ISRN Chemical Engineering The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Arsenate Removal from Water by Simultaneous Green Tea Nano-Zerovalent Iron and Ultrasonic Wave Wed, 09 Apr 2014 11:23:37 +0000 Nano-zerovalent iron (NZVI) was synthesized using green tea (GT) extract and it was used as an adsorbent in arsenate removal from water. FESEM, PSD, and XRD employed in the examination of particles and their characterizations. Results showed that the particles were spherical lumped together in a texture structure with sizes ranging from 20 to 70 nanometers. All experiments were accomplished in a batch mode. Adsorption isotherm, adsorption kinetics, and the effects of pH, GT-NZVI dosage, and ultrasonic wave power on arsenate separation capabilities were explored. The results suggested that the arsenate removal efficiency enhanced with increasing GT-NZVI dosage. Increase in pH from 3 to approximately 6 leads to increase in the removal efficiency; however, increasing the pH further decreased the removal efficiency. The effect of ultrasonic power on As(V) removal was dependent on pH and NZVI dosages. The positive effect was more pronounced at low adsorbent dosages and acidic solution in which the As(V) removal efficiency improved with increasing ultrasonic power. However, in highly alkali solutions As(V) removal efficiency reduced with increasing ultrasonic power. The adsorption kinetics followed second order, while the adsorption isotherm was fitted best with Langmuir equation at a maximum capacity of 34.2 mg g−1. Abolfazl Ashouri, Bagher Anvaripour, Mohsen Motavassel, and Nematolah Jaafarzadeh Haghighifard Copyright © 2014 Abolfazl Ashouri et al. All rights reserved. Analysis of Energy Characteristics of Rice and Coffee Husks Blends Thu, 13 Mar 2014 15:56:38 +0000 Production of first generation biofuels using food crops is under criticism over sustainability issues on food security. Tanzania is showing active interest in developing second generation biofuels to deal with some of such issues, especially from the feedstock point of view. This paper reports work done to determine energy characteristics of rice and coffee husks. The results show that coffee husks have better energy quality than rice husks, while heating values of coffee are 18.34 MJ/kg and 13.24 MJ/kg for rice husk. Thermogravimetric analysis made for coffee husks blended rice husks at a ratio of 75 : 25% vol. show better material degradation characteristics yielding low residual mass of 23.65%, compared to 26.50% of char and ash remaining in pure rice husks. Derivative thermogravimetric analysis shows comparable hemicellulose degradation peak values of −11.5 and −11.2 and cellulose −3.20 and −2.90 in pure coffee and rice husks, respectively. In coffee and rice husks blends, substantial reductions of hemicellulose and cellulose peaks were observed. Use of coffee and rice husks blends applying high temperature gasification would reduce the latter’s flammability, while increasing its flame retention characteristics, hence offering opportunities for production of clean syngas in a sustainable manner. Cuthbert F. Mhilu Copyright © 2014 Cuthbert F. Mhilu. All rights reserved. Effect of Various Pretreatment for Extracting Intracellular Lipid from Nannochloropsis oculata under Nitrogen Replete and Depleted Conditions Tue, 04 Mar 2014 08:37:58 +0000 Microalga is one of the most compelling microbial biomasses for biodiesel production. Various pretreatment processes, namely, enzyme treatment, lysis by acid, ultrasonicator, microwaves, autoclave, and 40% NaCl, for nitrogen replete and depleted algal cultures of Nannochloropsis oculata had been carried out to check the most feasible and effective technique to disrupt cells for procuring lipids, for which concentrations were determined. Fatty acid composition, essential functional groups, and cell disruption were analyzed by GC-MS, FT-IR Spectroscopy, and Nile Red fluorescent microscopy, respectively. The present investigation showed that lipid yield was higher in nitrogen depleted cells than that in normally nourished cells. GC-MS revealed the presence of major fatty acids—palmitic, oleic, stearic, arachidic, lauric, and linoleic acids. Highest efficiency was found when cells were pretreated using acid for 3 h. The lipid content was calculated as 33.18% and 54.26% for nitrogen rich cells and nitrogen starved cells, respectively. This work thus aided in identifying the most eligible pretreatment process to avail lipids from cells, to convert them to eco-friendly and nonpolluting biodiesel. Duraiarasan Surendhiran and Mani Vijay Copyright © 2014 Duraiarasan Surendhiran and Mani Vijay. All rights reserved. The Application of Response Surface Methodology in the Study of Photodegraded Industrial Dairy Effluents by the Photo-Fenton Process: Optimization and Economic Viability Wed, 19 Feb 2014 13:56:51 +0000 This study presents results from an application of Photo-Fenton process for organic-load reduction in dairy effluents. Process efficiency was evaluated in terms of percentage dissolved organic carbon, chemical oxygen demand, and biochemical oxygen demand (DOC, COD, and BOD, resp.), whose initial values were  mg O2 L−1,  mg O2 L−1, and  mg O2 L−1, respectively. We applied a statistical design represented by Box-Behnken factorial design inclusive of Fenton's reagent, the power of applied radiation (W), and pH factors. The set temperature value was 30°C with a reaction time of 60 min. The maximum efficiency obtained was at , Fenton reagent in the proportion of 35 g H2O2  3.6 g Fe2+, and ultraviolet radiation potency of 28 W. The results obtained for DOC, COD, and BOD were 81%, 90.7%, and 78.8%, respectively. Regarding the cost/benefit evaluation, the variables and their levels should be the following: pH 3.5, 35.0 g H2O2/Fe2+ 3.6 g, and 28 W UV, obtaining a reduction in concentration of 79.5% DOC. Carla Cristina Almeida Loures, Hélcio José Izário Filho, Ivy dos Santos Oliveira, Gisella Rossana Lamas Samanamud, André Luiz de Souza, and Messias Borges Silva Copyright © 2014 Carla Cristina Almeida Loures et al. All rights reserved. Hydrodynamics of a Novel Design Circulating Fluidized Bed Steam Reformer Operating in the Dense Suspension Upflow Regime Mon, 10 Feb 2014 06:28:56 +0000 Circulating fluidized bed steam reformers (CFBSR) represent an important alternative for hydrogen production, a promising energy carrier. Although the reactor hydrodynamics play crucial role, modeling efforts to date are limited to one-dimensional models, thus ignoring many of the flow characteristics of fluidized beds that have strong effects on the reactor efficiency. The flow inside the riser is inherently complex and requires at least two-dimensional modeling to capture its details. In the present work, the computational fluid dynamics (CFD) simulations of the hydrodynamics of the riser part of a novel CFBSR were carried out using two-phase Eulerian-Eulerian approach coupled with kinetic theory of granular flow and K-ε model. Cold flow simulations were carried under different fluidization regimes. It was found that catalyst of Geldart's type “A” particle is more efficient for flow inside the catalytic reactor and dense suspension upflow (DSU) fluidization regime yields the best homogeneous catalyst distribution in the riser and thus best reactor performance. The optimum range for catalyst flux was found to be higher than 1150 kg/m2·s for a gas flux of 6.78 kg/m2·s. It was also noted that the value of 500 Kg/m2·s for catalyst flux represents the critical value below which the riser will operate under pneumatic transport regime. Moataz Bellah M. Mousa, Seif-Eddeen K. Fateen, and Essam A. Ibrahim Copyright © 2014 Moataz Bellah M. Mousa et al. All rights reserved. Hybrid Organic-Inorganic Materials Based on Polyoxometalates and Ionic Liquids and Their Application in Catalysis Tue, 28 Jan 2014 08:18:18 +0000 An overview of the recent advances in the field of polyoxometalate, ionic liquid hybrids, is proposed with a special attention paid to their application in catalysis, more precisely biphasic and heterogeneous catalysis. Both components of the hybrids are separately outlined pointing to their useful properties and potential for catalysis, followed by the description of the hybrids preparation and synergy between components in a large range of organic transformations. And finally a vision on the future developments is proposed. Svetlana Ivanova Copyright © 2014 Svetlana Ivanova. All rights reserved. A Study on the Adhesion of Styrene-Butadiene Rubber with Red Kaolinite on Aluminum Surface Sun, 19 Jan 2014 09:35:31 +0000 The shear stress, strain, and modulus of styrene-butadiene rubber adhesive with and without kaolinite additive were studied on the aluminum surfaces to know the convenience of it in aluminum industries. The adhesives were cured at temperature of 200°C for different curing times (10, 30, 40, and 50 min) with and without 50 wt% kaolinite additives. The result found was good adhesion for styrene butadiene rubber adhesive without kaolinite additive and very poor adhesion with kaolinite additive. It was found that the maximum shear stress of adhesive without kaolinite additive was 2.3 kN/m2 with elongation of 0.23% and modulus of 100 kN/m2 at curing temperature of 200°C for period of time of 40 min. From images of adhesives after breaking of samples, the adhesive without additives failed because both adhesion and the cohesive energies of adhesive were failure; meanwhile, the failure of adhesive with kaolinite additive was due to failure in cohesive energy only. I. M. Alwaan Copyright © 2014 I. M. Alwaan. All rights reserved. Application of Mathematica Software to Solve Pulp Washing Model Sun, 29 Dec 2013 16:12:10 +0000 The removal of the bulk liquor surrounding the pulp fibers using less concentrated liquor is known as pulp washing. In the present study, a pulp washing model involving diffusion-dispersion through packed beds of finite length is presented. Separation of variables is applied to solve system of governing partial differential equations and the resulting equations are solved using Mathematica. Results from the present case are compared with those of previous investigators. The present case is giving better results than the previous investigators. Jitender Kumar, Ishfaq A. Ganaie, and Vijay K. Kukreja Copyright © 2013 Jitender Kumar et al. All rights reserved. Performance Comparison of α- and β-Amylases on Chitosan Hydrolysis Thu, 12 Dec 2013 14:06:20 +0000 The low solubility in common solvent and high viscosity resulting from its high molecular weight (MW) with fiber-like structure prevents a more widespread use of chitosan. This paper presents a performance comparison of nonspecific, commercially available enzymes, α- and β-amylases, for the hydrolysis of chitosan to lower its MW. The results showed that both enzymes demonstrate the ability to be used as catalysts in chitosan hydrolysis with β-amylase having better performance than α-amylase. The chitosan hydrolysis was influenced by not only the enzyme and the chitosan characteristics but also the hydrolysis condition. The optimum pH solution was 4 for α-amylase and 5 for β-amylase. The hydrolysis temperature was found to be optimal at 90 and 50°C for α- and β-amylases, respectively. Nur Rokhati, Prita Widjajanti, Bambang Pramudono, and Heru Susanto Copyright © 2013 Nur Rokhati et al. All rights reserved. Kinetic Study of Catalytic Esterification of Butyric Acid and Ethanol over Amberlyst 15 Wed, 23 Oct 2013 08:04:19 +0000 The esterification reaction of butyric acid with ethanol has been studied in the presence of ion exchange resin (Amberlyst 15). Ethyl butyrate was obtained as the only product which is used in flavours and fragrances. Industrially speaking, it is also one of the cheapest chemicals, which only adds to its popularity. The influences of certain parameters such as temperature, catalyst loading, initial concentration of acid and alcohols, initial concentration of water, and molar ratio were studied. Conversions were found to increase with an increase in both molar ratio and temperature. The experiments were carried out in a batch reactor in the temperature range of 328.15–348.15 K. Variation of parameters on rate of reaction demonstrated that the reaction was intrinsically controlled. Experiment kinetic data were correlated by using pseudo-homogeneous model. The activation energy for the esterification of butyric acid with ethanol is found to be 30 k J/mol. Nisha Singh, Raj kumar, and Pravin Kumar Sachan Copyright © 2013 Nisha Singh et al. All rights reserved. CFD Modeling of Particulates Erosive Effect on a Commercial Scale Pipeline Bend Sat, 05 Oct 2013 13:55:21 +0000 The computational fluid dynamics modeling of solid particles hydrodynamic based on the Lagrangian framework for diluted solid-gas flow through 90° gas pipeline bend is carried out to discover the effect of particles size distribution on particles flow pattern and their erosive effect on the bend. Particles size distribution has been obtained experimentally by measuring the sizes of solid particles that are flowing through the gas pipelines of Aghajari gas booster station. Also the erosion rate at the outer wall of the bend is predicted. The pipeline bend under study has a pipe diameter of 56 inches and ratios of the bend radius of the curvature to the pipeline diameter of 1.5. For the validation of computational model, firstly, the computational modeling is performed for a published experimental solid-gas flow data. The computational results include radial gas velocity and radial particle velocity profiles on planes which are at different angles through the bend. The comparison between the predicted numerical results and similar experimental data proves that the predictions of the computational model are acceptable. Finally, the particles' size distributions on each plane through the bend and the erosion rate on the outer wall of the bend have been obtained. The maximum rate of erosion is found to be 3.2 nm/s, occurring between 40 and 65° of the bend. Vahid Abdolkarimi and Rasool Mohammadikhah Copyright © 2013 Vahid Abdolkarimi and Rasool Mohammadikhah. All rights reserved. Modeling of Hydrodynamics in a 25 mm ϕ Pulsed Disk and Doughnut Column Thu, 19 Sep 2013 14:35:11 +0000 