Search for: initiator-concentrations
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    Asphaltenes biodegradation under shaking and static conditions

    , Article Fuel ; Vol. 117, issue. PART A , 2014 , pp. 230-235 ; ISSN: 00162361 Jahromi, H ; Fazaelipoor, M. H ; Ayatollahi, S ; Niazi, A ; Sharif University of Technology
    In this study the biodegradability of asphaltenes was investigated using four bacterial consortia isolated from oil contaminated soils and sludge. The species in consortium 1 were identified as Pseudomonas aeruginosa and Pseudomonas fluorescens. Consortium 2 contained Citrobacter amalonaticus and Enterobacter cloacae. Consortium 3 contained only one species identified as Staphylococcus hominis, and the species in consortium 4 were identified as Bacillus cereus, and Lysinibacillus fusiformis. Spectrophotometry at 281 nm wavelength was applied to quantify asphaltenes biodegradation. The biodegradation tests were performed in flasks with the initial asphaltenes concentrations of 2, 4, 10, 20,... 

    Theoretical and experimental investigations of the inverse emulsion polymerization of acrylamide

    , Article Journal of Applied Polymer Science ; Volume 132, Issue 22 , February , 2015 ; 00218995 (ISSN) Abdi, A ; Shahrokhi, M ; Ahmad Ramazani, S. A ; Vafa, E ; Sharif University of Technology
    John Wiley and Sons Inc  2015
    In this study, the inverse emulsion polymerization modeling of polyacrylamide with population balance equations (PBEs) was performed. The PBEs were derived on the basis of the zero-one kinetic model. The effects of the surfactant steric barrier and surfactant reaction with radicals, including monomeric radicals, on the radical entry rate into the particle were taken into account. In the modified model, the coagulation phenomenon was included through consideration of the effects of forces not included in the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory; these include hydration and steric forces in addition to DLVO forces. The effects of the surfactant and initiator concentrations on... 

    Removal of humic acid from aqueous solution using photocatalytic reaction on perlite granules covered by nano TiO2 particles

    , Article Journal of Molecular Liquids ; Volume 242 , 2017 , Pages 357-363 ; 01677322 (ISSN) Joolaei, H ; Vossoughi, M ; Rashidi Mehr Abadi, A ; Heravi, A ; Sharif University of Technology
    Humic acid (HA) constitutes a large portion of natural organic matter (NOM), and is the main precursor of toxic and cancerogenic Trihalomethanes compounds, formed during chlorination of drinking water. Therefore, it is essential that the humic acid be eliminated from water before treating it. The present study aims to investigate the photocatalytic degradation of humic acid (HA) using TiO2 nanoparticles immobilized on perlite granules (TIP), irradiated by UV light in a photoreactor. Samples of coated perlites were prepared by a dip coating method using a commercial powder of TiO2. Characteristics of the prepared samples were evaluated by X-ray and scanning electron microscope techniques.... 

    Fluoride ions removal using yttrium alginate biocomposite from an aqueous solution

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 30, Issue 1 , 2017 , Pages 1-6 ; 17281431 (ISSN) Kosari, M ; Sepehrian, H ; Sharif University of Technology
    Materials and Energy Research Center  2017
    Removal of fluoride ions was investigated using a new adsorbent of yttrium alginate biocomposite (YALG). Effect of various parameters such as pH, contact time, initial concentration of fluoride ions and temperature on the sorption capacity of adsorbent was studied. Performing a mathematical assessment of fluoride sorption, isotherm and kinetics models including Freundlich & Langmuir isotherms and pseudo first & second order kinetics were applied on experimental equilibrium results through this work. Isotherm analysis revealed that Langmuir model showed a better evaluation from sorption equilibrium data than Freundlich. Based on kinetics evaluation, the pseudo second-order equation was... 

    Data-based modeling and optimization of a hybrid column-adsorption/depth-filtration process using a combined intelligent approach

    , Article Journal of Cleaner Production ; Volume 236 , 2019 ; 09596526 (ISSN) Salehi, E ; Askari, M ; Aliee, M. H ; Goodarzi, M ; Mohammadi, M ; Sharif University of Technology
    Elsevier Ltd  2019
    Lack of robust techniques for optimization of hybrid separation systems is obvious in the literature. A novel hybrid approach for modeling and optimization of a hybrid process consisting of fixed-bed adsorption column (FBAC) and dead-end filtration (DEF) for the removal of methylene blue from water was presented. Artificial neural network (ANN), response surface methodology (RSM) and genetic algorithm (GA) were used for this purpose. ANN was employed to successfully approximate the breakthrough curves. Central composite design was used to investigate the impact of the operating variables, i.e. feed flowrate, initial concentration, adsorption bed length, and filter type on the removal rate as... 

    Adsorptive desulfurization of wild naphtha using magnesium hydroxide-coated ceramic foam filters in pilot scale: Process optimization and sensitivity analysis

    , Article Chemical Engineering and Processing - Process Intensification ; Volume 152 , 2020 Salehi, E ; Askari, M ; Afshar, S ; Eidi, B ; Aliee, M. H ; Sharif University of Technology
    Elsevier B.V  2020
    Ultra-deep desulfurization for production of clean fuels is of great significance from environmental outlook. In this paper, adsorptive desulfurization (ADS) of wild naphtha was investigated in pilot scale using Mg(OH)2-impregnated aluminosilicate ceramic foam filters (ASCFs) as adsorbent. Effects of four operating parameters including temperature, pressure, adsorption bed length and initial sulfur concentration on sulfur removal efficiency of the process were studied via central composite design of experiment methodology. Sobol's sensitivity analysis was employed to quantitatively determine the impacts of the operating parameters on the removal performance of the separation system. The... 

    Reductive leaching of indium from the neutral leaching residue using oxalic acid in sulfuric acid solution

    , Article International Journal of Minerals, Metallurgy and Materials ; Volume 28, Issue 3 , 2021 , Pages 373-379 ; 16744799 (ISSN) Maddah, F ; Alitabar, M ; Yoozbashizadeh, H ; Sharif University of Technology
    University of Science and Technology Beijing  2021
    The present study evaluates the reductive leaching of indium from indium-bearing zinc ferrite using oxalic acid as a reducer in sulfuric acid solution. The effect of main factors affecting the process rate, including the oxalic-acid-to-sulfuric-acid ratio, stirring rate, grain size, temperature, and the initial concentration of synergic acid, was precisely evaluated. The results confirmed the acceptable efficiency of dissolving indium in the presence of oxalic acid. The shrinking-core model with a chemical-reaction-controlled step can correctly describe the kinetics of indium dissolution. On the basis of an apparent activation energy of 44.55 kJ/mol and a reaction order with respect to the... 

    Theoretical study of diffusional release of a dispersed solute from a hollow cylindrical polymeric matrix

    , Article Scientia Iranica ; Volume 28, Issue 3 , 2021 , Pages 1428-1435 ; 10263098 (ISSN) Jooybar, E ; Tajsoleiman, T ; Abdekhodaie, M. J ; Sharif University of Technology
    Sharif University of Technology  2021
    The present study proposes an exact solution for the release kinetic of a solute from inside a hollow cylindrical polymeric matrix into an infinite medium when the initial concentration of the solute (A) is greater than the solubility limit (Cs). A combination of analytical and numerical methods was used to calculate the solute concentration profile and the release rate. The model was developed for two different conditions including: (1) The release medium was flowing through the hollow cylinder in which the boundary layer may be neglected, and (2) The release medium inside the hollow cylinder was stagnant where the boundary layer needed to be considered. The results indicated that the... 

    Removal of zirconium from aqueous solution by Aspergillus niger

    , Article Scientia Iranica ; Vol. 21, Issue. 3 , 2014 , pp. 772-780 ; ISSN: 10263098 Kalantari, H ; Yaghmaei, S ; Roostaazad, R ; Mohammad-Beigi, H ; Sharif University of Technology
    Removal of zirconium from its dilute aqueous solution using Aspergillus niger as a dried and living biomass was investigated. Through that, the effect of some operational parameters on biosorption, including pH, temperature, contact time, initial concentration of zirconium and dose of biomass, were studied. Based on the results, it was concluded that the uptake of zirconium by both dried and living biomasses is pH dependent, and maximum uptake was observed in pH = 3.1 for both biomasses. The maximum uptake capacity of the living biomass was obtained at 30°C. However, the biosorption of zirconium by dried biomass was not affected by temperature. The maximum uptake capacity for living and... 

    Studies on the recovery of uranium from nuclear industrial effluent using nanoporous silica adsorbent

    , Article International Journal of Environmental Science and Technology ; Volume 9, Issue 4 , October , 2012 , Pages 629-636 ; 17351472 (ISSN) Sepehrian, H ; Samadfam, M ; Asadi, Z ; Sharif University of Technology
    Springer  2012
    In this paper, the sorption of uranium onto nanoporous silica adsorbent in the presence of nitrate, sulfate, chloride, fluoride and phosphate was studied. The effect of contact time between the nanoporous sorbent and aqueous solution, pH and initial concentration of uranium was also investigated. Uranium sorption onto nanoporous silica adsorbent is a very fast process as sorption rate increases with pH increment. Optimum pH for uranium sorption was 4-8. Experimental sorption isotherm is successfully described by Langmuir and Freundlich models. The results obtained by batch experiments showed that the presence of high concentration of nitrate, sulfate, chloride and phosphate anions alone had... 

    Uranium(VI) sorption behavior onto amberlite CG-400 anion exchange resin: Effects of pH, contact time, temperature and presence of phosphate

    , Article Annals of Nuclear Energy ; Volume 48 , October , 2012 , Pages 21-24 ; 03064549 (ISSN) Semnani, F ; Asadi, Z ; Samadfam, M ; Sepehrian, H ; Sharif University of Technology
    Elsevier  2012
    In this paper, uranium sorption onto amberlite CG-400 anion exchange resin in the presence of phosphate anions was studied. The effect of contact time between the sorbent and aqueous solution, pH, initial concentration of uranium and temperature were also investigated. Kinetic studies show that uranium sorption onto amberlite CG-400 resin in the presence of phosphate is a fast process and follows pesudo-second-order kinetics. It was also found that the pH value and the presence of phosphate play very important roles in the uranium sorption onto CG-400 resin. Optimum pH for uranium sorption in the presence of phosphate anions was about 3.5. The experimental sorption isotherm is successfully... 

    Simulation and experimental evaluation of initiator and surfactant concentrations and temperature effects on styrene conversion and polymer particle size distribution in batch emulsion polymerization

    , Article Iranian Polymer Journal (English Edition) ; Volume 19, Issue 8 , Aug , 2010 , Pages 599-614 ; 10261265 (ISSN) Abedini, H ; Shahrokhi, M ; Sharif University of Technology
    Effects of initiator and surfactant concentrations and temperature on styrene conversion and polymer particle size distribution (PSD) in a batch emulsion polymerization are investigated through simulation and experimental studies. The detailed model based on population balance (zero-one model), accounting for nucleation, growth and coagulation phenomena has been used for prediction of particle size distribution. In checking the effect of initiator concentration on final PSD, it was noticed that when critical micelle concentration (CMC) is kept constant, the model cannot predict PSD very well. Thus, a correlation for calculating critical micelle concentration has been proposed and... 

    Idle time and gelation behavior in gelcasting process of PSZ in acrylamide system

    , Article Ceramic Transactions, 31 May 2009 through 5 June 2009 ; Volume 212 , JUL , 2010 , Pages 105-113 ; 10421122 (ISSN) ; 9780470876466 (ISBN) Sahraei Khanghah, N ; Faghihi Sani, M. A ; Sharif University of Technology
    Gelcasting is a novel forming method in fabricating complex three dimensional ceramic parts, and has many parameters and characteristics required to be specified. Up to now, few articles have been published on determination of the idle time of gelation precisely. In this work the chemorheology of gelation in aqueous solution of acrylamide and N, N′ methylenebisacrylamide monomer, and zirconia (PSZ) suspensions of this solution was investigated. As the viscosity of gel system increases abruptly in gelation point, idle time can be determined precisely by measurement of viscosity against time. Idle time can also be determined through temperature measurement against time since the reaction of... 

    Adsorptive behavior of an amberlite anion exchanger resin for uranium (VI) sorption in the presence of sulfate anions

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 29, Issue 2 , 2016 , Pages 170-175 ; 1728144X (ISSN) Kowsari, M. R ; Sepehrian, H ; