Korean Journal of Chemical Engineering (v.24, #6)
Repetitive control of CATOFIN process by Seung-Taek Seo; Wangyun Won; Kwang Soon Lee; Chansul Jung; Seokho Lee (921-926).
The CATOFIN process is a propane dehydrogenation process for production of propylene. It uses multiple adiabatic fixed-bed reactors where dehydrogenation and regeneration (decoking) are performed alternatively over roughly ten minutes of period for each operation. Taking advantage of the periodic operation, the present research concerns the development of a repetitive control method to improve the operation of the CATOFIN process. The controller is designed to perform feedback action during the regeneration cycle and to perform only state estimation during the dehydrogenation cycle. To improve the performance while overcoming the nonlinearity of the process, a linearized time-varying process was derived from a first-principle model and used for the controller design.
Keywords: CATOFIN Process; Repetitive Control; Fixed-bed Reactor
A planar catalytic combustion sensor using nano-crystalline F-doped SnO2 as a supporting material for hydrogen detection by Chi-Hwan Han; Dae-Ung Hong; Jihye Gwak; Sang-Do Han (927-931).
A planar catlytic combustion gas sensor based on Pd/Pt catalyst supported on F-doped SnO2 nano-crystalline materials has been designed and fabricated for hydrogen detection. The sensor consists of platinum heaters on an alumina plate coated with a catalytic layer and compensating layer. This sensor exhibited better performance than that of the sensors employing sensing material of Pd/Pt catalyst on γ-Al2O3 and of Pd/Pt catalyst on nano-crystalline SnO2. The detection limit of the sensor at 370 °C is in the concentration range of 0.5–5% (v/v), with an excellent linearity of signal voltage to the hydrogen gas concentration.
Keywords: Hydrogen Sensor; Catalytic Combustion; F-doped SnO2 ; Pd/Pt Catalyst
Dissolution kinetics of chromite overburden by using mineral acids by P. K. Swain; Gautam Roy Chaudhury; L. B. Sukla (932-935).
Two different mineral acids were used to determine the kinetics of dissolution of Ni and Fe from chromite overburden. Various leaching parameters were studied such as acid concentration, pulp density, temperature and particle size. Both Fe and Ni dissolution followed 1st order irreversible kinetics. The activation energy was also measured. Unified rate equations were established for Ni and Fe dissolution for two different mineral acids, HCl and H2SO4. The dissolution reaction was observed to follow diffusion control-dense-constant size spherical particles.
Keywords: Nickel Overburden; Kinetics; Activation Energy; Rate Equation
Furfural production by acid hydrolysis and supercritical carbon dioxide extraction from rice husk by Wirungrong Sangarunlert; Pornpote Piumsomboon; Somkiat Ngamprasertsith (936-941).
The aim of this research was to study the effect of furfural production from rice husk by hydrolysis accompanying supercritical CO2 (SC-CO2) extraction. The two-level fractional factorial design method was used to investigate the production process carried out with respect to furfural yield. The process variables are temperature range of 373–453 K, pressure 9.1–18.2 MPa, CO2 flow rate 8.3 × 10−5–1.7 × 10−4 kg/s (5–10 g/min), sulfuric acid concentration 1 to 7 (%wt) and ratio of liquid to solid (L/S) 5 : 1 to 15 : 1 (vol/wt). The results obtained from the experimental design showed that increasing temperature, pressure, CO2 flow rate and sulfuric acid concentration but decreasing ratio of liquid to solid would improve furfural yield. Moreover, furfural production by two-stage process (pre-hydrolysis and dehydration) can improve furfural yield further to be around 90% of theoretical maximum.
Keywords: Furfural Production; Acid Hydrolysis; Rice Husk; Supercritical Carbon Dioxide Extraction
Simulation of reactive precipitation processes using the network-of-zones model by Bahman ZareNezhad (942-946).
A 2-D network-of-zones model is extended and applied to a reactive precipitation process in batch mode. The simulations are performed for a network of size 2 × (10 × 10) for an elementary reaction through the solution of 1400 ODEs. The complicated interactions between mixing efficacy and the system kinetics are systematically investigated. When the stirrer speed is very slow, the crystal size distribution (CSD) of the product in the precipitator is determined by the intensity of mixing. Conversely, at higher stirrer speed, the CSD is controlled by the system kinetics. More effective mixing leads to an increase in the number of crystals, a reduction of the average size and a narrower crystal size distribution. The extended network-of-zones model presented in this work can be used conveniently for integrating computational fluid dynamics and reactive precipitation processes.
Keywords: Reaction; Precipitation; Mixing; Simulation; CSD
Dissolution kinetics of calcined ulexite in ammonium carbonate solutions by Asım Künkül; Nizamettin Demirkıran (947-952).
The leaching kinetics of calcined ulexite in ammonium carbonate was studied in this work. The effect of parameters of ammonium carbonate concentration, solid/liquid ratio, stirring speed, calcination temperature and reaction temperature was determined in the experiments. It was found that the conversion rate increased with increasing ammonium carbonate concentration, reaction temperature and decreasing solid/liquid ratio. However, the effect of stirring speed on the conversion rate was insignificant. The experimental data practised the heterogeneous and homogeneous models, and an acceptable model for the conversion rates of ulexite was determined to be a first-order pseudohomogeneous reaction model. The activation energy of dissolution process was determined to be 35.3 kJ/mol.
