Korean Journal of Chemical Engineering (v.33, #1)

Designing the process layout in a chemical plant is a complex and multidisciplinary task requiring input from experts in fields such as chemical, civil, mechanical, and instrument engineering. Plant layout entails the allocation of a given number of facilities on a given piece of land. Determining the optimal distribution of facilities in a plant requires an optimization calculation, including a variety of distance constraints, one of which is related to process safety. A few approaches have been taken to transform consequence analysis, such as toxic gas dispersion and its mitigation as well as the risks of fire and explosions, into mathematical equations as constraints of an optimization problem. An optimization problem with constraints related to safety is not easy to solve given limitations such as nonlinearity, uncertainty, and ethical difficulties in converting human life to costs for calculation purposes. However, safety concerns have increased to the point that developing this type of approach is necessary. The objective of this study was to review the current methodologies for plant layout optimization and to resolve facility siting issues. Process safety concepts are considered with a view to identifying gaps and issues with current methods in order to develop better methodologies for designing safer layouts.
Keywords: Consequence Modeling; Optimization; Plant Layout; Facility Siting; Quantitative Risk Analysis (QRA)

Hollow fiber supported liquid membrane was applied as a reactor to synthesize ethyl lactate from lactic acid. Lactic acid in the feed solution was extracted by tri-n-octylamine (TOA) and stripped by ethanol with p-toluene sulfonic acid acting as the catalyst to form ethyl lactate. Central composite design (CCD) was used to determine the significant factors and their interactions. The response surface was applied for optimization. An optimized yield of 30% was predicted and its validity was evaluated by comparison with experimental results at different concentrations of lactic acid in the feed solution, with good agreement achieved.
Keywords: Liquid Membrane; Hollow Fiber; Ethyl Lactate; Lactic Acid; CCD

Evaluation of multiloop chemical dosage control strategies for total phosphorus removal of enhanced biological nutrient removal process by Prithvi Sai Nadh Garikiparthy; Seung Chul Lee; Hongbin Liu; Srinivas Sahan Kolluri; Iman Janghorban Esfahani; Chang Kyoo Yoo (14-24).
We developed several control algorithms and compare their control performances for controlling the total phosphorous (TP) concentration in wastewater treatment plant, which has strong influent disturbances and the disturbance effects should be removed while maintaining better effluent quality. An anaerobic - anoxic - oxic (AAO) process, which is a well-known advanced nutrient removal process, was selected as a case study, which is modeled with activated sludge model no. 2. Six control strategies for TP control with a polymer addition were implemented in AAO process and evaluated by the plant’s performance, where the costs of the dosed chemical were compared among the six controllers. The experimental work showed that the advanced control techniques with feedback, feedforward and feedratio controllers were able to control the TP concentration in the effluent, which must be less than 1.50 g P/m3 which is the legal limitation, while reducing the necessary chemical cost. The results showed that the best TP removal performance in the effluent TP removal could be achieved by advanced feedback controller with the tuned control parameters, which showed the best effluent quality and control performance index as well as the cheapest cost of chemical dosage among the six TP control strategies.
Keywords: Activated Sludge Model; Chemical Dosage Control; Eutrophication; Feedforward Control; Multiloop Control; Total Phosphorous (TP)

This paper proposes a Markov decision process (MDP) based approach to derive an optimal schedule of maintenance, rehabilitation and replacement of the water main system. The scheduling problem utilizes auxiliary information of a pipe such as the current state, cost, and deterioration model. The objective function and detailed algorithm of dynamic programming are modified to solve the periodic replacement problem. The optimal policy evaluated by the proposed algorithm is compared to several existing policies via Monte Carlo simulations. The proposed decision framework provides a systematic way to obtain an optimal policy.
Keywords: Markov Decision Processes; Monte Carlo Simulation; Periodic Replacement; Survival Analysis; Dynamic Programming

This paper proposes a maximum likelihood estimation (MLE) method for estimating time varying local concentration of the target molecule proximate to the sensor from the time profile of monomolecular adsorption and desorption on the surface of the sensor at nanoscale. Recently, several carbon nanotube sensors have been developed that can selectively detect target molecules at a trace concentration level. These sensors use light intensity changes mediated by adsorption or desorption phenomena on their surfaces. The molecular events occurring at trace concentration levels are inherently stochastic, posing a challenge for optimal estimation. The stochastic behavior is modeled by the chemical master equation (CME), composed of a set of ordinary differential equations describing the time evolution of probabilities for the possible adsorption states. Given the significant stochastic nature of the underlying phenomena, rigorous stochastic estimation based on the CME should lead to an improved accuracy over than deterministic estimation formulated based on the continuum model. Motivated by this expectation, we formulate the MLE based on an analytical solution of the relevant CME, both for the constant and the time-varying local concentrations, with the objective of estimating the analyte concentration field in real time from the adsorption readings of the sensor array. The performances of the MLE and the deterministic least squares are compared using data generated by kinetic Monte Carlo (KMC) simulations of the stochastic process. Some future challenges are described for estimating and controlling the concentration field in a distributed domain using the sensor technology.
Keywords: Maximum Likelihood Estimation; Stochastic Processes; Chemical Master Equation; Carbon Nanotube-based Sensors; Sensor Array System

The separation of ethylenediamine (EDA) from aqueous solution is a challenging problem because its mixture forms an azeotrope. Pressure-swing distillation (PSD) as a method of separating azeotropic mixture were investingated. For a maximum-boiling azeotropic system, pressure change does not greatly affect the azeotropic composition of the system. However, the feasibility of using PSD was still analyzed through process simulation. Experimental vaporliquid equilibrium data of water-EDA system was studied to predict the suitability of thermodynamic model to be applied. This study performed an optimization of design parameters for each distillation column. Different combinations of operating pressures for the low- and high-pressure columns were used for each PSD simulation case. After the most efficient operating pressures were identified, two column configurations, low-high (LP+HP) and high-low (HP+ LP) pressure column configuration, were further compared. Heat integration was applied to PSD system to reduce low and high temperature utility consumption.
Keywords: Pressure-swing Distillation; Vapor-liquid Equilibrium (VLE); Water-ethylenediamine; Maximum-boiling Azeotrope; Process Simulation

Microfluidic room temperature ionic liquid droplet generation depending on the hydrophobicity and interfacial tension by Jung Wook Hwang; Joo-Hyung Choi; Bumjoon Choi; Gyudo Lee; Sang Woo Lee; Yoon-Mo Koo; Woo-Jin Chang (57-62).
We have characterized micro-droplet generation using water immiscible hexafluorophosphate ([PF6])- and bis(trifluoromethylsulfonyl)imide ([Tf2N])-based room temperature ionic liquids (RTILs). The interfacial tension between total 7 RTILs and phosphate buffered saline (PBS) was measured using a tensiometer for the first time. PBS is one of the most commonly used buffer solutions in cell-related researches. The measured interfacial tension ranges from 8.51 to 11.62 and from 9.56 to 13.19 for [Tf2N]- and [PF6]-based RTILs, respectively. The RTILs micro-droplets were generated in a microfluidic device. The micro-droplet size and generation frequency were determined based on continuous monitoring of light transmittance at the interface in microchannel. The size of RTIL micro-droplets was inversely proportional to the increase of PBS solution flow rate and RTILs hydrophobicity, while droplet generation frequency was proportional to those changes. The measured size of RTILs droplets ranged from 0.6 to 10.5 nl, and from 1.0 to 17.1 nl for [Tf2N]- and [PF6]-based RTILs, respectively. The measured frequency of generated RTILs droplets ranged from 2.3 to 37.2 droplet/min, and from 2.7 to 17.1 droplet/min for [Tf2N]- and [PF6]-based RTILs, respectively. The capillary numbers were calculated depending on the RTILs, and ranged from 0.51×10-3 to 1.06×10-3 and from 5.00×10-3 to 8.65×10-3, for [Tf2N]- and [PF6]-based RTILs, respectively. The interfacial tension between RTILs and PBS will contribute to developing bioprocesses using immiscible RTILs. Also, the RTILs micro-droplets will enable the high-throughput monitoring of various biological and chemical reactions using RTILs as new reaction media.
Keywords: Interfacial Tension; Light Transmittance; Micro-droplet; Microfluidic Device; Water Immiscible Room Temperature Ionic Liquids (RTILs)

Modeling and experimental studies of ammonia absorption in a spray tower by Jie Zhu; Zhenhua Liu; Jie Bai; Yunfeng Yang; Qin Peng; Shichao Ye; Mingzhe Chen (63-72).
We did an experimental study on ammonia absorption in a spray tower. The kinetic characteristics of droplets were investigated by considering the forces acting on a droplet. The gas-phase mass transfer coefficient was deduced with the Colburn analogy method. A simplified model for predicting NH3 capture with a spray tower has been presented based on mass transfer and ionic equilibrium, which was successfully validated against experimental data. The influences and the sensitivity analysis of main operating parameters on the absorption efficiency were analyzed. As the most sensitive parameter, the mean droplet diameter was obtained by fitting experimental data with an empirical correlation. The distributions of two typical process parameters along the absorber were also simulated. Decreasing the pH value of absorbent is an effective but restrictive way to strengthen the mass transfer rate on account of insufficient liquid-side resistance.
Keywords: Spray Tower; Ammonia; Model; Mass Transfer Coefficient; Absorption Efficiency

Performance analysis of K-based KEP-CO2P1 solid sorbents in a bench-scale continuous dry-sorbent CO2 capture process by Young Cheol Park; Sung-Ho Jo; Seung-Yong Lee; Jong-Ho Moon; Chong Kul Ryu; Joong Beom Lee; Chang-Keun Yi (73-79).
Korea Institute of Energy Research (KIER) and Korea Electric Power Corporation Research Institute (KEPCORI) have been developing a CO2 capture technology using dry sorbents. In this study, KEP-CO2P1, a potassium-based dry sorbent manufactured by a spray-drying method, was used. We employed a bench-scale dry-sorbent CO2 capture fluidized-bed process capable of capturing 0.5 ton CO2/day at most. We investigated the sorbent performance in continuous operation mode with solid circulation between a fast fluidized-bed-type carbonator and a bubbling fluidized-bed-type regenerator. We used a slip stream of a real flue gas from 2MWe coal-fired circulating fluidized-bed (CFB) power facilities installed at KIER. Throughout more than 50 hours of continuous operation, the temperature of the carbonator was maintained around 70-80 °C using a jacket-type heat exchanger, while that of the regenerator was kept above 180 °C using an electric furnace. The differential pressure of both the carbonator and regenerator was maintained at a stable level. The maximum CO2 removal was greater than 90%, and the average CO2 removal was about 83% during 50 hours of continuous operation.
Keywords: CO2 Capture; Dry Sorbents; Fluidized-bed Process; Bench-scale Unit; Continuous Operation

Selective hydrogenation of sunflower oil over Ni catalysts by Emilio Atilano Cepeda; Beatriz Calvo; Irene Sierra; Unai Iriarte-Velasco (80-89).
This work focuses on the influence of the support and the preparation method on the activity and selectivity of nickel catalysts in the hydrogenation of sunflower oil. Catalysts were prepared over silica and alumina supports following the incipient wetness impregnation and deposition-precipitation techniques. The activation process was followed by temperature-programmed reduction (TPR). Precipitation-deposition method allowed a stronger metal-support interaction than incipient wetness impregnation. A precipitation-deposition time of 14 h (which allowed a Ni loading of about 20wt%) was deemed as the most adequate from the standpoint of high specific surface area and strong Ni-support interaction. The selectivity to oleic acid was not affected by the preparation method, but it was significantly influenced by the type of support. In this regard, the catalysts prepared on silica are more active and produce less saturated fatty acids.
Keywords: Hydrogenation; Vegetable Oil; Nickel; Selectivity; Trans Fatty-acids

Optimization of biodiesel production from a calcium methoxide catalyst using a statistical model by Warakom Suwanthai; Vittaya Punsuvon; Pilanee Vaithanomsat (90-98).
Calcium methoxide catalyst was synthesized from quick lime and methanol, and further characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and energy dispersive X-ray spectroscopy (EDX). Response surface methodology (RSM) with a 5-level-3-factor central composite was applied for the calcium methoxide catalyzed transesterification of refined palm oil to investigate the effect of experimental factors on the methyl ester yield. A quadratic model with an analysis of variance (ANOVA) obtained from RSM is suggested for the prediction of methyl ester yield, and reveals that 95.99% of the observed variation is explained by the model. The optimum conditions obtained from RSM were 2.71 wt% of catalyst concentration, 11.5: 1 methanol-to-oil molar ratio, and 175 min of reaction time. Under these conditions, the produced biodiesel met the standard requirements for methyl ester yield.
Keywords: Biodiesel; Calcium Methoxide; Transesterification; Response Surface Methodology; Refined Palm Oil

Sustainable production of acetaldehyde from lactic acid over the carbon catalysts by Congming Tang; Jiansheng Peng; Xinli Li; Zhanjie Zhai; Hejun Gao; Wei Bai; Ning Jiang; Yunwen Liao (99-106).
The synthesis of acetaldehyde from lactic acid over the carbon material catalysts was investigated. The carbon materials were characterized by scanning electron microscopy for morphologic features, by X-ray diffraction for crystal phases, by Fourier transform infrared spectroscopy for functional group structures, by N2 sorption for specific surface area and by ammonia temperature-programed desorption for acidity, respectively. Among the tested carbon catalysts, mesoporous carbon displayed the most excellent catalytic performance. By acidity analysis, the medium acidity is a crucial factor for catalytic performance: more medium acidity favored the formation of acetaldehyde from lactic acid. To verify, we compared the catalytic performance of fresh activated carbon with that of the activated carbon treated by nitric acid. Similarly, the modified activated carbon also displayed better activity due to a drastic increase of medium acidity amount. However, in contrast to fresh carbon nanotube, the treated sample displayed worse activity due to decrease of medium acidity amount. The effect of reaction temperature and time on stream on the catalytic performance was also investigated. Under the optimal reaction conditions, 100% lactic acid conversion and 91.6% acetaldehyde selectivity were achieved over the mesoporous carbon catalyst.
Keywords: Decarbonylation; Lactic Acid; Bulk Chemicals; Mesoporous Carbon; Biomass

Titanium dioxide/tungsten disulfide (TiO2/WS2) composite photocatalysts were fabricated via a one-step hydrothermal synthesis process, using TiCl4 as titanium source and bulk WS2 as sensitizer. The morphology, structure, specific surface area and optical absorption properties of the composite photocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), specific surface area analyzer and ultraviolet-visible diffuse reflection spectrum (UV-vis DRS), respectively. The photocatalytic activity of as-prepared photocatalysts was evaluated by the degradation of methyl orange (MO) under illumination of 500W Xenon lamp. The results indicated that TiO2/WS2 composite photocatalysts possessed excellent photocatalytic activity, and ∼95% of the degradation rate for MO was reached when molar ratio of WS2 to TiO2 was 0.004 and the irradiation time was 60 min. Moreover, the carrier trapping experiment and fluorescence spectra showed that ·O 2 was the key component in the photocatalytic degradation process and O2 was reduced to be ·O 2 by the electrons from the conduction band of TiO2 and WS2 for the degradation of MO.
Keywords: TiO2 ; Bulk WS2 ; Visible-light; Methyl Orange; Photocatalytic Degradation Mechanism

Preparation of Cu/ZnO catalyst using a polyol method for alcohol-assisted low temperature methanol synthesis from syngas by Yeojin Jeong; Ji Yeon Kang; Ilho Kim; Heondo Jeong; Jong Ki Park; Jong Ho Park; Ji Chul Jung (114-119).
A polyol method was used to prepare Cu/ZnO catalysts for alcohol-assisted low temperature methanol synthesis from syngas. Unlike conventional low temperature methanol synthesis, ethanol was employed both as a solvent and a reaction intermediate. Catalyst characterization revealed that Cu/ZnO catalysts were successfully and efficiently prepared using the polyol method. Various preparation conditions such as PVP concentration and identity of ZnO precursor strongly influenced the catalytic activity of Cu/ZnO catalysts. Copper dispersion and catalyst morphology played key roles in determining the catalytic performance of the Cu/ZnO catalyst in alcohol-assisted low temperature methanol synthesis. A high copper dispersion and platelike Cu/ZnO structure led to high catalytic activity. Among the catalysts tested, 5_Cu/ZnO_Zn(Ac)2 had the best catalytic performance due to its high copper dispersion.
Keywords: Polyol Method; Copper Dispersion; Methanol Synthesis; Alcohol-assisted; Low Temperature

A glassy carbon electrode (GCE) was tailored with conducting polymer polythiophene and further immobilized by an enzyme glucose oxidase (GOx). A thin film of polymer was developed by electrochemical polymerization of thiophene monomer. During electrochemical polymerization of the monomer the enzyme GOx and the redox active mediator ferritin (Frt) were entrapped within this polymer matrix. In this novel approach, the entrapment of enzyme and mediators within a polymer matrix occurs without chemical reaction that could affect their activity. The entrapment of enzyme and mediator within the conducting polymer matrices increases the surface area of the electrode. The tailored GCE/Ptp/Frt/GOx electrode showed a high catalytic activity. The increased surface area causes a high rate of electron transfer between the electrode and Frt engaged as an electron transfer mediator. The electrochemical properties of the electrode were determined by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The fabricated bioanode showed a current density of 3.9mA cm−2 at 1.0 V vs. Ag/AgCl in a 45 mM glucose solution and suggests proficient chances in biofuel cells (BFCs) applications.
Keywords: Optimization; Conducting Polymer; Polythiophene; Entrapment; Glucose Oxidase

Nanoparticles of manganese oxide supported on tungsten oxide (WO3) were synthesized by an impregnation method using Mn(NO3)2 and Na2WO4 as a source of manganese and tungsten. Atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the physicochemical properties of compounds. Due to a highly dispersed state of manganese or insertion of manganese ions into the WO3 lattice, no manganese oxide peak was observed in the XRD patterns of the W1−x Mn x O3 nanoparticles. Investigation of W1−x Mn x O3 by AAS and EDX showed that the relative atomic abundance of Mn present in the bulk and on the surface of WO3 was 3.68% and 4.8% respectively. For the first time, the catalytic oxidation of olefins and alcohols, in the presence of these materials and hydrogen peroxide (H2O2) as a green oxidant at room temperature was studied. The recoverability and catalyst leaching of the W1−x Mn x O3 nanoparticles in epoxidation of styrene as a model reaction were also investigated.
Keywords: Nanoparticles; Heterogeneous; Oxidation; Olefins and Alcohols

A desulfurization process for model oil and real oil was investigated based on the chemical oxidation of mixed sulfur containing compounds in the presence of nitrogen compounds (indole and quinoline) using hydrogen peroxide as oxidizing agent and dodecamolibdophosphoric acid (H3PMo12O40) encapsulated in a kind of metal-organic framework (HKUST-1) as PMo@HKUST-1. The effect of isopropanol, ethanol and acetonitrile as extractive solvent and 1-ring (toluene, xylene and mesitylene) and 2-ring (naphthalene) aromatic hydrocarbons in desulfurization of model oil was studied. The desulfurization of sulfur-containing compounds was accelerated in the presence of aromatic hydrocarbons. In fact, a higher desulfurization efficiency of the heterogeneous catalyst could be achieved with system containing a polar solvent in contact with an aromatic hydrocarbon. Quinoline had no effect on oxidative desulfurization (ODS) reaction, whereas indole had a slightly negative effect. Presence of aromatic compounds had slightly positive effect on ODS reaction.
Keywords: Oxidative Desulfurization; Real Oil; Polyoxometalates; Metal-organic Frameworks

