Korean Journal of Chemical Engineering (v.34, #7)

Preparation of cationic functional polymer poly(Acryloxyethyltrimethyl ammonium chloride)/SiO2 and its adsorption characteristics for heparin by Jiying Men; Jianfeng Guo; Weihong Zhou; Nanyan Dong; Xilun Pang; Baojiao Gao (1889-1895).
Ion-exchange is a widely used purification technology in the heparin manufacturing process. To improve the rate and efficiency, the cationic monomer Acryloxyethyltrimethyl ammonium chloride (DAC) was grafted on silica gel particles by using a surface-initiated graft-polymerization technique, and a novel adsorption polymer of PDAC/SiO2 was prepared. The adsorption experiments of PDAC/SiO2 for heparin show that there are strong electrostatic interactions between heparin with a high density of negative charges and PDAC/SiO2 that exists in many quaternary ammonium cations. Comparing the adsorption kinetics of PDAC/SiO2 with D201 anionic strong alkali exchange resin, PDAC/SiO2 shows higher adsorption capacity and faster adsorption rate. The pH and temperature of solutions have a great influence on the adsorption amount, and there is a maximum adsorption capacity of 121mg/g when pH=7 at 25 °C. The adsorption of PDAC/SiO2 for heparin is an exothermic process and driven by entropy.
Keywords: Heparin; Cationic Monomer; Electrostatic Interaction; DAC; Adsorption

An elliptical Couette-Taylor (ECT) crystallizer with a unique sinusoidal Taylor vortex flow was developed to promote the recovery and size distribution of L-lysine crystals in cooling crystallization. When using the ECT crystallizer, the recovery was enhanced to a maximum of 100% with a mean residence time of only 15 min. When comparing the crystallization efficiency, the recovery and size distribution of the L-lysine crystals in the ECT crystallizer were over 33% and 50% higher, respectively, than those in the conventional MSMPR crystallizer and slightly higher than those in the circular Couette-Taylor (CT) crystallizer. This improved crystallization in the ECT crystallizer was explained in terms of the sinusoidal profile of the Taylor vortex intensity. Plus, since the nucleation and growth processes determine the recovery and crystal size distribution, the mean residence time, inner cylinder rotation speed, and feed concentration were all varied to investigate their influence on the crystallization efficiency.
Keywords: Taylor Vortex Flow; Cooling Crystallization; Nucleation; Growth; Mass Transfer; Couette-Taylor Crystallizer

A one-dimensional non-isothermal steady state model was developed to simulate the performance of three-reactor configurations for the oxidative dehydrogenation of ethane (ODHE) to ethylene. These configurations consist of side feeding reactor (SFR), conventional fixed bed reactor (CFBR) and membrane reactor (MR). The performance of these reactors was compared in the terms of C2H6 conversion, C2H4 and CO2 selectivity and temperature profiles. The use of sectional air injections on the wall of SFR with a limited number of injection points showed that the performance of reactor significantly improves and optimum pattern of oxygen consumption is also obtained. Moreover, our SFR with a liquid coolant medium operates in an effectively controlled temperature profile that is comparable with that of the MR, which is cooled by a coolant stream of air. Hence, an enhancement in the level of selectivity is obtained for the SFR configuration. Consequently, the side feeding procedure can decrease the high operating temperature problem and low ethylene selectivity in the ODHE process. According to obtained results, the SFR would be a proper alternative for both the MR and CFBR.
Keywords: Oxidative Dehydrogenation of Ethane; Side Feeding Reactor; Fixed Bed Reactor; Membrane Reactor; Mathematical Modeling

Heterogeneous amino acid-based tungstophosphoric acids as efficient and recyclable catalysts for selective oxidation of benzyl alcohol by Xiaoxiang Han; Yingying Kuang; Chunhua Xiong; Xiujuan Tang; Qing Chen; Chin-Te Hung; Li-Li Liu; Shang-Bin Liu (1914-1923).
A series of organic-inorganic composite catalysts, prepared by modifying tungstophosphoric acid (TPA; H3PW12O40) with different amino acids such as phenylalanine (Phe), alanine (Ala), and glycine (Gly) were synthesized. The physicochemical and acidic properties of these (MH) x H3−x PW12O40 (M=Phe, Ala, and Gly; x=1–3) composite materials were characterized by a variety of different analytical and spectroscopic techniques, namely TGA, XRD, FT-IR, XPS, and NMR, and exploited as heterogeneous catalysts for selective oxidation of benzyl alcohol (BzOH) with hydrogen peroxide (H2O2). Among them, the [PheH]H2PW12O40 catalyst exhibited the best oxidative activity with an excellent BzOH conversion of 99.0% and a desirable benzaldehyde (BzH) selectivity of 99.6%. Further kinetic studies and model analysis by response surface methodology (RSM) revealed that the oxidation of BzOH with H2O2 follows a second-order reaction with an activation energy of 56.7 kJ·mol−1 under optimized experimental variables: BzOH/H2O2 molar ratio=1 : 1.5 mol/mol, amount of catalyst=6.1 wt%, reaction time (x3)=3.8 h, and amount of water (x4)=30.2 mL.
Keywords: Amino Acid; Heteropolyacid; Benzaldehyde; Oxidation of Alcohol; Process Optimization; Kinetic Model

