International Journal of Chemical Engineering The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. A Novel Biosorbent, Water-Hyacinth, Uptaking Methylene Blue from Aqueous Solution: Kinetics and Equilibrium Studies Tue, 15 Apr 2014 14:08:02 +0000 The adsorption of MB dye from aqueous solution onto HCl acid treated water-hyacinth (H-WH) was investigated by carried out batch sorption experiments. The effect of process parameters such as pH, adsorbent dosage, concentrations and contact time, and ionic strength were studied. Adsorption of MB onto H-WH was found highly pH dependent and ionic strength shows negative impact on MB removal. To predict the biosorption isotherms and to determine the characteristic parameters for process design, Langmuir, Freundlich, Temkin, and Halsey isotherms models were utilized to equilibrium data. The adsorption kinetics was tested for pseudo-first-order (PFO), pseudo-second-order (PSO), intraparticle diffusion (IPD), and Bangham’s kinetic models. The Langmuir isotherm model showed the goodness-of-fit among the tested models for equilibrium adsorption of MB over H-WH and indicated the maximum adsorption capacity as 63.30 mg/g. Higher coefficient of determination () and better agreement between the qe (experimental) and (calculated) values predicted that PSO kinetic model showed the goodness-of-fit for kinetic data along with rate constant , , and , respectively, for the studied concentration range. At the initial stage of adsorption, the overall rate of dye uptake was found to be dominated by external mass transfer, and afterwards, it is controlled by IPD mechanism. Md. Nasir Uddin, Md. Tariqul Islam, and Sreejon Das Copyright © 2014 Md. Nasir Uddin et al. All rights reserved. The Experimental and Simulation Study of Selective Catalytic Reduction System in a Single Cylinder Diesel Engine Using NH3 as a Reducing Agent Tue, 15 Apr 2014 08:17:56 +0000 Selective catalytic reduction (SCR) technology has been widely used in automotive applications in order to meet the stringent limits on emission standards. The maximum NO conversion efficiency of an SCR depends on temperature and mass flow rate of an exhaust gas. In order to assess the suitability of Cordierite/Pt catalyst for low temperature application, an experimental work is carried out using single cylinder diesel engine for different load conditions by varying ammonia induction rate from 0.2 kg/hr to 0.8 kg/hr. The simulation is carried out using AVL FIRE for the validation of experimental results. From the study, it has been found that for 0.6 kg/hr ammonia induction rate the maximum conversion is achieved, whereas, for 0.8 kg/hr, conversion is reduced due to desorption of ammonia. Also it has been found that, at 75% of load, for all mass flow rates of ammonia the conversion was drastically reduced due to higher exhaust gas temperature and higher emission of unburnt hydrocarbons. More than 55% of NO conversion was achieved using Cordierite/Pt catalyst at a temperature of 320°C. Manoj Kumar Athrashalil Phaily, Sreekumar Jayachandra Sreekala, and Padmanabha Mohanan Copyright © 2014 Manoj Kumar Athrashalil Phaily et al. All rights reserved. Corrosion Inhibition Effect of Carbon Steel in Sea Water by L-Arginine-Zn2+ System Tue, 15 Apr 2014 07:16:05 +0000 The inhibition efficiency of L-Arginine-Zn2+ system in controlling corrosion of carbon steel in sea water has been evaluated by the weight-loss method. The formulation consisting of 250 ppm of L-Arginine and 25 ppm of Zn2+ has 91% IE. A synergistic effect exists between L-Arginine and Zn2+. Polarization study reveals that the L-Arginine-Zn2+ system functions as an anodic inhibitor and the formulation controls the anodic reaction predominantly. AC impedance spectra reveal that protective film is formed on the metal surface. Cyclic voltammetry study reveals that the protective film is more compact and stable even in a 3.5% NaCl environment. The nature of the protective film on a metal surface has been analyzed by FTIR, SEM, and AFM analysis. S. Gowri, J. Sathiyabama, and S. Rajendran Copyright © 2014 S. Gowri et al. All rights reserved. Neutralization of Soybean Oil Deodorizer Distillate for Vitamin Supplement Production Tue, 01 Apr 2014 08:10:12 +0000 Soybean oil deodorizer distillate (SODD), a byproduct of the soybean oil refining process, is a complex mixture of compounds, such as free fatty acids (FFA), hydrocarbons, and sterols, such as tocopherols, a class of major natural antioxidants with vitamin E activity. As the utilization of SODD for