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Records with Subject: Reaction Engineering
Showing records 1 to 25 of 117. [First] Page: 1 2 3 4 5 Last
Nonlinear Thermal Radiation and Chemical Reaction Effects on a (Cu−CuO)/NaAlg Hybrid Nanofluid Flow Past a Stretching Curved Surface
Naveed Ahmed, Fitnat Saba, Umar Khan, Syed Tauseef Mohyud-Din, El-Sayed M. Sherif, Ilyas Khan
March 12, 2020 (v1)
Keywords: (Cu−CuO)/NaAlg hybrid nanofluid, boundary layer, chemical reaction, curved stretching surface, heat and mass transfer, nonlinear thermal radiation, numerical results
The boundary layer flow of sodium alginate ( NaAlg ) based ( Cu − CuO ) hybrid nanofluid, over a curved expanding surface, has been investigated. Heat and mass transport phenomena have also been analyzed. Moreover, the impacts of chemical reaction, magnetic field and nonlinear thermal radiation are also a part of this study. This arrangement has great practical relevance, especially in the polymer and chemical industries. We have extended the Bruggeman model to make it capable of capturing the thermal conductivity of ( Cu − CuO ) / NaAlg hybrid nanofluid. We have employed some suitable transformations to obtain the governing system of nonlinear ODEs. Runge − Kutta − Fehlberg algorithm, accompanied by a shooting technique, has been employed to solve the governing system numerically. The changes in the flow and heat transfer distribution, due to various parameters, have been captured and portrayed in the form of graphs. It has been found that t... [more]
Screening of Amino Acids and Surfactant as Hydrate Promoter for CO2 Capture from Flue Gas
Jyoti Shanker Pandey, Yousef Jouljamal Daas, Nicolas von Solms
February 12, 2020 (v1)
Keywords: amino acids, Carbon Dioxide Capture, flue gas hydrate, sodium dodecyl sulfate
In this study, the kinetics of flue gas hydrate formation in bulk water in the presence of selected amino acids and surfactants are investigated. Four amino acids (3000 ppm) are selected based on different hydropathy index. Constant-ramping and isothermal experiments at 120 bar pressure and 1 °C temperature are carried out to compare their hydrate promotion capabilities with surfactant sodium dodecyl sulfate (SDS) (500−3000 ppm) and water. Based on experimental results, we report the correlation between hydrate promotion capability of amino acids and their hydrophobicity. Hydrophobic amino acids show stronger flue gas hydrate promotion capability than water and hydrophilic amino acids. We discuss the controlling mechanisms to differentiate between promoters and inhibitors’ roles among the amino acids. Between 2000−3000 ppm concentrations, hydrophobic amino acids have near similar promotion capabilities as SDS. This research highlights the potential use of amino acids as promoters or in... [more]
Characteristics of Low-Temperature Polyvinyl Chloride Carbonization by Catalytic CuAl Layered Double Hydroxide
Erwei Pang, Weijun Liu, Shuhua Zhang, Nengshuo Fu, Zhongxun Tian
February 12, 2020 (v1)
Keywords: catalytic PVC pyrolysis, CuAl layered double hydroxide (CuAl-LDH), PVC carbonization
A good way to make carbon materials was presented in low-temperature polyvinyl chloride (PVC) carbonization by catalysis. The process of low-temperature PVC carbonization by CuAl-layered double hydroxide (CuAl-LDH) was investigated by thermogravimetric analysis (TGA) and tubular furnace. The results show that CuAl-LDH accounting for 5% of PVC mass enabled acceleration of the dehydrochlorination in PVC as soon as possible and maximized the yield of the PVC carbonized product. The vacuum with 0.08 MPa, 20 °C/min heating rate and 90 min carbonized maintenance time were optimal for PVC carbonization. Moreover, the best morphology and yield of the carbonized product was provided at a carbonization temperature of 300 °C.
