Korean Journal of Chemical Engineering (v.30, #6)

Changes in the CO2 absorption rates and capacities of the absorbent 2-amino-2-methyl-1-propanol (AMP), blended with NH3 and other additives, were investigated toward performance improvement. The NH3-blended absorbent removed CO2 more efficiently than the AMP absorbent alone. However, absorbent loss through NH3 evaporation was observed under these conditions. A second absorbent, the tertiary amine triethanolamine (TEA), which has a low vapor pressure, was selected and blended with the NH3/AMP system to reduce NH3 evaporation. Its effects on NH3 loss and the absorption rate and capacity of the NH3/AMP system were investigated, and the optimum blending ratios were determined. In addition, the absorbent blend at the optimum blending ratio was compared to AMP alone and the commercially available absorbent monoethanolamine at the same weight ratio. The thermal stabilities of the absorbents, under conditions used in the CO2 absorption process, were compared by thermogravimetric analysis.
Keywords: CO2 Capture; CO2 Absorption; Absorbent Loss; Blending Absorbent Ratio; Thermogravimetric Analysis

Considering that kernel entropy component analysis (KECA) is a promising new method of nonlinear data transformation and dimensionality reduction, a KECA based method is proposed for nonlinear chemical process monitoring. In this method, an angle-based statistic is designed because KECA reveals structure related to the Renyi entropy of input space data set, and the transformed data sets are produced with a distinct angle-based structure. Based on the angle difference between normal status and current sample data, the current status can be monitored effectively. And, the confidence limit of the angle-based statistics is determined by kernel density estimation based on sample data of the normal status. The effectiveness of the proposed method is demonstrated by case studies on both a numerical process and a simulated continuous stirred tank reactor (CSTR) process. The KECA based method can be an effective method for nonlinear chemical process monitoring.
Keywords: Kernel Entropy Component Analysis; Process Monitoring; Fault Detection; Angular Structure

Modelling and analysis of pre-combustion CO2 capture with membranes by Ji Hye Choi; Myung-June Park; JeongNam Kim; Youngdeok Ko; See-Hoon Lee; Ilhyun Baek (1187-1194).
A pre-combustion CO2 capture system was modelled with three different membranes. It comprised an amine absorber for the elimination of H2S, high- and low-temperature water gas shift reactors for the conversion of CO to CO2 and a membrane to keep over 90% of the CO2 in the retentate. The absorber and equilibrium reactors were modelled using rigorous models, while the partial least squares model was used for three different types of membranes to predict the experimental results. The effectiveness of the modelling of the reactors and membranes was tested through comparison of simulated results with experimental data. The effects of operating pressure and membrane type are also discussed, and it was found that using a smaller membrane under high pressure lowered the membrane’s cost but also lowered energy recovery.
Keywords: Pre-combustion; CO2 Capture; Membrane; Modelling; Partial Least Squares (PLS) Model

An experimental study on the performance of a condensing tumbler dryer with an air-to-air heat exchanger by Yeongjin Do; Myungjong Kim; Taewan Kim; Seonghae Jeong; Sangho Park; Sangwoo Woo; Yeonghwan Kwon; Yoongho Jung; Jaekeun Lee; Youngchull Ahn (1195-1200).
The performance of energy consumption in the closed-loop tumbler dryer with a condenser for clothes drying is evaluated as a function of the heater capacity, the drying air flow rate inside the dryer, and the cooling air flow rate. The clothes dryer in laundries used in this study consists of a tumbling drum, condenser for condensing the humid and hot air flowing out the rotating drums, and electric heater for heating the circulating drying air. Tests were performed at the heating capacity of 1.9 kW to 2.7 kW, the drying air flow rate of 60 m3/h to 140 m3/h, and the cooling air flow rate of 100 m3/h to 240 m3/h. The total energy consumption, the drying time, and the condensate water rate were also investigated. Parametric results showed that a larger heater power resulted in shorter drying time. With increasing heater power, the air temperature and the condensate rate increased due to the higher humidity ratio in the air. The drying air flow rate and the cooling air flow rate did not have a significant effect on drying performance.
Keywords: Tumbler Dryer; Condenser; Heater Power; Energy Consumption; Drying Time; Cooling Air Flow; Drying Air Flow