Ethylene and mixed 2-butene cis/trans isomers metathesis: Influence of lanthanum as a second metal on the WO3/SiO2 catalysts by Narongrat Poovarawan; Thidaya Thitiapichart; Kongkiat Suriye; Joongjai Panpranot; Wimonrat Limsangkass; Francisco José Cadete Santos Aires; Piyasan Praserthdam (140-146).
Lanthanum (0.5, 0.6, 0.75, 0.9 and 1 wt%) was added as a second metal on the 9 wt% WO3/SiO2 catalysts by the incipient wetness impregnation method. The catalysts were tested in the metathesis reaction of ethylene and 2-butene using either pure 2% trans-2-butene and the mixture of 1% cis- and 1% trans-2-butene as the reaction feed and were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET), inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy, ion-exchange titration, FT-Raman, ammonia temperature programmed desorption (NH3-TPD) and reactant temperature programmed desorption (reactant-TPD). An optimum lanthanum loading at 0.5 wt% could improve dispersion of tungsten active phase and adsorption properties of the reactants on the catalysts. The adsorption of the mixed cis/trans-2-butene isomer was much improved on the La-WO3/SiO2 catalysts with 0.5 wt% La.
Keywords: Metathesis; Trans-2-butene; Cis-2-butene; Propylene, WO3/SiO2 ; Tungsten Dispersion

Ash deposition characteristics of Moolarben coal and its blends during coal combustion by Byoung-Hwa Lee; Sang-In Kim; Seung-Mo Kim; Dong-Hun Oh; Sushil Gupta; Chung-Hwan Jeon (147-153).
We report a systematic and comprehensive laboratory investigation of the ash deposition behavior of Moolarben (MO) coal, which has recently begun to be imported into Korea. Ash deposition experiments were conducted in a drop tube reactor, and a water-cooled ash deposit probe was inserted into the reactor to affix the ash. The tests were conducted using five types of single coals (two bituminous and three sub-bituminous, including MO coal) and blended coals (bituminous coal blended with sub-bituminous coal). Two indices represent ash deposition behavior: capture efficiency and energy-based growth rate. A thermomechanical analysis evaluated the melting behavior of the resulting ash deposits. The MO coal had the least ash deposition of the single coals due to its high melting temperature, indicated by high ash silica content. Indonesian sub-bituminous coals formed larger ash deposits and were sticky at low temperatures due to relatively high alkali content. However, blends with MO coal had greater ash deposition than blends with other bituminous coals. This non-additive behavior of MO coal blends is likely due to interactions between ash particles. Coals with higher silica content more effectively retain alkali species, resulting in lower melting temperatures and larger ash deposits. Therefore, we recommend that when blending in a boiler, silica-rich coals (SiO2>80%, SiO2/Al2O3> 5) should be blended with relatively low-alkali coals (Na2O+K2O<3%), and the blending ratio of the silica-rich coals indicates less than 10%, which can safely operate the boiler.
Keywords: Moolarben Coal; Ash Deposition; Capture Efficiency; Blended Coal

Three series of experiments were conducted to improve sediment microbial fuel cell (SMFC) performance. At first, dissolved oxygen level of catholyte was increased with native seaweed of the Caspian Sea. Power output was improved about 2-fold, and maximum power density of 46.14 8mW/m2 was produced in the presence of seaweed as biocathode in cathode compartment. Secondly, the best depth to embed anode was then determined. Anode was embedded in 3, 6, 9 and 12 cm below the sediment/water interface. The best depth to bury the anode was finally determined in 3 cm below the sediment/water interface, maximum generated power and current density of 42.156 mW/m2 and 282.92 mA/m2, were respectively obtained in this depth. In addition, influence of agitated flow on power generation from SMFC was investigated.
Keywords: Sediment Microbial Fuel Cell; Power Density; Biocathode; Turbulence Flow; Dissolved Oxygen

Removal of Pb2+ from the aqueous solution by tartrate intercalated layered double hydroxides by Yanming Shen; Xiaolei Zhao; Xi Zhang; Shifeng Li; Dongbin Liu; Lihui Fan (159-169).
Adsorption of Pb2+ ion by a tartrate intercalated MgAl layered double hydroxides (MgAl-TA LDHs) was studied. The adsorption isotherms and kinetics were investigated as a function of various experimental parameters using batch adsorption experiments. The results indicated that the adsorption isotherm was well described by Sips model. The kinetic adsorption data were fitted well to the pseudo-second-order kinetic equation. The adsorption of Pb2+ was controlled mainly by the chemical process combined with intraparticle diffusion. Parameters of adsorption thermodynamic suggested that the interaction of Pb2+ adsorbed by MgAl-TA LDHs adsorbents was thermodynamically spontaneous and endothermic.
Keywords: Layered Double Hydroxide; Hydrotalcite; Adsorption; Heavy Metal Ions

Removal of UO 2 2+ from aqueous solution using halloysite nanotube-Fe3O4 composite by Wenfang He; Yuantao Chen; Wei Zhang; Chunlian Hu; Jian Wang; Pingping Wang (170-177).
Halloysite nanotubes (HNTs) were modified with Fe3O4 to form novel magnetic HNTs-Fe3O4 composites, and the composites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The as-obtained results indicated that Fe3O4 nanoparticles were successfully installed on the surface of HNTs. The adsorption of UO 2 2+ on HNTs-Fe3O4 was investigated as a function of solid content, contact time, pH, ionic strength and temperature by batch experiments. The consequences revealed that the adsorption of UO 2 2+ onto HNTs-Fe3O4 was strongly dependent on pH and ionic strength. Equilibrium data fitted well with the Langmuir isotherm. The experimental results demonstrated that the adsorbents with HNTs-Fe3O4 had the largest adsorption capacity of 88.32 mg/g for UO 2 2+ .
Keywords: Halloysite Nanotubes-Fe3O4 ; Adsorption; UO 2 2+ ; Modification; pH

Ultrasound-assisted adsorption of textile dyes using modified nanoclay: Central composite design optimization by Aydin Hassani; Reza Darvishi Cheshmeh Soltani; Murat Kıranşan; Semra Karaca; Canan Karaca; Alireza Khataee (178-188).
The removal of two anionic dyes, C.I. Acid Orange 7 (AO7) and C.I. Acid Red 17 (AR17), by ultrasound-assisted adsorption on the modified nanoclay in aqueous solutions was studied. The modified nanoclay was characterized by SEM/EDX, BET, XRD and FT-IR techniques. The average crystal size for the interlayer spacing of the modified nanoclay was about 14.3 nm. Central composite design (CCD) was used for the optimization of the operational parameters, including the initial dye concentration, sonication time, adsorbent dosage and temperature. The results demonstrated a good agreement between the predicted values obtained by the model and the experimental values for both AO7 (R2= 0.959) and AR17 (R2=0.971).
Keywords: Anionic Dyes; Experimental Design; Nanoclay; Sono-adsorption

Electrochemical degradation of the Acid Orange 10 dye on a Ti/PbO2 anode assessed by response surface methodology by Gholamreza Bonyadinejad; Mansour Sarafraz; Mohsen Khosravi; Afshin Ebrahimi; Seyed Mahmood Taghavi-Shahri; Roya Nateghi; Sedighe Rastaghi (189-196).
The decolorization and degradation of the synthetic aqueous solution of the Acid Orange 10 (AO10) dye on Ti/PbO2 anode were investigated using the response surface methodology based on central composite design with three variables: current density, pH, and supporting electrolyte concentration. The Ti/PbO2 electrode was prepared by the electrochemical deposition method. The optimum conditions for AO10 decolorization in synthetic dye solution were electrolyte concentration of 117.04 mM, pH of 12.05, and current density of 73.64 mA cm−2. The results indicated that the most effective factor for AO10 degradation was current density. Furthermore, the color removal efficiency significantly increased with increasing current density. To measure AO10 mineralization under optimum conditions, the chemical oxygen demand (COD) and total organic carbon (TOC) removal were evaluated. Under these conditions, decolorization was completed and 63% removal was recorded for COD and 60% for TOC after 100 min of electrolysis.
Keywords: Electrochemical Degradation; Ti/PbO2 ; Acid Orange 10; Response Surface Methodology; Central Composite Design

Separation of mercury and arsenic from produced water via hollow fiber contactor: Kinetic and mass transfer analysis by Dolapop Sribudda; Thanaporn Wannachod; Prakorn Ramakul; Ura Pancharoen; Suphot Phatanasri (197-206).
The separation of Hg(II) and As(V) from produced water by hollow fiber contactors was investigated. Two identical hollow fiber modules were employed. The first module was used for extraction, while the second module was used for stripping. The optimum conditions achieved were 14% (v/v) of Aliquat336, 0.07 M thiourea, volumetric flow rate of 100 mL/min for aqueous solution and 0.02 M HCl of stripping solution. At such conditions, the maximum extraction of Hg(II) and As(V) attained 100% and 78.78%, respectively. Concurrently, the maximum stripping of Hg(II) and As(V) reached 47.88% and 6.66%, respectively. The overall mass transfer coefficients of Hg(II) and As(V) extraction were 2.31×10−6 and 1.15×10−6m/s, while the Hg(II) and As(V) stripping exhibited the overall mass transfer coefficients of 8.37×10−7 m/s and 9.05×10−7 m/s, respectively. Mass transfer coefficients of the organic layer diffusion (k0) had the most effect on the overall mass transfer coefficients.
Keywords: Hg(II); As(V); Hollow Fiber Contactor; Mass Transfer Coefficients; Kinetic

Degradation of ultrahigh concentration pollutant by Fe/Cu bimetallic system at high operating temperature by Bo Lai; Qingqing Ji; Yue Yuan; Donghai Yuan; Yuexi Zhou; Juling Wang (207-215).
To investigate the degradation of high concentration pollutant by Fe/Cu bimetallic system at a high operating temperature, 10,000mg/L acid orange 7 (AO7) aqueous solution was treated by Fe/Cu bimetallic system at 80 oC. First, the effect of the operating temperature (30-80 °C) on the reactivity of Fe/Cu bimetallic particles was investigated thoroughly. Then, the studies on the effect of theoretical Cu mass loading, Fe/Cu dosage, stirring speed and initial pH on the reactivity of Fe/Cu bimetallic particles at a high temperature (i.e., 80 °C) were carried out, respectively. The degradation and transformation process of AO7 was studied by using COD, TOC and UV-Vis spectra. The results indicate that high concentration pollutant could be removed effectively by Fe/Cu bimetallic system at a high operating temperature. And the removal efficiencies of AO7 by Fe/Cu bimetallic system were in accordance with the pseudofirst- order model. Finally, it was observed that the high temperature could accelerate mass transport rate and overcome the high activation energy barrier to significantly improve the reactivity of Fe/Cu bimetallic particles. Therefore, the higher removal efficiency could be obtained by Fe/Cu system at a high operating temperature. Thus, the high operating temperature played a leading role in the degradation of high concentration pollutant.
Keywords: Operating Temperature; High Concentration Pollutant; Fe/Cu Bimetallic Particles; Wastewater Treatment

Immobilization of cellulase on functionalized cobalt ferrite nanoparticles by Raghvendra Ashok Bohara; Nanasaheb Devappa Thorat; Shivaji Hariba Pawar (216-222).
Amine functionalized cobalt ferrite (AF-CoFe2O4) magnetic nanoparticles (MNPs) were used for immobilization of cellulase enzyme via 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDS) and N-hydroxy-succinimide (NHS) coupling reaction. The structural, morphological and magnetic properties of AF-CoFe2O4 were determined. TEM micrograph revealed a mean diameter of ∼8 nm and showed that the AF-CoFe2O4 remain distinct with no significant change in size after binding with cellulase. Fourier transform infrared (FT-IR) spectroscopy confirmed the binding of cellulase to AF-CoFe2O4. The properties of immobilized cellulase were investigated by optimizing binding efficiency, pH, temperature and reusability. The results showed that the immobilized cellulase has higher thermal stability than free cellulase, which might be due to covalent interaction between cellulase and AF-CoFe2O4 surface. The immobilized cellulase also showed good reusability after recovery. Therefore, AF-CoFe2O4 MNPs can be considered as promising candidate for enzyme immobilization.
Keywords: Immobilization; Cellulase; Cobalt Ferrite; Bio-catalysis; Superparamagnetic Nanoparticles