Keywords: Ammonium Carbonate; Calcined Ulexite; Reaction Kinetics; Leaching
Kinetic parameters using an immobilized tetrahexylammonium chloride catalyst in glycidyl methacrylate reaction with carbon dioxide by Sang-Wook Park; Byoung-Sik Choi; Dae-Won Park; Seong-Soo Kim; Jae-Wook Lee (953-959).
A soluble copolymer-supported catalyst containing pendant tetrahexylammonium chloride was synthesized by the radical copolymerization of p-chloromethylated styrene with styrene followed by the addition reaction of the resulting copolymer with trihexylamine. Initial absorption rate of carbon dioxide into glycidyl methacrylate (GMA) solutions containing the catalyst was measured in a semi-batch stirred tank with a plane gas-liquid interface at 101.3 kPa. The reaction rate constants of the elementary reaction between carbon dioxide and GMA were evaluated from analysis of the mass transfer mechanism accompanied by the elementary reactions based on film theory. Solvents such as toluene, N-methyl-2-pirrolidinone, and dimethyl sulfoxide influenced the reaction rate constants. Furthermore, this catalyst was compared to monomeric tetrahexylammonium chloride under the same reaction conditions.
Keywords: Immobilized Tetrahexylammonium Chloride; Absorption; Carbon Dioxide; Glycidyl Methacrylate
Electrodeposition of palladium on the copper lead frame: Electrode reaction characteristics and the effects of primary additives by Jin-Woo Lee; Jeh-Beck Ju; Joong-Do Kim (960-964).
This study is mainly concerned with the electrodeposition of palladium on the copper alloy lead frame used for semiconductor assembly process. The role and effect of additives on palladium electrodeposition were studied by using various electrochemical methods. Ortho-formylbenzenesulfonic acid as a primary additive was used in palladium plating on the lead frame in this study. The electrochemical characteristics of electrode reaction were measured by the hanging mercury drop electrode for electrochemical system and the qualities of the plated surface of lead frames were also examined. The additive agent in Pd solution could have been classified as the grain refiner. It acted as the electroactive species, which increased the polarization and decreased the roughness, by adsorption on the electrode in palladium pre-plated process. The reduction of palladium ion was identified to be an irreversible reaction and the diffusion coefficient of palladium ion and the reaction rate constant were obtained from chronopotentiometry experiment.
Keywords: Palladium; Electrodeposition; Lead Frame; Additives; Electrochemistry
Characterization of metal (Ba, Al, Si, V, and W)-incorporated TiO2 and toluene photodecomposition in the presence of H2O by Seong-il Yoon; In-Gyung Jung; Misook Kang (965-974).
This study focused on toluene photodecomposition in the presence of H2O over metal (Ba, Al, Si, V, and W)-incorporated TiO2. The nanometer-sized, metal-TiO2 photocatalyst samples, including Ba2+, Al3+, Si4+, V5+, and W6+ ions, were prepared by using the solvothermal method. The X-ray photoelectron spectroscopy (XPS) results showed that the Ti-OH peak, which indicates hydrophilicity, increased with increasing Al and Si ion components but decreased with increasing Ba, V, and W ion components. The contact angles were distributed over the range of 0–10° on almost all films (200-nm thick) after irradiation for 2 h, and in particular approached 0° on the Al-TiO2 and Si-TiO2 nanometer-sized films after just 30 min. The toluene (100 ppm) photodecomposition in the continuous system increased in the order of Al-TiO2>Si-TiO2>pure TiO2>W-TiO2>Ba-TiO2>V-TiO2, and the maximum toluene conversion rate achieved was 45% over Al-TiO2 film after 120 min. The toluene conversion remarkably increased; however, over all photocatalysts, with H2O addition during the toluene photo-decomposed reaction, and in particular, the conversion reached up to 90% after 120 min over Al-TiO2 and Si-TiO2 with increased hydrophilicity. After photoreaction for 24 h, minimal carbon was deposited on the photocatalyst under both reaction conditions, with and without H2O addition, although the deposited carbon amounts were smaller for the former. These results confirmed that the hydrophilicity of the photocatalyst had a greater effect on toluene decomposition, while the photocatalytic deactivation could be retarded by H2O supplementation during toluene decomposition.
Keywords: Solvothermal Method; Metal-TiO2 ; Hydrophilicity; Toluene Decomposition; H2O Addition
Fracture properties of silica/carbon black-filled natural rubber vulcanizates by Young Chun Ko; Gayoung Park (975-979).
Crack growth property of natural rubber (NR) vulcanizate with varying silica/carbon black content was examined. Tensile specimen with edge cut was used for estimating fracture properties. All filled NR specimens showed critical cut-size (C cr ), which is related to abrupt decrease in tensile strength. Carbon black-filled NR, S0 (Si/N330=0/50) has higher tensile strength than equivalently loaded silica-filled NR vulcanizates, S5 (Si/N330=50/0). When the precut size of specimen was less than critical cut-size, tensile strength of S1 (Si/N330=10/40) composition was the highest and that of S5 was the lowest. The critical cut-size passes through a maximum for S2 (Si/N330=20/30) and then decreases gradually with silica loading. An interesting result was that silica and carbon black-blended compounds gave higher critical cut size than the all-carbon black compounds, S0. The inherent flaw size decreased from 246 μm for S0 to 80 μm for S5 as the silica content increased.
Keywords: Silica; Carbon Black (N330); Fracture; Critical Cut-size; Inherent Flaw-size
Media configuration and recirculation of upflow anaerobic floating filter for piggery wastewater treatment by Seunghwan Lee; Hongshin Lee; Seongeok Lee; Sukhuma Chitapornpan; Chart Chiemchaisri; Chongrak Polprasert; Kyuhong Ahn (980-988).
An upflow anaerobic floating filter media (UAFF) reactor was applied to the treatment of synthetic and real piggery wastewater. The effect of media configuration and internal recirculation on the system performance was studied. In the first experiment, three-UAFF reactors filled with different media, i.e., polypropylene beads, sponge cubes and coconut fiber were continuously fed with synthetic wastewater at upflow velocity of 0.04 m h−1. The COD removal efficiency in the reactor filled with sponge cubes was highest at 90%, whereas the others filled with polypropylene beads and coconut fibers with lower specific surface area were about 80%. In the second experiment, three-UAFF reactors with sponge were applied to treat real piggery wastewater. COD removal efficiencies were found to be about 80% and methane production rate of 0.26 l l r −1 d−1. The system performance could be slightly improved by 10% when applying internal recirculation. A sludge blanket (60–70% of total biomass) plays an important role in the system when applied to the treatment of piggery wastewater containing high suspended solid concentration.
Keywords: Anaerobic Filter; Floating Media; Media Configuration; Upflow Anaerobic Floating Filter Media Reactor
Co-combustion of coal and biomass in a circulating fluidized bed combustor by Chaiwat Prompubess; Lursuang Mekasut; Pornpote Piumsomboon; Prapan Kuchontara (989-995).
In this research, co-combustion of coal and rice husk was studied in a circulating fluidized bed combustor (CFBC). The effects of mixed fuel ratios, primary air and secondary air flow rates on temperature and gas concentration profiles along riser (0.1 m inside diameter and 3.0 m height) were studied. The average particle size of coal from Maetah used in this work was 1,128 mm and bed material was sand. The range of primary air flow rates was 480–920 l/min corresponding to U g of 1.0–2.0 m/s for coal feed rate at 5.8 kg/h. The recirculation rate through L-valve was 100 kg/hr. It was found that the temperatures along the riser were rather steady at about 800–1,000 degrees Celsius. The introduction of secondary air improved combustion and temperature gradient at the bottom of the riser, particularly at a primary air flow rate below 1.5 m/s. Blending of coal with biomass, rice husk, did improve the combustion efficiency of coal itself even at low concentration of rice husk of 3.5 wt%. In addition, the presence of rice husk in the feed stocks reduced the emission of both NO x and SO2.
Keywords: Circulating Fluidized Bed; Biomass; Coal; Co-combustion
Distribution and characteristics of pyrolysis products from automobile shredder residue using an experimental semi-batch reactor by Hyun Tae Joung; Yong Chil Seo; Ki Heon Kim; John Hee Hong; Tae Wook Yoo (996-1002).
Automobile shredder residue (ASR) generated by end-of-life vehicles, comprises more than 20% of a new vehicle by weight. Significant amounts of polymers in ASR, such as Poly Propylene (PP), Poly Ethylene (PE), Acrylonitrile Butadiene Styrene (ABS), Ethylene Propylene Ethylidene Nobomene (EPDM), rubber, Polyethylene Terephthalate (PET), Poly Amide (PA), and Poly Vinyl Chloride (PVC), can be used as energy or chemical sources, whereas other components, such as tires, rubber, glass, wood, sand/dust, and heavy metals inhibit the recycling of ASR. In many countries, landfill use of ASR is regulated, so landfill costs have increased, as has inappropriate disposal; sending ASR to landfills will be needed to be regulated in Korea. Pyrolysis has been suggested as an economically feasible recycling and recovery technique for ASR in Korea and other advanced countries. Before such technology is implemented, the characteristics of pyrolyzed products should be investigated. Shredded samples from the facility were collected, and calorific value, elemental analysis, and leaching tests were performed to determine ASR characteristics. Pyrolysis experiments were conducted at five different temperatures, 400, 500, 600, 700, and 800 °C, and the product distributions of gas, tar, and char were investigated. The optimal temperature for ASR pyrolysis, in terms of yield efficiency, was found to be 600 °C. The mean calorific value was also found to be higher in this case; thus, ASR can be treated as an auxiliary fuel. During pyrolysis, there were high ignition losses of light and heavy fluff, due to the presence of organic materials. The leaching concentrations of all tested heavy metals were found to be within the Korean guideline values. In terms of carbon number distributions, pyrolysis of ASR at 600 °C was optimal. For further utilization of pyrolysis products as fuel, the characteristics of char, oil, and gas were investigated with an experimental batch reactor.
Keywords: Automobile Shredder Residue (ASR); End-of-life Vehicle (ELV); Shredder Dust (SD); Pyrolysis
Ozonation of polycyclic aromatic hydrocarbon in hexane and water: Identification of intermediates and pathway by Young-Ik Choi; Andrew Hong (1003-1008).
The recalcitrant nature of pyrene and other polycyclic aromatic hydrocarbons (PAHs) lies in part in their low solubility in water, rendering them less susceptible to chemical and biological degradation. To overcome this remediation obstacle, this work investigates the use of a 2-stage ozonation process, first in nonpolar hexane phase then in polar aqueous phase, for the treatment of hydrophobic contaminants using pyrene as a model compound. The objectives of this research are to break down pyrene by using ozonation, identify the intermediates of pyrene, show a general degradation pathway of pyrene subject to ozonation and test the biodegradability of intermediates and byproducts of pyrene in the aqueous phase. The first stage briefly ozonates the contaminant at high concentration in organic solvent hexane, which facilitates very efficient conversion of the hydrophobic compounds into ring-opened polar intermediates containing alcohol, aldehyde, and acid functional groups.
Keywords: Chemical; Degradation; PAHs; Pyrene; Ozone
Cerium(IV)-mediated electrochemical oxidation process for destruction of organic pollutants in a batch and a continuous flow reactor by Subramanian Balaji; Sang Joon Chung; Manickam Matheswaran; Il Shik Moon (1009-1016).
The mediated electrochemical oxidation (MEO) process with Ce(IV) and nitric acid as the oxidizing medium was employed for the destruction of various model organic pollutants in batch and continuous organic feeding modes. A near complete destruction was observed for all the model organic pollutants studied. The effects of organic concentration, temperature, concentration of Ce(IV), concentration of nitric acid and feeding time on the organic destruction efficiency were investigated. Under the experimental conditions of 80 °C and 0.95 M Ce(IV) in 3 M nitric acid, nearly 90% destruction was achieved based on CO2 production and 95% based on TOC and COD nearly for all the organic compounds studied in batch organic addition. In the case of continuous organic addition with in situ electroregeneration of Ce(IV) by the electrochemical cell a good destruction efficiency was obtained. For long term organic feeding (120 min) the destruction efficiency was found to be 85% based on CO2 evolution and 98–99% based on TOC and COD analyses. A model was proposed for calculating the CO2 formation constant during the continuous process of organic addition. The model predicted a steady state CO2 evolution pattern for the destruction process during continuous organic feeding. The experimental results obtained confirmed the predicted trends for the destruction process. The changes in enthalpy, entropy, activation energy and free energy for EDTA degradation were found to be 26.7 kJ/mol, −230 J/(mol·K), 29.7 kJ/mol, and 118 kJ/mol respectively.
Keywords: Mediated Electrochemical Oxidation; Electrochemical Cell; Cerium(IV); Organic Destruction
Photocatalytic oxidation of NO x over visible-light-responsive nitrogen-doped TiO2 by Lin Zhou; Xin Tan; Lin Zhao; Ming Sun (1017-1021).
In order to utilize visible-light in photocatalytic conversion of NO x , nitrogen atoms were doped in commercially available photocatalytic TiO2 powders by impregnating method. The crystal structures of TiO2 were not changed after calcination process. Analysis by X-ray photoelectron spectroscopy (XPS) indicated that N atoms were incorporated in the bulk phase of TiO2 as N-Ti-O linkages. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible-light region were observed. These N-doped TiO2 powders exhibited photocatalytic activity of the oxidation of NO x under visible-light irradiation. The sample mixed with 20 wt% ammonium carbonate and calcined in 600 °C showed best photocatalytic activity and its activity can be restored by rinsing with water after long-term operation.
Keywords: Photocatalysis; Nitrogen Doped Titania; Visible-Light Induced; Nitrogen Oxides; Environment
Preparation of Ag-sensitized ZnO and its photocatalytic performance under simulated solar light by Feng Peng; Hancai Zhu; Hongjuan Wang; Hao Yu (1022-1026).
ZnO was prepared rapidly by microwave heating method. The results of scanning electron microscopy show that the leaflike ZnO is composed of self-assembled ZnO particles of 30–50 nm. Ag-sensitized ZnO composite was prepared by UV-photoreduction and glycol reduction, respectively. The composite was characterized by means of scanning electron microscopy, X-ray diffraction and photoluminescence. The ZnO and Ag/ZnO prepared were applied in photocatalytic degradation of phenol and methyl orange as model of organic pollutant in water under simulated solar light. The results show that Ag doping in both methods of UV-photoreduction and glycol reduction can remarkably improve the photocatalytic activity of ZnO under simulated solar light. The utilization ratio of Ag in glycol reduction is high and the optimum content of Ag in Ag/ZnO composite is only 1.33%. Therefore, the glycol reduction is a novel and excellent method for preparing Ag-sensitized ZnO composite with high photocatalytic activity.
Keywords: Nanostructures; Photocatalysis; ZnO; Photocatalytic Degradation; Solar Light
Novel biodiesel production technology from soybean soapstock by Zhong-Ming Wang; Jin-Suk Lee; Ji-Yeon Park; Chuang-Zhi Wu; Zhen-Hong Yuan (1027-1030).
This paper describes an attractive method to make biodiesel from soybean soapstock (SS). A novel recovery technology of acid oil (AO) from SS has been developed with only sulfuric acid solution under the ambient temperature (25±2 °C). After drying, AO contained 50.0% FFA, 15.5% TAG, 6.9% DAG, 3.1% MAG, 0.8% water and other inert materials. The recovery yield of AO was about 97% (w/w) based on the total fatty acids of the SS. The acid oil could be directly converted into biodiesel at 95 °C in a pressurized reactor within 5 hours. Optimal esterification conditions were determined to be a weight ratio of 1 : 1.5 : 0.1 of AO/methanol/sulfuric acid. Higher reaction temperature helps to shorten the reaction time and requires less catalyst and methanol. Ester content of the biodiesel derived from AO through one-step acid catalyzed reaction is around 92%. After distillation, the purity of the biodiesel produced from AO is 97.6% which meets the Biodiesel Specification of Korea. The yield of purified biodiesel was 94% (w/w) based on the total fatty acids of the soapstock.
Keywords: Biodiesel; Soybean Soapstock (SS); Acid Oil (AO); One Step Esterification
Photocatalytic activity of nitrogen-substituted TiO2 deposited with Pt and Ru by Jaekyung Yoon; Sanghyun Bae; Eunjung Shim; Hyunku Joo (1031-1036).