Freeze drying of quince (Cydonia oblonga): Modelling of drying kinetics and characteristics by Sheckoufe Adhami; Amir Rahimi; Mohammad Sadegh Hatamipour (1201-1206).
Drying kinetics of quince (Cydonia oblonga) in mashed form was investigated in a pilot scale freeze dryer. Experiments were conducted in various operating conditions, and the effects of initial moisture content, heat load power and the initiation time of heat application were investigated on drying rate and performance of the dryer. The experimental data of the moisture changes were correlated through non-linear regression and an appropriate mathematical model was obtained. The drying kinetics of the sample was determined on the basis of the pre-identified mathematical models as a function of operating parameters. The obtained values of mean relative percent deviation for the kinetics models of the primary and secondary drying stages are 7.47% and 5.94%, respectively. It is revealed that by applying a high heat load power at the beginning of the process the drying time is reduced significantly.
Keywords: Freeze Drying; Lyophilisation; Quince; Cydonia oblonga; Kinetics Model

A theoretical analysis of buoyancy-driven instability under transient basic fields is conducted in an initially quiescent, fluid-saturated, horizontal porous layer. Darcy’s law is used to explain characteristics of fluid motion, and the anisotropy of permeability is considered. Under the Boussinesq approximation, the energy stability equations are derived following the energy formulation. The stability equations are analyzed numerically under the relaxed energy stability concept. For the various anisotropic ratios, the critical times are predicted as a function of the Darcy-Rayleigh number, and the critical Darcy-Rayleigh number is also obtained. The present predictions are compared with existing theoretical ones.
Keywords: Buoyancy-driven Convection; Anisotropic Porous Medium; Energy Mmethod

Optimal oxygen concentration strategy through an isothermal oxidative coupling of methane plug flow reactor to obtain a high yield of C2 hydrocarbons by Amideddin Nouralishahi; Hassan Pahlavanzadeh; Mohammadmehdi Choolaei; Elaheh Esmaeili; Amir Yadegari (1213-1221).
An optimal oxygen concentration trajectory in an isothermal OCM plug flow reactor for maximizing C2 production was determined by the algorithm of piecewise linear continuous optimal control by iterative dynamic programming (PLCOCIDP). The best performance of the reactor was obtained at 1,085 K with a yield of 53.9%; while, at its maximum value, it only reached 12.7% in case of having no control on the oxygen concentration along the reactor. Also, the effects of different parameters such as reactor temperature, contact time, and dilution ratio (N2/CH4) on the yield of C2 hydrocarbons and corresponding optimal profile of oxygen concentration were studied. The results showed an improvement of C2 production at higher contact times or lower dilution ratios. Furthermore, in the process of oxidative coupling of methane, controlling oxygen concentration along the reactor was more important than controlling the reactor temperature. In addition, oxygen feeding strategy had almost no effect on the optimum temperature of the reactor. Finally, using the optimal oxygen strategy along the reactor has more effect on ethylene selectivity compared to ethane.
Keywords: Oxidative Coupling of Methane (OCM); Modelling; Optimization; Reaction Engineering; Optimal Control

Preparation and properties of sulfated zirconia for hydrolysis of ethyl lactate by Weixing Li; Yingxiang Ni; Weiwei Liu; Weihong Xing; Nanping Xu (1222-1228).
Sulfated zirconia catalysts are proposed for the reversible hydrolysis of ethyl lactate instead of liquid acids. Sulfated zirconia catalysts were prepared by precipitation-impregnation method. The zirconium hydroxide was produced from zirconium oxychloride by adding aqueous ammonia and then impregnated in sulfuric acid. The solid samples were obtained by filtration and evaporation of the mixtures, respectively. After the samples were calcined, the sulfated zirconia catalysts were prepared. The results showed that the catalyst prepared by evaporation has higher catalytic activity. The physicochemical characteristics of the sulfated zirconia catalysts were studied by thermal analysis, X-ray powder diffraction (XRD), temperature programmed desorption of ammonia (NH3-TPD) and N2 adsorption-desorption, respectively. By the precipitation-impregnation-evaporation method, the optimal sulfated zirconia catalyst of tetragonal phase was prepared under liquid-solid ratio of 5ml/g, 1 mol/L of H2SO4 and calcination at 650 °C for 3 h. The conversion of the ethyl lactate was 87.8% in 3 h at 85 °C with the catalyst loading 2 wt% and initial molar ratio of water to ethyl lactate 20: 1.
Keywords: Sulfated Zirconia; Hydrolysis; Ethyl Lactate; Catalyst, Precipitation-impregnation Method

