Korean Journal of Chemical Engineering (v.32, #3)
Novel double-walled microspheres based on chitosan, sodium cellulose sulfate and sodium tripolyphosphate: Preparation, characterization and in vitro release study by Li-Ying Zhu; Xiao-Qin Yan; Hong-Man Zhang; Shan-Jing Yao; Ling Jiang (369-372).
A novel double-walled microsphere composed of chitosan, sodium cellulose sulfate (NaCS) and sodium tripolyphosphate (TPP) was prepared. TPP was used as ionic crosslinker. The morphology of the microspheres was observed by microscope and SEM, and the results showed that the double-walled microsphere was smooth outside, with rough interior surface. FTIR spectra analysis was performed to investigate the PEC formation among chitosan, NaCS, and TPP. In vitro release studies of BSA showed that the double-walled microspheres had regular and sustainable release profiles in simulated colonic fluid (SCF). Our results indicated that the double-walled microspheres prepared could be used as a candidate protein drug carrier for the colon.
Keywords: Chitosan; Sodium Cellulose Sulfate; Sodium Tripolyphosphate; Double-walled Microshperes; In Vitro Drug Release
Capture of CO2 from coal using chemical-looping combustion: Process simulation by Ming Luo; Shuzhong Wang; Jiabin Zhu; Longfei Wang; Mingming Lv (373-382).
Coal direct chemical-looping combustion (CLC) and coal gasification CLC processes are the two basic approaches for the application of the CLC technology with coal. Two different combined cycles with the overall thermal input of 1,000MW (LHV) were proposed and simulated, respectively, with NiO/NiAl2O4 as an oxygen carrier using the ASPEN software. The oxygen carrier circulation ratio in two CLC processes was calculated, and the influence of the CLC process parameters on the system performance such as air reactor temperature and the turbine inlet supplementary firing temperature was investigated. Results found were that the circulation ratio of the oxygen carrier in the coal gasification CLC process is smaller than that in the coal direct CLC process. In the coal direct CLC combined system, the system efficiency is 49.59% with the CO2 capture efficiency of almost 100%, assuming the air reactor temperature at 1,200 °C and the fuel reactor temperature at 900 °C. As a comparison, the system efficiency of coal gasification CLC combined system is 40.53% with the CO2 capture efficiency of 85.2% when the turbine inlet temperature is at 1,350 °C. Increasing the supplementary firing rate or decreasing the air reactor temperature can increase the system efficiency, but these will reduce the CO2 capture efficiency.
Keywords: Chemical-looping Combustion; Coal; CO2 Capture; ASPEN Plus
Analysis of hybrid membrane and chemical absorption systems for CO2 capture by Michael Binns; Se-Young Oh; Dong-Hun Kwak; Jin-Kuk Kim (383-389).
Amine-based absorption of CO2 is currently the industry standard technology for capturing CO2 emitted from power plants, refineries and other large chemical plants. However, more recently there have been a number of competing technologies under consideration, including the use of membranes for CO2 separation and purification. We constructed and analyzed two different hybrid configurations combining and connecting chemical absorption with membrane separation. For a particular flue gas which is currently treated with amine-based chemical absorption at a pilot plant we considered and tested how membranes could be integrated to improve the performance of the CO2 capture. In particular we looked at the CO2 removal efficiency and the energy requirements. Sensitivity analysis was performed varying the size of the membranes and the solvent flow rate.
Keywords: Membrane Separation; Chemical Absorption; CO2 Capture; Process Design; Hybrid Separation
Experimental and numerical study on the effects of surfactant as drag reducing agent in paraffin wax oil pipeline by Hochang Jang; Yvan Christian Supartono; Jeonghwan Lee (390-396).
This study presents an experimental and simulated approach to investigate the drag-reducing phenomenon of surfactants. The experiments to examine the effects of surfactant as a drag reducing agent (DRA) were conducted using the Fann VG viscometer. The paraffin wax oil samples were treated with different temperatures, surfactant concentrations, and surfactant compositions. We used two discrete surfactant compositions, measured apparent viscosities of paraffin wax oil samples for different conditions, and analyzed the effectiveness of DRA based on apparent viscosity results. To examine the effects of surfactant as DRA, under a pipeline transport situation, we used the results from the experiments for a simulation with assumed field operational data. The simulation results are consistent with experimental data. We have observed that, on paraffin wax oil, pressure loss inside the pipeline is inversely related to surfactant concentration and temperature. We verified, experimentally and numerically, that surfactant can act as DRA and can be a possible solution to pipeline friction-related problems in an oil field. However, with paraffin wax oil, the change of temperature has a greater effect than does change of surfactant concentration or composition.