One-pot synthesis of high fructose corn syrup directly from starch with SO 4 2− /USY solid catalyst by Yong Sun; Caixia Xiong; Huihui Chen; Xianhai Zeng; Xing Tang; Tingzhou Lei; Lu Lin (1924-1929).
An efficient process was developed for the conversion of starch directly into high fructose corn syrup (HFCS) by using SO4 2−/USY solid catalyst in water. The SO 4 2− /USY catalyst was found to act as a bifunctional catalyst with high activity for both hydrolysis of starch and isomerization of glucose, achieving a one-step preparation path of HFCS from starch. An optimal HFCS yield, containing 58.34% glucose and 27.84% fructose (mass fraction), was obtained at 150 °C for only 1 h.
Keywords: Starch; HFCS; SO4 2−/USY Catalyst; Hydrolysis; Isomerization

We present a simple route to prepare mesoporous hollow silica particles containing an Au core, i.e., yolk/shell particles, by sol-gel and selective etching processes. Using tetraethoxysilane as a silica precursor, zinc acetate as a base catalyst, and cetyltrimethylammonium chloride as a soft template in the presence of Au nanoparticles, double-layered mesoporous shells were produced in one step. Elemental analysis showed that the inner shell consists of zinc silicate and the outer shell is pure silica. Au/mesoporous silica yolk/shell nanoparticles were obtained by selective etching of the zinc oxide phase with citrate buffer. The particle structure and composition were studied by transmission electron microscopy with energy disperse spectroscopy, UV-vis spectroscopy, X-ray diffraction, and nitrogen sorption experiments. Formation of double shells on the Au core in a single step was explained by a difference in the formation rates of the silica and zinc silicate phases. Au/mesoporous yolk/shell particles showed a high catalytic activity for reduction of 4-nitrophenol.
Keywords: Yolk-shell; Gold; Mesoporous Silica; Mixed Oxide; Catalyst

Effect of oxidation states of Mn in Ca1−x Li x MnO3 on chemical-looping combustion reactions by Byeong Sub Kwak; No-Kuk Park; Jeom-In Baek; Ho-Jung Ryu; Misook Kang (1936-1943).
We investigated the effect of the oxidation state of Mn in CaMnO3 perovskite particles to improve their oxygen transfer performance for chemical-looping combustion (CLC). Li was introduced in the Ca site of CaMnO3 to increase the Mn oxidation state. Ca1−x Li x MnO3 particles were synthesized by the solid-state method, and the amount of Li added ranged from 0 to 0.015 mol. The structure of the synthesized Ca1−x Li x MnO3 particles was examined using XRD, and all particles were confirmed to have a CaMnO3 perovskite structure. The shape and chemical properties of the prepared particles were characterized by using SEM and CH4-TPD. The binding energy and oxidation state of the different elements in the Ca1−x Li x MnO3 particles were measured by XPS. When Li was added, the oxidation state of Mn in Ca1−x Li x MnO3 was higher than that of Mn in CaMnO3. The oxygen transfer performance of the particles was determined by an isothermal H2-N2/air and CH4-CO2/air redox cycle at 850 °C, repeated ten times, using TGA. All particles showed an oxygen transfer capacity of about 8.0 to 9.0 wt%. Among them, Ca0.99Li0.01MnO3 particles had the best performance and the oxygen transfer capacity under H2-N2/air and CH4-CO2/air atmosphere was 8.47 and 8.75 wt%, respectively.
Keywords: Chemical Looping Combustion; Oxygen Carrier; Perovskite; CaMnO3 ; Li Promoter

