Korean Journal of Chemical Engineering (v.29, #5)

The photodegradation efficiency (PE) of gaseous toluene was investigated by using titanium dioxide (TiO2) film doped of ruthenium (Ru)-dye/platinum (Pt) in a 3,600 L pilot reactor. Ru-dye was applied as a sensitizer to enhance PE of toluene in both UV and visible wavelength range since its major peaks are 225 nm, 325 nm, 375 nm, and 525 nm. PE by using Pt/TiO2 was more enhanced since Pt plays a role as an electron trapper in UV light range. The 3.2 μm thickness of TiO2 film was optimized for the highest PE. The highest PE was 75%, 85%, and 90% by TiO2, Pt/TiO2, and Ru-dye/Pt/TiO2 film, respectively.
Keywords: Gaseous Toluene; Ru-dye/Pt/TiO2 ; Pilot-photoreactor; Continuous Flow Reactor

Photocatalytic degradation (PCD) of polyphenols (gallic acid) from E. camaldulensis leaves on TiO2/MCM-41 was investigated in order to get rid of substances harmful to aquatic life. The TiO2/MCM-41 catalysts with titania loading of 2–40% were synthesized by hydrothermal method using rice husk silica and tetraethyl orthotitanate as silica and titania sources, respectively. The obtained catalysts were characterized by XRD, TEM, Zeta potential analyzer, N2 adsorption-desorption and diffuse reflectance UV spectroscopy. Hexagonal array of MCM-41 was confirmed, but its crystallinity decreased dramatically with titania loading. Zeta potential of TiO2/MCM-41s surface varied from 2.11 to 6.00 with the increase of TiO2 from 0 to 100 wt%. Band gap energy of TiO2 shifted from 394.1 to 425.1 nm after adding 60%MCM-41 (40%TiO2/MCM-41), facilitating the ease of OH establishment. Gallic acid - a weak acid solution (pKa=4.0) around 27 ppm was favorable to dissolve in water. PCD of gallic acid was carried out on irradiating of 400W of mercury lamp. The results showed gallic acid solution about 10 wt% properly adsorbed on 10%TiO2/MCM-41 and effectively degraded at pH solution of 9.0. PCD completed at 60 minutes of irradiation time through catalyst concentration of 0.17 g/L and obeyed pseudo-first order. Intermediate products were formic, oxalic, pyruvic, malanic and maleic acids that finally mineralized to CO2 and H2O as downstream products.
Keywords: Eucalyptus; Polyphenols; Gallic Acid; MCM-41; Titania; Degradation

A single sugar α-linked glucuronic acid based oligosaccharide (SSGO) is water soluble oligosaccharides (WSOS) obtained by Gluconacetobacter hansenii PJK (KCTC 10505BP) as a byproduct during bacterial cellulose (BC) production. In this study, SSGO was used for the improvement of BC production by the vinegar bacterium, Acetobacter xylinum, which produces heteropolysaccharides as a byproduct. The addition of 1.0% SSGO to the chemically defined medium (CDM) resulted in an 89.3% increase in BC production by A. xylinum after 15 days of cultivation under static condition, and a 52.3% increase in BC production by G. hansenii. Both the dry cell weight and live cell density of A. xylinum increased 50% with the addition of 1.0% SSGO. SSGO successfully improved BC production by A. xylinum.
Keywords: Bacterial Cellulose; Acetobacter xylinum ; Gluconacetobacter hansenii ; Water Soluble Oligosaccharides; Characterization

Design and optimization of a dividing wall column by factorial design by Nguyen Van Duc Long; Moonyong Lee (567-573).
A factorial design methodology was applied to the design of a dividing wall column, solving the complex multivariable problems and simultaneously optimizing the interacting variables to achieve the best design with respect to total annual cost. Column structure was practically optimized with a minimum of simulation runs. The proposed design method was tested in the design and optimization of an NGL recovery system; it allowed interactions between variables to be identified and quantified. The column system designed by the proposed method reduced reboiler energy consumption and total annual cost by 28.23% and 25.49%, respectively, in case 1, and those by 25.63% and 18.85%, respectively, over conventional distillation in case 2.
Keywords: Distillation Process; Dividing Wall Column; Factorial Design; Structure Design

Effects of burner type on a bench-scale entrained flow gasifier and conceptual modeling of the system with Aspen Plus by Joongwon Lee; Seik Park; Haikyung Seo; Miyeong Kim; Simoon Kim; Junhwa Chi; Kitae Kim (574-582).
The integrated gasification combined cycle (IGCC) system is well known for its high efficiency compared with that of other coal fueled power generating systems. In this study, gasification using different types of burners with different oxygen supply angles in a bench-scale entrained flow gasifier was investigated. The effects of the oxygen gas supply angle of the coal burner and resulting oxygen supply location in the gasifier on the syngas composition and temperature of the gasifier were experimentally examined. These changes had a significant influence on the syngas composition of the final stream, carbon conversion, and efficiencies. According to the experimental results, the models using the Aspen Plus process simulator were positioned to define the effects of the experimental parameters and to find the optimum operating conditions in the bench gasifier facility.
Keywords: Gasification; Entrained Flow Gasifier; Aspen Plus; Modeling

Systematic synthesis of untimed operating procedures has always been considered as an important design issue for batch chemical processes. An automaton-based method is developed in the present study to perform this task automatically. On the basis of the proposed methodical model-building principles, two distinct types of automata can be constructed to characterize the plant behaviors and control specifications, respectively. An admissible supervisor can be produced by applying the parallel composition operation with these models. For the purpose of identifying the most efficient operation procedures, the supervisor can then be integrated with a set of auxiliary automata to set the operation target(s) and, also, to impose upper limits on the total numbers of actuator actions and operation steps. Three examples are presented to demonstrate the feasibility and correctness of the proposed approach.
Keywords: Automaton; Batch Process; Discrete-event System; Supervisory Controller; Synthesis

Conditional monitoring of moisture content in a fluidized bed dryer by the acoustic emission signature by Farhad Karimi; Rahmat Sotudeh-Gharebagh; Reza Zarghami; Mojgan Abbasi; Navid Mostoufi (595-600).
Wetted rice particles were dried in a fluidized bed and the corresponding passive acoustic emissions signals (AES) were recorded at a given frequency to study the drying phenomena and bed hydrodynamic changes as well. The results show that the end time of the constant rate zone and the end of the falling rate can be determined from the variation of standard deviation and kurtosis of AES, respectively. Frequency domain analysis was also used to quantify the moisture content of solids. For this end, the original signal was decomposed into ten sub-signals, and it was found that the energy of the 4th sub-signal can be correlated with the moisture content. The results show that the acoustic emission measurement is applicable as a practical method for on-line condition monitoring of drying process in fluidized bed dryers.
Keywords: Fluidized Bed Dryer; Moisture Content; Online Monitoring; Acoustic Emission

The adsorption of methane on two activated carbons with different physical properties was measured. Adsorption isotherms were obtained by static volumetric method at different temperatures and pressures. The experimental results sow the best gas storage capacity was 113.5 V/V at temperature 280 K and pressure 8.5MPa on an activated carbon with surface area 1,060 m2/gr. An artificial neural network (ANN) based on genetic algorithm (GA) was used to predict amount of adsorption. The experimental data including input pressure, temperature and surface area of adsorbents as input parameters were used to create a GA-ANN simulation. The simulation results were compared with the experimental data and a good agreement was observed. The simulation was applied to calculate isosteric heat of adsorption by using the Clausius-Clapeyron equation. Comparison of the calculated adsorption heat showed different surface heterogeneity of the adsorbents.
Keywords: Methane; Activated Carbon; Adsorption; Artificial Neural Network; Genetic Algorithm

This paper presents an investigation of the effects of temperature gradient distribution by the aid of a secondary burner on exergetic and environmental functions of the cement production process. For this reason, the burning system of the cement production (kiln & preheater) process was simulated in four thermal areas. Three lines of cement production with 2,000, 2,300 and 2,600 ton/day were investigated. Fuel injection ratio into the secondary burner, from 10 to 40 percent was studied for each line. The obtained results show that, for cyclone preheaters, fuel injection into the secondary burner up to a proportion resulting in the minimum temperature required for alite formation (2,200 °C) in the kiln burning zone is suitable. For shaft preheaters, however, according to percent calcinations, there exists an optimum proportion for 15 to 20 percent injection fuel into secondary burner. Finally, it was shown that the secondary burner application can reduce the exergy losses about 25 percent, which leads to a reduction of the green house gases of about 35000 cubic meters per year for each ton per day of clinker production.
Keywords: Exergy Analysis; Green House Gases; Secondary Burner; Cement Production; Driving Force