Co-Firing of Sawdust and Liquid Petroleum Gas in the Application of a Modified Rocket Stove
Paisan Comsawang, Suwat Nanetoe, Nitipong Soponpongpipat
February 12, 2020 (v1)
Keywords: co-firing, LPG stove, pyrolysis, rocket stove, sawdust
The heating rate, firepower, and thermal efficiency of a modified rocket stove using sawdust and liquid petroleum gas (LPG) as co-firing fuel were investigated. Three modified rocket stoves with a height of 400 mm and outside diameters of 225, 385, and 550 mm were tested. It was found that there was an insignificant difference in heating rate and firepower when stoves were tested without co-firing with LPG. In this case, the stove heating rate was in the range of 1.49−1.55 °C/min. When LPG was used, the heating rate tended to linearly increase with the increase of LPG flow rate. The heating rate was in range of 2.42−2.80, 2.63−3.27, and 3.07−4.22 °C/min when LPG consumption rates were 2.38 × 10−5, 3.33 × 10−5, and 5.00 × 10−5 kg/s, respectively. The slight increase of stove heating rate and firepower was seen when the stove diameter was increased from 225 to 385 mm. The increase of stove diameter from 385 to 550 mm resulted in a huge increase of heating rate and firepower. Thermal effi... [more]
Hierarchical Cs−Pollucite Nanozeolite Modified with Novel Organosilane as an Excellent Solid Base Catalyst for Claisen−Schmidt Condensation of Benzaldehyde and Acetophenone
Aleid Ghadah Mohammad S., Fitri Khoerunnisa, Severinne Rigolet, T. Jean Daou, Tau-Chuan Ling, Eng-Poh Ng
February 12, 2020 (v1)
Keywords: Claisen–Schmidt condensation, Cs–pollucite, hierarchical structure, nanozeolite, non-microwave instant heating, organosilane porogen
Cs−pollucite can be a potential solid base catalyst due to the presence of (Si-O-Al)−Cs+ basic sites. However, it severely suffers from molecular diffusion and pore accessibility problems due to its small micropore opening. Herein, we report the use of new organosilane, viz. dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPOAC), as a promising pore-expanding agent to develop the hierarchical structure in nanosized Cs−pollucite. In respect to this, four different amounts of TPOAC were added during the synthesis of hierarchical Cs−pollucite (CP-x, x = 0, 0.3, 1.0, or 2.0, where x is the molar ratio of TPOAC) in order to investigate the effects of TPOAC in the crystallization process of Cs−pollucite. The results show that an addition of TPOAC altered the physico-chemical and morphological properties of hierarchical Cs−pollucite, such as the crystallinity, crystallite size, pore size distribution, surface areas, pore volume, and surface basicity. The prepared solids were al... [more]
Analyses for Synthesis Gas from Municipal Solid Waste Gasification under Medium Temperatures
Qinyang Gu, Wei Wu, Baosheng Jin, Zheng Zhou
February 12, 2020 (v1)
Keywords: Energy Efficiency, oxygen content, syngas evolution, syngas quality
Municipal solid waste (MSW) gasification could be a novel method that shows the various advantages over traditional MSW treatments in China. Other research concluded that MSW gasification was operating by the assistant heat, and the gasification may occur under medium temperature. So, this study is aimed to investigate MSW gasification and pyrolysis behavior and analyze the syngas evolution and reaction mechanism. The MSW samples were collected in daily life and the experiments were carried out in a fixed tubular reactor below 650 °C. The effects of medium temperature and oxygen content on syngas quality were elucidated in depth. The results have shown that temperature can promote the syngas quality in the range of 550−650 °C, because the increasing temperature strengthens the reaction rate. The oxygen content should be controlled in a certain range, or oxidation reactions will be more prominent during gasification. The optimal gasification condition in this study was obtained at 650 °... [more]