An integrated process for continuous cellulosic bioethanol production by Minhee Han; Yule Kim; Woo-Sung Cho; Gi-Wook Choi; Bong-Woo Chung (223-229).
A high-efficiency, integrated bioethanol production process was developed in this study, using Miscanthus as lignocellulosic biomass. The continuous process involved a twin-screw extruder, a pretreated biomass washing/dewatering process, and a saccharification/fermentation process. In addition, the integration process was designed for the reuse of pretreatment solution and the production of highly concentrated bioethanol. Pretreatment was performed with 0.72 M NaOH solution at 95 °C using an 80 rpm twin-screw speed and a flow rate of 90mL/min (18 g/min of raw biomass feeding). Following washing and dewatering steps, the pretreated biomass was subjected to simultaneous saccharification and bioethanol fermentation processes. The maximum ethanol concentration, yield from biomass, and total volume obtained were 59.3 g/L, 89.9%, and 60 L, respectively, using a pretreated biomass loading of 23.1% (w/v) and an enzyme dosage of 30 FPU/g cellulose. The results presented here constitute an important contribution toward the production of bioethanol from Miscanthus.
Keywords: Miscanthus ; Twin-screw Extruder; Reuse of Pretreatment Solution; Integration Process; Simultaneous Saccharification and Fermentation (SSF)

The objective of this study was to enhance the lipid productivity in microalga Tetraselmis sp. through the salinity variation during cultivation. When marine alga Tetraselmis sp. was cultivated in a wide range of salinities, 0 through 70 practical salinity unit (PSU), enriched with F/2 medium, relatively low salinities below 35 PSU resulted in higher growth rates and lipid productivities under both N-deficient and -sufficient conditions, as compared to high salinities above 45 PSU. Nitrogen limitation did not stimulate lipid production in this species. Although high salinity increased lipid content, overall lipid productivities were lowered than those under low salinity conditions due to the decreased biomass production. When the salinity shifted from 35 to 22 PSU during cultivation, total lipid content increased from 20 to 26 (w/w) % within four days, and no significant change of fatty acids composition was observed.
Keywords: Microalgae; Tetraselmis ; Lipid Production; Salinity Shift; Biodiesel

The current study presents a novel approach for the removal of Ni(II) from aqueous environments using plant gum-based (PG) and clay-based (CL) nanobiocomposite (NBC) composed of ZnO nanoparticles and chitosan. Parameters like pH, contact time, temperature, initial metal concentration and adsorbent dosage were optimized. Under optimized conditions, maximum removal of Ni(II) was noted as 90.1% and 95.5% in the case of PG-NBC and CL-NBC, respectively. Equilibrium studies suggested a homogeneous mode of adsorption. Good linearity was observed for the pseudo-first order kinetic model, suggesting a physical mode of adsorption. Thermodynamic studies showed an endothermic and spontaneous nature of adsorption. The mechanism was further elucidated using SEM, EDX, AFM and FT-IR analysis. Ex-situ studies showed a maximum Ni(II) removal of 87.34% from electroplating wastewater using CL-NBC in column mode. Regeneration studies suggested that CL-NBC could be consistently reused up to 4 cycles.
Keywords: Adsorption; Nanobiocomposite (NBC); Nickel(II); Wastewater

Isothermal vapor-liquid equilibrium data for the binary system of dimethyl ether (DME)+dimethyl carbonate (DMC) were measured at 303.15, 313.15, 323.15, 333.15 and 343.15 K using a circulation-type equilibrium apparatus with on-line gas chromatography analysis. The experimental data were correlated with the Peng-Robinson equation of state (PR-EoS) using the van der Waals one fluid mixing rule and the Peng-Robinson equation of state (PR-EoS) using the Wong-Sandler mixing rule combined with the NRTL excess Gibbs free energy model. This system showed negative deviation from Raoult’s law, and no azeotropic behavior was observed for all the temperature ranges studied here. Calculated results with PR-EoS using both two mixing rules showed good agreement with experimental data.
Keywords: Vapor Liquid Equilibria; Dimethyl Ether (DME); Dimethyl Carbonate (DMC); Peng-Robinson Equation of State (PR-EoS)

Hydrogen bond dynamics in liquid water: Ab initio molecular dynamics simulation by Cheolhee Kim; Min Sun Yeom; Eunae Kim (255-259).
The effect of intermolecular interaction on the distribution of the harmonic vibrational frequencies of water molecules was investigated through ab initio molecular dynamics simulations based on the Born-Oppenheimer approach. For single water, the effect of the dynamics of the oxygen atom in single water and the simulation time step on the frequency distribution were examined. The distributions of the OH stretching and HOH bending vibrational frequencies of liquid water were compared to those of single water. The probability distributions of the change in OH bond length and the lifetime of the dangling OH bond were also obtained. The distribution of the frequencies was strongly affected by the long lifetime of the dangling OH bond, resulting in the formation of hydrogen bonds between water molecules.
Keywords: Ab Initio Molecular Dynamics Simulation; Born-oppenheimer Approach; Water; Hydrogen Bond; Vibrational Frequency

Using a high-pressure variable-volume view cell, the vapor-liquid equilibria of the binary system CO2 and 1-butyl-3-methylimidazolium tridecafluorohexylsulfonate ([BMIM][TDfO]) were determined. The CO2 mole fraction ranged from 0.104 to 0.952 over a temperature range of 298.2-323.2 K. Both the Peng-Robinson and Soave-Redlich- Kwong equations of state were applied with two different mixing rules to correlate with the experimentally obtained results. Increasing the alkyl chain length in perfluorinated sulfonate anion mother structure from methyl to hexyl markedly increased the CO2 solubility. To investigate the effect of the number of fluorine atoms in the anion on the phase behavior of imidazolium-based ionic liquid, these experimental results were then compared with those reported in previous experimental studies of 1-alkyl-3-methylimidazolium cations-including ionic liquid+CO2 binary system.
Keywords: Carbon Dioxide; Phase Equilibrium; 1-Alkyl-3-methylimidazolium Tridecafluorohexyl Sulfonate; VLE

Solvent recovery in solvent deasphalting process for economical vacuum residue upgrading by Seonju Ahn; Sangcheol Shin; Soo Ik Im; Ki Bong Lee; Nam Sun Nho (265-270).
The solvent deasphalting (SDA) process is a heavy oil upgrading process and used to separate asphaltene, the heaviest and most polar fraction of vacuum residue (VR) of heavy oil, by using density differences, to obtain deasphalted oil (DAO). The SDA process consists of two main stages: asphaltene separation and solvent recovery. Solvent recovery is a key procedure for determining the operating cost of the SDA process, because it uses a considerable amount of costly solvent, the recovery of which consumes huge amounts of energy. In this study, the SDA process was numerically simulated by using three different solvents, propane, n-butane, and isobutane, to examine their effect on the DAO extraction and the effect of the operating temperature and pressure on solvent recovery. The process was designed to contain one extractor, two flash drums, and two steam strippers. The VR was characterized by identifying 15 pseudo-components based on the boiling point distribution, obtained by performing a SIMDIS analysis, and the API gravity of the components. When n-butane was used, the yield of DAO was higher than in the other cases, whereas isobutane showed a similar extraction performance as propane. Solvent recovery was found to increase with temperature and decrease with pressure for all the solvents that were tested and the best results were obtained for propane.
Keywords: Solvent Deasphalting; Vacuum Residue; Solvent Recovery; Numerical Simulation; Propane; Butane

