فهرست مطالب

Iranian Journal of Chemistry and Chemical Engineering - Volume:38 Issue: 4, 2019
  • Volume:38 Issue: 4, 2019
  • تاریخ انتشار: 1398/05/10
  • تعداد عناوین: 25
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  • Fatemeh Masoodiyeh, Javad Karimi Sabet *, Mohammadreza Mozdianfard Pages 1-9
    Like any other precipitation process, in supercritical water hydrothermal synthesis (SWHS), the need to improve product quality and minimize production cost requires understanding and optimization of Particle Size Distribution (PSD). In this work, using Population Balance Equation (PBE) containing nucleation and growth terms, the reactive precipitation of zirconia nanoparticles prepared by SWHS in the batch reactor was modeled. An optimization method using genetic algorithm function in MATLAB environment was developed to find simultaneously the kinetic parameters of nucleation and crystal growth rates, used for predicting PSD in PBE. The methodology developed evaluated kinetic parameters at comparable order of magnitudes to those presented in the literature, indicating a reasonable validation of the modeling method adopted. PSD results, however, showed a weak convergence of experimental and those predicted, suggesting that here, aggregation most likely played a considerable role in the PBE modeling of SWHS preparation of the zirconia nanoparticles.
    Keywords: Zirconia, Supersaturation, nucleation, growth rate, supercritical hydrothermal synthesis
  • Rajini Murugesan, Karunakaran Marimuthu *, Kasirajan Kasinathan, Maheswari Sathiah, Chandramohan Rathinam Pages 11-17
    Cadmium oxide (CdO) thin films were deposited on the glass substrate by the modified SILAR method, using cadmium acetate dihydrate and ammonium hydroxide aqueous solution as precursors. The structural, surface morphological, elemental composition and optical properties of the deposited films were investigated via X-Ray Diffraction (XRD), scanning electron microscopy, EDAX, optical absorption, photoluminescence, and FT-IR spectroscopy. The XRD analysis reveals that the films were polycrystalline with cubic structure. Both crystallinity and grain size were found to increase with increasing solution concentration. The energy-dispersive spectroscopic analysis confirmed the presence of Cd and O elements. The films exhibited a maximum transmittance (50% - 70%) in the infra-red region. Transmittance was found to increase with increasing precursor concentration and estimated bandgap energy (Eg) was in the range of 2.17 – 2.21 eV.
    Keywords: CdO, thin films, XRD, SILAR, Optical studies
  • Sajjad Keshipour *, Maryam Houshyar, Zahra Fatemi Pages 19-26
    Esterification reactions of some polyols and diols were investigated in the presence of SnO2 and nano-SnO2 and the results were compared with the catalyst-free conditions. High conversions were obtained for most of the reactions in the presence of SnO2 and nano-SnO2 which shows the high catalytic activity of SnO2 and nano-SnO2 for the esterification reaction. Low cost of the catalysts compared to alkyl tins, high safety compared to protic acids such as sulfuric acid and high chemical and thermal stability of the catalysts make the reactions interesting for the large-scale production of various polyol esters. Due to the important role of the polyol esters in various industries especially in the lubricant industry, the introduced approach can be interesting.
    Keywords: Esterification, Polyol esters, Diesters, SnO2, Nanoparticles
  • Sajedeh Zandieh *, Navabeh Nami, Zinatossadat Hossaini Pages 27-35

    The aim of doing this research is a one-pot three-component synthesis of 1-aminoalkyl-2- naphthol and naphthoxazine derivatives using the condensation of β-naphthol with various aldehydes and amines in the presence of ionic liquid {[(secondary butyl) methyl] imidazolium bromide} {[sec-bmim]+ Br-, as an efficient catalyst and solvent. The catalyst was prepared according to a previously published literature procedure using 1-methyl imidazole and 2-bromo butane. Furthermore, the catalyst could be recovered conveniently and reused. This protocol has proved to be efficient in terms of good to excellent yields, lower reaction times, mild reaction conditions, eco-friendly methodology, clean reaction profiles, and a simple work‐up procedure. The reactions carried out in 25˚C and mild reaction conditions without any need to high temperature.