Catalytic combustion of volatile aromatic compounds over CuO-CeO2 catalyst by Hongmei Xie; Qinxiang Du; Hui Li; Guilin Zhou; Shengming Chen; Zhaojie Jiao; Jianmin Ren (1944-1951).
Ce1−x Cu x O2 oxide solid solution catalysts with different Ce/Cu mole ratios were synthesized by the one-pot complex method. The prepared Ce1−x Cu x O2 catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H2 temperature-programmed reduction (H2-TPR). Their catalytic properties were also investigated by catalytic combustion of phenyl volatile organic compounds (PVOCs: benzene, toluene, xylene, and ethylbenzene) in air. XRD analysis confirmed that the CuO species can fully dissolve into the CeO2 lattice to form CeCu oxide solid solutions. XPS and H2-TPR results indicated that the prepared Ce1−x Cu x O2 catalysts contain abundant reactive oxygen species and superior reducibility. Furthermore, the physicochemical properties of the prepared Ce1−x Cu x O2 catalysts are affected by the Ce/Cu mole ratio. The CeCu3 catalyst with Ce/Cu mole ratio of 3.0 contains abundant reactive oxygen species and exhibits superior catalytic combustion activity of PVOCs. Moreover, the ignitability of PVOCs is also affected by the respective physicochemical properties. The catalytic combustion conversions of ethylbenzene, xylene, toluene, and benzene are 99%, 98.9%, 94.3%, and 62.8% at 205, 220, 225, and 225 °C, respectively.
Keywords: Ce1−x Cu x O2 Oxide Solid Solution; Catalyst; Phenyl VOCs; Catalytic Combustion; Reactive Oxygen Species

A comparative study of models for molten carbonate fuel cell (MCFC) processes by Tae Young Kim; Beom Seok Kim; Tae Chang Park; Yeong Koo Yeo (1952-1960).
The necessity of this work arose from the need for identification of a comprehensive plant model that can be used in the model-based control of the MCFC plant. Various models for molten carbonate fuel cell (MCFC) processes are presented and evaluated in this paper. Both a rigorous model based on mass and energy balances and implicit models based on operation data were investigated and analyzed. In particular, auto-regressive moving average (ARMA) model, least-squares support vector machine (LSSVM) model, artificial neural network (ANN) model and partial least squares (PLS) model for a MCFC system were developed based on input-output operating data. Among these models, the ARMA model showed the best agreement with plant operation data.
Keywords: Molten Carbonate Fuel Cell; ARMA Modeling; Partial Least Squares; Artificial Neural Network; Least-squares Support Vector Machine

Co-processing of heavy oil with wood biomass using supercritical m-xylene and n-dodecane solvents by Doo-Wook Kim; Anton Koriakin; Soon-Yong Jeong; Chang-Ha Lee (1961-1969).
Heavy oil was co-processed with wood biomass by using supercritical m-xylene and n-dodecane. The effects of the solvent, temperature, hydrogen, and catalyst on vacuum residue (VR) upgrading were evaluated using residue conversion, coke formation, and product distribution as performance parameters. VR was subjected to co-processing with microcrystalline cellulose (cellulose) or oil palm empty fruit bunch fiber (EFB), and the parameters were compared with those obtained from VR upgrading. Co-processing of VR/cellulose using a catalyst and hydrogen led to higher conversion (72.6 wt%) than co-processing of VR/EFB at 400 °C and the highest yield of light product (65.7 wt%). Using the Fe3O4 catalyst with H2 for co-processing positively influenced generation of the light product fraction. VR upgrading and co-processing using supercritical solvents could eliminate a certain amount of sulfur compounds from heavy oil. Co-processing of wood biomass with petroleum feedstocks in existing oil refineries can reduce the capital costs of bulk treatment.
Keywords: Co-processing; Supercritical Solvent; Vacuum Residue; Cellulose; EFB

A composite material polyaniline-Zr(IV) phosphoborate (PZPB) was synthesized via sol-gel method by the combination of Zr(IV) phosphoborate and polyaniline. The PZPB composite material was characterized by various analytical techniques. The PZPB composite material was found to be selective for Hg2++ metal ion due to the high distribution coefficient values for Hg2++ metal ion in all mediums. The PZPB composite material was used for Hg2++ removal under different experimental conditions. The antibacterial activity of PZPB composite material was also studied against E. coli.
Keywords: Polyaniline; Composite Material; Toxic Metals; Adsorption; Kinetics; Thermodynamics

We experimentally determined the effects of microwave-assisted persulfate oxidation (MAPO) on absorbance spectra, specific ultraviolet absorbance at a wavelength of 254 nm (SUVA254), and color in treating landfill leachate. The effects of treatment temperature (60≤T≤90 °C) and sodium persulfate (SPS) concentration (0.05≤[SPS]≤0.3 M) were characterized. An absorbance band in the visible region disappeared after MAPO, but the absorbance in UV region remained. SUVA254 of treated leachate varied from 2.3 to 14.7 L/mg·m. Color number (CN) removal of 99% (CN=0.004 cm−1) was achieved within 30min with MAPO at 80 °C and [SPS]=0.2 M. As T and [SPS] increased, CN and total organic carbon decreased, but SUVA254 increased.
Keywords: Advanced Oxidation; Process Technology; Removal; Spectroscopy; Wastewater

Mineral content in fishes in the lower course of the itapecuru river in the state of Maranhão, Brazil by Heliene Leite Ribeiro Porto; Antonio Carlos Leal de Castro; James Werllen de Jesus Azevedo; Leonardo Silva Soares; Cássia Fernanda Chagas Ferreira; Marcelo Henrique Lopes Silva; Helen Roberta Silva Ferreira (1985-1991).
Concentrations of calcium, iron, potassium, magnesium, phosphorus, zinc, copper, selenium and nickel were determined in the muscle tissue of seven species of fish (Plagioscion squamosissimus, Geophagus surinamensis, Prochilodus lacustres, Curimata sp., Schizodon dissimilis, Ageneiosus ucayalensis and Hypostomus plecostomus) collected from the lower course of the Itapecuru River in the state of Maranhão, Brazil. The samples were digested in a nitricperchloric solution and analyzed using an inductively coupled plasma atomic emission spectrometer, with the construction of specific calibration curves for each element. The highest concentrations of constituent minerals were found for phosphorus, potassium, nickel and magnesium (399.83, 144.60, 90.20 and 29.49 mg 100 g−1, respectively) in G. surinamensi, P. lacustres and Curimata sp. The lowest concentrations were found for copper, zinc, iron and selenium (0.12, 0.51, 1.05 and 8.31 mg 100 g−1, respectively) in Curimata sp., S. dissimilis, A. ucayalensis and P. squamosissimus. The concentrations of all minerals can be considered low and are below the maximum limit established by Brazilian legislation for the human ingestion of fish meat. A comparison of the seven species of fish investigated revealed no statistically significant differences regarding the concentrations of minerals, suggesting that size and different dietary habits do not exert an influence on absorption. The low concentrations of metals, such as Fe, Cu, Zn and Ni, may be related to the environmental conditions of the mouth of the river, which receives ocean inputs that produce particular tide cycles with a strong dispersion capacity, thereby diminishing residence time in the water column and reducing the availability of these metals to species of fish.
Keywords: Fish; Soft Tissue; Minerals; Spectrophotometry

The preparation and characterization of polymer-coated mesoporous silica nanoparticles (MSNs) and their application in Subtilisin (Alcalase®) immobilization were investigated. For the synthesis of polymer-coated MSNs, acrylic acid (AA) and chitosan (CS) mixture were blended as poly(acrylic acid) (PAA) and CS polymer layer onto MSNs via in-situ polymerization technique. Then, both uncoated MSNs and polymer-coated mesoporous silica nanoparticles (CS-PAA/MSNs) were characterized by taking into account properties such as morphologic pattern, size distribution, surface charge of the particles as well as thermogravimetric stability with SEM, TEM, Zetasizer and TGA analyses. Subtilisin was immobilized onto polymer-coated mesoporous silica nanoparticles via adsorption technique. For optimizing the enzyme immobilization process, the percent enzyme loading depending on the matrix amount, immobilization time and pH were investigated. Then, the activity values of immobilized enzyme and free enzyme were compared at various pH and temperature values. The maximum enzyme activity was achieved at pH 9.0 for both immobilized and free enzyme. Immobilized enzyme showed more stability at higher temperatures compared with free enzyme. Furthermore, the operational and storage stability of immobilized enzyme were determined. The activity of immobilized enzyme was reduced from 100% to 45.83% after five repeated uses. The storage stability of immobilized enzyme was found to be higher than that of free enzyme. The activity of immobilized enzyme was reduced from 100% to 60% after 28 days of storage time. We concluded that the polymer-coated MSNs were a suitable matrix for Subtilisin immobilization compared to uncoated MSNs.
Keywords: Nanobiocatalysis; Silica Nanoparticles; Chitosan; Poly(acrylic) Acid; Enzyme Immobilization; Subtilisin; Optimal Conditions