Esterification of sludge palm oil using trifluoromethanesulfonic acid for preparation of biodiesel fuel by Adeeb Hayyan; Mohd Ali Hashim; Mohamed Elwathig Saeed Mirghani; Maan Hayyan; Inas Muen AlNashef (1229-1234).
Trifluoromethanesulfonic acid (TFMSA) was used to reduce the high free fatty acids (FFA) content in sludge palm oil (SPO). The FFA content of SPO was converted to fatty acid methyl ester (FAME) via esterification reaction. The treated sludge palm oil was used as a raw material for biodiesel production by transesterification process. Several working parameters were optimized, such as dosage of catalyst, molar ratio, reaction temperature and time. Less than 2% of the FFA content was the targeted value. The results showed that the FFA content of SPO was reduced from 16% to less than 2% using the optimum conditions. The yield of the final product after the alkaline transesterification was 84% with 0.07% FFA and the ester content was 96.7%. All other properties met the international standard specifications for biodiesel quality such as EN 14214 and ASTM D6751.
Keywords: Biodiesel; Esterification; Free Fatty Acids; Transesterification; Sludge Palm Oil; Trifluoromethanesulfonic Acid

The optimal balance of ammonium and nitrite is essential for successful operation of the subsequent anammox process. We conducted a partial nitritation experiment using an upflow air-lift reactor to provide operational parameters for achieving the optimal ratio of ammonium to nitrite, by feeding supernatant of anaerobic digester effluent, highnitrogen containing rejection water. Semi-continuous operation results show that HRT should be set between 15 and 17 hours to achieve the optimum ration of 1.3 of NO2-N/NH4-N. In the UAR, nitritation was the dominant reaction due to high concentration of ammonia and low biodegradable organics. The influent contained low concentrations of hydroxylamine and hydrazine. However, hydrazine increased during partial nitritation by ∼60–130% although there was no potential anammox activity in the reactor. The partial nitritation process successfully provided the ratio of nitrogen species for the anammox reaction, and relived the nitrite restraint on the anammox activity by increasing hydrazine concentration.
Keywords: Hydrazine; Hydroxylamine; Nitrite; Partial Nitritation; Anammox

Removal of nitric oxide and sulfur dioxide from flue gases using a FeII-ethylenediamineteraacetate solution by Hai-Song Zhu; Yan-Peng Mao; Yu Chen; Xiang-Li Long; Wei-Kang Yuan (1241-1247).
The combined absorption of NO and SO2 into the Fe(II)-ethylenediamineteraacetate(EDTA) solution has been realized. Activated carbon is used to catalyze the reduction of FeIII-EDTA to FeII-EDTA to maintain the ability to remove NO with the Fe-EDTA solution. The reductant is the sulfite/bisulfite ions produced by SO2 dissolved into the aqueous solution. Experiments have been performed to determine the effects of activated carbon of coconut shell, pH value, temperature of absorption and regeneration, O2 partial pressure, sulfite/bisulfite and chloride concentration on the combined elimination of NO and SO2 with FeII-EDTA solution coupled with the FeII-EDTA regeneration catalyzed by activated carbon. The experimental results indicate that NO removal efficiency increases with activated carbon mass. There is an optimum pH of 7.5 for this process. The NO removal efficiency increases with the liquid flow rate but it is not necessary to increase the liquid flow rate beyond 25 ml min−1. The NO removal efficiency decreases with the absorption temperature as the temperature is over 35 °C. The Fe2+ regeneration rate may be speeded up with temperature. The NO removal efficiency decreases with O2 partial pressure in the gas streams. The NO removal efficiency is enhanced with the sulfite/bisulfite concentration. Chloride does not affect the NO removal. Ca(OH)2 and MgO slurries have little influence on NO removal. High NO and SO2 removal efficiencies can be maintained at a high level for a long period of time with this heterogeneous catalytic process.
Keywords: FeII-EDTA; Nitric Oxide; Absorption; Activated Carbon; Sulfur Dioxide

