional polymer solar cells, ITO and Al work as electron and hole collecting electrodes in this inverted structure, respectively. We have found the optimal thickness of ZnO and MoO3 to be 100 nm and 5 nm, respectively. The highest PCE was obtained to be 3.32% under AM 1.5 illumination at 1,000W/m2, which is the highest PCE of inverted solar cells reported previously in the literature.
Keywords: Polymer Solar Cells; Invert Structure; Zinc Oxide; Molybdenum Oxide
Effect of synthesis condition and annealing on the sensitivity and stability of gas sensors made of Zn-doped γ-Fe2O3 particles by Taeyang Kim; Andrew Sharp; Bing Guo (1003-1009).
Gas sensors made of flame-synthesized Zn-doped γ-Fe2O3 nanoparticles were found to have high sensitivity and high aging resistance. Zinc-doped γ-Fe2O3 nanoparticles and microparticles were synthesized by flame spray pyrolysis (FSP). Gas sensors were fabricated with as-synthesized particles, and with particles that had been annealed. The sensors’ response to acetone vapor and H2 was measured as fabricated, and measured again after the sensors were aged for three days. The sensors made from as-synthesized particles showed a gas sensing sensitivity 20 times higher than the literature value. However, sensors made of microparticles lost their sensing ability after three days of aging; sensors made of nanoparticles retained their gas sensing capability after aging. Sensors made of annealed particles did not have significant gas sensing capabilities. Analysis using the William and Hall method showed that the microstrains decreased significantly in both H2/O2 and H2/Air flame synthesized particles after annealing. The results showed that sensors made of flame-synthesized particles have much higher sensitivity than sensors made of particles previously reported. Especially, sensors made of flame-synthesized nanoparticles are resistant towards aging. This aging resistance may be attributed to the particles’ ability to retain their microstrains.
Keywords: Flame Spray Pyrolysis (FSP); Gas Sensing; Sensitivity; Aging; Microstrains
Synthesis of mesoporous silica from bottom ash and its application for CO2 sorption by Chao Chen; Kwang-Seok You; Ji-Whan Ahn; Wha-Seung Ahn (1010-1014).
A supernatant solution of silicate species extracted from bottom ash in a power plant was used to prepare a mesoporous silica by the synthesis protocol of SBA-15. XRD, N2 adsorption-desorption, and TEM confirmed a disordered mesopore structure. The pore volume and average pore size of the product were significantly larger than SBA-15 prepared using pure chemicals, and complementary textural mesoporosity was detected. When the mesoporous silica was tested for carbon dioxide sorption after polyethyleneimine (PEI) impregnation, substantially higher CO2 sorption capacity (169 mg CO2/g-sorbent) was achieved than that of PEI-impregnated pure SBA-15 under the same test conditions. High CO2 sorption capacity was maintained when the gas composition was changed to 15% CO2, and the hybrid material exhibited satisfactory performances during the 10 recycle runs.
Keywords: Bottom Ash; Mesoporous Silica; SBA-15; Polyethyleneimine; Carbon Dioxide Capture
Multiple effects of operating variables on heat transfer in three-phase slurry bubble columns by Ik Sang Shin; Sung Mo Son; Dae Ho Lim; Yong Kang; Heon Jung; Ho Tae Lee (1015-1020).
Characteristics of heat transfer were investigated in pressurized slurry bubble column reactors whose diameter was either 0.051, 0.076, 0.102 or 0.152 m (ID) and 1.5 m in height, respectively. Effects of gas velocity (U G ), solid contents (S C ), pressure (P), liquid viscosity (µ L ) and column diameter (D) on the heat transfer coefficient (h) between the immersed vertical heater and the column were determined. Multiple effects such as UG and D, P and D, µ L and D, and S C and D on the value of heat transfer coefficient were discussed. Temperature fluctuations were also measured and analyzed by adapting chaos theory, which was used to explain the effects of operating variables on the heat transfer in the column. The heat transfer coefficient increased with increasing gas velocity, pressure or solid content in the slurry phase, but decreased with increasing liquid viscosity or column diameter. The decrease trend of h with increasing column diameter was somewhat sensitive when the gas velocity was relatively high (U G ⩾12 cm/s). The effects of column diameter on the h value became almost linear when the operating pressure (P=4−10 kg f /cm2), liquid viscosity (µ L =20−38 mPa·s) or solid content in the slurry phase (S C =10−20 wt%) was relatively high and gas velocity was relatively low, within these experimental conditions. The heat transfer coefficient was well correlated in terms of dimensionless groups as well as operating variables.
Keywords: Temperature Fluctuations; Heat Transfer; Slurry Bubble Column; Pressure; Viscous; Column Diameter
Dispersion polymerization of N-vinyl-2-pyrrolydone using fluorine-based surfactants in supercritical carbon dioxide by Jungin Shin; Won Bae; Hwayong Kim (1021-1027).
We carried out a dispersion polymerization of N-vinyl-2-pyrrolydone using fluorine-based surfactants, which included poly(heptadecafluorodecyl acrylate) (PHDFDA) or poly(heptadecafluorodecyl methacrylate) (PHDFDMA) in supercritical carbon dioxide (scCO2). An FE-SEM and an image analyzer were used to characterize particle morphology, size, and size distribution of the resulting polymer taking into account effect of the surfactant, initiator, and monomer concentrations.
Keywords: N-vinyl-2-pyrrolydone; Supercritical Carbon Dioxide; Dispersion Polymerization
Correlation between the ash composition and melting temperature of waste incineration residue by Mi-Ran Kim; Jeong-Gook Jang; Sang-Keun Lee; Bu-Yeon Hwang; Jea-Keun Lee (1028-1034).
The correlation between the ash composition of various incinerated waste residues and their melting temperatures was examined by using their chemical composition parameters. There was a low correlation between the melting temperatures and the acidic oxide content in the ashes. However, the composition parameters derived from the basic oxides showed a good correlation with the ash melting temperature. The composition parameter, P7, which is defined as the ratio of basic oxides (CaO+MgO+K2O+Na2O) to acidic oxides (SiO2+Al2O3+Fe2O3), showed a strong correlation with the ash melting temperature. By fitting the composition parameter to the experimental data, the correlation equation for the half fluid temperature (HFT) was found to be HFT=426.77P 7 2 −736.76P7+1592.3 with a correlation coefficient of 0.91. The correlation equation could be used to predict the melting temperatures of various waste incineration residues. The relative error between the measured and predicted melting temperature was approximately 5%. Overall, these parameters and correlation equations can be used to predict and reduce the melting temperature of incineration residues.
Keywords: Ash Composition; Melting Temperature; Incineration Residues; Composition Parameter; Correlation Equation