A continuous Couette-Taylor (CT) crystallizer was used to apply a multiple feeding mode strategy to enhance the crystal size and size distribution of L-lysine crystals in cooling crystallization. With a 5-min mean residence time, feed concentration of 900 g/l, and rotation speed of 700 rpm, the multiple feeding mode strategy Run-III (D21) produced a large crystal size of 139 μm and coefficient of variation (CV) for the size distribution of 0.39, both of which were significantly enhanced when compared with the conventional feeding mode Run-I (D1) that produced a crystal size of 82 μm and CV for the size distribution of 0.53. Essentially, the crystal size was enhanced around 70%, while the size distribution was improved around 28%. Finally, the impact of the multiple feeding mode strategy on the crystal size and size distribution is explained in terms of effective control of the supersaturation.
Keywords: Multiple Feeding Mode; Taylor Vortex Flow; Couette-taylor Crystallizer; Cooling Crystallization; Nucleation; Growth; Mass Transfer; Heat Transfer

Isobaric vapor-liquid equilibrium of 2-propanone+2-butanol system at 101.325 kPa: Experimental and molecular dynamics simulation by Hardjono; Asalil Mustain; Profiyanti Hermien Suharti; Dhoni Hartanto; Ianatul Khoiroh (2011-2018).
Isobaric vapor-liquid equilibrium (VLE) data for binary mixtures of 2-propanone+2-butanol have been measured at 101.325 kPa. The measurements were in a modified recirculating type of Othmer equilibrium still. All the data passed the thermodynamics consistency test and no azeotropic behavior was exhibited. The experimental VLE data were correlated with the Wilson, non-random two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) activity coefficient models. The correlation results showed that the experimental data were well correlated with those models. The experimental data also showed slight deviations from the predicted results using UNIFAC and modified UNIFAC (Dortmund) models. To gain more insight into the nature of interactions between 2-propanone molecule and alcohol, we analyzed the hydrogen-bonds, the electrostatic (Coulomb) interactions, and the van der Waals (Lennard- Jones) interaction energies extracted from MD simulations. In addition, the structural property of liquid phase was characterized through radial distribution function (RDF) to establish favorable interactions between 2-propanone and 2-butanol in the mixture.
Keywords: Vapor-liquid Equilibrium; Molecular Dynamic; Ebulliometer; 2-Propanone; 2-Butanol

Designing an atmosphere controlling hollow fiber membrane system for mango preservation by Hong Liu; Linxiang Fu; Huan Liu; Caili Zhang; Bing Cao; Pei Li (2019-2026).
We devised an atmosphere controlling facility to gain a longer life span for mango. A membrane module made of polyethersulfone/polydimethylsiloxane (PES/PDMS) composite membrane was applied to selectively permeate CO2 from the gas mixture of the fruit container. To design the membrane separation system, two models were introduced into our mathematical simulations: (1) an equilibrium model giving the optimal membrane area, the compositions of CO2 and O2 in the fruit container, feed flow rate and pressures on both the feed and permeate sides of the module, and (2) a dynamic model simulating the change in the gas composition of the fruit container with time. The pressure build-up in the bore side of the hollow fiber was also discussed using the Hagen-Poiseuille equation. The best membrane module configuration was obtained based on the pressure build-up analysis. That was (1) the vacuum pressure should be set at 0.1 bar, (2) the hollow fiber inner diameter should be 0.45 mm, and (3) the vacuum should be applied at both ends of the hollow fiber bore sides.
Keywords: Membranes; Coatings; Application; Fibers; Separation Techniques

It is difficult to find physical properties data for systems containing ionic liquids, excess molar enthalpies, binary interaction parameter, etc. In this study, the excess molar enthalpies were measured for water+ethanol+ionic liquid system using a isothermal microcalorimeter at 298.15 K. The ionic liquid used was 1-butyl 3-methyl imidazolium tetrafluoroborate, [BMIM] [BF4]. The isothermal microcalorimeter (IMC) is a flow-type calorimeter that measures the heat of mixing directly, using specific mixing cell. By employing NRTL, electrolyte-NRTL and UNIQUAC models, binary interaction parameters were determined and investigated for the correlation with vapor liquid equilibrium (VLE). The e-NRTL model with the partial dissociation was employed to correlate the ionic liquid system. The binary data of VLE system were used from literatures. Specifically, UNIQUAC volume and surface area parameters were determined using Bondi radius.
Keywords: Isothermal Microcalorimeter (IMC); Ionic Liquids; NRTL; Electrolyte NRTL; UNIQUAC; Partial Dissociation; Bondi Radius

Response surface methodology for the evaluation of guanidine hydrochloride partitioning in polymer-salt aqueous two-phase system by Mohsen Pirdashti; Kamyar Movagharnejad; Abbas Ali Rostami; Behnia Shahrokhi (2033-2042).
The current study employed response surface methodology (RSM) with a face-centered central composite design (CCD) to indicate the essential variables on the partition coefficient of guanidine hydrochloride (GuHCl) in the poly (ethylene glycol) (PEG)-phosphate aqueous two-phase system (ATPS). To evaluate the partition coefficients of GuHCl in the mentioned ATPS, the pH (7.0, 8.5 and 10.0), GuHCl concentration (1.0, 3.5 and 6.0% w/w), PEG molecular weight (2,000, 4,000 and 6,000 gmol−1) and PEG/potassium phosphate concentrations ratio were selected as independent variables. A quadratic model is suggested to find the impact of these variables. The suggested model has a strong harmony with the experimental data. The results of the model display that the GuHCl concentration and weight percent of the salt in feed have a large and small influence on the GuHCl partitioning.
Keywords: Guanidine Hydrochloride; Aqueous Two-phase Systems; Partitioning; Response Surface Methodology

Quantification of the risk for hydrate formation during cool down in a dispersed oil-water system by Gye-Hoon Kwak; Kun-Hong Lee; Bo Ram Lee; Amadeu K. Sum (2043-2048).
Gas hydrates are considered a nuisance in the flow assurance of oil and gas production since they can block the flowlines, consequently leading to significant losses in production. Hydrate avoidance has been the traditional approach, but recently, hydrate management is gaining acceptance because the practice of hydrate avoidance has become more and more challenging. For better management of hydrate formation, we investigated the risk of hydrate formation based on the subcooling range in which hydrates form by associating low, medium, and high probability of formation for a gas+oil+water system. The results are based on batch experiments which were performed in an autoclave cell using a mixture gas (CH4: C3H8=91.9 : 8.1 mol%), total liquid volume (200 ml), mineral oil, watercut (30%), and mixing speed (300 rpm). From the measurements of survival curves showing the minimum subcooling required before hydrate can form and hydrate conversion rates for the initial 20 minutes, we developed a risk map for hydrate formation.
Keywords: Gas Hydrates; Flow Assurance; Risk Map; Hydrate Risk Management

A novel procedure for processing the xenotime mineral concentrate of southwestern Sinai (55.4% RE2O3 and 0.9% U3O8) has been studied. This procedure is based on leaching of uranium and rare earths from the xenotime concentrate using ferric sulfate solution by hydrolytic leaching with ferric ion, wherein ferric iron is precipitated to generate acid for the leaching step. The obtained slurry is washed by water and sulfuric acid. The relevant conditions of the ferric ion leaching of the concentrate and the washing step have been optimized. From the obtained sulfate liquor, rare earths are directly precipitated as oxalates. Uranium is extracted from the REE-free sulfate solution using ion exchange resin Amberlite IRA-400. Highly pure oxide products of the two interesting metal values, REEs and U, have properly been prepared.
Keywords: Xenotime; Ferric Sulfate; Sulfuric Acid; Uranium; Rare Earths; Ion Exchange Resin

The cloud-point pressure of poly(t-butylaminoethyl methacrylate) [Poly(TBAEMA)] in various solvents such as supercritical carbon dioxide (CO2), dimethyl ether (DME) and t-butylaminoethyl methacrylate (TBAEMA) was measured to maximum pressure and temperature of 218.79 MPa and 452.9 K, respectively. The phase behavior for the Poly(TBAEMA)+CO2+TBAEMA mixture was investigated according to the various contribution factors, such as pressure, temperature and concentration with TBAEMA mass fraction of 9.9 wt%, 10.4 wt%, 14.9 wt%, 24.4 wt% and 35.2 wt%. The cloud point curves for the Poly(TBAEMA)+CO2+DME (15.6–78.7 wt%) systems show the variation of the (p, T) curve from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region as DME concentration increases. The experimental data for the CO2+TBAEMA system were reported at the broad temperature range of 313.2 K to 393.2 K and the pressure range of 3.70 MPa to 20.62 MPa. The CO2+TBAEMA binary system shows the type-I phase behavior with a continuous critical mixture curve, and is correlated by Peng-Robinson equation of state with the critical properties for TBAEMA obtained by Joback and Lyderson group contribution method.
Keywords: Poly(t-Butylaminoethyl Methacrylate); T-butylaminoethyl Methacrylate; High Pressure Phase Behavior; Cloud Point Behavior; Carbon Dioxide; Dimethyl Ether