Synergistic Effect on the Non-Oxygenated Fraction of Bio-Oil in Thermal Co-Pyrolysis of Biomass and Polypropylene at Low Heating Rate
Dijan Supramono, Adithya Fernando Sitorus, Mohammad Nasikin
February 12, 2020 (v1)
Keywords: Biomass, co-pyrolysis, corn cobs, heat transfer, polypropylene, synergistic effect
Biomass pyrolysis and polypropylene (PP) pyrolysis in a stirred tank reactor exhibited different heat transfer phenomena whereby heat transfer in biomass pyrolysis was driven predominantly by heat radiation and PP pyrolysis by heat convection. Therefore, co-pyrolysis could exhibit be expected to display various heat transfer phenomena depending on the feed composition. The objective of the present work was to determine how heat transfer, which was affected by feed composition, affected the yield and composition of the non-polar fraction. Analysis of heat transfer phenomena was based on the existence of two regimes in the previous research in which in regime 1 (the range of PP composition in the feeds is 0−40%), mass ejection from biomass particles occurred without biomass particle swelling, while in regime 2 (the range of PP composition in the feeds is 40−100%), mass ejection was preceded by biomass particle swelling. The co-pyrolysis was carried out in a stirred tank reactor with heat... [more]
Pd/Au Based Catalyst Immobilization in Polymeric Nanofibrous Membranes via Electrospinning for the Selective Oxidation of 5-Hydroxymethylfurfural
Danilo Bonincontro, Francesco Fraschetti, Claire Squarzoni, Laura Mazzocchetti, Emanuele Maccaferri, Loris Giorgini, Andrea Zucchelli, Chiara Gualandi, Maria Letizia Focarete, Stefania Albonetti
February 12, 2020 (v1)
Keywords: electrospinning, HMF oxidation, polymeric catalytic membranes
Innovative nanofibrous membranes based on Pd/Au catalysts immobilized via electrospinning onto different polymers were engineered and tested in the selective oxidation of 5-(hydroxymethyl)furfural in an aqueous phase. The type of polymer and the method used to insert the active phases in the membrane were demonstrated to have a significant effect on catalytic performance. The hydrophilicity and the glass transition temperature of the polymeric component are key factors for producing active and selective materials. Nylon-based membranes loaded with unsupported metal nanoparticles were demonstrated to be more efficient than polyacrylonitrile-based membranes, displaying good stability and leading to high yield in 2,5-furandicarboxylic acid. These results underline the promising potential of large-scale applications of electrospinning for the preparation of catalytic nanofibrous membranes to be used in processes for the conversion of renewable molecules.
Photoelectrocatalytic Hydrogen Peroxide Production Using Nanoparticulate WO3 as Photocatalyst and Glycerol or Ethanol as Sacrificial Agents
Ioannis Papagiannis, Nikolaos Balis, Vassilios Dracopoulos, Panagiotis Lianos
February 12, 2020 (v1)
Keywords: Ethanol, glycerol, hydrogen peroxide, photoelectrocatalysis, WO3
Photoelectrochemical production of hydrogen peroxide was studied by using a cell functioning with a WO3 photoanode and an air breathing cathode made of carbon cloth with a hydrophobic layer of carbon black. The photoanode functioned in the absence of any sacrificial agent by water splitting, but the produced photocurrent was doubled in the presence of glycerol or ethanol. Hydrogen peroxide production was monitored in all cases, mainly in the presence of glycerol. The presence or absence of the organic fuel affected only the obtained photocurrent. The Faradaic efficiency for hydrogen peroxide production was the same in all cases, mounting up to 74%. The duplication of the photocurrent in the presence of biomass derivatives such as glycerol or ethanol and the fact that WO3 absorbed light in a substantial range of the visible spectrum promotes the presently studied system as a sustainable source of hydrogen peroxide production.