The hydrodynamic parameters, namely, dispersed phase holdup and flooding throughput, have been investigated in 25 mm diameter pulsed disk and doughnut column (PDDC), in no mass transfer conditions. In this work, using existing correlations on plate pulsed columns, the dispersed phase holdup and the flooding throughput are empirically modelled well using the slip velocity concept. A good agreement is observed between experimental values and predicted values obtained from empirical correlation. The experimental data for dispersed phase holdup and flooding throughput has been modelled using the Van Delden model to describe the hydrodynamics characteristics of a PDDC and necessary adjustable parameters for drop size distribution and dispersed phase holdup are updated for 30% TBP-nitric acid system. The model parameters were estimated by minimizing the absolute error between experimental and theoretical values of flooding throughput and holdup data. It was found that the measured values and observed trends could be described accurately using this model after fitting holdup and flooding data. The error between the experimental and theoretical values of flooding throughput and holdup was found to be less than 10%. Rajnish Kumar, D. Sivakumar, Shekhar Kumar, and U. Kamachi Mudali Copyright © 2013 Rajnish Kumar et al. All rights reserved. Kinetics and Product Selectivity (Yield) of Second Order Competitive Consecutive Reactions in Fed-Batch Reactor and Plug Flow Reactor Thu, 12 Sep 2013 15:23:50 +0000 This literature compares the performance of second order competitive consecutive reaction in Fed-Batch Reactor with that in continuous Plug Flow Reactor. In a kinetic sense, this simulation study aims to develop a case for continuous Plug Flow Reactor in pharmaceutical, fine chemical, and related other chemical industries. MATLAB is used to find solutions for the differential equations. The simulation results show that, for certain cases of nonelementary scenario, product selectivity is higher in Plug Flow Reactor than Fed-Batch Reactor despite the fact that it is the same in both the reactors for elementary reaction. The effect of temperature and concentration gradients is beyond the scope of this literature. Subash Chandra Bose Selvamony Copyright © 2013 Subash Chandra Bose Selvamony. All rights reserved. Prediction the Vapor-Liquid Equilibria of CO2-Containing Binary Refrigerant Mixtures Using Artificial Neural Networks Tue, 10 Sep 2013 15:50:43 +0000 Artificial neural network (ANN) technique has been applied for estimation of vapor-liquid equilibria (VLE) for eight binary refrigerant systems. The refrigerants include difluoromethane (R32), propane (R290), 1,1-difluoroethane (R152a), hexafluoroethane (R116), decafluorobutane (R610), 2,2-dichloro-1,1,1-trifluoroethane (R123), 1-chloro-1,2,2,2-tetrafluoroethane (R124), and 1,1,1,2-tetrafluoroethane (R134a). The related experimental data of open literature have been used to construct the model. Furthermore, some new experimental data (not applied in ANN training) have been used to examine the reliability of the model. The results confirm that there is a reasonable conformity between the predicted values and the experimental data. Additionally, the ability of the ANN model is examined by comparison with the conventional thermodynamic models. Moreover, the presented model is capable of predicting the azeotropic condition. Ahmad Azari, Saeid Atashrouz, and Hamed Mirshekar Copyright © 2013 Ahmad Azari et al. All rights reserved. Thermohydraulic Analysis of Shell-and-Tube Heat Exchanger with Segmental Baffles Thu, 05 Sep 2013 14:21:07 +0000 In this study, the experimental analysis was performed on the shell-and-tube type heat exchanger containing segmental baffles at different orientations. In the current work, three angular orientations () 0°, 30°, and 60° of the baffles were analyzed for laminar flow having the Reynolds number range 303–1516. It was observed that, with increase of Reynolds number from 303 to 1516, there was a 94.8% increase in Nusselt number and 282.9% increase in pressure drop. Due to increase of Reynolds number from 303 to 1516, there is a decrease in nondimensional temperature factor for cold water () by 57.7% and hot water () by 57.1%, respectively. Amarjit Singh and Satbir S. Sehgal Copyright © 2013 Amarjit Singh and Satbir S. Sehgal. All rights reserved. Evaluation of Packed-Bed Reactor and Continuous Stirred Tank Reactor for the Production of Colchicine Derivatives Tue, 03 Sep 2013 12:00:31 +0000 Bioconversion of colchicine into its pharmacologically active derivative 3-demethylated colchicine (3-DMC) mediated by P450BM3 enzyme is an economic and promising strategy for the production of this inexpensive and potent anticancer drug. Continuous stirred