Mechanism of Ce promoting SO2 resistance of MnO x /γ-Al2O3: An experimental and DFT study by Xiaopeng Zhang; Zhuofeng Li; Jijun Zhao; Yuezong Cui; Bojian Tan; Jinxin Wang; Chengxiang Zhang; Gaohong He (2065-2071).
Various physico-chemical techniques and theoretical chemistry computations are used to obtain a deep insight into the mechanism of Ce improving SO2 resistance of the catalyst Mn0.4Ce x /Al2O3 (x stands for the molar ratio of Ce : Al). Theoretical computation with density functional theory (DFT) shows that Ce modification enhances the adsorption energy of SO2 adsorbed on Ce surrounding, resulting in the preferential adsorption of SO2 on Ce surrounding. It protects the surface Mn from SO2 poisoning, leading to a better SO2 resistance. FT-IR and TG results are in good accordance with DFT results. FT-IR results suggest that absorption peaks related to SO4 2− cannot be detected in Mn0.4Ce0.12/Al2O3. Moreover, TG results show that weight loss peaks due to sulfated MnO x decomposition disappears after Ce addition. Therefore, Ce modification inhibits sulfates formation on active components lead to a better resistance to SO2 of Mn0.4Ce0.12/Al2O3.
Keywords: Selective Catalytic Reduction; MnO x ; Density Functional Theory; Modification; SO2 Poisoning

Formation and stability study of silver nano-particles in aqueous and organic medium by Md. Niamul Haque; Sunghyun Kwon; Daechul Cho (2072-2078).
Colloidal silver nanoparticles were obtained by chemical reduction of silver nitrate in water and organic solvent with sodium borohydride. The effects of oxidant, reducing agent, stabilizer, and temperature, during the growth of silver nanoparticles were discussed. As the reaction proceeded in aqueous medium a characteristic plasmon absorption peak between 390-420 nm appeared as presence of silver nanoparticles. The peak intensities and shifting (blue or red) were altered in accordance with some applied factors. The formed silver nanoparticles were found to be with particles size range from 3 to 20 nm. The change rates of Ag+ ions to Ag0 in aqueous and organic solvent are strongly temperature dependent, although reduction can take place at room temperature. The silver nano-colloid with negative zeta potential also has been confirmed to be more stable. Obtained nanoparticles were characterized by UV-vis spectrophotometer, particle analyzer for zeta (ζ) potential, polydispersity index (PDI), and transmission electron microscope (TEM).
Keywords: UV-vis Spectra; Chemical Reduction; Silver Nanoparticles; Poly (vinyl) Pyro-lidone (PVP); Transmission Electron Microscope (TEM); Polydispersity Index (PDI)

A facile and straightforward method has been developed to synthesize silver nanoparticles decorated on reduced graphene oxide (RGO) nanosheets through hydrothermal reaction. The composite was characterized by XRD, UV-Visible spectroscopy, SEM and TEM techniques. In this synthesized RGO-Ag nanocomposite, the Ag nanoparticles size ranges 30-50 nm. Moreover, the RGO-Ag composites exhibited excellent photocatalytic activity towards the degradation of methylene blue (MB) in presence of sunlight. This photocatalytic reaction is completed within 20 min and the rate of reaction depends on the amount of RGO present in the nanocomposites.
Keywords: RGO-Ag Nanocomposite; Hydrothermal Synthesis; Photocatalytic Degradation; Methylene Blue; Photostability