    Keywords: Ionic liquid, {[sec-bmim]+Br-}, multicomponent reaction, aminoalkylnaphthol, naphthoxazine
  • Mahesh Kancherla, Mohan Reddy Katlakanti, Kondaiah Seku, Vijayakumar Badathala * Pages 37-49
    Synthesis of 2,3-dihydroquinazolin-4(1H)-ones using H3BO3/montmorillonite K10 (H3BO3/mont K10) catalyst has been reported. H3BO3/mont K10 and H3BO3/mont K30 have been prepared and used as catalysts in the reaction between anthranilamide and benzaldehyde to prepare 2-phenyl-2,3-dihydroquinazolin-4(1H)-one. The catalysts have been characterized for their physico-chemical properties by XRD, IR, BET surface analysis, TGA, SEM, and DRIFTS. H3BO3/mont K10 has shown better catalytic activity among the catalysts tested for the synthesis of 2-phenyl-2,3-dihydroquinazolin-4(1H)-one. The reaction conditions have been optimized for 2-phenyl-2,3-dihydroquinazolin-4(1H)-one and the reusability of H3BO3/mont K10 has also been investigated. Several 2,3-dihydroquinazolin-4(1H)-one derivatives have been synthesized in good to excellent yields using the optimized reaction conditions.
    Keywords: Clays, catalysts, H3BO3, mont K10, H3BO3, mont K30, 2, 3-dihydroquinazolin-4(1H)-ones
  • Ahmad Poursattar Marjani *, Jabbar Khalafy, Paria Eslamipour, Mehdi Ahmadi Sabegh Pages 51-57
    Multicomponent condensation of 1-naphthol, malononitrile, and arylglyoxals in the presence of Mg-Al hydrotalcite under solvent-free MicroWave (MW) conditions gave a new series of 2-amino-4-aroyl-4H-benzo[h]chromene-3-carbonitriles in high yields (70-89%). The structure of all products was elucidated by their FT-IR, 1H-NMR, 13C-NMR spectral data and microanalysis.
    Keywords: Arylglyoxals, 1-Naphthol, Malononitrile, Mg-Al hydrotalcite, 4H-benzo[h]chromenes, Microwaves, multicomponent reaction
  • Ismail Khalil Warad *, Mohammed Al Nuri, Oraib Ali, Ibrahim M. Abu Reidah, Assem Barakat, Taibi Ben Hadda, Abdelkader Zarrouk, Smaail Radi, Rachid Touzani, Elmsellem Hicham Pages 59-68

    Two new hexahydropyrimidine compounds were prepared in high yield by condensation of an equimolar amount of 1,3-diamine with 2-dipyridylketone at room temperature in dichloromethane. The desired hexahydropyrimidine structures were confirmed on the basis of their UV-Visible, elemental analysis, FT-IR, 1H-NMR, TG/DTG, and EI-MS data. Hirschfield and DFT/B3LYP theoretical analyses were performed and their output results were compared to experimental data.

    Keywords: Hexahydropyrimidine, Hirschfield surface, NMR, DFT
  • Satya Deepika Neelapala, Naveen Lashok Yaranal, Harshini Dasari * Pages 69-77
    La1-xSrxAlO3 (x=0 to 0.4) perovskite materials were synthesized by the reverse strike co-precipitation method and their soot oxidation activity was evaluated. All the catalysts synthesized were characterized using XRD, BET specific surface area, FESEM and XPS techniques. As analyzed by XRD, La1-xSrxAlO3 perovskite from x=0 to 0.35 showed the formation of the rhombohedralphase, while for La0.6Sr0.4AlO3 sample the secondary phases SrO, La2O3, and Al2O3 were also noticed. Sr-doped samples exhibited higher BET specific surface area when compared to pure LaAlO3. FESEM analysis showed that there is a change in morphology upon doping of Sr into LaAlO3 lattice. The O1s spectra observed from XPS analysis showed that the La0.75Sr0.25AlO3 sample contained higher amounts of adsorbed oxygen. La, Sr, and Al existed in +3, +2 and +3 oxidation states respectively in all the synthesized samples as confirmed by XPS. Soot oxidation activity tests showed that La0.75Sr0.25AlO3 exhibited higher catalytic activity relative to other catalysts due to the enhanced amount of reactive adsorbed oxygen species.
    Keywords: Sr-doped LaAlO3, Reverse strike co-precipitation synthesis, Soot Oxidation, Oxygen vacancies
  • Ahmad Nakhaei *, Shirin Ramezani Pages 79-90