Fractionation of barley straw with dilute sulfuric acid for improving hemicellulose recovery by Kyung Yoen Won; Byung Hwan Um; Seung Wook Kim; Kyeong Keun Oh (614-620).
Dilute acid fractionation of barley straw improves dissolving hemicellulose fraction of the straw, while leaving the cellulose more reactive and accessible to enzyme as a strategy of pretreatment. To characterize the fractionation process, the effects of the acid concentration, temperature and reaction time on the hemicellulose removal as well as on the formation of by-products (furfural, 5-hydroxymethylfurfural and acetic acid) were investigated. The optimum fractionation conditions of barley straw were 1% (w/v) concentration of sulfuric acid, 158 °C of reaction temperature and 15 min of reaction time. Under the optimum conditions, 87% of xylan was hydrolyzed and recovered in liquid hydrolyzate, which was 7% higher than that of the predicted yield. The hydrolyzate contained glucose 2.44 g/L, arabinose 1.70 g/L, xylose 13.41 g/L, acetic acid 1.55 g/L, levulinic acid 0.03 g/L, 5-HMF 0.03 g/L and furfural 0.75 g/L.
Keywords: Barley Straw; Response Surface Methodology (RSM); Pretreatment; Hemicellulose; Sugar Decompositions

Active and stable cobalt-based non-precious metal catalysts for the oxygen reduction reaction (ORR) in PEM fuel cells were developed through high-temperature pyrolysis of metal-porphyrins supported on carbon. The roles of substituted porphyrins, carbon support, and catalyst loading on ORR activity were studied using rotating disc electrode (RDE) measurements. It was observed that the carbon support plays a major role in improving the catalytic activity. The results showed that among the supported catalysts, the homemade mesocarbon-supported cobalt-porphyrin catalyst with 20 wt% loading displayed higher ORR activity; the cell performance showed maximum current density of 1.1 A cm−2 at 0.13 V in H2/O2 fuel cells.
Keywords: Non-precious Metal Catalyst; Metal-porphyrin; ORR Activity; Rotating Disc Electrode; Polymer Electrolyte Membrane Fuel Cells

This study discusses the impact of different operating parameters on the bed material particle size and heavy metal distribution, and evaluates the impact of bed material heavy metal on the environment through TCLP and Vibrio fischeri test. The experimental results show that the bed material particle size distribution inclines to smaller particle sizes as the operating temperature increases. When there is Na, the particle size increases due to the agglomeration of eutectic. As for the heavy metal distribution, the combination of the fine particle sizes (<0.59mm) with a large surface area and the large particle sizes with multiple eutectics has a higher heavy metal concentration. According to the results of leaching concentration of bed materials with different particle sizes, the heavy metals with large (>0.84 mm) and fine (<0.59 mm) particle sizes have the maximum leaching concentration. As for the biological toxicity, when the temperature is 700 °C or Na concentration is 0.3%, the biological toxicity is at its maximum, which may due to a high accumulation of heavy metals.
Keywords: Agglomeration; Fluidized Bed; Heavy Metal; TCLP; Biological Toxicity

Modeling of a paper-making wastewater treatment process using a fuzzy neural network by Mingzhi Huang; Jinquan Wan; Yan Wang; Yongwen Ma; Huiping Zhang; Hongbin Liu; Zhanzhan Hu; ChangKyoo Yoo (636-643).
An intelligent system that includes a predictive model and a control was developed to predict and control the performance of a wastewater treatment plant. The predictive model was based on fuzzy C-means clustering, fuzzy inference and neural networks. Fuzzy C-means clustering was used to identify model’s architecture, extract and optimize fuzzy rule. When predicting, MAPE was 4.7582% and R was 0.8535. The simulative results indicate that the learning ability and generalization of the model was good, and it can achieve a good predication of effluent COD. The control model was based on a fuzzy neural network model, taking into account the difference between the predicted value of COD and the setpoint. When simulating, R was 0.9164, MAPE was 5.273%, and RMSE was 0.0808, which showed that the FNN control model can effectively change the additive dosages. The control of a paper-making wastewater treatment process in the laboratory using the developed predictive control model and MCGS (monitor and control generated system) software shows the dosage was computed accurately to make the effluent COD remained at the setpoint, when the influent COD value or inflow flowrate was changed. The results indicate that reasonable forecasting and control performances were achieved through the developed system; the maximum error was only 3.67%, and the average relative error was 2%.
Keywords: Fuzzy Neural Network; Industrial Wastewater Treatment; Predictive Control; Fuzzy C-means Clustering; Hybrid Algorithm