tank reactor (CSTR) and packed-bed reactor (PBR) of 3 L and 2 L total volumes were compared for the production of 3-demethylated colchicine (3-DMC) a colchicine derivative using Bacillus megaterium MTCC*420 under aerobic conditions. Statistical optimization technique was utilized with the most significant variables, that is, dissolved oxygen (DO), colchicine concentration, and process time for optimization. The validation of the model was performed by experiments on the predicted values in an individual run, and the optimum parameters were DO (~50%), colchicine concentration (7.5 g/L), and process time (39 h) resulted in a maximum bioconversion of 3-DMC 3.36 g/L. The PBR reactor achieved much higher productivity (6.58 g/L/h) as reported by earlier researchers. This is the first report on the use of PBR for bioconversion of colchicine. Kashyap Kumar Dubey, Dhirendra Kumar, Punit Kumar, Shafiul Haque, and Arshad Jawed Copyright © 2013 Kashyap Kumar Dubey et al. All rights reserved. Radiation and Chemical Reaction Effects on Unsteady Double Diffusive Convective Flow past an Oscillating Surface with Constant Heat Flux Sun, 01 Sep 2013 13:34:19 +0000 This paper presents an analysis of combined heat and mass transfer flow past an oscillating vertical plate under the action of radiation effects and chemical reaction when heat is supplied to the plate at constant rate. The governing equations are solved in closed form by Laplace-transform technique. The results are obtained for temperature, concentration, velocity, skin friction, Nusselt number, and Sherwood number. The effects of various parameters on flow variables are illustrated graphically, and the physical aspects of the problem are discussed. Arpita Jain Copyright © 2013 Arpita Jain. All rights reserved. Dehydrogenation of Methylcyclohexane: Parametric Sensitivity of the Power Law Kinetics Thu, 01 Aug 2013 10:41:01 +0000 For heterogeneous catalytic reactions, the empirical power law model is a valuable tool that explains variation in the kinetic behavior with changes in operating conditions, and therefore aids in the development of an appropriate and robust kinetic model. In the present work, experiments are performed on 1.0 wt% Pt/Al2O3 catalyst over a wide range of experimental conditions and parametric sensitivity of the power law model to the kinetics of the dehydrogenation of methylcyclohexane is studied. Power law parameters such as order of the reaction, activation energy, and kinetic rate constants are found dependent upon the operating conditions. With H2 in the feed, both apparent order of the reaction and apparent activation energy generally increase with an increase in pressure. The results suggest a kinetic model, which involves nonlinear dependence of rate on the partial pressure of hydrogen and adsorption kinetics of toluene or some intermediate. Muhammad R. Usman, David L. Cresswell, and Arthur A. Garforth Copyright © 2013 Muhammad R. Usman et al. All rights reserved. Synthesis and the Effects of New Melamine Superplasticizer on the Properties of Concrete Tue, 30 Jul 2013 13:06:26 +0000 This work deals with the synthesis of new melamine superplasticizer (NMS) with high molecule weight and comparatively high processing thermostability by the reaction among melamine, formaldehyde, and sulfonated glucose. The surface activity and the structure of new melamine superplasticizer and their performance in concrete were evaluated. The effect of molecular weight of synthesized new melamine superplasticizer on the performance of the concrete was determined. The results showed that the new melamine superplasticizer has been proved to be more efficient as a superplasticizer used in concrete. Huqun Wang, Xiaofeng Yang, Weifeng Xiong, Xiaobin Liu, and Zhimin Zhang Copyright © 2013 Huqun Wang et al. All rights reserved. A Comparative Study of Recycling of Used Engine Oil Using Extraction by Composite Solvent, Single Solvent, and Acid Treatment Methods Thu, 11 Jul 2013 13:43:48 +0000 Engine oils are made from crude oil and its derivatives by mixing of certain other chemicals (additives) for improving their certain properties. Lubricating oil is used to lubricate moving parts of engine, reducing friction, protecting against wear, and removing contaminants from the engine, act as a cleaning agent, and act as an anticorrosion and cooling agent. This research effort focuses on comparative study of re-refined engine oils by extraction of composite solvent, single solvent, and acid treatment methods. Composite solvent was made up of butanol-propane and butanone; propane was used as single solvent. Different properties of refined oil and waste oil were analyzed, such as cloud and pour point, flash point, specific gravity, ash content, viscosity, moisture ratio and acid value. On the basis of experimental work, it was found that the iron contamination decreased from 50 ppm to 13 ppm for composite solvent; for propane solvent it decreased up to 30 ppm and 15 ppm for acid treatment. Results from the flash point, pour point, viscosity, specific gravity, and ash percentage were improved at different degrees, but the best results were seen by using the composite solvent with having drawback of expensiveness. Rashid Abro, Xiaochun Chen, Khanji Harijan, Zulifqar A. Dhakan, and Muhammad Ammar Copyright © 2013 Rashid Abro et al. All rights reserved. Biosorption of Cr(III) and Pb(II) by Schoenoplectus californicus and Insights into the Binding Mechanism Wed, 10 Jul 2013 13:42:49 +0000 Biosorption and desorption of chromium and lead on shoots biomass of Schoenoplectus californicus were investigated by performing batch sorption tests in different conditions of pH, biosorbent dose, and initial concentration in simple and binary solutions. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were employed to describe sorption equilibrium. Filters and biomass were characterized before and after treatments by environmental scanning electron microscopy and X-ray energy-dispersive spectrometry. The optimal conditions for biosorption were found to be pH 5 for both metals. The contact time to reach pseudoequilibrium changed as a function of pH and the metal studied. The highest optimisation of biosorbent dose was 5 g L−1 at pH 7 and 15 g L−1 at pH 5 for both metals. The most effective extracting agents for lead and chromium proved to be HNO3 and NaOH, respectively. The recovery of lead was greater than of chromium because the Cr(III) sorption mechanisms involve a stronger binding energy than the mechanisms for Pb(II), such as in intern sphere complexes. Both metals accounted for a high % removal (>90%) under the best sorption conditions. The use of Schoenoplectus californicus proved to be an efficient and economical alternative for the treatment of effluents contaminated with lead and chromium. Tomás Agustín Rearte, Patricia Beatriz Bozzano, Maria Luisa Andrade, and Alicia Fabrizio de Iorio Copyright © 2013 Tomás Agustín Rearte et al. All rights reserved. Recovery of Value-Added Products from Hydrothermal Carbonization of Sewage Sludge Thu, 20 Jun 2013 12:42:06 +0000 This paper is about the conversion of wet waste stream into valuable products via thermal processing. Hydrothermal carbonization of sewage sludge was carried out at 200°C and 2.1 MPa in a closed reactor for 1–6 h. Main products were in solid and liquid phases. The resulting hydrochar was shown to have H/C and O/C ratios moving towards natural lignite, improved energetic content, and adsorption property in terms of iodine number. The aqueous solution was found to contain high concentration of plant food nutrients, especially nitrogen and potassium. They may be desirable for subsequent fuel and chemical production as well as applications in agriculture. The study shows that valuable products can be generated successfully from sewage sludge using hydrothermal carbonization. Pannarai Saetea and Nakorn Tippayawong Copyright © 2013 Pannarai Saetea and Nakorn Tippayawong. All rights reserved. Materials for Chemical-Looping with Oxygen Uncoupling Wed, 08 May 2013 14:34:19 +0000 Chemical-looping with oxygen uncoupling (CLOU) is a novel combustion technology with inherent separation of carbon dioxide. The process is a three-step process which utilizes a circulating oxygen carrier to transfer oxygen from the combustion air to the fuel. The process utilizes two interconnected fluidized bed reactors, an air reactor and a fuel reactor. In the fuel reactor, the metal oxide decomposes with the release of gas phase oxygen (step 1), which reacts directly with the fuel through normal combustion (step 2). The reduced oxygen carrier is then transported to the air reactor where it reacts with the oxygen in the air (step 3). The outlet from the fuel reactor consists of only CO2 and H2O, and pure carbon dioxide can be obtained by simple condensation of the steam. This paper gives an overview of the research conducted around the CLOU process, including (i) a thermodynamic evaluation, (ii) a complete review of tested oxygen carriers, (iii) review of kinetic data of reduction and oxidation, and (iv) evaluation of design criteria. From the tests of various fuels in continuous chemical-looping units utilizing CLOU materials, it can be established that almost full conversion of the fuel can be obtained for gaseous, liquid, and solid fuels. Tobias Mattisson Copyright © 2013 Tobias Mattisson. All rights reserved. Development and Environmental Applications of Activated Carbon Cloths Thu, 14 Mar 2013 18:19:24 +0000 Activated carbon cloths have received