    The novel fluorescentheterocyclic bidentate ligands have been synthesized by the high yields reaction of 8-(4-chlorophenyl)-3-Iso-butyl-3H-imidazo[4',5':3,4]benzo[1,2-c]isoxazol-5-amine with p-hydroxybenzaldehyde and p-chlorobenzaldehyde. The ligands reacted with Zn(II) ion to gained novel complexes. The optical properties of these structures were checked and the outcomes represented that they showed interesting photophysical properties. Optimized geometries and assignment of the IR bands and NMR chemical shifts of the new complexes were also computed by using Density Functional Theory (DFT) methods that were in good agreement with the experimental values, confirming the suitability of the optimized geometries for Zn(II) complexes. These new compounds have shown potent antibacterial properties and their antibacterial activity (MIC) against Gram-positive and Gram-negative bacterial species were also specific.

    Keywords: Zn(II) complex, Antibacterial activity, Schiff Base, Bidentate ligand, Density Functional Theory (DFT)
  • Jagannath Roy *, Saikat Maitra Pages 91-100
    Aluminosilicate gel precursor having mullite composition was synthesized from inorganic salts of aluminum and silicon by employing the sol-gel method. Chemical analysis, surface area, and bulk density measurements were performed to characterize the dried gel. The course of the palletization was examined by FT-IR analysis which confirmed the diphasic nature of the gel. SEM and XRD analysis were performed to study microstructure and phase development. ThermoGravimetric (TG) analysis of the dried gel was performed at multiple heating rates and from the results obtained; kinetics of thermal dehydration was studied by applying Friedman differential and Kissinger-Akahira-Sunose integral isoconversional procedures. It was observed that the total dehydration process of the gel was accomplished by two different stages and both the stages followed second-order rate kinetics. The first stage was assigned to the dehydration of silicon hydroxide gel whereas the second stage was associated with aluminum hydroxide gel dehydration.
    Keywords: Sol-gel process, Dehydration kinetics, Activation Energy, Friedman method, Kissinger-Akahira-Sunose approximation
  • Farid Mirhoseini, Ali Reza Salabat * Pages 101-114
    This research work intended to study some important operational parameters on the photocatalytic activity of a new type of poly(methyl methacrylate) (PMMA)/IL-TiO2 nanocomposite, prepared by microemulsion method. For the first step, it is confirmed that the prepared nanocomposite has a significant effect on photodecomposition of the Trypan Blue (TB), as an anionic hydrophilic azo dye, and good antibacterial activity against Bacillus spp., as Gram positive bacteria, under visible light. After that, the operational parameters such as TiO2 content in photocatalyst, the thickness of the nanocomposite film, visible light intensity, and pH of the solution have been studied. In order to have a precise study on the photocatalytic performance of the prepared nanocomposite, the hydroxyl radical dosage in photocatalytic experiments and oxidative stress in the antibacterial experiment have been measured. This strategy was performed to show the extreme effect of TiO2 dosage on the photocatalytic activity of the nanocomposite.
    Keywords: Poly(methyl methacrylate), Ionic liquid, TiO2 Nanoparticles, Photodecomposition, Nanocomposite
  • Dragana Blagojević, Dragica Lazić *, Dragana Kešelj, Branko Škundrić, Pero Dugić, Gordana Ostojić Pages 115-125
    The X-ray fluorescence spectrometry and the MA.BM.006 reference spectrophotometric methods were used to determine the content of SiO2 (%) in bauxites from different deposits. The treatment of samples prior to the analysis involved the following steps: annealing, melting using the borax method,  and the formation of beads. Certified reference bauxite samples were used for the calibration curve. The calibration curve was produced with the correlation coefficient of r =0.9999 and the standard error of  S = 0.0246. The average residual value between the content of SiO2 determined using the XRF method, and the reference method was 0.045, with a standard deviation of 0.068. The XRF method was statistically verified by the F- and t- tests (using the standard sample and the reference method). The values obtained in the tests show that the XRF method yields accurate results and that there are no standard errors.
    Keywords: XRF method, spectrophotometric method, bauxite, silicon dioxide