Vapor-liquid equilibra for cyclohexane+2-propoxyethanol and cyclohexane+2-butoxyethanol systems by Sujin Kim; Yun Kyung Choi; Dongmyung Kim; Moon Sam Shin (644-649).
2-propoxyethanol (C3E1) and 2-butoxyethanol (C4E1) are nonionic surfactants which are a particularly interesting class of substances due to both inter-molecular and intra-molecular association, related to the presence of O and OH in the same molecule. Binary (vapor+liquid) equilibrium data were measured for cyclohexane+2-propoxyethanol and cyclohexane+2-butoxy ethanol systems at temperatures ranging from 303.15 K to 323.15 K at 10 K intervals. A static apparatus was used in this study. Two systems show positive deviation from Raoult’s law and no azeotrope. The experimental data were correlated well with Peng-Robinson-Stryjek-Vera equation of state using Wong-Sandler mixing rule incorporating the non-random-two-liquid model.
Keywords: Surfactants; 2-Propoxyethanol; 2-Butoxyethanol; Cyclohexane; Association

A novel enzymatic extraction combined with response surface methodology was developed for polysaccharide extraction from marine algae. Box-Behnken design was employed to optimize concentration of enzyme, ratio of water to raw material and extraction time for high extraction yields. The optimal extraction conditions were as follows: a concentration of enzyme of 778.01 mg/g with ratio of water to raw material of 86.80 and extraction time of 129.93 min for Gelidium amansii and a concentration of enzyme of 997.03 mg/g with ratio of water to raw material of 98.76 and extraction time of 117.69 min for Laminaria japonica Aresch. Under the optimal conditions, extraction yields were 48.36% and 32.47%, respectively. Experimental data were fitted by multiple regression analysis to a secondorder polynomial equation and were statistically analyzed. The predicted model matched the experimental data well with coefficients of determination (R2) of 0.9864 and 0.9892, respectively.
Keywords: Marine Algae; Enzymatic Extraction; Polysaccharides; Response Surface Methodology

PRSV equation of state parameter modeling through artificial neural network and adaptive network-based fuzzy inference system by Tahmaseb Hatami; Masoud Rahimi; Hiua Daraei; Ehsan Heidaryan; Ammar Abdulaziz Alsairafi (657-667).
Two different modeling methods have been proposed to relate the Peng-Robinson-Stryjek-Vera (PRSV) parameter, κ 1, to some common thermodynamic constants, including critical temperature (T c ), critical pressure (P c ), acentric factor (ω) and molecular weight (Mw). The methods are artificial neural network (ANN) and adaptive networkbased fuzzy inference System (ANFIS). A set of 159 data points (116, 23 and 20) was used for construct training, validating and testing, respectively. The radius parameter of ANFIS was determined through genetic algorithm (GA) optimization technique. The ANN and especially ANFIS results are in a good agreement with most of the compound groups.
Keywords: Peng-Robinson-Stryjek-Vera Parameter; Artificial Neural Network; Adaptive Network-Based Fuzzy Inference System; Genetic Algorithm