Kinetic and equilibrium studies on the biosorption of textile dyes onto Plantago ovata seeds by Manickam Periyaraman Premkumar; Vaidyanathan Vinoth Kumar; Ponnusamy Senthil Kumar; Palanichamy Baskaralingam; Vasanthakumar Sathyaselvabala; Thangaraj Vidhyadevi; Subramanian Sivanesan (1248-1256).
The powdered seeds of Plantago ovata (PSPO) were utilized for the removal of Malachite Green (MG) and Rose Bengal (RB) dyes from aqueous media by batch adsorption. The Fourier transform infra red spectroscopy (FTIR) results showed that both the dyes were adsorbed between the cellulose matrices, and this has been verified from the intensifying and narrowing aromatic C-H bending vibration. The morphology of the dye laden adsorbent was studied by scanning electron microscopy (SEM), which showed that the dyes were adsorbed between the cellulose matrices of the adsorbent. The PSPO was found to be very effective for the removal of MG and RB at pH 7, and equilibrium was attained within 200 min. The kinetic study indicated that the rate limiting step for MG and RB adsorption may be chemisorption and intraparticle diffusion. Adsorption equilibrium data were fitted to Langmuir, Freundlich, Redlich-Peterson and Temkin adsorption isotherms. It is inferred from the equilibrium studies that the adsorption of MG follows the Freundlich isotherm and the adsorption of RB follows the Langmuir isotherm. The maximum monolayer adsorption capacity of the PSPO was found to be 86.23 mg/g for MG and 81.23 mg/g for RB, respectively.
Keywords: Adsorption; Equilibrium; Kinetics; Malachite Green; Plantago ovate ; Rose Bengal

Microwave-assisted urea-modified sorghum biomass for Cr (III) elimination from aqueous solutions by Muhammad Salman; Makshoof Athar; Umar Farooq; Huma Nazir; Anam Noor; Saba Nazir (1257-1264).
The present study concentrated on the use of an agro-waste biodegradable sorghum biomass in its simple and modified forms for the binding of Cr (III) ions. A relatively new method of modification was adopted using urea under microwave irradiation. FTIR analysis showed the presence of oxygen and nitrogen bearing functional groups in unmodified (UMS) and modified (MS) sorghum biomass. The appearance of new bands and shifts in the peaks confirmed the modification. The influence of different process parameters such as the adsorbent dose, solution pH, contact time, agitation speed and initial metal ion concentration was studied thoroughly to evaluate optimum conditions for adsorption. Maximum adsorption for Cr (III) ions occurred at pH 5.0–6.0 using UMS and MS. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models in a non-linear fashion were used to explain the phenomenon. Maximum adsorption capacity was 7.03 and 16.36 mg of Cr (III) per gram of UMS and MS, respectively. Adsorption mechanism was explored by pseudo-first- and pseudo-second-order kinetic models, and it was found that the process followed pseudo-second-order kinetics. Thermodynamic study indicated the process favorability. The study concluded that urea modification under microwave irradiation produces a non-toxic and more effective adsorbent for Cr (III) remediation by inducing new nitrogen bearing functional groups to sorghum biomass.
Keywords: Sorghum; Urea Modification; Non-linear Equilibrium; Surface Area; Thermodynamics

Polyvinylchloride-blend-styrene butadiene rubber based nanocomposite cation exchange membranes were prepared by solution casting technique. Iron-oxide nanoparticles and Ag-nanolayer were simultaneously utilized as filler and surface modifier in membrane fabrication. The effects of Ag-nanolayer film thickness on membrane physicochemical and antibacterial characteristics of nanocomposite PVC-blend-SBR/Iron-oxide nanoparticles were studied. SEM images showed membrane roughness decreasing by Ag nanolayer thickness increasing. Membrane charge density and selectivity declined by Ag nanolayer coating up to 5 nm in membranes and then showed increasing trend by more nanolayer thickness. Ionic flux also showed increasing trend. Membranes showed good ability in E-Coli removal. 20 nm Ag-nanolayer coated membrane showed better performance compared to others.
Keywords: Cation Exchange Membrane; Fabrication/Modification; Ag Nanolayer/Fe-Ni Oxide Nanoparticles; Physico Chemical/Antibacterial Characteristic; Synergy Phenomenon