Synthesis of colloidal plasmonic microspheres via spontaneous formation and three-dimensional assembly of metal nanoparticles by Hyojin Park; Keumrai Whang; Yonghee Shin; Jungchul Lee; Taewook Kang (2086-2091).
We report the synthesis of colloidal plasmonic microspheres by taking advantage of emulsions of polydimethylsiloxane (PDMS) in metal precursor solution. Within the emulsion, both the spontaneous formation and threedimensional (3D) assembly of metal nanoparticles take place at room temperature. The number of the nanoparticles being assembled in the microsphere is controllable according to the concentration of a metal precursor. In addition, owing to the surface charge and porosity of PDMS, positively charged and neutral molecules can be more concentrated in the plasmonic microsphere. We use this plasmonic microsphere for the detection of environmentally and biologically important molecules via surface-enhanced Raman spectroscopy, since 3D assembly of metal nanoparticles in the microsphere is size-comparable to a probed volume of incident light.
Keywords: Plasmonic Microsphere; Metal Nanoparticles; 3D Assembly; Surface-enhanced Raman Spectroscopy (SERS); Polydimethylsiloxane (PDMS)

Hydrogel-based sensory structures were developed by embedding polydiacetylene supramolecules into poly-(ethylene glycol)-diacrylate (PEG-DA) to detect chemical gases and cyclodextrin and to determine pH values on the basis of a fluorescence change. We found the optimal condition for patterning-fabrication by controlling the volumetric mixture ratio of the water-soluble PEG-DA and aqueous polydiacetylene vesicle solution. Then, we determined that this hydrogel-based polydiacetylene structure optically responded selectively against vapor-phase targets: ammonia, ethanol, and aldehyde; aqueous solutions with various pH values; and cyclodextrin derivatives. These results could be extended to various label-free sensing applications of hydrogel-based chemo-biosensors.
Keywords: Hydrogel; PEG-DA; Polydiacetylene; Chemo-biosensor

Electrochemical detection of trace arsenic(III) in aqueous phase was studied with a porous gold (PAu) electrode, which was prepared by paper-based templating method. Square wave voltammetry was performed in As(III) solutions. The limit of detection of 0.1 ppb was obtained with a linear detection range of 0.1–14 ppb, which complies with the regulations for As(III) content in drinking water. The analysis of roughness factor and diffusion coefficient showed that the porous structure of the PAu electrode might have a stronger contribution to improving the sensitivity and selectivity of the target ion, compared to bulk gold electrode.
Keywords: Arsenic; Porous Gold; Square Wave Voltammetry; Electrochemical Detection

Optimization and analysis of reaction injection molding of polydicyclopentadiene using response surface methodology by Hyeon-Gook Kim; Hye Jeong Son; Dong-Koo Lee; Dong-Woo Kim; Hye Jin Park; Deug-Hee Cho (2099-2109).
Reaction injection molding (RIM) process conditions for polydicyclopentadiene (PolyDCPD) were optimized by using a Box-Behnken design (BBD) from the response surface methodology (RSM). The RIM process parameters, such as smoke time, exotherm time, highest exotherm and PolyDCPD conversion, were tuned by changing the variables (the amount of catalyst, cocatalyst and moderator). Under the optimized condition, the ring-opening metathesis polymerization reaction of dicyclopentadiene did not occur within 100 s, the maximum temperature was reached within 4 min, and the polydicyclopentadiene conversion was over 98%. Therefore, dicyclopentadiene could be safely put into the mold in a total cycle time of less than 6 min and produce PolyDCPD with mechanical properties sufficient for industry applications.
Keywords: Polydicyclopentadiene; Dicyclopentadiene; Ring-opening Metathesis; Box-Behnken Design; Reaction Injection Molding

Electrospun poly (ε-caprolactone) (PCL) nanofibers containing molecularly imprinted polymer (MIP) nanoparticles based on methacrylic acid (MAA) were prepared for controlled release of dexamethasone (Dexa). First, the MIPs consisting of Dexa were synthesized via precipitation polymerization. Their recognition sites formation and thermal properties were investigated by FTIR and TGA tests, respectively. The results showed that by selecting a monomer: template (MAA:Dexa) molar ratio of 6 : 1, MIP nanoparticles were produced with imprinting factor of 1.80. The FESEM and TEM images showed the MIPs average diameter of 394±9.7 nm and appropriate immobilization of them in PCL nanofibers, respectively. Moreover, the cumulative release of Dexa from the MIP-loaded nanofibrous samples was studied by UV-vis spectrophotometry and revealed a suitable controlled release of the drug during four days. Afterward, Dexa release followed Higuchi model which indicated the main mechanism was governed by Fickian diffusion theory.
Keywords: Poly (ε-caprolactone); Molecular Imprinting; Nanofiber; Dexamethasone; Precipitation Polymerization; Drug Release