Nitridation Reaction of Titanium Powders by 2.45 GHz Multimode Microwave Irradiation using a SiC Susceptor in Atmospheric Conditions
Jun Fukushima, Keiichiro Kashimura, Hirotsugu Takizawa
February 3, 2020 (v1)
Keywords: microwave processing, on demand process, SiC susceptor, titanium nitride
A titanium nitride (TiN) coating using microwaves can be accomplished in air, and satisfies the required conditions of an on-demand TiN coating process. However, the coating mechanism using microwaves is not completely clear. In this study, to understand the detailed mechanism of microwave titanium nitridation in air, the quantity of nitrogen and oxygen in reacted TiN powder has been investigated by an inert melting method. Titanium powders were irradiated with microwaves by a multi-mode type 2.45 GHz microwave irradiation apparatus, while also being held at various temperatures for two different dwell times. X-ray diffraction (XRD) results revealed that nitridation of the powder progressed with increasing process temperature, and the nitridation corresponds to the powder color after microwave irradiation. The nitrogen contents of the samples increased with increasing processing temperature and dwell time, unlike oxygen. It is postulated that the reaction of convected air with titanium... [more]
Hydrothermal Liquefaction of Microalga Using Metal Oxide Catalyst
Alejandra Sánchez-Bayo, Rosalía Rodríguez, Victoria Morales, Nima Nasirian, Luis Fernando Bautista, Gemma Vicente
February 3, 2020 (v1)
Keywords: biocrude, hydrothermal liquefaction, metal-oxide catalyst, microalgae
The yield and composition of the biocrude obtained by hydrothermal liquefaction (HTL) of Nannocloropsis gaditana using heterogeneous catalysts were evaluated. The catalysts were based on metal oxides (CaO, CeO2, La2O3, MnO2, and Al2O3). The reactions were performed in a batch autoclave reactor at 320 °C for 10 min with a 1:10 (wt/wt) microalga:water ratio. These catalysts increased the yield of the liquefaction phase (from 94.14 ± 0.30 wt% for La2O3 to 99.49 ± 0.11 wt% for MnO2) as compared with the thermal reaction (92.60 ± 1.20 wt%). Consequently, the biocrude yields also raised in the metal oxides catalysed HTL, showing values remarkably higher for the CaO (49.73 ± 0.9 wt%) in comparison to the HTL without catalyst (42.60 ± 0.70 wt%). The N and O content of the biocrude obtained from non-catalytic HTL were 6.11 ± 0.02 wt% and 10.50 ± 0.50 wt%, respectively. In this sense, the use of the metal oxides decreased the N content of the biocrude (4.62 ± 0.15−5.45 ± 0.11 wt%), although, the... [more]
Comparative Analysis of Combustion Stability of Diesel/Ethanol Utilization by Blend and Dual Fuel
Wojciech Tutak, Arkadiusz Jamrozik
January 19, 2020 (v1)
Keywords: combustion duration, combustion stability, diesel fuel, dual fuel engine, Ethanol, ignition delay, rate of heat release
The aim of the work is a comparison of two combustion systems of fuels with different reactivity. The first is combustion of the fuel mixture and the second is combustion in a dual-fuel engine. Diesel fuel was burned with pure ethanol. Both methods of co-firing fuels have both advantages and disadvantages. Attention was paid to the combustion stability aspect determined by COVIMEP as well as the probability density function of IMEP. It was analyzed also the spread of the maximum pressure value, the angle of the position of maximum pressure. The influence of ethanol on ignition delay time spread and end of combustion process was evaluated. The experimental investigation was conducted on 1-cylinder air cooled compression ignition engine. The test engine operated with constant rpm equal to 1500 rpm and constant angle of start of diesel fuel injection. The engine was operated with ethanol up to 50% of its energy fraction.
Quality Properties and Pyrolysis Characteristics of Cassava Rhizome Pellets Produced by Alternating between Pelletizing and Torrefaction
Nitipong Soponpongpipat, Paisan Comsawang, Suwat Nanetoe
January 7, 2020 (v1)
Keywords: cassava rhizome, pellets, pyrolysis characteristics, TGA, torrefaction
This work investigated quality properties of pellets of raw cassava rhizome (P-RC), pellets of pelletized cassava rhizome followed by torrefaction (T-CP), and pellets of torrefied cassava rhizome followed by pelletizing (P-TC). Torrefaction was conducted at temperatures of 230, 250, and 280 °C for 30 min. Pyrolysis characteristics of T-CP and P-TC at torrefied temperatures of 230 and 250 °C were studied using thermogravimetric analysis. It was found that at the similar torrefied temperature, P-TC had a higher bulk density, energy density, and pellet durability than that of T-CP and P-RC while T-CP had a higher HHV and moisture absorption than P-TC and P-RC. The bulk density of P-TC was 1.13−1.19 and 1.33−1.52 times higher than that of P-RC and T-CP, respectively. The HHV of T-CP was 1.07 and 1.29 times higher than P-TC and P-RC, respectively. The energy density of P-TC was 1.24−1.56 and 1.20−1.41 times higher than that of P-RC and T-CP. In terms of Pellet Fuel Institute (PFI) standard,... [more]
Evaluation of Nano Zero-Valent Iron (nZVI) Activity in Solution and Immobilized in Hydrophilic PVDF Membrane for Drimaren Red X-6BN and Bisphenol-a Removal in Water
Larissa L. S. Silva, Júlio A. Caldara, Ana Maria Rocco, Cristiano P. Borges, Fabiana V. Fonseca
January 7, 2020 (v1)
Keywords: Bisphenol-a, Drimaren red X-6BN, nZVI, polyacrylic acid, PVDF membranes
Fenton reactions that involve nano zero-valent iron (nZVI) have shown high promise in the removal of organic pollutants. In this work, nZVI stabilized with carboxymethyl cellulose (CMC) was evaluated for drimaren red X-6BN (DRX-6BN, 10 mg/L) and bisphenol-a (BPA, 800 mg/L) removal. Oxidation reactions were conducted for removal of both compounds by varying nZVI/CMC concentration (0.01−5 g/L), hydrogen peroxide (H2O2, 0.01−0.1 g/L), and pH (3−9). DRX-6BN degradation rate was the highest (kinetic constant (kobs) = 4.622 h−1) when working at pH 3 and 3 g/L of nZVI/CMC. Increasing H2O2 concentration could not improve the reaction. For BPA, all the conditions tested showed removals of more than 96% with 0.02 g/L of H2O2. This result was compared with the activity of nZVI loaded in hydrophilic PVDF (Polyvinylidene fluoride) membranes by polyacrylic acid (PAA) to entrap nanoparticles to the membrane surface. As expected, the attachment of nZVI onto the membranes diminished nanoparticles’ acti... [more]
New Aspects on the Modeling of Dithiolactone-Mediated Radical Polymerization of Vinyl Monomers
Anete Joceline Benitez-Carreón, Jesús Guillermo Soriano-Moro, Eduardo Vivaldo-Lima, Ramiro Guerrero-Santos, Alexander Penlidis
December 16, 2019 (v1)
Keywords: dithiolactones, kinetic modeling, methyl methacrylate, RAFT polymerization, vinyl monomers
A kinetic model for the dithiolactone-mediated radical polymerization of vinyl monomers based on the persistent radical effect and reversible addition (negligible fragmentation) was used to calculate the polymerization rate and describe molar mass development in the polymerization of methyl methacrylate at 60 °C, using 2,2-azobisisobutyronitrile (AIBN) as an initiator, as well as dihydro-5-phenyl-2(3H)-thiophenethione (DTL1) and dihydro-2(3H)-thiophenethione (DTL2) as controllers. The model was implemented in the PREDICI commercial software. A good agreement between experimental data and model predictions was obtained.