Keywords: Surfactant; Drag Reducing Agent (DRA); Pressure Loss; Viscosity; Pipeline
A pore-scale model for the cathode electrode of a proton exchange membrane fuel cell by lattice Boltzmann method by Gholam Reza Molaeimanesh; Mohammad Hadi Akbari (397-405).
A pore-scale model based on the lattice Boltzmann method (LBM) is proposed for the cathode electrode of a PEM fuel cell with heterogeneous and anisotropic porous gas diffusion layer (GDL) and interdigitated flow field. An active approach is implemented to model multi-component transport in GDL, which leads to enhanced accuracy, especially at higher activation over-potentials. The core of the paper is the implementation of an electrochemical reaction with an active approach in a multi-component lattice Boltzmann model for the first time. After model validation, the capability of the presented model is demonstrated through a parametric study. Effects of activation over-potential, pressure differential between inlet and outlet gas channels, land width to channel width ratio, and channel width are investigated. The results show the significant influence of GDL microstructure on the oxygen distribution and current density profile.
Keywords: Proton Exchange Membrane Fuel Cell; Lattice Boltzmann Method; Cathode Electrode; Electrochemical Reaction; Pore-scale Model
The mechanism of higher alcohol formation on ZrO2-based catalyst from syngas by Yingquan Wu; Hongjuan Xie; Yongli Kou; Noritatsu Tsubaki; Yizhuo Han; Yisheng Tan (406-412).
A chain growth scheme for the synthesis of alcohols from carbon monoxide and hydrogen is proposed based on the chemical enrichment method on ZrO2-based catalyst. Methanol addition has no obvious effect on the STY of C2+ alcohols, indicating that COH→CCOH is a slow initial growth step. Addition of ethanol and propanols can enhance the STY of isobutanol, especially n-propanol, revealing that n-propanol is largely the precursor of isobutanol. Results of large alcohols addition further reveal the relationship between small alcohols and large alcohols of formation. Also, addition of aldehydes has a similar effect on the formation of higher alcohols, indicating that alcohols exist in the form of aldehydes before desorption. Anisole are introduced into syngas for confirmation of predicted intermediates and the result indicates that formyl species is participated both in the formation of methanol and higher alcohols. Reaction temperature has a significant effect on the chain growth of alcohols synthesis. Under low temperature, chain growth occurs with CO insertion and alcohols are linear products. Isobutanol appears and becomes the main product during C2+ alcohols undergo an aldo-condensation reaction at high temperature.
Keywords: Mechanism; Syngas; Enrichment; Higher Alcohol; Isobutanol
Improvement of cassava stem hydrolysis by two-stage chemical pretreatment for high yield cellulosic ethanol production by Bunpot Klinpratoom; Anissara Ontanee; Chalerm Ruangviriyachai (413-423).
We used sodium chlorite followed by sodium hydroxide as a two-stage pretreatment of cassava stem for removal of lignin and hemicellulose to obtain a substrate with high cellulose content prior to hydrolysis. Response surface methodology was applied to determine the optimum hydrolysis conditions of two-stage pretreated cassava stem. After pretreatment, the cellulose content of cassava stem increased from 42.10% to 86.45%, concomitant with decreases in lignin (87.59%) and hemicellulose (78.18%) content. Acid hydrolysis of two-stage pretreated cassava stem under optimum conditions allowed obtaining a hydrolyzate rich in reducing sugar, with a yields up to 67.37%. Conversely, inhibitors were detected at very low concentrations. The fermentation of the hydrolyzate resulted in an ethanol yield of 22.58 g/100 g substrate corresponding to a theoretical ethanol yield of 84.41%. The results demonstrate that two-stage pretreatment is effective for improving cellulose hydrolyzability, resulting in high fermentable sugar and low fermentation inhibitor concentrations.
Keywords: Cassava Stem; Two-stage Pretreatment; Response Surface Methodology; Reducing Sugar; Cellulosic Ethanol
Application of content optimized ZnS-ZnO-CuS-CdS heterostructured photocatalyst for solar water splitting and organic dye decomposition by Eunpyo Hong; Taeseok Choi; Jung Hyeun Kim (424-428).
Heterostructured ZnS-ZnO-CuS-CdS photocatalyst was synthesized via a sequential fabrication approach (ZnS→thermal treatment (ZnS-ZnO)→CuS formation (ZnS-ZnO-CuS)→CdS addition (ZnS-ZnO-CuS-CdS)). Each component in this heterostructure has its own role for photocatalytic reaction. The oxide content controlled by thermal processing condition is a crucial factor for improving photocatalytic activity, and the CuS and CdS contents are controlled by their feedstocks. The effects of heterostructure composition on the solar water splitting and organic dye decomposition were investigated under 1 sun irradiation (100 mW/cm2, AM 1.5G filter). The content optimized ZnS-ZnO-CuS-CdS photocatalyst produces 2452.7 μmol g−1 h−1 hydrogen, and it decomposes methyl blue much faster than the other cases. Thus, heterostructured photocatalysts can benefit the use of electrons and holes for improved photocatalytic activity.
Keywords: Photocatalytic Hydrogen Production; Dye Decomposition; Heterostructure; ZnS-ZnO-CuS-CdS; Optimal Composition
Electrochemical characterization of mixed matrix heterogeneous cation exchange membranes modified by simultaneous using ilmenite-co-iron oxide nanoparticles by Sayed Mohsen Hosseini; Alireza Hamidi; Abdolreza Moghadassi; Sayed Siavash Madaeni (429-435).
Mixed matrix heterogeneous cation exchange membranes were prepared by solution casting technique. Ilmenite-co-iron oxide nanoparticle was also employed as inorganic filler additive in membrane fabrication. The effect of the used additives on membrane electrochemical properties was studied. Membrane ion exchange capacity, membrane potential, transport number and selectivity all were improved by use of FeTiO3/Fe3O4 nanoparticles in membrane matrix. Utilizing FeTiO3-co-Fe3O4 nanoparticles in the casting solution also led to increase in ionic flux obviously. The modified membranes containing FeTiO3-co-Fe3O4 nanoparticles showed higher transport number, selectivity and ionic flux compared to modified membrane containing ilmenite. Electrodialysis experiment in laboratory scale also showed higher cation removal for modified membrane containing FeTiO3-co-Fe3O4 nanoparticles compared to other modified membranes and pristine ones. Results showed that membrane areal electrical resistance declined sharply by use of FeTiO3-co-Fe3O4 nanoparticles in membrane matrix. Moreover, modified membrane containing ilmenite showed lower electrical resistance compared to others. Results showed that oxidative stability of membranes was decreased slightly by use of FeTiO3/Fe3O4 nanoparticles in membrane matrix. The results revealed that modified membranes in this study are comparable with that of other commercial ones.
Keywords: Composite Ion Exchange Membrane; Ilmenite-co-iron Oxide Nanoparticles; Synergy; Electrodialysis; Adsorption-ion Exchange; Preparation/Characterization
Characterization of high-alumina coal fly ash based silicate material and its adsorption performance on volatile organic compound elimination by Guojun Yuan; Jianbin Zhang; Yongfeng Zhang; Yinan Yan; Xinxin Ju; Junmin Sun (436-445).
A highly stable silicate material from high-alumina coal fly ash was prepared and characterized using X-ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thermal analysis, X-ray photoelectron spectroscopy, and elemental analysis. The spectral results show that the silicate material was mainly composed of six elements, C, Ca, O, Si, Mg, and Al, in the form of Ca2+, Mg2+, Al3+, SiO3 2−, and CO3 2− ions. Some adsorbed water and/or water of crystallization was also observed. The silicate material showed exceptionally high capability to adsorb volatile organic compounds (VOCs). The results of dynamic adsorption behavior show that the silicate material presents similar properties with commercial activated carbon and stronger absorption properties than commercial diatomite for the adsorption of VOCs. The FTIR spectral results show weak hydrogen bonding interactions of the silicate material with three VOCs.
Keywords: High-alumina Coal Fly Ash; Silicate Material; Volatile Organic Compounds; Column Breakthrough Curve; Hydrogen Bonding
Comparative kinetic study of functionalized carbon nanotubes and magnetic biochar for removal of Cd2+ ions from wastewater by Manimaran Ruthiraan; Nabisab Mujawar Mubarak; Raj Kogiladas Thines; Ezzat Chan Abdullah; Jaya Narayan Sahu; Natesan Subramanian Jayakumar; Poobalan Ganesan (446-457).