In this work, Pt- and Ru-deposited, nitrogen-substituted TiO2 were prepared and characterized by the discoloration of MB and H2 evolution. The characteristics were evaluated in terms of methylene blue (MB) discoloration, open circuit voltage (OCV), photocurrent (I ph ), and hydrogen production. First, the Pt-deposited TiON revealed comparable activity in MB discoloration, while both TiONs resulted in somewhat less activity than P25. Second, an external bias was systematically applied to electrodes made of the prepared samples, resulting in −0.41∼0.51 OCV, −400∼400 μA and noticeable hydrogen evolution above 300 μA in absolute value when a bias of −1.5∼1.5 V was applied to the working electrode of P25. The electrolyte and light intensity affected the light-responsive characteristics of the photocatalysts, confirming the relationship between OCV, I ph and H2 and that metal deposition slightly inhibited the I ph and H2 evolution while Ru-deposited TiON did not degrade MB effectively.
Keywords: Photocatalyst; Nitrogen-doped; Metal Deposition; Photocurrent; Methylene Blue
Electrochemical properties of gel polymer electrolyte based on poly(acrylonitrile)-poly(ethylene glycol diacrylate) blend by Byung-Won Cho; Da Hye Kim; Hee-Woo Lee; Byung-Ki Na (1037-1041).
Gel type electrolyte was formulated by blending of PEDGA and PAN. PEDGA is a UV curable polymer which forms a chemical crosslink by UV or heat. Gel type electrolyte is very stable in ionic conductivity and interfacial resistance for a long storage time. It has the advantage of manufacturing the battery in a continuous process because oligomer crosslinking occurs in few seconds without heating. Discharge capacity and cycle life were increased by using LiPF6/LiCF3SO3 mixed lithium salt and adding inorganic filler such as TiO2.
Keywords: Gel-type Polymer Electrolyte; Mixed Lithium Salts; Ceramic Fillers; PAN; PEDGA
Control of residual organic matter to reduce bacterial regrowth potential for wastewater reuse by Shijun Kim; Jeongsook Kim; Yutaka Suzuki (1042-1046).
Several problems have been reported about accumulated microorganisms in reclaimed water distribution systems. This paper presents the results of residual organic matter (OM) removal and apparent bacterial regrowth potential of treated wastewater obtained from laboratory-scale experiments using advanced biological treatments: two immobilization processes in series and a membrane bioreactor (MBR) process. Furthermore, a nanofiltration (NF) membrane process was applied to effluents of both advanced biological treatments. The immobilization process removed large molecular weight (MW) fractions >5,000 since immobilized microorganisms had sufficiently acclimated. The NF membrane was more effective in rejecting large MW fractions in the effluents of the immobilization and the MBR treatments. But it was difficult to reject small MW fractions <1,000 by NF. Neutral hydrophilic fraction of DOC was reduced by both advanced biological processes, and it can be thought that the microorganisms in the advanced processes could decompose and grow on some part of the neutral hydrophilic fraction. Quantity of attached microorganisms in the second immobilization reactor was significantly reduced compared to that in the first immobilization reactor. This suggests that apparent bacterial regrowth potential is controlled by the accumulation of effective microorganisms in the first reactor.
Keywords: Wastewater Reuse; Bacterial Regrowth; Biological Advanced Treatment
Adsorption behaviors of the aminated chitosan adsorbent by Zhao Yan; Su Haijia; Tan Tianwei (1047-1052).
Using inverse suspension technology, a novel aminated chitosan adsorbent with higher adsorption ability for metal cations and metal anions was prepared. Through cross-linking amination reaction, the content of amidocyanogen of aminated chitosan adsorbent was enhanced four times than that of chitosan cross-linked adsorbent. As can be seen from the results, the adsorption ability of the novel aminated chitosan adsorbent for (Nicit)− and Cr(VI) was enhanced remarkably. When the initial concentration of metallic ion was 1,000 mg/L, the adsorption capacity of the novel aminated chitosan adsorbent for nickel citrate and Cr(VI) was up to 30.2 mg/g and 28.7 mg/g, respectively. And the adsorption capacity of the novel aminated chitosan adsorbent for Ni2+ was still higher. So the new aminated chitosan adsorbent offers not only a higher uptake for metal cations but also a better adsorption capacity for metal anions.
Keywords: Heavy Metallic Anion; Adsorption; Chitosan; Cross-linking; Aminated
Long-term preservation of high initial bioluminescence of lyophilized Photobacterium phosphoreum: Effect of skim milk and saccharose at various temperatures by Thuan-Hieu Tran; Woo-Jin Chang; Young-Bum Kim; Joo-Young Yoon; Yoon-Mo Koo; Eun-Ki Kim; Jin-Hwan Kim (1053-1057).
A lyophilization method for long-term preservation of the initial bioluminescence of Photobacterium phosphoreum was investigated. The initial bioluminescence of lyophilized P. phosphoreum at different temperatures, −20 °C, 4 °C, room temperature (16–25 °C) and 45 °C, was monitored for 6 months with different additives. Saccharose, skim milk, and a mixture of saccharose and skim milk were tested. Skim milk showed the best protection for bioluminescence among the additives used. The initial bioluminescence remained high during 6 months at a wide range of storage temperatures, i.e., −20 °C, 4 °C, and room temperature, with skim milk as an additive. The average bioluminescence of lyophilized P. phosphoreum using skim milk as additive reached 33392 RLU within 30 min of regeneration. Bioluminescence increased slightly after 10 h of incubation.
Keywords: Photobacterium phosphoreum ; Initial Bioluminescence; Lyophilization; Long-Term Preservation
Effect of essential and nonessential amino acid compositions on the in vitro behavior of human mesenchymal stem cells by Kyung-Min Choi; Hee-Hoon Yoon; Young-Kwon Seo; Kye-Yong Song; Soon-Yong Kwon; Hwa-Sung Lee; Yong Soon Park; Young-Jin Kim; Jung-Keug Park (1058-1063).
Mesenchymal stem cells (MSCs) from bone marrow appear to be an attractive tool for use in tissue engineering and cell-based therapies due to their multipotent capacity. The majority of studies on MSCs have been restricted to the roles of growth factors, cytokines, and hormones. Based on previous reports demonstrating the important roles of amino acids, we sought to evaluate the effect of essential amino acids (EAs) and nonessential amino acids (NEAs) on the proliferation and differentiation of MSCs. The results showed that the EA/NEA compositions during culture could significantly modulate MSC proliferation and differentiation and, especially, that EAs served as a potent positive modulator in the proliferation of MSCs without causing a deficit in the differentiation capacity of the cells. These results will be very useful in the production of MSC-based cell therapy products for use in the field of tissue engineering and regenerative medicine.
Keywords: Amino Acid; Proliferation; Differentiation; Mesenchymal Stem Cell; Bone Marrow
Simultaneous removal of SO2, NO and particulate by pilot-scale scrubber system by Seung-Ho Jung; Gwi-Taek Jeong; Gwang-Yeon Lee; Jin-Myeong Cha; Don-Hee Park (1064-1069).
SO x and NO x have both previously been identified as primary precursors of acid rain, and thus the abatement of SO x and NO x emissions constitutes a major target in the field of air pollution control. In this study, the efficacy of a pilot-scale scrubber was evaluated with regard to the simultaneous removal of SO2, NO and particulate with wet catalysts. The removal efficiencies of particulate were measured to be 83, 92 and 97% with catalyst flux of 0.5, 0.8 and 1.5 L/min, respectively. The average removal efficiencies of particulate with different nozzles were approximately 94 and 90% with FF6.5 (5/8 in.) and 14 W (1.0 in.) nozzles, respectively. At least 96–98% of particulate and SO2 were removed, regardless of the stage number of reactor. In a one-stage scrubber, 83.3% removal efficiency of NO was achieved after 48 hours; however, the two-stage scrubber achieved an NO removal efficiency of 95.7%. Regardless of the liquid-gas ratio, SO2 and particulate were removed effectively, whereas NO was removed about 84% and 74% under liquid-gas ratio conditions of 39.32 L/m3 and 27.52 L/m3, respectively. In experiments using STS and P.P. pall ring as packing material, particulate and SO2 removal efficiency values in excess of 98% were achieved; however, NO removal was correlated with the different packing materials tested in this study. With the above optimum operation conditions, even after 20 hours, the removal efficiency for NO stayed at 95% or higher, the removal efficiency for SO2 stayed at 97% or higher, and the removal efficiency for particulate stayed at 92% or higher. In accordance, then, with the above results, it appears that this process might be utilized in scrubber systems, as well as systems designed to simultaneously remove particulate, SO2 and NO from flue gas.
Keywords: Scrubber; SO2 ; NO; Particulate; Simultaneous Removal
Preparation and characterization of natural rubber foams: Effects of foaming temperature and carbon black content by Eun-Kyoung Lee; Sei-Young Choi (1070-1075).
The influence of the foaming temperature and carbon black content on the cure behavior and mechanical properties of natural rubber foams was investigated at five temperature zones by 5 °C interval and different feeding ratios of the carbon black. The physical properties of the foamed NRs were then measured as a function of the foaming temperature and carbon black content, respectively. The optimal temperature for vulcanization and foaming of NRs in this study was considered to be 165 °C where density of the foamed NR is lower than that at other four temperature zones. The thickness of each of the struts formed within the rubber matrix decreased with the increasing foaming temperature, while it increased with the increasing carbon black content, supporting the density characteristics. The tensile properties of the foamed NRs such as tensile strength, tear strength and modulus gradually increased with the increasing and carbon black content, while elongation at break decreased.
Keywords: Vulcanization; Cure Behavior; Foaming; Cure Rate Index
Synthesis and applications of unsaturated polyester resins based on PET waste by Jinkyung Kim; Dookyo Jeong; Changho Son; Younghee Lee; Eunyong Kim; Il Moon (1076-1083).
Three types of unsaturated polyester resins were synthesized from the glycolysis of polyethylene terephthalate (PET) plastic waste, considering environment, cost and properties for their applications. These synthesized unsaturated polyester resins could be used for various construction processes and materials such as no dig pipelining (NDR-1), pultrusion (PLR-1) and polymer concrete (PCR-1). PET was taken from common soft-drink bottles, and ethylene glycol (EG), diethylene glycol (DEG) and MPdiol glycol mixtures were used for the depolymerization at molar ratios. The glycolyzed PET 1 st products (oligomers) were reacted with maleic anhydride, phthalic anhydride and dicyclopentadiene (DCPD) (especially for polymer concrete) to form unsaturated polyester resins with mixed styrene. The lab scale (1–5 kg) and pilot plant scale-up tests (200 kg) were experimented to evaluate the processing characteristics, viscosity, acid number and curing behaviors. The main properties such as hardness, flexural strength, tensile strength, heat distortion temperature, elongation, and chemical resistance were determined based on the various uses of the three resins. Furthermore, the applicability and the properties of these developed resins were verified through many real application tests.
Keywords: PET Waste; Glycolysis; Unsaturated Polyester Resins; Construction Material
Growth of ZnO nanoneedles on silicon substrate by cyclic feeding chemical vapor deposition: Structural and optical properties by Suk Lee; Ahmad Umar; Sang Hoon Kim; N. Koteeswara Reddy; Yoon-Bong Hahn (1084-1088).
Well-crystallized ZnO nanoneedles were grown on Au-coated Si(100) substrate by cyclic feeding chemical vapor deposition (CFCVD) process using diethyl zinc and oxygen as precursors for zinc and oxygen, respectively. Morphological investigations revealed that the as-grown nanoneedles exhibited sharpened tips and wider bases, having the typical diameters at their bases and tips, 60±10 nm and 20±10 nm, respectively. Detailed structural characterizations confirmed that the as-grown products were single crystalline with a wurtzite hexagonal phase and were grown preferentially along the  direction. The room-temperature photoluminescence (PL) spectrum showed a strong and sharp UV emission at 378 nm with a very weak, suppressed and broad green emission at 520 nm, substantiating good optical properties for the as-grown ZnO nanoneedles.
Keywords: ZnO; Nanoneedles; Cyclic Feeding Chemical Vapor Deposition; Optical Properties
Size-controlled electrochemical synthesis of palladium nanoparticles using morpholinium ionic liquid by Jong-Ho Cha; Ki-Sub Kim; Sukjeong Choi; Sun-Hwa Yeon; Huen Lee; Chul-Soo Lee; Jae-Jin Shim (1089-1094).
We have successfully synthesized morpholinium ionic liquid-stabilized palladium (Pd) nanoparticles by electrochemical reduction. For characterization of Pd nanoparticles, FT-IR, UV-visible spectroscopy, and Transmission electron microscopy (TEM) were employed. The FT-IR spectrum of Pd nanoparticles indicated the surface binding of the IL to the nanoparticles. The UV-visible spectrum showed that nano-sized Pd particles were produced. The particle size was controlled by the adjustment of the current density, temperature, and electrolysis duration. The TEM images showed an average size of 2.0, 2.2, 2.4, 2.9, 3.5, 3.9, and 4.5 nm. Nearly a 0.5 nm-sized control of the nanoparticle was achieved. The particle size increased with a decrease in the current density and an increase in temperature and electrolysis duration. The electron diffraction patterns of resulting nanoparticles indicated that the particles had a crystalline structure.
Keywords: Ionic Liquid; Morpholinium Salt; Palladium Nanoparticles; Electrochemical Synthesis; Size Control
Effect of reactant composition on the production of MoSi2 by self-propagating high-temperature synthesis by Sang Hwan Kim; Sang-Cheol Yeo; Gong Won Kang (1095-1100).
The effect of reactant composition, particle size of silicon, density of powdered compacts, and reaction atmosphere on the characteristics of molybdenum disilicide produced from molybdenum and silicon powders by self-propagating high-temperature synthesis, was studied in a pressurized reaction chamber at 1.5 bar. The atomic ratio of silicon to molybdenum (Si/Mo) was changed from 1.0 to 2.6 in order to investigate the effect of reactant composition on the characteristics of self-propagating high-temperature synthesis. Stable combustion was observed for the values of atomic ratios of silicon to molybdenum from 1.8 to 2.2 and SHS-produced material consisted of a uniform and single-phased MoSi2. In the meantime unstable combustion such as oscillatory, spinning, and surface combustion was detected for the values of atomic ratios of silicon to molybdenum less than 1.8 or larger than 2.2. SHS-produced material under unstable combustion includes the impurities of Mo5Si3, Mo3Si, unreacted Mo and Si resulting from the layered or reacted-on-surface structures, which give lower degree of reaction and possibly poor electrical properties of heating element MoSi2. The value of criterion α suggested by Shkadinskii et al. to differentiate stable combustion from unstable one, is found to be 0.74 for producing molybdenum disilicide by self-propagating high-temperature synthesis. Stable combustion was detected for the values of α greater than 0.74 (α>0.74) to give the uniform and single-phased product while unstable combustion was observed for the values of α less than 0.74 (α<0.74) to result in a non-uniform and multiphase product. This critical value will help the industry to produce uniform and high-purity molybdenum disilicide by self-propagating high-temperature synthesis processes.
Keywords: Molybdenum Disilicide; Self-Propagating High-Temperature Synthesis; Stable Combustion; Spinning Combustion; Heating Element
Modification of Nafion membranes by incorporation of cationic polymers for reduction of methanol permeability by Dong Hoon Kang; Dukjoon Kim (1101-1105).
A small amount of basic polymer was incorporated in the Nafion membrane. Compared with the re-cast Nafion membrane, the Nafion/basic polymer membrane reduced the methanol permeability considerably. The equilibrium water uptake and proton conductivity decreased, but the thermal and mechanical stability was enhanced with increasing concentration of basic polymer. These property changes were caused by formation of cation/anion complex between acidic Nafion and basic polymer molecules. The effects of the types and molecular weights of basic polymers on the methanol permeability and proton conductivity were not significant.
Keywords: Nafion Membrane; Methanol Permeability; Proton Conductivity; Polymer Electrolyte
Effect of interaction of operation parameters on elutriation behavior in a vortexing fluidized bed by Chien-Song Chyang; Hou-Peng Wan; Li-Chi Su (1106-1112).