Esterification of Free Fatty Acids with Glycerol within the Biodiesel Production Framework
Juan Francisco García Martín, Javier Carrión Ruiz, Miguel Torres García, Chao-Hui Feng, Paloma Álvarez Mateos
December 16, 2019 (v1)
Keywords: biodiesel, esterification, free fatty acids, glycerol, waste cooking oil
Companies in the field of the collection and treatment of waste cooking oils (WCO) for subsequent biodiesel production usually have to cope with high acidity oils, which cannot be directly transformed into fatty acid methyl esters due to soap production. Since glycerine is the main byproduct of biodiesel production, these high acidity oils could be esterified with the glycerine surplus to transform the free fatty acids (FFA) into triglycerides before performing the transesterification. In this work, commercial glycerol was esterified with commercial fatty acids and commercial fatty acid/lampante olive oil mixtures over tin (II) chloride. In the first set of experiments, the esterification of linoleic acid with glycerol excess from 20 to 80% molar over the stoichiometric was performed. From 20% glycerol excess, there was no improvement in FFA reduction. Using 20% glycerol excess, the performance of a biochar obtained from heavy metal-contaminated plant roots was compared to that of SnCl... [more]
Simulation of Batch Slow Pyrolysis of Biomass Materials Using the Process-Flow-Diagram COCO Simulator
Chaiyot Tangsathitkulchai, Natthaya Punsuwan, Piyarat Weerachanchai
December 11, 2019 (v1)
Keywords: biomass pyrolysis, cassava pulp residue, coconut shell, longan fruit seed, palm kernel cake, palm shell, process simulation model
The commercial COCO simulation program was used to mimic the experimental slow pyrolysis process of five different biomasses based on thermodynamic consideration. The program generated the optimum set of reaction kinetic parameters and reaction stoichiometric numbers that best described the experimental yields of solid, liquid and gas products. It was found that the simulation scheme could predict the product yields over the temperature range from 300 to 800 °C with reasonable accuracy of less than 10% average error. An attempt was made to generalize the biomass pyrolysis behavior by dividing the five biomasses into two groups based on the single-peak and two-peak characteristics of the DTG (derivative thermogravimetry) curves. It was found that this approximate approach was able to predict the product yields reasonably well. The proposed simulation method was extended to the analysis of slow pyrolysis results derived from previous investigations. The results obtained showed that the p... [more]
The Production of Engineered Biochars in a Vertical Auger Pyrolysis Reactor for Carbon Sequestration
Patrick Brassard, Stéphane Godbout, Vijaya Raghavan, Joahnn H. Palacios, Michèle Grenier, Dan Zegan
December 10, 2019 (v1)
Keywords: agricultural biomass, auger reactor, engineered biochar, forest residues, pyrolysis, response surface methodology
Biomass pyrolysis and the valorization of co-products (biochar, bio-oil, syngas) could be a sustainable management solution for agricultural and forest residues. Depending on its properties, biochar amended to soil could improve fertility. Moreover, biochar is expected to mitigate climate change by reducing soil greenhouse gas emissions, if its C/N ratio is lower than 30, and sequestrating carbon if its O/Corg and H/Corg ratios are lower than 0.2 and 0.7, respectively. However, the yield and properties of biochar are influenced by biomass feedstock and pyrolysis operating parameters. The objective of this research study was to validate an approach based on the response surface methodology, to identify the optimal pyrolysis operating parameters (temperature, solid residence time, and carrier gas flowrate), in order to produce engineered biochars for carbon sequestration. The pyrolysis of forest residues, switchgrass, and the solid fraction of pig manure, was carried out in a vertical au... [more]
Reduction of Furfural to Furfuryl Alcohol in Liquid Phase over a Biochar-Supported Platinum Catalyst
Ariadna Fuente-Hernández, Roland Lee, Nicolas Béland, Ingrid Zamboni, Jean-Michel Lavoie
December 10, 2019 (v1)
Keywords: biochar, furfural, furfuryl alcohol (FA), hydrogenation, maple, platinum catalyst
In this work, the liquid phase hydrogenation of furfural has been studied using a biochar-supported platinum catalyst in a batch reactor. Reactions were performed between 170 °C and 320 °C, using 3 wt % and 5 wt % of Pt supported on a maple-based biochar under hydrogen pressure varying from 500 psi to 1500 psi for reaction times between 1 h and 6 h in various solvents. Under all reactive conditions, furfural conversion was significant, whilst under specific conditions furfuryl alcohol (FA) was obtained in most cases as the main product showing a selectivity around 80%. Other products as methylfuran (MF), furan, and trace of tetrahydrofuran (THF) were detected. Results showed that the most efficient reaction conditions involved a 3% Pt load on biochar and operations for 2 h at 210 °C and 1500 psi using toluene as solvent. When used repetitively, the catalyst showed deactivation although only a slight variation in selectivity toward FA at the optimal experimental conditions was observed.