We did a comparative study between functionalized multiwall carbon nanotube (FMWCNTs), and magnetic biochar was carried out to determine the most efficient adsorbent to be employed in the Cd2+ ion removal. We optimized parameters such as agitation speed, contact time, pH and adsorbent dosage using design expert vrsion 6.08. The statistical analysis reveals that optimized condition for highest removal of Cd2+ are at pH 5.0, with dosage 1.0 g, agitation speed and contact time of 100 rpm and 90 minutes, respectively. For the initial concentration of 10mg/l, the removal efficiency of Cd2+ using FMWCNTs was 90% and and 82% of magnetic biochar. The maximum Cd2+ adsorption capacities of both FMWCNTs and magnetic biochar were calculated: 83.33mg/g and 62.5mg/g. The Langmuir and Freundlich constants for FMWCNTs were 0.056 L/mg and 13.613 L/mg, while 0.098 L/mg and 25.204 L/mg for magnetic biochar. The statistical analysis proved that FMWCNTs have better adsorption capacity compared to magnetic biochar and both models obeyed the pseudo-second-order.
Keywords: MWCNT; Cadmium; Heavy Metal; Adsorption; Functionalization; Magnetic Biochar
Photo-electro-oxidation assisted peroxymonosulfate for decolorization of acid brown 14 from aqueous solution by Nemat Jaafarzadeh; Farshid Ghanbari; Mahsa Moradi (458-464).
We investigated the simultaneous application of peroxymonosulfate (PMS) and electrogenerated H2O2 in presence of ultra violet (UV) to decolorize Acid Brown 14 (AB14). The effects of various operating parameters were evaluated on performance of the hybrid system for decolorization and degradation of AB14. The results showed that the optimal conditions were at UV light intensity of 2.08mW/cm2, pH=4, 200 mA applied current and 3mM PMS. Moreover, presence of transitional metals (Co2+, Fe2+ and Cu2+) increased decolorization of AB14 significantly. Decolorization was promoted from 80.9% to 97% by addition of Fe2+ within 20 min reaction time. First-order model was fitted for this system in absence and presence of Fe2+ with rate constants of 1.937×10−3 and 3.595×10−3 s−1 respectively. Scavenging experiments confirmed that sulfate and hydroxyl radicals were equally effective in degradation of AB14. This hybrid process increased the average oxidation state (AOS) from 0.2 to 2.3.
Keywords: Peroxymonosulfate; Photo-electro-oxidation; Sulfate Radical; Dye; Average Oxidation State
Investigation on the role of ion exchange resin in the crystallization process for the purification of vancomycin by Sung-Jae Kim; Jin-Hyun Kim (465-470).
We investigated the cause of a difference in the crystallization aspect depending on a surface area-increasing material (ion exchange resin) in the vancomycin crystallization process with increased surface area per volume of reaction solution (S/V). The result in terms of whether or not crystallization occurred was reversed when the ionic form of the ion exchange resin was altered. In addition, it was shown that the pH range of a solution for vancomycin crystallization was 4–7. Eventually, it was confirmed that vancomycin crystallization was affected by a change in pH of a crystallization solution depending on the ionic form of the ion exchange resin. Furthermore, in the absence of ion exchange resin, the time required for crystallization increased as the pH rose from 4–7. In addition, the size of the vancomycin crystal increased as the pH decreased.
Keywords: Vancomycin; Crystallization; Surface Area-increasing Material; Ion Exchange Resin; Ionic Form
Ortho-hydroxylation of mammalian lignan enterodiol by cytochrome P450s from Actinomycetes sp. by EunOk Jung; Kwon-Young Choi; Da-hye Jung; Hyungdon Yun; Byung-Gee Kim (471-477).
An animal lignin, enterodiol (END), is known to be formed by conversion of secoisolariciresinol from flaxseed by intestinal bacteria. Thirteen bacteria strains were examined for their hydroxylation activity for END. Among them, Streptomyces avermitilis MA-4680 and Nocardia farcinica IFM10152 showed the highest hydroxylation activity for END. Reaction products profiled using GC/MS revealed that four products mono-hydroxylated in aliphatic position (Al-OH-END) and three products mono-hydroxylated in aromatic ring (Ar-OH-END) were found in S. avermitilis MA-4680, whereas only two Ar-OH-ENDs were detected in the case of N. farcinica IFM10152. From 15mg/L of END, 900 μg/L of Al-OH-END and 210 μg/L of 4-hydroxy END (4-OH-END) were produced by S. avermitilis MA-4680, and 300 μg/L of 2-hydroxy END (2-OH-END) and 480 μg/L of 4-OH-END were obtained by N. farcinica IFM10152. To find the P450s are responsible for the substrate specificity to END, 33 P450s from S. avermitilis MA-4680 and 26 P450s from N. farcinica IFM10152 were cloned and compared with coexpression of putidaredoxin reductase (camA) and putidaredoxin (camB) from Pseudomonas putida as redox partners in E. coli. As a result, Nfa45180 showed the highest hydroxylation activity especially for ortho-hydroxylation in aromatic ring in vivo. The results of the docking simulation of END into the homology model of Nfa45180 explained the reason for regio-specificity of the hydroxylation. To our knowledge, this is the first report of regioselective hydroxylation of END using microorganism P450s.
Keywords: Cytochrome P450; Enterodiol; CYP154; GC/MS
Removal of strontium ions from nuclear waste using synthesized MnO2-ZrO2 nano-composite by hydrothermal method in supercritical condition by Seyed Javad Ahmadi; Neda Akbari; Zahra Shiri-Yekta; Mohammad Hossein Mashhadizadeh; Morteza Hosseinpour (478-485).
This study focuses mainly on the synthesis of MnO2-ZrO2 nano-composite as a new inorganic adsorbent. Supercritical water was used as a preparation medium for particle deposited materials. MnO2-ZrO2 was prepared from metal nitrate solutions in supercritical region. The resulting sample was characterized by Fourier transform infrared (FTIR), X-ray fluorescence (XRF), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscope (TEM). Analyses of the TEM images show the possibility for crystallizing nano-sized particles. The synthesized adsorbent was then used for the removal of strontium(II) from the nuclear waste. Moreover, a number of factors such as aqueous phase pH, contact time and initial metal ions concentration in the adsorption process were investigated. Comparison of the adsorption efficiency of the MnO2-ZrO2 nano-particles with those of the non-nano particles shows a shift of uptake of the metal ions vs. pH curves towards lower pH values and a significant improvement in adsorption of strontium ions was observed by using the nano-adsorbent. The kinetic data corresponds well to the pseudo-second-order equation. The adsorption data for strontium(II) were well fitted by the Langmuir isotherm. The synthesized nano-composite also showed a strong affinity toward the removal of Y(III), Ni(II), Pb(II) and Co(II) from the nuclear radioactive waste.
Keywords: Supercritical Water Synthesis; MnO2-ZrO2 Nano-composite; Ion Exchanger; Strontium; Adsorption
A conical shape-evolution model for the control of sapphire crystal growth in Kyropoulos (KY) method by Do Won Song; Kwang Seok Kim; Hyo Kim (486-493).
Generally, the process of sapphire crystal growing in the KY furnace has to be monitored in order to reduce the power of heater continuously as the crystal grows to occupy the crucible. However, it has been difficult to control the heater power as the weight and diameter of crystal change because the solid-liquid interface could not be easily located from on-site measurement. Hence, first, the model was developed to locate the crystal-melt interface and to estimate its dynamic feature during the crystal growth by incorporating the mass and the force balances. This model was applied to analyze the data obtained from the industry-scale crystal growth experiment (for the production of the sapphire crystals in the KY method). Finally, the shape and the dynamic feature of crystallizing front are analytically verified by generating some bands of small bubbles along the crystal-melt interface called a comb-pattern experiment.
Keywords: Conical Shape-evolution Model; Sapphire Crystal; Kyropoulos Method; Mass and Force Balances; Comb-pattern Experiment
Molecular dynamics simulation of carbon molecular sieve preparation for air separation by Elham Yaghoobpour; Ali Ahmadpour; Nafiseh Farhadian; Mojtaba Shariaty-Niassar (494-500).
Carbon deposition process on activated carbon (AC) in order to produce carbon molecular sieve (CMS) was simulated using molecular dynamics simulation. The proposed activated carbon for simulation includes micropores with different characteristic diameters and lengths. Three different temperatures of 773 K, 973 K, and 1,273 K were selected to investigate the optimum deposition temperature. Simulation results show that the carbon deposition process at 973 K creates the best adsorbent structure. While at lower temperature some micropore openings are blocked with carbon atoms, at higher temperature the number of deposited carbons on the micropores does not change significantly. Also, carbon deposition process confirms the pseudo-second-order kinetic model with an endothermic behavior. To evaluate the sieving property of adsorbent products, nitrogen and oxygen adsorption on the initial and final adsorbent products are examined. Results show that there is not any considerable difference between the equilibrium adsorption amounts of nitrogen and oxygen on the initial and final adsorbents especially at low pressure (P<10 atm). Although, adsorption kinetics curves of these gases change significantly after the carbon deposition process in comparison with the initial sample. These observations indicate that the final adsorbent has high selectivity towards oxygen compared with the nitrogen, so it can be called a carbon molecular sieve. All simulated results are in good agreement with experiments.
Keywords: Carbon Molecular Sieve; Molecular Dynamics Simulation; Carbon Deposition; Adsorption Kinetics; Air Separation
Novel nanocomposite heterogeneous cation exchange membrane prepared by MWCNTs-co-silver nanolayer composite nanoparticles: Physico/chemical characterization and investigation of concentration effect by Akbar Zendehnam; Mehrfam Rabieyan; Sayed Mohsen Hosseini; Saeideh Mokhtari (501-510).
Nanocomposite polyvinyl chloride/multi walled carbon nano tubes (MWCNTs)-co-silver (Ag) nanolayer composite nanoparticles heterogeneous ion exchange membranes were prepared by solution casting techniques. MWCNTs-co-Ag nanolayer composite nanoparticles were prepared by magnetron sputtering method. The effect of used composite nanoparticles and electrolyte’s concentration on physico/chemical properties of membranes was studied. Scanning and transmission electron microscopy and X-ray diffraction results showed uniform distribution and crystalline structure for the composite nanoparticles. Images also showed relatively uniform distribution for the membranes. Membrane transport number, selectivity and electrical conductivity were improved by increase of additive content in membrane matrix. All mentioned parameters were also enhanced by increase of electrolyte concentration. Membranes exhibited lower selectivity/transport number for bivalent ions compared to monovalent type. Membrane average roughness was decreased slightly by increase of additive content. Membrane ionic flux was decreased initially by increase of additive content up to 0.5%wt and then began to increase by more additive concentration. Mechanical stability of membranes was also improved by using of composite nanoparticles in membrane matrix. Modified membrane containing 4%wt composite nanoparticles showed better electrochemical properties compared to others.
Keywords: Mixed Matrix Membrane; Multi Walled Carbon Nano Tubes-co-silver Nanolayer Composite Nanoparticles; Plasma Treatment; Physico/Chemical Characterization; Concentration Effect
Adsorption behavior of α-tocopheryl succinate and α-tocopheryl polyethylene glycol succinate onto weakly basic anion exchange resins by Liyun Kong; Zhiguo Zhang; Huabin Xing; Qiwei Yang; Baogen Su; Zongbi Bao; Yiwen Yang; Qilong Ren (511-520).
Polyethylene glycol (PEG) esters are important, nontoxic and biodegradable non-ionic surfactants. A key procedure in producing PEG esters is their separation from unreacted or excess acids. We propose an adsorption method using the weakly basic anion exchange resins for the separation of organic acids and PEG esters for the first time. With α-tocopheryl polyethylene glycol succinate (TPGS) and α-tocopheryl succinate (α-TS) as the examples of PEG ester and organic acid, respectively, single-component equilibrium experiments revealed the great potential of this method. Studies on the adsorption equilibrium, thermodynamics and kinetics of α-TS onto a weakly basic anion exchange resin were also carried out. This research is not only important for the production of TPGS, but also instructive for the separation of other PEG-esters from the reaction mixtures.
Keywords: PEG Esters; Organic Acids; Adsorption; Weakly Basic Anion Exchange Resin
High-pressure solubility of carbon dioxide in pyrrolidinium-based ionic liquids: [bmpyr][dca] and [bmpyr][Tf2N] by Byung-Chul Lee; Sang Gyu Nam (521-533).