growing attention because they offer comparative advantages over the traditional powdered or granular forms of this well-known adsorbent, providing further potential uses for technological innovations in several fields. The present article provides an overview of research studies and advances concerned with the development of activated carbon cloths and their use as adsorbent in environmental applications, mostly reported in the last years. The influence of some fabrics and textile wastes used as precursors, and of main activation process variables on the development and physicochemical, mechanical and/or electrical properties of the resulting activated carbon cloths are first reviewed. Then, investigations dealing with the removal of water and air pollutants by adsorption onto activated carbon cloths, including advances toward optimizing their regeneration after organic vapors saturation, are presented. Ana Lea Cukierman Copyright © 2013 Ana Lea Cukierman. All rights reserved. Analytical Modelling of a Spray Column Three-Phase Direct Contact Heat Exchanger Sun, 03 Mar 2013 15:34:17 +0000 An analytical model for the temperature distribution of a spray column, three-phase direct contact heat exchanger is developed. So far there were only numerical models available for this process; however to understand the dynamic behaviour of these systems, characteristic models are required. In this work, using cell model configuration and irrotational potential flow approximation characteristic models has been developed for the relative velocity and the drag coefficient of the evaporation swarm of drops in an immiscible liquid, using a convective heat transfer coefficient of those drops included the drop interaction effect, which derived by authors already. Moreover, one-dimensional energy equation was formulated involving the direct contact heat transfer coefficient, the holdup ratio, the drop radius, the relative velocity, and the physical phases properties. In addition, time-dependent drops sizes were taken into account as a function of vaporization ratio inside the drops, while a constant holdup ratio along the column was assumed. Furthermore, the model correlated well against experimental data. Hameed B. Mahood, Adel O. Sharif, Seyed Ali Hosseini, and Rex B. Thorpe Copyright © 2013 Hameed B. Mahood et al. All rights reserved. Gasification Coupled Chemical Looping Combustion of Coal: A Thermodynamic Process Design Study Thu, 31 Jan 2013 11:49:54 +0000 A thermodynamic investigation of gasification coupled chemical looping combustion (CLC) of carbon (coal) is presented in this paper. Both steam and CO2 are used for gasification within the temperature range of 500–1200°C. Chemical equilibrium model was considered for the gasifier and CLC fuel reactor. The trends in product compositions and energy requirements of the gasifier, fuel reactor, and air reactor were determined. Coal (carbon) gasification using 1.5 mol H2O and 1.5 mol CO2 per mole carbon at 1 bar pressure and 650°C delivered maximum energy (−390.157 kJ) from the process. Such detailed thermodynamic studies can be useful to design chemical looping combustion processes using different fuels. Sonali A. Borkhade, Preksha A. Shriwas, and Ganesh R. Kale Copyright © 2013 Sonali A. Borkhade et al. All rights reserved. Zeolites: Promised Materials for the Sustainable Production of Hydrogen Thu, 31 Jan 2013 10:39:53 +0000 Zeolites have been shown to be useful catalysts in a large variety of reactions, from acid to base and redox catalysis. The particular properties of these materials (high surface area, uniform porosity, interconnected pore/channel system, accessible pore volume, high adsorption capacity, ion-exchange ability, and shape/size selectivity) provide crucial features as effective catalysts and catalysts supports. Currently, new applications are being developed from the considerable existing knowledge about these important and remarkable materials. Among them, those applications related to the development of processes with less impact on the environment (green processes) and with the production of alternative and cleaner energies are of paramount importance. Hydrogen is believed to be critical for the energy and environmental sustainability. It is a clean energy carrier which can be used for transportation and stationary power generation. In the production of hydrogen, the development of new catalysts is one of the most important and effective ways to address the problems related to the sustainable production of hydrogen. This paper explores the possibility to use zeolites as catalysts or supports of catalysts to produce hydrogen from renewable resources. Specifically, two approaches have been considered: reforming of biomass-derived compounds (reforming of