Qualitative Analysis of Transesterification of Waste Pig Fat in Supercritical Alcohols
Jeeban Poudel, Malesh Shah, Sujeeta Karki, Sea Cheon Oh
December 10, 2019 (v1)
Keywords: biodiesel, supercritical ethanol, supercritical methanol, transesterification, waste pig fat
In this work, the characteristics of waste pig fat degradation using supercritical alcohols have been studied. Comparative analysis of the influence of supercritical methanol and supercritical ethanol as solvents on the transesterification was the primary focus of this research. The experiments were carried out with waste pig fat to alcohol weight ratios of 1:1.5 (molar ratio: 1:40.5 for methanol and 1:28 for ethanol), 1:2.0 (molar ratio: 1:54 for methanol and 1:37.5 for ethanol) and 1:2.5 (molar ratio: 1:67.5 for methanol and 1:47 for ethanol) at transesterification temperatures 250, 270 and 290 °C for holding time 0, 15, 30, 45 and 60 min. Increase in the transesterification and holding time increased the conversion while increase in alcohol amount from 1:1.5 to 1:2.0 and 1:2.5 had minimal effect on the conversion. Further, majority of the ester composition in using SCM as solvent falls in the carbon range of C17:0, C19:1 and C19:2 while that for SCE falls in the carbon range of C18:... [more]
Kinetic Studies and Moisture Diffusivity During Cocoa Bean Roasting
Leydy Ariana Domínguez-Pérez, Ignacio Concepción-Brindis, Laura Mercedes Lagunes-Gálvez, Juan Barajas-Fernández, Facundo Joaquín Márquez-Rocha, Pedro García-Alamilla
December 10, 2019 (v1)
Keywords: activation energy, cocoa bean roasting, diffusivity coefficients, kinetic models
Cocoa bean roasting allows for reactions to occur between the characteristic aroma and taste precursors that are involved in the sensory perception of chocolate and cocoa by-products. This work evaluates the moisture kinetics of cocoa beans during the roasting process by applying empirical and semi-empirical exponential models. Four roasting temperatures (100, 140, 180, and 220 °C) were used in a cylindrically designed toaster. Three reaction kinetics were tested (pseudo zero order, pseudo first order, and second order), along with 10 exponential models (Newton, Page, Henderson and Pabis, Logarithmic, Two-Term, Midilli, Verma, Diffusion Approximation, Silva, and Peleg). The Fick equation was applied to estimate the diffusion coefficients. The dependence on the activation energy for the moisture diffusion process was described by the Arrhenius equation. The kinetic parameters and exponential models were estimated by non-linear regression. The models with better reproducibility were the... [more]
Modeling and Observer-Based Monitoring of RAFT Homopolymerization Reactions
Patrick M. Lathrop, Zhaoyang Duan, Chen Ling, Yossef A. Elabd, Costas Kravaris
December 10, 2019 (v1)
Keywords: measurements with delay, multi-rate observer, nonlinear sampled-data system, parameter fitting, RAFT polymerization
Reversible addition−fragmentation chain−transfer (RAFT) polymerization of methyl methacrylate (MMA) is modeled and monitored using a multi-rate multi-delay observer in this work. First, to fit the RAFT reaction rate coefficients and the initiator efficiency in the model, in situ 1 H nuclear magnetic resonance (NMR) experimental data from small-scale (400 mL) reflux reactions is then used to validate the fitted model. The fitted model accurately predicts the polymer properties of the large-scale reactions with slight discordance at late reaction times. Based on the fitted model, a multi-rate multi-delay observer coupled with an inter-sample predictor and dead time compensator is designed, to account for the asynchronous multi-rate measurements with non-constant delays. The multi-rate multi-delay observer shows perfect convergence after a few sampling times when tested against the fitted model, and is in fair agreement with the real data at late reaction times when implemented ba... [more]
Equilibrium and Kinetic Studies of Biosorptive Removal of 2,4,6-Trichlorophenol from Aqueous Solutions Using Untreated Agro-Waste Pine Cone Biomass