Kinetic modeling of biodiesel production by mixed immobilized and co-immobilized lipase systems under two pressure conditions by Jong Ho Lee; Sung Bong Kim; Hah Young Yoo; Ja Hyun Lee; Chulhwan Park; Sung Ok Han; Seung Wook Kim (1272-1276).
A kinetic model of mixed immobilized lipase (MIL) and co-immobilized lipase (CIL) systems was investigated by calculating the kinetic parameters based on the reaction mechanisms for lipase-catalyzed transesterification of soybean oil and methyl alcohol. The kinetic parameters were assessed under atmospheric and supercritical fluid conditions. Although the CIL system had a higher initial reaction rate, the effect of substrate inhibition by methanol was higher than that in the MIL system. The initial reaction rate of MIL and CIL decreased under atmospheric conditions as the methanol concentration increased. However, the initial reaction rate of MIL and CIL increased until methanol concentration increased to twice that of oil under the supercritical fluid condition. As a result, the inhibition effect by methanol was identified through a kinetic analysis. A simulated model can be used to predict the optimal conditions for biodiesel production under atmospheric and supercritical conditions.
Keywords: Kinetic Model; Lipase; Enzyme Immobilization; Co-immobilization; Transesterification

Life cycle assessment to evaluate the green house gas emission from oil palm bio-oil based power plant by Nurul Suhada Abdur Rasid; Syed Shatir Asghrar Syed-Hassan; Sharifah Aishah Syed Abdul Kadir; Mohammad Asadullah (1277-1283).
The objective of this study is to assess the green house gas (GHG) emission for the production of bio-oil from oil palm biomass and its utilization for 10 MW power generation by evaluating the life cycle carbon footprint analysis. The life cycle GHG emission assessment includes four main stages, which cover the oil-palm cultivation, palm oil mill operation, biomass transportation and pyrolysis process for the production of bio-oil and its utilization for 10MW power generation. The results obtained suggest that the palm bio-oil has potential as a carbon neutral renewable energy source in the future. More importantly, it has no negative impact on the environment as the amount of CO2 emitted to the atmosphere during combustion of this fuel is lower than that of the CO2 absorbed from the atmosphere during cultivation stage.
Keywords: Life Cycle Analysis; Carbon Footprint; Bio-oil; Pyrolysis; Oil Palm Biomass

Phase behavior of aqueous two-phase systems (ATPS) containing cationic (SDS) and anionic (CTAB) surfactants and its application to theanine extraction was studied. Results indicated the ATPS could form under the certain SDS/CTAB molar ratio; there was a reasonable consistency between the conductivity and the formation region of ATPS, and the viscosity was higher in the formation region of ATPS. Additionally, the phase ratio increased with increase of CATB concentration, and the interfacial film between the top phase and the bottom phase was resilient. Moreover, the theanine extraction with ATPS was realized in the waste liquid of tea polyphenol production (WLTPP), and the partition coefficient of theanine decreased with increase of WLTPP concentration, whereas the extraction rate of theanine increased. The partition coefficient decreased with increasing SDS/CTAB molar ratio, and the extraction rate of theanine increased with increase of SDS/CTAB molar ratio.
Keywords: Phase Behavior; Aqueous Two-phase Systems; Surfactant; Extraction; Theanine

Liquid-liquid equilibrium (LLE) data for the system of (water+formic acid+2-ethyl-1-hexanol) were experimentally determined at T=(298.2, 308.2, 318.2, and 328.2) K and atmospheric pressure. A type-2 LLE was obtained for this ternary system. The influence of temperature on the equilibrium characteristics was found to be smallat the temperatures studied. Distribution coefficients and separation factors were calculated over the immiscibility regions. The experimental tie-line data were correlated using the UNIQUAC model. The values of the interaction parameters between each pair of the components were obtained for this thermodynamic model. The root mean square deviation (RMSD) between the observed and calculated mass fractions was 0.61%.
Keywords: Liquid-liquid Equilibrium; Tie-line Data; Formic Acid; 2-Ethyl-1-hexanol; UNIQUAC Model; Separation Factor; Distribution Coefficient