  • Mohammad Mahmoodabadi, Hamid Khoshdast *, Vahideh Shojaei Pages 127-140
    Methylene blue was efficiently removed from aqueous solution by foam flotation using a rhamnolipid biosurfactant as a dye collector. The effects of four parameters, namely, pH (1.5–11.5), frother concentration (5–65 ppm), aeration rate (2–6 L/min) and rhamnolipid to methylene blue weight ratio (0.5–6.5), on dye removal were studied and optimized using response surface methodology. Results showed that dye removal increases by increasing of all parameters; however, the nonlinear trend was observed for the effects of frother concentration and rhamnolipid to methylene blue ratio. Optimum removal conditions, resulting in about 93% dye removal, was achievedat pH value of 11.5, methyl isobutyl carbinol (MIBC) concentration of 35 ppm, airflow rate of 4 L/min, and rhamnolipid to methylene blue ratio of 3.5, after only 10 min flotation. Investigations also showed that the presence of electrolyte can significantly decrease the removal efficiency. Kinetics study revealed that the process follows the first-order model with a rate constant of about 0.288 sec- This study demonstrates that rhamnolipid could be considered as a potentially efficient and environment-friendly collector for the treatment of dye contaminated wastewater.
    Keywords: Methylene blue, Rhamnolipid biosurfactant, Foam flotation, Experimental design, Water recovery
  • Hamid Doosthosseini, Zeinab Salehi *, Mojtaba Rezaei, Pejman Ghelich Pages 141-148
    In this work, a novel and modified method for the solvent purification of Curcumin is presented, a composite of normal hexane & 2-propanol solvents was used to separate the fat content and other impurities. The process was modeled considering the response surface methodology as described by the central composite design. The adjusted R-squared was 0.9443 indicating the variation between the regressors (solvent composition, solvent-to-oleoresin ratio, and temperature) in relation to the selected responses (product purity and process yield) were well described by the constructed model. Optimum conditions were 90% w/w 2-propanol in the solvent, 1.5 solvent-to-oleoresin weight ratio and 5°C temperature with predicted 95.94% purity and 35.77% yield, F values were significant for both models. Therefore, the development of high purity products is achievable with this novel method with economic advantages.
    Keywords: curcumin, Purification, Response surface methodology, FT-IR, NMR, Curumin Gelatin Complex
  • Sajad Moradi, Elham Moosavi, Ramin Karimzadeh * Pages 149-165
    The main objective of this research is stability determination of activated carbon adsorbent at fixed bed adsorption column for desulfurization of diesel fuel by mathematical modeling. This model is based on mass balances. Equations that are the outcome of mass balances are known as the second degree of partial differential equations, and they must be solved together simultaneously to generate appropriate breakthrough curves at the end of the bed. On the other hand, running momentum balance by using some assumptions, lead to the Ergun equation which clearly represents pressure drop through adsorption bed. The mentioned equations have been solved simultaneously in MATLAB software and the solution method was the finite difference. After ensuring the validity of the model, scaling up is done to determine adsorbent stability and quantify its performance in an industrial dimension bed. Then the effective parameters on the bed operation and adsorbent stability were identified. Also, the batch adsorption isotherm experiments were carried out at room temperature to determine the maximum capacity of adsorbent in sulfur compound adsorption. Using capped bottles containing 10 mL solutions which contain dibenzothiphen (DBT) dissolved in n-decane and 0.1 g of activated carbon that were equilibrated for 5 hours. Concentrations of Thiophenic Compound (TC) solutions were 330,462,660,990, and 1,320 mg/L of TC. The experiment method was according to some author’s studies. The fluid velocity and mass transfer resistance for diffusion in adsorbent’s pores are the most important parameters in adsorption bed’s behavior and generating of breakthrough curves. The lowest the fluid velocity, the more time the fluid stays in bed and the bed's efficiency raises in terms of pollutant removal accordingly, as well as bed saturated in a longer time.
    Keywords: Adsorption, Mathematical modeling, Desulfurization, Diesel Fuel, Activated Carbon, stability
  • Toktam Abbasniabase, Ahmad Asoodeh, Gholam Reza Habibi, Ali Reza Haghparast * Pages 167-172