Solubility data of carbon dioxide (CO2) in two pyrrolidinium-based ionic liquids: 1-butyl-1-methylpyrrolidinium dicyanamide ([bmpyr][dca]) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpyr] [Tf2N]) are presented at pressures up to about 30MPa and temperatures from 303.2 K to 343.2 K. The solubility was determined by measuring bubble or cloud point pressures of mixtures of CO2 and ionic liquid using a high-pressure equilibrium apparatus equipped with a variable-volume view cell. The CO2 solubility in the ionic liquid in terms of the mole fraction or the molality increased with the increase of the equilibrium pressure at a given temperature, but decreased with the increase of temperature at a given pressure. At a given temperature, the mole fraction of CO2 dissolved in the ionic liquid increased rapidly as pressure increased. CO2 solubility in the mole fraction almost reached saturation around 0.65 for [bmpyr][dca] and around 0.8 for [bmpyr][Tf2N], respectively. The experimental data for the CO2+ ionic liquid systems were correlated using the Peng-Robinson equation of state (PR-EoS). The mixing rules of the Wong-Sandler type rather than the classical mixing rules of the van der Waals type were coupled with the PR-EoS. The resulting modeling approach proved to be able to correlate the CO2 solubilities in aforementioned ionic liquids over the aforementioned range of temperature and pressure within 5% average deviations.
Keywords: Solubility; Carbon Dioxide (CO2); Ionic Liquid; Pyrrolidinium; Correlation; Peng-Robinson Equation of State; Wong-Sandler Mixing Rules
Synthesis of poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate)-capped silver nanoparticles and their application to blue polymer light-emitting diodes by Young Yun Kim; Woo Jin Hyun; Keum Hwan Park; Seong Ji Ye; O. Ok Park (534-539).
Organic light-emitting diodes (OLED) and polymer light-emitting diodes (PLED) are promising candidates for future display applications due to their superior properties, but their efficiency and stability need to be improved to expand their application to large-size display panels and lightings. One of the most remarkable ways to enhance the efficiency of PLEDs is to incorporate metal nanoparticles and utilize their localized surface plasmon resonance (LSPR). We report on the improvement of blue PLEDs efficiency by the insertion of silver nanoparticles (Ag NPs) capped by poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS). Ag NPs were synthesized with PEDOT : PSS as a stabilizer and then deposited on an indium tin oxide (ITO) anode using a simple spin-coating process without any aggregation. The result of deposition was confirmed by SEM and TEM images, and by Raman spectrum. Optical properties of the PEDOT : PSS-capped Ag NPs on ITO and the interaction between Ag NPs and Lumation blueJ, a blue light-emitting polymer, were measured using a UV-Vis spectrophotometer, a photoluminescence (PL) spectrophotometer, and a time-resolved photoluminescence spectrophotometer (TRPL). As a result, the introduction of PEDOT : PSS-capped Ag NPs to the blue PLEDs was found to have been successfully conducted. The fabricated blue PLEDs with Ag NPs exhibited a 15% increase of external quantum efficiency. This was thought to originate from the localized surface plasmon coupling of the PEDOT : PSS-capped Ag NPs with Lumation BlueJ.
Keywords: Organic Light-emitting Diodes (OLED); Localized Surface Plasmon Resonance (LSPR); PEDOT : PSS; PEDOT : PSS/Silver Nanoparticles; Plasmonic Enhancement
Formation of stable hydrocarbon oil-in-water nanoemulsions by phase inversion composition method at elevated temperature by Soon Sik Kwon; Bong Ju Kong; Wan Goo Cho; Soo Nam Park (540-546).
Stable hydrocarbon oil (hexadecane, C16)/nonionic surfactant (HCO-60, Span 80)/water system oil-in-water nanoemulsions were prepared by the phase inversion composition method at elevated temperature. To minimize droplet size, the composition ratio for stable nanoemulsions, we experimented by changing the HLB value, oil/surfactant ratio, and droplet volume fraction. When the HLB mix value 11, the nanoemulsions show a minimal sample droplet size of 360.3 nm. By varying the oil/surfactant ratio from 0.6 to 1.4, we found the optimum oil/surfactant ratio to be approximately 0.6, which corresponds to the minimum droplet size of 71.8 nm. We also varied the droplet volume fraction; when the droplet volume fraction is 0.06, the droplet size is very small. For the emulsion with the minimal droplet size, the polydispersity index is less than 0.3, which reflects a good monodispersity of the nanoemulsion. Viscosity and electrical conductivity measurements were carried out for determining the internal structure of the bicontinuous phase during the emulsification. When the water content ranges from 4 to 6 w/w%, the systems may have a bicontinuous or lamellar phase. Oil-in-water nanoemulsion stability assessment was performed by observing the droplet size as a function of storage time; we did not observe any change in droplet size over the course of a month.
Keywords: Nanoemulsions; Phase Inversion Composition Method; Ostwald Ripening; Bicontinuous; Long-term Stability
Synthesis and characterization of glyceryl monooleate-based polyester by Puyou Jia; Caiying Bo; Lihong Hu; Yonghong Zhou (547-551).
A unique biobased polyester poly(succinic acid-glyceryl monooleate) (PSAGMO) was synthesized and characterized from succinic acid (SA) and glyceryl monooleate (GMO). The polyester was characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic response spectroscopy (NMR). The polyester was used as the plasticizer of poly (vinyl chloride) (PVC). The mechanical properties and the thermodynamic properties of the blends were characterized. The TG-DTA data indicated that the thermal degradation temperature (T d ) of PVC blends plasticized with PSAGMO could increase from 249.3 °C to 255.6 °C. The DMA showed that the glass transition temperature (Tg) of the PVC blends decreased from 49.5 °C to 35 °C. The mechanical properties indicated that the PSAGMO could decrease the tensile strength and increase the elongation at break of the PVC blends. This study may lead to the development of new type of PVC plasticizer based on renewable resource.
Keywords: Polyester; Poly(vinyl chloride); Blends; Thermal Stability
Thermal curing and degradation kinetics of terpolymer resins derived from vanillin oxime, formaldehyde and p-chloro-/p-methylacetophenone by Narendra Pal Singh Chauhan (552-562).
A novel class of linear terpolymer resins have been prepared from various macromers formed by vanillin oxime (VO), formaldehyde (F) and p-chloro/p-methylacetophenone in the presence of an acid as catalyst by convenient polycondensation process. The conversion of different macromers into respective terpolymeric resin was studied by DSC analysis from −50 °C to 250 °C. The first thermal transition endotherms ranging from 108–137 °C (VOFCA) and 125–150 °C (VOFMA) are due to expulsion of water molecules, and the second thermal transition exotherms 177–247 °C (VOFCA) and 183.9–249.8 °C (VOFMA) are attributed to the formation of methylene linkage between macromers moieties by utilizing methlol groups at terminals. The activation energy required for conversion of methylol into methylene groups for VOFCA and VOFMA was 3.4 and 3.9 kJ/mol, respectively. Structural confirmations were determined through IR, Uv-Vis, 1H NMR spectroscopy and GPC data. The activation energy (Ea) and thermodynamic parameters of the thermal decomposition process were investigated with thermogravimetric analysis (TGA) by isoconversional integral Kissinger-Akahira-Sunose (KAS) and differential Friedman methods. Empirical kinetic models, as well as generalized master plots, were applied to explain the degradation mechanisms of terpolymer resins. The degradation reaction follows Avrami-Erofeev (nucleation and growth) at initial stage to Jander (three-dimensional diffusion) model for PVOMAF and Jander (two-dimensional diffusion) for PVOFCA governed mechanisms. Among all the tested terpolymers, both resins revealed better activity compared to standard drugs as Gentamycin, Amphicilin, Chloramphenicol, Ciprofloxacin and Noorfloxacin.
Keywords: Polycondensation; Vanillin Oxime; TG-DTG; Characterization; Isoconversional; Kinetics; Mechanism; Antibacterial Activity
Enhancing performance of quantum dot-based light emitting diodes by using poly(methyl methacrylate)@quantum dot hybrid particles by Hyun Chang Kim; Cheolsang Yoon; Young-Geon Song; Young-Joo Kim; Kangtaek Lee (563-566).
Quantum dots (QDs) are attractive alternatives for organic phosphors in light emitting diodes (LEDs) due to their high quantum yield and photostability. Various methods have been developed for fabrication of LEDs using QDs, yet the reduction in quantum yield during film formation still limits their practical applications. We prepared hybrid particles by coating spherical poly(methyl methacrylate) (PMMA) particles with the CdSe/ZnS QDs, and dispersed them in the PMMA matrix. The PMMA particles were derived from the same material as the PMMA matrix, so that they could not only act as a spacer but also match the refractive index between the polymer particles and matrix. The PMMA@QD hybrid particles exhibited higher quantum yield in both suspension and film states than the pristine QDs. In addition, the dispersion state of QDs in PMMA matrix was significantly improved by using the hybrid particles. Finally, it was demonstrated that the QD-based LED device containing the PMMA@QD hybrid particles exhibited enhancement in both color conversion and luminous efficiencies.
Keywords: Quantum Dot; Light Emitting Diode; Poly(methyl methacrylate); Hybrid Particles; Dispersion