Study on optimal conditions and adsorption kinetics of copper from water by collodion membrane cross-linked poly-γ-glutamic acid by Xiangting Wu; Aiyin Wang; Xiaojie Zheng; Guoxing Li; Xinjiao Dong; Mingjiang Wu (1295-1300).
Poly-γ-glutamic acid (γ-PGA) is a novel polyamino acid formed through microorganism fermentation and biosynthesis. In the present test, membrane (PGA-C) formation by γ-PGA and collodion was performed by using 0.1% glutaraldehyde as a cross-linking agent. A study was conducted on the PGA-C adsorption of Cu2+, specifically the related adsorption equilibrium and kinetics, desorption and regeneration. The results show that with an initial solution pH=5.5 and at 318 K, the static adsorption isotherm behavior of PGA-C is in compliance with the Langmuir model and is beneficial to the adsorption of the metal. Meanwhile, with the reaction lasting for 30min, adsorption equilibrium was reached with a maximum adsorption capacity up to 7.431 mg/g. The entire reaction process follows the pseudo-second-order kinetics. By using PGA-C, good regeneration results were obtained after adsorption-generation-adsorption cycling with an HCl solution (0.1 mol/L) as regeneration liquid.
Keywords: γ-PGA; Cu2+ ; Collodion; Adsorption Kinetics; Optimal Conditions

Effect of drainage channel dimensions on the performance of wave-plate mist eliminators by Mohammad Hadi Hamedi Estakhrsar; Roohollah Rafee (1301-1311).
We investigated the effects of drainage channel dimensions on droplet removal efficiency and pressure drop of the gas droplet flow in a wave-plate mist eliminator. Droplet dispersion in turbulent gas flows is numerically simulated using eddy interaction model (EIM) and Eulerian-Lagrangian method. Reynolds stress transport model (RSTM) with enhanced wall treatment and shear stress transport (SST) k-ω model are used for simulating the turbulent airflow. Comparison between the numerical simulations and available experimental data shows that eddy lifetime constant (C L ) can affect the results significantly, and by selecting suitable values of the eddy lifetime constant, both turbulence models give reasonable predictions of droplet removal efficiency. Simulations of gas droplet flow in the eliminators with various drainage channel dimensions show that the drainage channel length (L DC ) has a greater effect on droplet removal efficiency than the drainage channel width (W DC ).
Keywords: Numerical Simulation; Wave-plate MistEliminator; Drainage Channel Dimensions; Removal Efficiency; Eddy Lifetime Constant

The enantioselective separation of levocetirizine via a hollow fiber supported liquid membrane was examined. O,O′-dibenzoyl-(2R,3R)-tartaric acid ((−)-DBTA) diluted in 1-decanol was used as a chiral selector extractant. The influence of concentrations of feed and stripping phases, and extractant concentration in the membrane phase, was also investigated. A mathematical model focusing on the extraction side of the liquid membrane system was presented to predict the concentration of levocetirizine at different times. The extraction and recovery of levocetirizine from feed phase were 75.00% and 72.00%, respectively. The mass transfer coefficients at aqueous feed boundary layer (k f ) and the organic liquid membrane phase (k m ) were calculated as 2.41×102 and 1.89×102 cm/s, respectively. The validity of the developed model was evaluated through a comparison with experimental data, and good agreement was obtained.
Keywords: Levocetirizine; (−)-DBTA; Liquid Membrane; Hollow Fiber; Enantioselective Separation