The excess molar volumes and excess molar enthalpies at T=298.15 K and atmospheric pressure for the binary systems {CH3CHClCH2Cl (1)+CH3(CH2) n−1OH (2)} (n=5 to 8) have been determined over the whole range of composition from the density and heat flux measurements using a digital vibrating-tube densimeter and an isothermal calorimeter, respectively. The measured excess molar volumes of all binary mixtures showed positive symmetrical trend with values increasing with chain length of 1-alkanol. Similarly, excess enthalpy values of all binary mixtures showed skewed endothermic behavior with values increasing with chain length of 1-alkanol. The maxima of excess molar enthalpy values were observed around x1=0.65 with excess enthalpy value ranging from 1,356.8 J/mol (1-pentanol) to 1,543.4 J/mol (1-octanol). The experimental results of both H m E and V m E are fitted to a modified version of Redlich-Kister equation using the Padé approximant to correlate the composition dependence. The experimental H m E data were also fitted to three local-composition models (Wilson, NRTL, and UNIQUAC). The correlation of excess enthalpy data in these binary systems using UNIQUAC model provides the most appropriate results.
Keywords: Excess Molar Properties (Volumes and Enthalpies); Padé Approximation; Thermodynamic Models; 1,2-Dichloropropane; 1-Alkanols

The phase behavior curves of binary and ternary system were measured for poly(alkyl methacrylate) in supercritical CO2, as well as for the poly(alkyl methacrylate)+dimethyl ether (DME) (or 1-butene) in CO2. The solubility curves are reported for the poly(alkyl methacrylate)+DME in supercritical CO2 at temperature from (300 to 465) K and a pressure from (3.66 to 248) MPa. Also, The high-pressure static-type apparatus of cloud-point curve was tested by comparing the measured phase behavior data of the poly(methyl methacrylate) [PMMA]+CO2+20.0 and 30.4 wt% methyl methacrylate (MMA) system with literature data of 10.4, 28.8 and 48.4 wt% MMA concentration. The phase behavior data for the poly(alkyl methacrylate)+CO2+DME mixture were measured in changes of the pressure-temperature (p, T) slope and with DME concentrations. Also, the cloud-point pressure for the poly(alkyl methacrylate)+1- butene solution containing supercritical CO2 shows from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region at concentration range from (0.0 to 95) wt% 1-butene at below 455 K and at below 245MPa.
Keywords: Poly(alkyl methacrylate); Poly(methyl methacrylate); Poly(ethyl methacrylate); Poly(propyl methacrylate); Poly(butyl methacrylate); Cloud-point Pressures; Supercritical CO2 ; Dimethyl Ether

Flame retardant coated polyolefin separators for the safety of lithium ion batteries by Ju-Young Lee; Sung-Hee Shin; Seung-Hyeon Moon (285-289).
A thermally stable and flame-retardant separator is proposed to improve the safety of lithium ion batteries. The separator is prepared by dip-coating both sides of a conventional tri-layer polyolefin separator with brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO). Significantly reduced thermal shrinkage and flammability are exhibited without decreases in the pore size or porosity of the conventional separator. By using the BPPO-coated separator, an electrochemical half-cell composed of a lithium metal anode and a LiCoO2 cathode are successively tested. The resulting stable cycle performances are demonstrated. It is expected that the BPPO-coated separator can be a capable candidate as a separator for the safe of lithium ion batteries.
Keywords: Lithium Ion Batteries; Separator; Safety; Thermal Stability; Flame Retardant

High surface area polyaniline (HSA PANI) nanofibers were synthesized through oxidative polymerization of aniline in compressed CO2 using cobalt chloride as an additive. SEM and TEM analyses showed that the HSA PANI nanofibers had a coarse surface of very thin nanofibers. The HSA PANI nanofibers had a fairly uniform diameter range of 70-90 nm with a length of 0.5–1 µm, and showed an electrical conductivity (EC) of 3.46 S/cm. TGA analysis revealed that the HSA PANI nanofibers had more doping substances than did ordinary PANI nanofibers. In the case of the HSA PANI nanofibers, direct measurement of the surface area using gas adsorption method showed high value of 68.4m2/g, which was nearly twice that of ordinary PANI nanofibers. The HSA PANI nanofibers were used to fabricate the hydrogen sensor, exhibiting a large increase in resistance upon exposure to hydrogen gas. The hydrogen sensor in this work showed excellent characteristics, such as high sensitivity and short response time. The limit of detection (LOD) and limit of quantification (LOQ) of the hydrogen sensor were very low to show 40 ppm and 133 ppm of hydrogen, respectively.
Keywords: Carbon Dioxide; Polyaniline; Nanofiber; Hydrogen Sensor

Improving the tensile strength of carbon nanotube yarn via one-step double [2+1] cycloadditions by HeeJin Kim; Jaegeun Lee; Byungrak Park; Jeong-Hoon Sa; Alum Jung; Teawon Kim; Junbeom Park; Woonbong Hwang; Kun-Hong Lee (299-304).
The tensile strength of a CNT yarn was improved through simple one-step double [2+1] cycloaddition reactions that crosslinked the constituent CNTs using a polyethylene glycol (PEG)-diazide crosslinker. The FT-IR spectrum confirmed that the azide groups in the PEG-diazide were converted into aziridine rings, indicating that the cycloaddition reaction was successful. The generation of crosslinked CNTs was also supported by the observation of N1s peak in the XPS spectrum and the increased thermal stability of the material, as observed by TGA. The tensile strength of the CNT yarn was increased from 0.2GPa to 1.4GPa after the crosslinking reaction when twisted at 4000 twists/ meter. The appropriate selection of the crosslinker may further optimize the CNT yarn crosslinking reaction. The simplicity of this one-step crosslinking reaction provides an economical approach to the mass production of high-strength CNT yarns.
Keywords: Carbon Nanotube Yarn; Crosslinking; (PEG)-diazide