A systematic investigation on elutriation behavior conducted in a vortexing fluidized bed (VFB) cold model is studied. The effects of various parameters on the elutriation are investigated from the data obtained by using ‘response surface methodology’ (RSM) to determine the relationship between elutriation rate and operating conditions. The results show that all the interactions among primary air flow rate, secondary air flow rate, fine particle size, secondary air inlet diameter, and imaginary circle diameter had significant influences on elutriation behavior in the VFB. The modified regression models of the ‘specific elutriation rate constant’ (K*) were also submitted in this study.
Keywords: Vortexing Fluidized Bed; Elutriation; Response Surface Methodology; Specific Elutriation Rate Constant
Simultaneous removal of SO2 and NO by low cost sorbent-catalysts prepared by lime, fly ash and industrial waste materials by Tianjin Li; Yuqun Zhuo; Junyong Lei; Xuchang Xu (1113-1117).
The potential of the sorbent-catalysts prepared from three low cost materials, i.e., the lime, fly ash and some industrial waste material containing iron oxide, have been investigated for simultaneous removal of SO2 and NO x from flue gas in the temperature range 700–850 °C. NH3 was chosen as the reducing agent for NO reduction in this study. Experimental results showed that SO2 and NO could be simultaneously removed efficiently in the absence of O2 at the temperature window of 700–800 °C. The effect of product layer generated from SO2 removal on NO removal was not obvious. NO removal efficiency was strongly inhibited by O2, which was attributed to the partial oxidation of NH3 to NO over the sorbent-catalysts in the presence of oxygen. Neither NO2 nor N2O by-product was detected both in the absence and presence of O2. Three routes were suggested to overcome the negative effect of O2.
Keywords: Multi-pollutant Control; Desulphurization; Denitrification; Flue Gas; Calcium Oxide
Modeling and coordinative optimization of NO x emission and efficiency of utility boilers with neural network by Yi Zhang; Yanjun Ding; Zhansong Wu; Liang Kong; Tao Chou (1118-1123).
An empirical model to predict the boiler efficiency and pollutant emissions was developed with artificial neural networks based on the experimental data on a 360 MW W-flame coal fired boiler. The temperature of the furnace was selected as an intermediate variable in the hybrid model so that the predictive precision of NO x emissions was enhanced. The predictive precision of the hybrid model was improved compared with the direct model. Three optimal operational objects were proposed in order to minimize the fuel and environmental costs. Based on the neural network model and optimal objects, a genetic algorithm was employed to seek real-time solution every 30 seconds. Optimum manipulated variables such as excess air, primary air and secondary air were obtained under different optimal objects. The above algorithm interconnected with a distributed control system (DCS) formed the supervisory control and achieved real-time coordinated optimization control of utility boilers.
Keywords: Coal Combustion; Efficiency; NO x ; Coordinative Optimization; Artificial Neural Networks; Genetic Algorithm
Selective removal of sulfur compounds in city-gas by adsorbents by Chang Hyun Ko; Hirn-Ill Song; Jong-Ho Park; Sang-Sup Han; Jong-Nam Kim (1124-1127).
Silver nitrate impregnated on beta zeolite (BEA), mesoporous silica MCM-41 and SBA-15 (AgNO3/BEA, AgNO3/MCM-41, AgNO3/SBA-15) were prepared to remove sulfur compounds selectively in city-gas, which contains tetrahydrothiophene and tert-butylmercaptane. Sulfur adsorption capacity was determined when the sulfur concentration of effluent gas in breakthrough test reached 0.1 ppm, which is acceptable sulfur concentration for hydrogen production in a reformer for fuel cells. As the AgNO3 concentration in AgNO3/BEA, AgNO3/MCM-41, and AgNO3/SBA-15 increased, their sulfur adsorption capacities also increased. Although microporous zeolite BEA has smaller pore volume and lower surface area than those of mesoporous silica MCM-41 and SBA-15, the sulfur adsorption capacity of AgNO3/BEA was higher than those of AgNO3/MCM-41 and AgNO3/SBA-15. Adsorbed sulfur molecules per impregnated silver nitrate and the shape change of breakthrough curves depending on the adsorption temperature showed that not only chemisorption but also physisorption was involved in sulfur compounds adsorption on AgNO3 impregnated adsorbent.
Keywords: Beta Zeolite; Mesoporous Silica; Desulfurization; City-gas; Selective Adsorption
Development of a pilot-scale acid gas removal system for coal syngas by Seung Jong Lee; Soung Hyoun Kim; Kyoung Hoon Kang; Young Don Yoo; Yongseung Yun (1128-1132).
The Korean pilot-scale gasification facility consists of a coal gasifier, hot gas filtering system, and acid gas removal (AGR) system. The syngas stream from the coal gasification at the rate of 100–120 Nm3/hr included pollutants such as fly ash, H2S, COS, etc. The acid gas, such as H2S and COS, is removed in the AGR system before generating electricity by gas engine and producing chemicals like Di-methyl Ether (DME) in the catalytic reactor. A hydrolysis system was installed to hydrolyze COS into H2S. The designed operation temperature and pressure of the COS hydrolysis system are 150 °C and 8 kg/cm2. After the hydrolysis system, COS was reduced below 1 ppm at the normal operating condition. The normal designed operation temperature and pressure of the AGR system are below 40 °C and 8 kg/cm2. Fe-chelate was used as an absorbent. H2S was removed below 0.5 ppm in the AGR system when the maximum concentration of H2S was 900 ppm. A small scale COS adsorber was also installed and tested to remove COS below 0.5 ppm. COS was removed below 0.1 ppm after the COS adsorbents such as the activated carbon and ion exchange resin.
Keywords: Gasification; Syngas; COS Hydrolysis; Acid Gas Removal; Absorbent; Fe-chelate