Physicochemical properties between pristine and aged AgNPs for the evaluation of nanotoxicity by Joongso Choi; Ha Nee Umh; Jaehoon Sim; Hyeon Ho Shin; Younghun Kim (1321-1325).
The use of nanomaterials in industrial and commercial applications is growing, and official reports concerning the possible environmental and health effects of nanoparticles are steadily increasing. An understanding of the potential toxicity of nanomaterials is important for creating sustainable and safe nanotechnologies. To test the cytotoxicity of nanomaterials, quantitative and qualitative analyses of raw nanomaterials should be priorities. However, the fundamental properties of raw materials will change compared to those of aged materials in biological media due to the interaction between nanomaterials and media composition. Therefore, the correlation and interdependence between pristine physicochemical properties (PChem) of raw nanomaterials before the toxicity test and aged PChem in biological media were evaluated using modified test guidelines originally suggested by the OECD WPMN (Organization for Economic Cooperation and Development, Working Party on Manufactured Nanomaterials) for peer-reviewed papers concerning silver nanoparticles, during the period of 2005 to 2010. In addition, we investigated whether the suggested analysis tools are applicable to define the PChem of AgNPs with regard to cytotoxicity.
Keywords: Nanomaterials; Physicochemical Properties; Silver Nanoparticles; Toxicity

We studied the hydrodynamics of a gas-liquid-solid semi-fluidized bed relating to packed bed formation and bed pressure drop with irregular homogeneous binary mixtures in a 0.05 m internal diameter Perspex column, with water and air (secondary) as fluidizing medium at constant static bed height of 0.08 m. A homogeneous binary mixture has been taken for easy formation of a semi-fluidized bed. Air is supplied centrally below the bottom grid in radial direction with a special design air sparger after the bed is first fluidized by the liquid. Experimental parameters studied included superficial gas and liquid velocities, average particle size and density and the bed expansion ratio. Empirical and semi-empirical models were developed. The calculated values from predicted models were compared with the experimental values and fairly good agreement was obtained.
Keywords: Gas-liquid-solid Semi-fluidization; Irregular Homogeneous Binary Mixtures; Bed Pressure Drop; Top Packed Bed Formation; Dimensional and Statistical Analyses

Co-immobilization of Candida rugosa and Rhyzopus oryzae lipases and biodiesel production by Jong Ho Lee; Sung Bong Kim; Hah Young Yoo; Ja Hyun Lee; Sung Ok Han; Chulhwan Park; Seung Wook Kim (1335-1338).
Candida rugosa lipase and Ryzopus oryzae lipase were simultaneously immobilized on silica gel following enzyme pretreatment. The factors affecting the co-immobilization process, such as reaction time and enzyme ratio, were investigated. Biodiesel was then produced by using the co-immobilized enzyme matrix. A batch system was employed with stepwise methanol feeding, and the continuous process involved a packed-bed reactor. Under optimal immobilization conditions, the activity was approximately 16,000 U/g·matrix. When co-immobilized enzyme was used with optimized stepwise methanol feeding, conversion of biodiesel reached about 99% at 3 h and was maintained at a level of over 90% for about 30 reuses.
Keywords: Biodiesel; Enzymatic Process; Co-immobilization; Lipase

Production of furfural and cellulose from barley straw using acidified zinc chloride by Tae Hoon Kim; Young Jae Jeon; Kyeong Keun Oh; Tae Hyun Kim (1339-1346).
An effective fractionation process was sought to produce furfural and cellulose-rich solid from barley straw. Acidified zinc chloride (ZnCl2) was used as a catalyst in order to achieve hemicellulose recovery in the form of liquid hydrolysate. This fractionation process recovered 55.6% of XM (xylan and mannan) in the untreated barley straw under best reaction conditions (10% acidified ZnCl2, 150 °C, 30 min, and 1/15 of S/L ratio). Hemicellulose hydrolysate was converted into furfural using hydrothermal reaction without additional catalyst. The furfural conversion yield at various reaction temperatures (150, 180, and 210 °C) was in the range of 59.9–64.5%. The two parameters that affected performance in fractionation processing were reaction temperature and time. Reaction severity (Log R0) was used to evaluate the effects of two processing parameters on hemicellulose recovery. In the ZnCl2 treatment, the data indicated that the proper range of severity was 2.95–3.07 because the XM recovery yield decreased as the reaction condition became more severe beyond that point.
Keywords: Barley Straw; Fractionation; Severity Factor; ZnCl2 ; Hemicellulose