The study was conducted to optimize the selective extraction and recovery of Cu(II) in the presence of Zn(II) and Ni(II) from the leach liquor of waste printed circuit boards (PCBs). The extraction experiments were carried out according to 24 factorial design of experiment to optimize the extraction factors. The design was analyzed using MINITAB to determine the main effects and interactions of the chosen extraction factors. The factors chosen were: extraction pH, amount of Cyanex 272 in dispersed phase during MC-Xs preparation, amount of MC-Xs and temperature. The pH, amount of MC-Xs and temperature were found to be statistically significant. The optimized experimental conditions for the Cu(II) extraction in presence of Zn(II) and Ni(II) were extraction pH 6.0, amount of Cyanex 272 in dispersed phase 3 g, amount of MC-Xs 2.5 g and Temperature 45 °C. Factorial design of experiment was also carried out to determine the Cu(II) stripping factors from the loaded MC-Xs using H2SO4 solution. The liquid-liquid extraction Cu(II) was conducted with the prime aim to evaluate the nature of Cu(II) complex extracted by Cyanex 272. Results showed that the extraction species is [Cu(HA2)(Ac)·2HA]. Finally, a complete process for the separation and recovery of Cu(II), Zn(II) and Ni(II) from the leach liquor of waste PCBs was conducted based on the optimized experimental condition and effect of pH on extraction.
Keywords: Copper; Cyanex 272; Factorial Design; Microcapsules; Printed Circuit Board

TiN films were deposited onto a glass substrate by DC facing target sputtering, and the effects of N2 flow rate on the film properties were investigated. Prepared TiN films had a rock salt (NaCl-type) structure with a very low resistivity (∼30 μΩ·cm) and gold-like color. Increase in the N2 flow rate played an important role in controlling the properties of TiN films, such as Ti/N ratio and growth orientation. The growth orientation changed from a (111) phase to (200), with the ratio of N/Ti becoming near stoichiometric. The change in the growth orientation was caused by the increase in the N2 flow rate, which weakens the kinetic energy of the bombarding particles. The observed phenomenon is explained by an energy loss in the reactive plasma due to the difference in the inner degree of freedom of the molecular gas causing the reduction in the effective energy for radicals.
Keywords: TiN; Facing Target Sputtering; FTS; Molecular Discharge; Texture Coefficient

Synthesis of highly concentrated suspension of chemically converted graphene in organic solvents: Effect of temperature on the extent of reduction and dispersibility by Viet Hung Pham; Thanh Truong Dang; Tran Viet Cuong; Seung Hyun Hur; Byung-Seon Kong; Eui Jung Kim; Jin Suk Chung (680-685).
We report the effect of temperature on the extent of graphene oxide reduction by hydrazine and the dispersibility of the resulting chemically converted graphene (CCG) in polar organic solvents. The extent of graphene oxide reduction at high temperatures was only slightly higher than at low temperatures (30–50 °C), while the dispersibility of the resulting CCG in organic solvents decreased markedly with increasing temperature. The low dispersibility of CCGs prepared at high temperatures was greatly affected by reduction and influenced by the formation of an irreversible agglomerate of CCG at high temperatures. The reduction of graphene oxide at low temperatures is necessary to prepare highly dispersible CCG in organic solvents. CCG prepared at 30 °C is dispersible in N-methyl-2-pyrrolidone concentrations as high as 0.71 mg/mL. The free-standing paper made of this CCG possessed an electrical conductivity of more than 22,000 S/m, one of the highest values ever reported.
Keywords: Chemically Converted Graphene; Graphene Oxide; Hydrazine Reduction; Colloidal Suspension; Dispersibility; Organic Solvent

High functional ophthalmic lens materials, poly(HEMA-co-MMA)s, were prepared by the copolymerization of HEMA, MMA, NVP, EDGMA, and N,N-dimethylacrylamide in the presence of silver nanoparticles. Silver nanoparticles have antimicrobial properties and a hydrophilic monomer N,N-dimethylacrylamide has excellent biocompatibility and oxygen transmissibility. The water content was in the range of 36.63–44.45%, indicating the characteristics of general water-content contact lenses, and the refractive index was measured to be in the range of 1.423–1.435. Meanwhile, the oxygen transmissibility ranged from 10.63×10−11 to 18.85×10−11 (cm2/sec)(mlO2/ml×mmHg) increasing with increasing the addition ratio of N,N-dimethylacrylamide. The polymeric materials satisfied the basic characteristics required for ophthalmic contact lenses. The polymers can be used to fabricate antimicrobial hydrogel contact lenses with high oxygen transmissibility.
Keywords: Silver Nanoparticle; N,N-dimethylacrylamide; Oxygen Permeability; Water Content; Antimicrobial Property