    The intracellular protozoan parasite, Theileria annulata, induces uncontrolled proliferation and transformation in bovine B lymphocytes and monocytes in blood circulation andlymph nodes of host cells. This uncontrolled replication happens in the macroschizont stage of the life cycle of the parasites. The development of a rapid and efficient technique is likely to necessitate for isolation of purified schizonts from host cells. This is necessary for the isolation of highly purified RNA, protein or glycoproteins of schizonts from host cells. This study aimed to isolate the purified schizont based on the aerolysin–nocodazole technique. Aerolysin which was purified from gram-negative pathogen aeromonas hydrophila has an ability to form discrete channels and unstable eukaryotic cell membranes in 0C• and low concentration.  Nocodazole used for parasite separation from the microtubule network of infected lymphocytes and monocytes. In purified schizonts, no large nucleus of host cells visualized in giemsa and DAPI staining. The isolated schizonts were free and intact from host cells. Intact T.annulata schizonts obtained from this study are suitable for purification of RNAs, proteins, glycolipids, and glycoproteins of schizonts free of host cell debris.
    Keywords: Aerolysin, Schizont, Theileria annulata, Nocodazole, Percoll, Leukocytes
  • Hamid Zentou, Nurul Shafiqah Rosli, Cham Hue Wen, Kafel Abdul Azeez, Chandima Gomes * Pages 173-182
    In the last few decades, finding alternatives to fossil fuels has become a hot issue across all international frontiers. The Intergovernmental Panel on Climate Change (IPCC) has shed light on the feasibility of using biofuels to meet the growing energy demand as well as to reduce CO2 emissions which are a major cause of global warming, especially in the transportation sector. The production and use of biofuels in developing countries have further advantages, including social and economic benefits. On the other hand, the biofuel industry in some developing countries is facing critical challenges related to food security, land availability, production cost, etc. In this regard, several studies have recently been conducted to address these issues, and this paper comprehensively reviews these cases with respect to the successes, failures, and challenges faced by developing countries, such as Brazil, Africa and India, in expanding their biofuel production. It is clear that all the efforts devoted to promoting the biofuel sector are still insufficient to come over the challenges associated with biofuel production despite the achievements realized in some experiences as Brazil. However, the Brazilian experience cannot be spread over other countries. Implementation of policies with regard to the specifications of each country that integrate with the other sector without intersection is highly recommended. Moreover, further efforts are needed from scientists to reduce biofuel production costs, which may promote the biofuel market as an alternative to fossil fuel.
    Keywords: Biofuel, challenge, success, developing countries, Bioethanol
  • Rajeev Kumar Dohare *, Alok Singh, Priyanka Jain, Kailash Singh, Sushant Upadhyaya, Madhu Agrawal Pages 183-191
    Ethanol is largely used as a solvent in the synthesis of varnishes and perfumes. It is also used as a preservative for biological products, fuel, and gasoline additives. Anethanol-water mixture, normally obtained by fractional distillation yields an azeotropic solution consisting of approximately 95 w% of ethanol. The synthesis of ethanol in a reactive distillation column with the azeotropic feed at 20ºC with ethylene oxide as another reactant feed for the reaction with water to produce ethylene glycol was simulated in Aspenplus. Simulated results show 98.82 mol% purity of ethanol in the reactive distillation column. In order to reduce the energy consumption in reactive distillation, a Reactive Heat Integrated Distillation Column (R-HIDiC) is proposed for the same purity of ethanol product. From the simulated results, it has been found that the overall energy utilization in the proposed distillation column is reduced by 65% as compared to the conventional reactive distillation column. The pressure profile, temperature profile, and concentration profile of the reactive distillation column and the column proposed are also compared.
    Keywords: Reactive heat-integrated distillation column, Simulation, ethylene oxide, ethylene glycol, ethanol-water
  • Shahin Khosharay *, Mariano Pierantozzi Pages 193-208

    This work investigates the modeling of the surface tension and the interface of liquid mixtures. Nine binary liquid mixtures of (DMSO+alcohols), (2-Propanol+2,2,4-trimethylpentane), (Tetrahydrofuran+2-Propanol), (Tetrahydrofuran+2,2,4-trimethylpentane), and (ethano+glycerol) are considered. Additionally, one ternary liquid mixture of (Tetrahydrofuran+2-Propanol+2,2,4-trimethylpentane) is considered. Firstly, two correlations were used to model the surface tension. One of these correlations has one adjustable parameter, and the other has five fitting parameters. Then the model based on the equality of the chemical potentials at the interface and the liquid phase was used. The surface tension and interfacial composition are computed by using this model. This approach was used in two ways, including activity-based and fugacity-based models. The UNIFAC activity model and PSRK EOS equation of state were applied to compute activity and fugacity, respectively. Moreover, the effect of the partial molar volume on predictions was investigated. The results of the applied models show that the correlation with five adjustable parameters and the fugacity-based model have the best results. Also, the increase in the non-ideality of these systems results in a better performance of the fugacity-based model, therefore the application of the partial molar volume is necessary.

    Keywords: Surface tension, Liquid mixtures, Activity, Fugacity, Correlation
  • Syed Kazmi, Zahoor Awan *, Saud Hashmi Pages 209-221
    With the increased amount of focus is being put towards reducing the emissions results from fossil fuel usually composed of hydrocarbons and impurities. The study aim at utilizing the ability of 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF4]. Ionic liquid as the suitable solvent for the extraction of the thiophene and its derivatives from the model gasoline. The process simulation was performed on the ASPEN plus(V8.8) with the help of UNIFAC as the thermodynamic model, previously NRTL was used as the method to calculate the interaction. The different parametric analysis was calculated for the removal of thiophene-based compounds from model gasoline. Outcomes acquired shows the significance of imidazolium-based ionic liquid(ILs) 1-octyl-3-methylimidazolium tetrafluoroborate towards the separation about S-contents from the liquid fuels at an optimum process condition of 30ᵒC and 2 bar pressure with the 1:1 ratio of ionic liquid and model gasoline which confirms the experimental outcomes obtained previously in the literature. By using these mild conditions, easy phase separation, high reusability, and various other process parameters have been established based on the process simulation model using ASPEN plus.
    Keywords: Imidazolium based ionic liquid, Unifac, Gasoline, Desulfurization, Thiophene
  • Majid Abedi Lenji, Masoud Haghshenasfard, Mahsa Baghban Salehi *, Asefe Mousavi Moghdam, Mohsen Vafaie Sefti Pages 223-236
    Excessive water production through fractures become an important problem in oil exploration of fractured reservoirs. For this purpose, polymer gels were prepared by crosslinking of aqueous solutions of polymer and crosslinker for the purpose of water management in high water cut fractured reservoirs. A copolymer of sulfonated polyacrylamide was used as polymer and chromium triacetate (Cr(OAc)3) and aluminum nitrate nonahydrate (Al(NO3)3.9H2O) were used as inorganic crosslinkers at 90oC. Two quadratic models were presented for the two inorganic polymer gel systems to predict the gelation time by using a central composite design which showed highly significant results. The results also showed that polymer concentration was the main effect on gelation time. Increasing polymer concentration leads to accelerate the gelation process and then decrease of gelation time. Based on the gelation time and strength of three dimensional structure of polymer gel, the selected polymer gels of Cr(OAc)3 and Al(NO3)3.9H2O were applied to study the performance of polymer gel system in fractured core with the same polymer concentration of 37071 ppm and the crosslinker concentration of 13096 ppm and 2707 ppm, respectively. Also, the gelation time of these polymer gels was determined 12 h and 34 h, respectively. For this purpose, the coreflooding test was carried out to measure the output flow rate before and after polymer gel treatment in order to calculate the Residual Resistance Factor (RRF). As a result, after polymer gel treatment, the output flow rate decreased intensively and by increasing injection pressure, the RRF decreased gradually. The polymer gels of Cr(OAc)3 and Al(NO3)3.9H2O in the fracture were renitent up to 70 and 60 bar against the water pressure drop, while these polymer gels were renitent up to 60 and 40 bar against the oil pressure drop, respectively. The polymer gel of Cr(OAc)3 demonstrated higher residual resistance factor than the polymer gel of Al(NO3)3.9H2O.
    Keywords: Polymer gel treatment, Inorganic crosslinker, Gelation time, Fracture core, Residual resistance factor
  • Reza Nasr *, Neda Rahaei Pages 237-250
    Falling film evaporators, due to their high heat transfer coefficients, low energy loss, rather a low holdup time, and the ability to handle high capacities have broad applications in food industries. Thus, this kind of evaporator is being used in the production of temperature sensitive compounds such as syrups. In this study, through modelling of the falling film evaporator with the use of Computational Fluid Dynamics (CFD) we have tried to investigate the effect of adding flow turbulator (baffles) on the inner side of the tubes and assess the key parameters for increasing the efficiency of the evaporator. The simulation was conducted using ANSYS FUENT (v 0.16.0). Results indicate that placing baffles would have a significant effect on increasing evaporator efficiency. The results of the parametric study showed that by installing baffles, the amount of juice evaporation rate can be increased, however, both the evaporator length and volume fraction can be reduced. The results showed that the heat transfer coefficient has increased from 10000 W/m2 °C in the case of the typical evaporator to 25000 W/m2 °C in the case of a baffled tube wall.
    Keywords: Falling film evaporator, Optimization, Simulation, CFD, Baffle
  • Ebrahim Taghinezhad *, Vali Rasooli Sharabiani, Mohammad Kaveh Pages 251-260
    The effects of hot air temperature (40, 50 and 60 oC) and Radiation Intensity (RI) (0.21, 0.31 and 0.41 w/cm2) on the response variables (drying time, Head Parboiled Rice Yield (HPRY), color value and hardness)) of parboiled rice were investigated. The drying was performed using hybrid hot air–infrared drying. The optimization of drying variables and the relationship between response variables and the influence factors were analyzed using response surface methodology (RSM).  Based on RSM results, the best mathematical model for prediction of HPRY, hardness and color value and drying time of samples was linear(R2= 0.96), quadratic(R2= 0.99), linear(R2= 0.93) and linear(R2= 0.99) equation, respectively. The HPRY (62.13- 68.13%) and hardness (130.27- 247.3 N) increased with increasing drying temperature and RI, while the color value (19.77- 18.03) and drying time (59.72- 34.41 min) decreased. The optimized parameters of drying were obtained 55 oC drying temperature and 0.41 w/ cm2 RI.
    Keywords: Hybrid drying, Parboiling, Quality, Rice, RSM
  • Muhammad Bilal *, Bibi Ambreen, Javed Ali, Irfana Shahid, Muhammad Adnan, Syed Hassan, Asad Ullah Khan Pages 261-272