bioethanol) and water splitting using solar energy. This paper examines the role of zeolites in the preparation of highly active and selective ethanol steam reforming catalysts and their main properties to be used as efficient water splitting photocatalysts. Antonio Chica Copyright © 2013 Antonio Chica. All rights reserved. Impurities Effect on Carbonate Reactive Crystallization for the Wastewater Tue, 22 Jan 2013 09:20:45 +0000 Reactive crystallization designed to separate nickel or copper ion from effluents has been advanced for applying to actual industrial wastewater containing impurities. In the primary reaction of this method, metal sulfate solution reacts with sodium carbonate solution in a semibatch crystallizer. In the present study, during the process of nickel or copper ions incorporation, inhibitory effect on seed growth of impurities, like cobalt, manganese, zinc, and borate and phosphate ions, was investigated. Through the 8-hour reactive crystallization, obtained particles’ characters and metals removal efficient were examined. Considering analyses data on metal component ratio in produced crystals, metal ions initial uptake rate was found to be different by the kind of seeds and impurities. And the centrifugation was performed against obtained crystals aimed for examining target metal purity improvement. The results indicated that copper components can incorporate and remove other metal ions easily. In addition, when the anions are used as impurities, depending on the kind of anions, the effect of damaging the surface of seeds or producing many fine particles has been confirmed. Y. Shimizu and I. Hirasawa Copyright © 2013 Y. Shimizu and I. Hirasawa. All rights reserved. Derivation of a Multiparameter Gamma Model for Analyzing the Residence-Time Distribution Function for Nonideal Flow Systems as an Alternative to the Advection-Dispersion Equation Thu, 10 Jan 2013 15:13:40 +0000 A new residence-time distribution (RTD) function has been developed and applied to quantitative dye studies as an alternative to the traditional advection-dispersion equation (AdDE). The new method is based on a jointly combined four-parameter gamma probability density function (PDF). The gamma residence-time distribution (RTD) function and its first and second moments are derived from the individual two-parameter gamma distributions of randomly distributed variables, tracer travel distance, and linear velocity, which are based on their relationship with time. The gamma RTD function was used on a steady-state, nonideal system modeled as a plug-flow reactor (PFR) in the laboratory to validate the effectiveness of the model. The normalized forms of the gamma RTD and the advection-dispersion equation RTD were compared with the normalized tracer RTD. The normalized gamma RTD had a lower mean-absolute deviation (MAD) (0.16) than the normalized form of the advection-dispersion equation (0.26) when compared to the normalized tracer RTD. The gamma RTD function is tied back to the actual physical site due to its randomly distributed variables. The results validate using the gamma RTD as a suitable alternative to the advection-dispersion equation for quantitative tracer studies of non-ideal flow systems. Irucka Embry, Victor Roland, Oluropo Agbaje, Valetta Watson, Marquan Martin, Roger Painter, Tom Byl, and Lonnie Sharpe Copyright © 2013 Irucka Embry et al. All rights reserved. The Food Additive Polyglycerol Polyricinoleate (E-476): Structure, Applications, and Production Methods Wed, 09 Jan 2013 14:20:25 +0000 The food additive named polyglycerol polyricinoleate (PGPR) and identified with the code E-476 (PGPR) is used as emulsifier in tin-greasing emulsions for the baking trade and for the production of low-fat spreads. However, the main application of PGPR is in the chocolate industry, where, besides its action as an emulsifier, it also has important properties as a viscosity modifier and thus improves the moulding properties of the molten chocolate. An additional property of PGPR in chocolate is its ability to limit fat bloom. Known chemical methods for preparing this emulsifier involve long reaction times and high operating temperatures, which adversely affect the quality of the final product leading to problems of coloration and odors that could make it inadvisable for the food industry. As an alternative, the enzymatic synthesis of PGPR by the catalytic action of two lipases has been developed. The enzymes act in mild reaction conditions of temperature and pressure, neutral pH, and in a solvent-free system, which makes the process environmentally friendly and avoids side reaction, so that the product has a higher purity and quality. Josefa Bastida-Rodríguez Copyright © 2013 Josefa Bastida-Rodríguez. All rights reserved.