A simple synthesis of Ag2+x Se nanoparticles and their thin films for electronic device applications by Duc Quy Vo; Dang Duc Dung; Sunglae Cho; Sunwook Kim (305-311).
A simple method to synthesize silver selenide nanoparticles has been proposed. By changing the ratio of Se-oleylamine complex and silver acetate in the reacting mixture at different temperatures, both size and stoichiometry of the silver selenide particles could be successfully controlled. The size of the nanoparticles was adjusted by changing reaction temperatures. The synthesized silver selenide nanoparticles showed size changes from 3 to 10 nm when the corresponding reaction temperatures were 40–100°C, respectively. In addition to the size change, the stoichiometry of the synthesized nanoparticles (Ag2+x Se) could be adjusted by simply varying the ratio of Ag to Se precursors. Through XPS analyses the x value in Ag2+x Se was determined, and it changed between 0.54 and −0.03 by varying Ag/Se ratio from 2/0.75 to 2/4. The optical property of the nonstoichiometric Ag2+x Se nanoparticles was different from that of stoichiometric Ag2Se nanoparticles, but showed the plasmon absorption of Ag-Ag network. The plasmon absorption was decreased with the increased concentration of the Se precursor. Finally, the Ag2+x Se thin film in this work showed large magnetoresistance and successfully applied to prepare high-performance Schottky diode. The Ag2.06Se film exhibited the magnetoresistance effect up to 0.9% at only 0.8 T at room temperature. The voltage drop and breakdown voltage of the Schottky diode were 0.5 V and 9.3 V, respectively.
Keywords: Silver Selenide; Optical Property; Magnetoresistance; Schottky Diode

Preparation of monodisperse poly(styrene-co-divinylbenzene) microspheres by vibration dispersion method by Ye Wang; Guobing Li; Song Chen; Rongshuang Si; Jiangyang Fan (312-318).
Monodisperse micron-size poly(styrene-co-divinylbenzene) (PST-DVB) microspheres were successfully prepared by vibration dispersion. A vibrator was used to generate a controlled vibration to jet from a single nozzle of 200 µm to produce uniform droplets. The effects of variations in selected process parameters upon the droplets formation and the diameter of the microspheres were investigated. It was demonstrated that changes in the velocity of oil phase, drive frequency and destabilization amplitude have significant effects on the formation of uniform droplets and the average diameter of the microspheres. Rational polynomial regression equations of the above parameters were established. Based on these equations, we could calculate the operation conditions to produce uniform droplets with the desirable diameter.
Keywords: Monodisperse; Poly(Styrene-co-divinylbenzene); Vibration Dispersion Method; Droplets; Drop Size

Synthesis and characterization of polyhedral oligomeric silsesquioxane-based waterborne polyurethane nanocomposites by Hengameh Honarkar; Mohammad Barmar; Mehdi Barikani; Parvin Shokrollahi (319-329).
A series of aqueous polyurethane nanocomposites were prepared using various amounts (0.3-4.6 wt%) of a diol functionalized polyhedral oligomeric silsesquioxane (POSS) by the prepolymer mixing method. N,N-bis(2-hydroxy ethyl-2-amino ethane sulfonic acid sodium salt (BES sodium salt) was used as the anionic internal emulsifier and ionic center. The molecular structure of the samples was characterized by ATR-FTIR spectroscopy. We investigated the effect of the POSS contents on the properties of the specimens by particle size and viscosity measurements, X-ray diffractometry, mechanical behavior assessment, dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis and morphological studies. The results showed that with increasing the POSS contents, particle size, viscosity, tensile strength, modulus, T g , and thermal stability of the synthesized samples were improved. Also, SEM and TEM images indicated that a homogeneous morphology was obtained in the 1.2 wt% POSS-based sample. AFM results showed that the surface roughness increased as the POSS amounts increased.
Keywords: Nanocomposites; Aqueous Polyurethane; POSS; Anionic; Emulsifier

To improve the physical and gas barrier properties of biodegradable poly(lactic acid) (PLA) film, two graphene nanosheets of highly functionalized graphene oxide (0.3 wt% to 0.7 wt%) and low-functionalized graphene oxide (0.5 wt%) were incorporated into PLA resin via solution blending method. Subsequently, we investigated the effects of material parameters such as loading level and degree of functionalization for the graphene nanosheets on the morphology and properties of the resultant nanocomposites. The highly functionalized graphene oxide (GO) caused more exfoliation and homogeneous dispersion in PLA matrix as well as more sustainable suspensions in THF, compared to low-functionalized graphene oxide (LFGO). When loaded with GO from 0.3 wt% to 0.7 wt%, the glass transition temperature, degree of crystallinity, tensile strength and modulus increased steadily. The GO gave rise to more pronounced effect in the thermal and mechanical reinforcement, relative to LFGO. In addition, the preparation of fairly transparent PLA-based nanocomposite film with noticeably improved barrier performance achieved only when incorporated with GO up to 0.7wt%. As a result, GO may be more compatible with hydrophilic PLA resin, compared to LFGO, resulting in more prominent enhancement of nanocomposites properties.
Keywords: Graphene Oxide; Poly(Lactic Acid); Nanocomposite Film; Barrier Properties

Deep Eutectic Solvents are promising greener and cheaper alternatives to ionic liquids. The applications involving these solvents depend largely on their physical and chemical properties. However, a DES may possess both desirable and undesirable properties for a certain application. In such situations, mixing two DESs, each possessing a unique set of properties, may yield one with a more suitable set of physical and chemical properties for the same application. In this work, the variation in the physical properties of Reline upon addition of Glyceline was investigated. While a positive deviation of excess molar volume was observed, a negative deviation of viscosity was recorded with the increase in Glyceline mol% indicating a disruption of the ordered structure of Reline. The highest deviation in both cases was observed at 30 mol% Glyceline. The physical properties measured were density, viscosity, pH, RI and conductivity. The Glyceline molar percentage studied was 0 to 100mol% while temperature was varied within the range of 20 °C to 80 °C.
Keywords: Mixture; Eutectic; Reline; Glyceline; Molar Volume; Ionic Liquids

Electrochemical sensor applications of Pt supported porous gold electrode prepared using cellulose-filter by Jieun Kim; Seung Yeon Oh; Jae Yeong Park; Younghun Kim (344-349).
A facile and rapid method for the synthesis of porous gold (PAu) electrodes on cellulose-filters is proposed. Morphology and active surface area of the electrode greatly influence the electrochemical properties of sensor. Compared to smooth electrode and glassy carbon, PAu and Pt/PAu electrode showed high roughness due to porous structure, which is helpful in electrochemical sensing of target molecules. The electrochemical sensing performance of Pt/PAu electrode was evaluated to detect hydrogen peroxide, glucose, and perchloric acid. The amperometric results with various concentrations of target molecules showed potential applications of Pt/PAu electrode in sensitive and effective chemical sensors.
Keywords: Porous Gold; Syringe Filter; Hydrogen Peroxide; Electrochemical Sensor