tocopherol extraction is shown to be not economically viable, SODD in the semirefined form (neutral) is an interesting alternative to animal and possibly human diet enrichment. This study aimed to evaluate the SODD neutralization process varying the alkali (Na2CO3) concentration, temperature, and homogenization time. The optimal conditions for the neutralizing process, in order to obtain the greatest reduction in FFA content, the lowest leaching of tocopherols, and the greatest yield, were the following: Na2CO2 concentration of 4.34 N, temperature of 45.8°C, and homogenization time of 3 min 20 s. The FFA content was reduced from 53.4% to 6.1% after the initial neutralization, thus requiring a second neutralization step. The final FFA content was of 1.8% and total tocopherol (TT) accounted for about 11% of SODD. Cibelem Iribarrem Benites, Bruno Colling Klein, and Soely Maria Pissini Machado Reis Copyright © 2014 Cibelem Iribarrem Benites et al. All rights reserved. Catalytic Cascade Dehydration-Etherification of Fructose into 5-Ethoxymethylfurfural with SO3H-Functionalized Polymers Mon, 31 Mar 2014 07:52:28 +0000 A series of SO3H-functionalized polymers were prepared and employed as heterogeneous catalysts for one-pot transformation of fructose into 5-ethoxymethylfurfural (EMF) that is considered to be one of potential liquid biofuels. A high EMF yield of 72.8% could be obtained at 110°C for 10 h, and the polymeric acid catalysts could be recycled for five times without significant loss of catalytic performance. Hu Li, Qiuyun Zhang, and Song Yang Copyright © 2014 Hu Li et al. All rights reserved. Catalytic Transformation of Fructose and Sucrose to HMF with Proline-Derived Ionic Liquids under Mild Conditions Thu, 27 Mar 2014 11:24:46 +0000 L-Proline derived ionic liquids (ILs) used as both solvent and catalyst were efficient for transformation of fructose and sucrose to 5-hydroxymethylfurfural (HMF) in the presence of water. Response surface methodology (RSM) was employed to optimize fructose dehydration process, and a maximum HMF yield of 73.6% could be obtained at 90°C after 50 min. The recycling of the IL exhibited an almost constant activity during five successive trials, and a possible reaction mechanism for the dehydration of fructose to HMF was proposed. Hu Li and Song Yang Copyright © 2014 Hu Li and Song Yang. All rights reserved. Analytical Simulation of Flow and Heat Transfer of Two-Phase Nanofluid (Stratified Flow Regime) Tue, 25 Mar 2014 12:34:33 +0000 Nanofluids have evoked immense interest from researchers all around the globe due to their numerous potential benefits and applications in important fields such as cooling electronic parts, cooling car engines and nuclear reactors. An analytical study of fluid flow of in-tube stratified regime of two-phase nanofluid has been carried out for CuO, Al2O2, TiO3, and Au as applied nanoparticles in water as the base liquid. Liquid film thickness, convective heat transfer coefficient, and dryout length have been calculated. Among the considered nano particles, Al2O3 and TiO2 because of providing more amounts of heat transfer along with longer lengths of dryout found as the most appropriate nanoparticles to achieve cooling objectives. Mohammad Abbasi and Zahra Baniamerian Copyright © 2014 Mohammad Abbasi and Zahra Baniamerian. All rights reserved. Adsorption Studies for Arsenic Removal Using Activated Moringa oleifera Wed, 05 Mar 2014 15:56:23 +0000 A new low cost adsorbent, activated Moringa oleifera has been developed for aqueous arsenic removal. Batch experiments were revealed that As removal was up to 71.3% using activated Moringa oleifera. Kinetics studies revealed that Langmuir isotherm was followed with a better correlation than the Freundlich isotherm. The thermodynamic parameters such as , , and were computed from the experimental data. These values show that the adsorption is endothermic and spontaneous in nature. Thus, this recently developed cost-effective novel biosorbent, activated Moringa oleifera can be used as household level to mitigate the arsenic problem. T. Sumathi and G. Alagumuthu Copyright © 2014 T. Sumathi and G. Alagumuthu. All rights reserved. Molecular Dynamics Study of Hydrogen on Alkali-Earth Metal Cations Exchanged X Zeolites Sun, 23 Feb 2014 10:56:29 +0000 The self-diffusion of hydrogen in Ca2+-, Mg2+- and Ba2+-exchanged X zeolites (Mg46X, Ca46X, and Ba46X) has been studied by molecular dynamics (MD) simulations for various temperatures and loadings. The results indicate that in the temperature range of 77–298 K and the loading range of 1–80 molecules/cell, the self-diffusion coefficients are found to range from  m2·s−1 to  m2·s−1 which are in good agreement with the experimental values from the quasielastic neutron scattering (QENS) and pulse field gradients nuclear magnetic resonance (PFG NMR) measurements. The self-diffusion coefficients decrease with loading due to packing of sorbate-sorbate molecules which causes frequent collusion among hydrogen molecules in pores and increases with increasing temperature because increasing the kinetic energy of the gas molecules enlarges the mean free path of gas molecule. The mechanism of diffusion of hydrogen molecules in these zeolites is transition diffusion. Knudsen diffusion occurs at low loading and the molecular bulk diffusion occurs at higher loading. For given temperature and loading, the self-diffusion coefficients decrease in the order , due to the different sizes and locations of the divalent cations. Moreover, the effect of concentration of molecular hydrogen on self-diffusion coefficient also is analyzed using radial distribution function (RDF). Du Xiaoming Copyright © 2014 Du Xiaoming. All rights reserved. Nanocasting Process to Pore-Expanded Ordered Mesoporous Carbons with 2D Hexagonal Mesostructure Sun, 23 Feb 2014 09:16:51 +0000 Pore-expanded ordered mesoporous carbons with 2D hexagonal mesostructure were synthesized by a simple nanocasting process. We adopted sucrose as carbon precursors, mesoporous silica materials SBA-15 as the hard templates, and hexane as micelle swelling agents. The pore size distribution of OMCs was narrow and centered at 5.4 nm, which is larger than the upper limit of pore diameters typically reported for CMK-3. The BET surface area and mesopore volume of PE-CMK-3 can reach to 1213.47 /g and 1.56 /g, respectively, indicating that choosing large pore size materials as template is good for preparation of high performance of OMCs. Chongwen Jiang, Keyuan Zhou, and Xin Zhong Copyright © 2014 Chongwen Jiang et al. All rights reserved. Some Investigations on Protease Enzyme Production Kinetics Using Bacillus licheniformis BBRC 100053 and Effects of Inhibitors on Protease Activity Wed, 19 Feb 2014 14:12:31 +0000 Due to great commercial application of protease, it is necessary to study kinetic characterization of this enzyme in order to improve design of enzymatic reactors. In this study, mathematical modeling of protease enzyme production kinetics which is derived from Bacillus licheniformis BBRC 100053 was studied (at 37°C, pH 10 after 73 h in stationary phase, and 150 rpm). The aim of the present paper was to determine the best kinetic model and kinetic parameters for production of protease and calculating (inhibition constant) of different inhibitors to find the most effective one. The kinetic parameters (Michaelis-Menten constant) and (maximum rate) were calculated 0.626 mM and 0.0523 mM/min. According to the experimental results, using DFP (diisopropyl fluorophosphate) and PMSF (phenylmethanesulfonyl fluoride) as inhibitors almost 50% of the enzyme activity could be inhibited when their concentrations were 0.525 and 0.541 mM, respectively. for DFP and PMSF were 0.46 and 0.56 mM, respectively. Kinetic analysis showed that the Lineweaver-Burk model was the best fitting model for protease production kinetics DFP was more effective than PMSF and both of them should be covered in the group of noncompetitive inhibitors. Zahra Ghobadi Nejad, Soheila Yaghmaei, Nazanin Moghadam, and Bahareh Sadeghein Copyright © 2014 Zahra Ghobadi Nejad et al. All rights reserved. Preparation and Characterization of Jute Cellulose Crystals-Reinforced Poly(L-lactic acid) Biocomposite for Biomedical Applications Sun, 16 Feb 2014 09:43:49 +0000 Crystalline cellulose was extracted from jute by hydrolysis with 40% H2SO4 to get mixture of micro/nanocrystals. Scanning electron microscope (SEM) showed the microcrystalline structure of cellulose and XRD indicated the Iβ polymorph of cellulose. Biodegradable composites were prepared using crystalline cellulose (CC) of jute as the reinforcement (3–15%) and poly(lactic acid) (PLA) as a matrix by extrusion and hot press method. CC was cellulose derived from mercerized and bleached jute fiber by acid hydrolysis to remove the amorphous regions. FT-IR studies showed hydrogen bonding between the CC and the PLA matrix. The X-ray diffraction (XRD) and differential scanning calorimetry (DSC) studies showed that the percentage crystallinity of PLA in composites was found to be higher than that of neat PLA as a result of the nucleating ability of the crystalline cellulose. Furthermore, Vicker hardness and yield strength were found to increase with increasing cellulose content in the composite. The SEM images of the fracture surfaces of the composites were indicative of poor adhesion between the CC and the PLA matrix. The composite with 15% CC showed antibacterial effect though pure films but had no antimicrobial effect; on the other hand its cytotoxicity in biological medium was found to be medium which might be suitable for its potential biomedical applications. Mohammed Mizanur Rahman, Sanjida Afrin, Papia Haque, Md. Minhajul Islam, Mohammed Shahidul Islam, and Md. Abdul Gafur Copyright © 2014 Mohammed Mizanur Rahman et al. All rights reserved. Development of Activated Carbon from Cotton Fibre Waste as Potential Mercury Adsorbent: Kinetic and Equilibrium Studies Wed, 05 Feb 2014 11:11:17 +0000 The study attempted to develop the activated carbon of cotton fibre (ACCF) from cotton waste as a high Hg2+ adsorbent media and characterize physicochemical properties using scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) and Hg2+ adsorption kinetic by batch adsorption study with the function of contact time, solution pH, dosages of ACCF, and Hg concentration. The SEM-EDS study revealed that ACCF is composed of carbon (95.1%) and phosphorus pentoxide (4.9%). Obtained results of adsorption kinetics showed that 15 min of contact time is required to achieve the equilibrium state and wide range of pH (4.08–7) is favourable for maximum Hg adsorption. The Hg2+ adsorption capacity showed a decreasing trend with increasing dose of ACCF, whereas a reverse response of adsorption capacity was pronounced with increasing Hg concentration. The data was well described by Freundlich isotherm model and determined the high Hg2+ adsorption capacity of ACCF (169.2 mg/g). To our knowledge, the application of ACCF in removing Hg2+ is the first study. High Hg2+ adsorption capacity, economic feasibility, availability of cotton fibre waste, and simple preparation method concluded that it could be used as a novel low-cost and environmentally sound adsorbent media for removing high rate of Hg2+ from aqueous phase. Jatindra N. Bhakta, Piyali Bhakta Majumdar, and Yukihiro Munekage Copyright © 2014 Jatindra N. Bhakta et al. All rights reserved. Product Characterization and Kinetics of Biomass Pyrolysis in a Three-Zone Free-Fall Reactor Tue, 04 Feb 2014 12:38:03 +0000 Pyrolysis of biomass including palm shell, palm kernel, and cassava pulp residue was studied in a laboratory free-fall reactor with three separated hot zones. The effects of pyrolysis temperature (250–1050°C) and particle size (0.18–1.55 mm) on the distribution and properties of pyrolysis products were investigated. A higher pyrolysis temperature and smaller particle size increased the gas yield but decreased the char yield. Cassava pulp residue gave more volatiles and less char than those of palm kernel and palm shell. The derived solid product (char) gave a high calorific value of 29.87 MJ/kg and a reasonably high BET surface area of 200 m2/g. The biooil from palm shell is less attractive to use as a direct fuel, due to its high water contents, low calorific value, and high acidity. On gas composition, carbon monoxide was the dominant component in the gas product. A pyrolysis model for biomass pyrolysis in the free-fall reactor was developed, based on solving the proposed two-parallel reactions kinetic model and equations of particle motion, which gave excellent prediction of char yields for all biomass precursors under all pyrolysis conditions studied. Natthaya Punsuwan and Chaiyot Tangsathitkulchai Copyright © 2014 Natthaya Punsuwan and Chaiyot Tangsathitkulchai. All rights reserved. Optimization of Process Parameters by Statistical Experimental Designs for the Production of Naringinase Enzyme by Marine Fungi Tue, 04 Feb 2014 06:51:54 +0000 Naringinase has attracted a great deal of attention in recent years due to its hydrolytic activities which include the production of rhamnose and prunin and debittering of citrus fruit juices. Screening of fifteen marine-derived fungi, locally isolated from Ismalia, Egypt, for naringinase enzyme production, indicated that Aspergillus niger was the most promising. In solid state fermentation (SSF) of the agroindustrial waste, orange rind was used as a substrate containing naringin. Sequential optimization strategy, based on statistical experimental designs, was employed to enhance the production of the debittering naringinase enzyme. Effects of 19 variables were examined for their significance on naringinase production using Plackett-Burman factorial design. Significant parameters were further investigated using Taguchi’s (L16 ) orthogonal array design. Based on statistical analysis (ANOVA), the optimal combinations of the major constituents of media for maximal naringinase production were evaluated as follows: 15 g orange rind waste, 30 mL moisture content, 1% grape fruit, 1% NaNO3, 0.5% KH2PO4, 5 mM MgSO4, 5 mM FeSO4, and the initial pH 7.5. The activity obtained was more than 3.14-fold the basal production medium. Abeer Nasr Shehata and Abeer Abas Abd El Aty Copyright © 2014 Abeer Nasr Shehata and Abeer Abas Abd El Aty. All rights reserved. Studies on Biosorption of Methylene Blue from Aqueous Solutions by Powdered Palm Tree Flower (Borassus flabellifer) Sun, 02 Feb 2014 12:32:30 +0000 Biosorption experiments were carried out for the removal of methylene blue (MB) using palm tree male flower (PTMF) as the biosorbent at various pH, temperature, biosorbent, and adsorbate concentration. The optimum pH was found to be 6.0. The kinetic data were fitted in pseudofirst-order and second-order models. The equilibrium data were well-fitted in Langmuir isotherm and the maximum equilibrium capacities of the biosorbent were found to be 143.6, 153,9, 157.3 mg/g at 303, 313, and 323 K, respectively. Thermodynamic data for the adsorption system indicated spontaneous and endothermic process. The enthalpy and entropy values for adsorption were obtained as 15.06 KJ/mol and 0.129 KJ/mol K, respectively, in the temperature range of 303–323 K. A mathematical model for MB transported by molecular diffusion from the bulk of the solution to the surface of PTMF was derived and the values of liquid phase diffusivity and external mass transfer coefficient were estimated. M. Srinivas Kini, M. B. Saidutta, and V. Ramachandra Murty Copyright © 2014 M. Srinivas Kini et al. All rights reserved. Numerical Simulation and Analysis of CO2 Removal in a Polypropylene Hollow Fiber Membrane Contactor Thu, 30 Jan 2014 17:47:51 +0000 This present study shows a comprehensive 2D numerical model for removal of CO2 in a polypropylene (PP) hollow fiber membrane contactor (HFMC) using the computational fluid dynamics (CFD) method. Monoethanolamine (MEA) solution was used as the liquid absorbent in a nonwetting mode. The simulation results represented that higher liquid velocity and concentration and lower gas velocity and concentration led to higher percent of CO2 removal. The most proper parameters for CO2 removal were less than 1 mol m−3 gas concentration and 0.2 m s−1 gas flow rate, and for MEA the values were above 8 mol m−3 concentration and approximately 1 m s−1 liquid velocity. Furthermore, the model was validated with the experiment results. Therefore, the modeling results provided references to the selection of absorbents and operation parameters in the experimental study and pilot-scale applications. Zhien Zhang, Yunfei Yan, Li Zhang, and Shunxiang Ju Copyright © 2014 Zhien Zhang et al. All rights reserved. Kinetics of Thermal Degradation of Recycled Polyvinyl Chloride Resin Thu, 30 Jan 2014 10:27:43 +0000 The goal of this study is to find the effect of time and temperature on the thermal degradation of recycled polyvinyl chloride (PVC) resin. The isothermal rate of reaction of recycled PVC resin was investigated at the following temperatures to: 100, 110, 120, 130, and 140°C at period of times ranging from 10 to 50 min. The result shows that the rate of reaction of recycled PVC increases with increasing temperatures. The reaction rate constant for temperatures ranging from 100 to 140°C was doubled from 0.028–0.056 mol·L−1·S−1. The process was found to be zero order reaction at all range of temperatures 100–140°C. The activation energy of the thermal weight loss was calculated at different temperatures . The average enthalpy and entropy of reaction at temperature of 298°K were determined. I. M. Alwaan Copyright © 2014 I. M. Alwaan. All rights reserved. CFD Simulation of the Discharge Flow from Standard Rushton Impeller Wed, 29 Jan 2014 00:00:00 +0000 The radial discharge jet from the standard Rushton turbine was investigated by the CFD calculations and compared with results from the Laser Doppler Anemometry (LDA) measurements. The Large Eddy Simulation (LES) approach was employed with Sliding Mesh (SM) model of the impeller motion. The obtained velocity profiles of the mean ensemble-averaged velocity and r.m.s. values of the fluctuating velocity were compared in several distances from the impeller blades. The calculated values of mean ensemble-averaged velocities are rather in good agreement with the measured ones as well as the derived power number from calculations. However, the values of fluctuating velocities are obviously lower from LES calculations than from LDA measurements. Bohuš Kysela, Jiří Konfršt, Ivan Fořt, and Zdeněk Chára Copyright © 2014 Bohuš Kysela et al. All rights reserved. Long-Term Prediction of Biological Wastewater Treatment Process Behavior via Wiener-Laguerre Network Model Wed, 22 Jan 2014 09:48:23 +0000 A Wiener-Laguerre model with artificial neural network (ANN) as its nonlinear static part was employed to describe the dynamic behavior of a sequencing batch reactor (SBR) used for the treatment of dye-containing wastewater. The model was developed based on the experimental data obtained from the treatment of an effluent containing a reactive textile azo dye, Cibacron yellow FN-2R, by Sphingomonas paucimobilis bacterium. The influent COD, MLVSS, and reaction time were selected as the process inputs and the effluent COD and BOD as the process outputs. The best possible result for the discrete pole parameter was . In order to adjust the parameters of ANN, the Levenberg-Marquardt (LM) algorithm was employed. The results predicted by the model were compared to the experimental data and showed a high correlation with and a low mean absolute error (MAE). The results from this study reveal that the developed model is accurate and efficacious in predicting COD and BOD parameters of the dye-containing wastewater treated by SBR. The proposed modeling approach can be applied to other industrial wastewater treatment systems to predict effluent characteristics. Yasaman Sanayei, Naz Chaibakhsh, Ali Chaibakhsh, Ali Reza Pendashteh, Norli Ismail, and Tjoon Tow Teng Copyright © 2014 Yasaman Sanayei et al. All rights reserved. Continuous Catalyst-Free Esterification of Oleic Acid in Compressed Ethanol Sun, 19 Jan 2014 06:55:34 +0000 The esterification of oleic acid in a continuous catalyst-free process using compressed ethanol was investigated in the present study. Experiments were performed in a tubular reactor and variables investigated were temperature, pressure, and oleic acid to ethanol molar ratio for different residence time. Results demonstrated that temperature, in the range of 473 K to 573 K, and pressure had a positive effect on fatty acid ethyl esters (FAEE) production. In the experimental range investigated, high conversions can be obtained at low ethanol concentrations in the reaction medium and it was observed that oleic acid to ethanol molar ratios greater than 1 : 6 show no significant increase in conversion. Nonnegligible reaction conversions (>90%) were achieved at 573 K, 20 MPa, oleic acid to ethanol molar ratio of 1 : 6, and 20 minutes of residence time. Ana Carolina de Araujo Abdala, Vitor Augusto dos Santos Garcia, Caroline Portilho Trentini, Lúcio Cardozo Filho, Edson Antonio da Silva, and Camila da Silva Copyright © 2014 Ana Carolina de Araujo Abdala et al. All rights reserved. Experimental Investigation of the Interaction between Rising Bubbles and Swirling Water Flow Thu, 16 Jan 2014 08:01:32 +0000 This study experimentally investigates the interaction between rising bubbles and swirling water flow imposed around the central (vertical) axis of a bubble plume in a cylindrical water tank. Small air bubbles are successively released from the bottom of the tank to generate a bubble plume, and a stirring disc at the bottom of the tank is rotated to impose a swirling water flow around the central axis of the bubble plume. The bubbles disperse further with the increasing rotational speed of the stirring disc. Some bubbles shift toward the central axis of the swirling flow when is high. The nondimensional swirling velocity of water reduces with increasing bubble flow rate when is lower than a certain value. However, it is less affected by the bubbles when is higher. The precessional amplitude for the upper end of the vortex core increases due to the presence of the bubbles. With increasing , the nondimensional precessional velocity decreases, and the bubble effect also reduces. Tomomi Uchiyama and Shunsuke Sasaki Copyright © 2014 Tomomi Uchiyama and Shunsuke Sasaki. All rights reserved. Sonochemical Synthesis of Cobalt Ferrite Nanoparticles Mon, 23 Dec 2013 11:54:45 +0000 Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides) that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques. Partha P. Goswami, Hanif A. Choudhury, Sankar Chakma, and Vijayanand S. Moholkar Copyright © 2013 Partha P. Goswami et al. All rights reserved. Toward Green Chemical Engineering Tue, 19 Nov 2013 16:59:18 +0000 Antonia Pérez de los Ríos, Francisco José Hernández Fernández, María Gómez Gómez, Said Galai, and Pascual Pérez Ballesta Copyright © 2013 Antonia Pérez de los Ríos et al. All rights reserved. Effect of Additives and Process Variables on Enzymatic Hydrolysis of Macauba Kernel Oil (Acrocomia aculeata) Thu, 31 Oct 2013 18:49:42 +0000 This work investigates the production of free fatty acids (FFAs) from the enzymatic hydrolysis of macauba kernel oil. Experiments evaluate the effect of different enzymes and the addition of salts, surfactants, and solvents to the reaction medium, as well as the effect of process variables. Results showed that FFA yields obtained for use of Lipozyme RM IM were higher than those obtained from Lipozyme TL IM and Lipozyme 435. The addition of salts and surfactants did not promote increased production of FFAs, while adding n-hexane and heptane to the reaction medium led to an increased reaction rate. It can be observed for the results that the temperature, water :  oil mass ratio, and enzyme percentage had positive effects on the FFA yield in the range of 35°C to 55°C, 1 :  20 to 1 :  2, and 1 to 15%, respectively, and that, from these limits, increases in these variables did not cause significant increase in FFA yields. The addition of buffer promoted an increase in yield FFAs, as well as the pH of the buffer, and it was reported that an agitation of 400 rpm resulted in the highest yields in the investigated range. Djéssica Tatiane Raspe, Lúcio Cardozo Filho, and Camila da Silva Copyright © 2013 Djéssica Tatiane Raspe et al. All rights reserved. Chemical Pretreatment Methods for the Production of Cellulosic Ethanol: Technologies and Innovations Thu, 10 Oct 2013 14:40:14 +0000 Pretreatment of lignocellulose has received considerable research globally due to its influence on the technical, economic and environmental sustainability of cellulosic ethanol production. Some of the most promising pretreatment methods require the application of chemicals such as acids, alkali, salts, oxidants, and solvents. Thus, advances in research have enabled the development and integration of chemical-based pretreatment into proprietary ethanol production technologies in several pilot and demonstration plants globally, with potential to scale-up to commercial levels. This paper reviews known and emerging chemical pretreatment methods, highlighting recent findings and process innovations developed to offset inherent challenges via a range of interventions, notably, the combination of chemical pretreatment with other methods to improve carbohydrate preservation, reduce formation of degradation products, achieve high sugar yields at mild reaction conditions, reduce solvent loads and enzyme dose, reduce waste generation, and improve recovery of biomass components in pure forms. The use of chemicals such as ionic liquids, NMMO, and sulphite are promising once challenges in solvent recovery are overcome. For developing countries, alkali-based methods are relatively easy to deploy in decentralized, low-tech systems owing to advantages such as the requirement of simple reactors and the ease of operation. Edem Cudjoe Bensah and Moses Mensah Copyright © 2013 Edem Cudjoe Bensah and Moses Mensah. All rights reserved. Examination of Perovskite Structure CaMnO3-δ with MgO Addition as Oxygen Carrier for Chemical Looping with Oxygen Uncoupling Using Methane and Syngas Mon, 30 Sep 2013 10:35:50 +0000 Perovskite structure oxygen carriers with the general formula CaMnxMg1-xO3-δ were spray-dried and examined in a batch fluidized bed reactor. The CLOU behavior, reactivity towards methane, and syngas were investigated at temperature 900°C to 1050°C. All particles showed CLOU behavior at these temperatures. For experiments with methane, a bed mass corresponding to 57 kg/MW was used in the reactor, and the average CH4 to CO2 conversion was above 97% for most materials. Full syngas conversion was achieved for all materials utilizing a bed mass corresponding to 178 kg/MW. SEM/EDX and XRD confirmed the presence of MgO in the fresh and used samples, indicating that the Mg cation is not incorporated into the perovskite structure and the active compound is likely pure CaMnO3-δ. The very high reactivity with fuel gases, comparable to that of baseline oxygen carriers of NiO, makes these perovskite particles highly interesting for commercial CLC application. Contrary to NiO, oxygen carriers based on CaMnO3-δ have no thermodynamic limitations for methane oxidation to CO2 and H2O, not to mention that the materials are environmentally friendly and can utilize much cheaper raw materials for production. The physical properties, crystalline phases, and morphology information were also determined in this work. Dazheng Jing, Tobias Mattisson, Henrik Leion, Magnus Rydén, and Anders Lyngfelt Copyright © 2013 Dazheng Jing et al. All rights reserved. Chemical Reaction Effect on Transient Free Convective Flow past an Infinite Moving Vertical Cylinder Sat, 28 Sep 2013 16:16:47 +0000 An analysis is performed to study the heat and mass transfer on the flow past an infinite moving vertical cylinder, in the presence of first-order chemical reaction. The closed-form solutions of the dimensionless governing partial differential equations are obtained in terms of Bessel's functions and modified Bessel's functions by the Laplace transform technique. The transient velocity profiles, temperature profiles, and concentration profiles are studied for various sets of physical parameters, namely, the chemical reaction parameter, Prandtl number, Schmidt number, thermal Grashof number, mass Grashof number, and time. The skin friction, Nusselt number, and Sherwood number are also obtained and presented in graphs. It is observed that in presence of as well as increase in chemical reaction the flow velocity decreases. Also, in presence of destructive chemical reaction the concentration profile and Sherwood number tend to the steady state at large time. Ashish Paul and Rudra Kanta Deka Copyright © 2013 Ashish Paul and Rudra Kanta Deka. All rights reserved. Carbonic Anhydrase: An Efficient Enzyme with Possible Global Implications Tue, 24 Sep 2013 10:22:01 +0000 As the global atmospheric emissions of carbon dioxide (CO2) and other greenhouse gases continue to grow to record-setting levels, so do the demands for an efficient and inexpensive carbon sequestration system. Concurrently, the first-world dependence on crude oil and natural gas provokes concerns for long-term availability and emphasizes the need for alternative fuel sources. At the forefront of both of these research areas are a family of enzymes known as the carbonic anhydrases (CAs), which reversibly catalyze the hydration of CO2 into bicarbonate. CAs are among the fastest enzymes known, which have a maximum catalytic efficiency approaching the diffusion limit of 108 M−1s−1. As such, CAs are being utilized in various industrial and research settings to help lower CO2 atmospheric emissions and promote biofuel production. This review will highlight some of the recent accomplishments in these areas along with a discussion on their current limitations. Christopher D. Boone, Sonika Gill, Andrew Habibzadegan, and Robert McKenna Copyright © 2013 Christopher D. Boone et al. All rights reserved. Life Cycle Costs and Life Cycle Assessment for the Harvesting, Conversion, and the Use of Switchgrass to Produce Electricity Mon, 23 Sep 2013 15:56:34 +0000 This paper considers both LCA and LCC of the pyrolysis of switchgrass to use as an energy source in a conventional power plant. The process consists of cultivation, harvesting, transportation, storage, pyrolysis, transportation, and power generation. Here pyrolysis oil is converted to electric power through cocombustion in conventional fossil fuel power plants. Several scenarios are conducted to determine the effect of selected design variables on the production of pyrolysis oil and type of conventional power plants. The set of design variables consist of land fraction, land shape, the distance needed to transport switchgrass to the pyrolysis plant, the distance needed to transport pyrolysis oil to electric generation plant, and the pyrolysis plant capacity. Using an average agriculture land fraction of the United States at 0.4, the estimated cost of electricity from pyrolysis of 5000 tons of switchgrass is the lowest at $0.12 per kwh. Using natural gas turbine power plant for electricity generation, the price of electricity can go as low as 7.70 cent/kwh. The main advantage in using a pyrolysis plant is the negative GHG emission from the process which can define that the process is environmentally friendly. Nuttapol Lerkkasemsan and Luke E. K. Achenie Copyright © 2013 Nuttapol Lerkkasemsan and Luke E. K. Achenie. All rights reserved.