    Titanium dioxide is semiconductor metal oxide having many applications in photocatalytic activities, cosmetics and in the food industry. It exists in three major crystalline forms: anatase, rutile and brookite. The solvents play a major role in the synthesis, stability and morphology of the metal oxide nanoparticles. It affects both the phase and particle size of metal oxide. The main focus of the present study is to establish the effects of solvent on the phase of TiO2 nanoparticle. Titanium dioxide (TiO2) nanoparticles have been synthesized by the sol-gel method using different solvents. The XRD results showed that the average crystallite size of all the samples was in the range of 5-25 nm. TiO2 nanoparticles prepared in different solvents gave different FT-IR peaks. AFM data clarified that the majority of samples showed spherical shape with average particle size ranging from 10-68 nm. The nanoparticles prepared in diethanolamine, acetic acid, and propionic acid solvents showed comparatively good antibacterial activity due to the rutile phase of the nanoparticles. the pH of the solvent also influences titanium dioxide structure and antibacterial properties

    Keywords: Solvents effect, Titanium dioxide Nanoparticles, Sol-gel Method, Phase of TiO2
  • Morteza Cheraghi, Ali Bagherian Sahlavani, Iraj Mohammad Fam * Pages 273-291

    Events leading up to the release of toxic chemicals in the processing plants are one of the main hazards of chemical industries that can endanger employees and also people in neighborhood. In this study, DOW's Chemical Exposure Index (CEI) is used to determine hazard distances of possible toxic chemical releases in one of the South Pars gas refineries. To do this, 318 considerable release scenarios were identified and by process parameters and CEI equations, airborne quantity, chemical exposure index and hazard distances were calculated. In the worst case of a toxic chemical release, hazard distance of the studied refinery is 10000 meters. The Sludge Catcher unit is the most dangerous unit in terms of toxic chemical release. In addition to the advantages of the CEI observed in this study also some limitations were observed including sensitivity to process parameters, no consideration of the material inventory and the concentration in the CEI calculations

    Keywords: Chemical Exposure Index (CEI), Release, Toxic, Airborne