Nadavala Siva Kumar, Mohammad Asif, Anesh Manjaly Poulose, Madala Suguna, Mansour I. Al-Hazza
December 10, 2019 (v1)
Keywords: 2,4,6-trichlorophenol, biosorption, kinetics and isotherm models, pine cone powder
The present work discusses the adsorptive removal of a phenolic pollutant, i.e., 2,4,6-trichlorophenol (TCP), using low cost untreated agricultural waste pine cone powder (PCP). The present biosorbent was thoroughly characterized with the help of FTIR, SEM, XRD, and CHN analysis. The presence of amine (-NH2), hydroxyl (-OH) and carbonyl (C=O) functional groups was detected by the FTIR analysis. The important biosorption factors like agitation time, biomass dosage, initial adsorbate concentration, and the initial pH were examined by batch studies. The biosorption kinetic process was fast, reaching equilibrium in 75 min. The experimental kinetic data revealed an excellent agreement with the pseudo second order (PSO) model. On the other hand, the Langmuir isotherm model best described the equilibrium data with the maximum biosorption capacity (qmax) of 243.90 mg/g. These values are better than the adsorption capacities of most agro-based untreated adsorbents previously reported in the lit... [more]
Effect of Assisted Ultrasonication and Ozone Pretreatments on Sludge Characteristics and Yield of Biogas Production
Tuan Minh Le, Phong Thanh Vo, Tuan Anh Do, Lien Thi Tran, Hoa Thi Truong, Thanh Thao Xuan Le, Yi-Hung Chen, Chia-Chi Chang, Ching-Yuan Chang, Quoc Toan Tran, Tran Thanh, Manh Van Do
December 10, 2019 (v1)
Keywords: biogas, ozonation, sludge pretreatment, solubilization, ultrasonic
The effects of ultrasonic and ozonation pretreatments on organic solubilization, anaerobic biodegradability, and biogas production were elucidated in this study. Two pretreatment methods for batch anaerobic digestion for biogas recovery with the same material and experimental conditions were the focus for comparison. Anaerobic digestion experiments were conducted at ambient temperature with the solid retention time set to 25 days. The obtained results indicated that the soluble chemical oxygen demand increased from 0.344 without pretreatment to 1.023 and 1.228 g/L with ultrasound and ozone pretreatments, respectively, whereas the yields of biogas production in the 25 days increased by 32.3 and 52.9% via ultrasonic irradiation and ozonation relative to the control case, respectively. The biodegradability of the organic compounds of the samples for the cases of ultrasound, ozone pretreatments, and control achieved 55.9, 64.31, and 39.18%, respectively, in terms of chemical oxygen demand... [more]
Siderite Formation by Mechanochemical and High Pressure−High Temperature Processes for CO2 Capture Using Iron Ore as the Initial Sorbent
Eduin Yesid Mora Mendoza, Armando Sarmiento Santos, Enrique Vera López, Vadym Drozd, Andriy Durygin, Jiuhua Chen, Surendra K. Saxena
December 10, 2019 (v1)
Keywords: calcination, Carbon Dioxide Capture, carbonation, carbonation kinetics, iron ore, mechanochemical reactions, recyclability
Iron ore was studied as a CO2 absorbent. Carbonation was carried out by mechanochemical and high temperature−high pressure (HTHP) reactions. Kinetics of the carbonation reactions was studied for the two methods. In the mechanochemical process, it was analyzed as a function of the CO2 pressure and the rotation speed of the planetary ball mill, while in the HTHP process, the kinetics was studied as a function of pressure and temperature. The highest CO2 capture capacities achieved were 3.7341 mmol of CO2/g of sorbent in ball milling (30 bar of CO2 pressure, 400 rpm, 20 h) and 5.4392 mmol of CO2/g of absorbent in HTHP (50 bar of CO2 pressure, 100 °C and 4 h). To overcome the kinetics limitations, water was introduced to all carbonation experiments. The calcination reactions were studied in Argon atmosphere using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. Siderite can be decomposed at the same temperature range (100 °C to 420 °C) for the samples... [more]
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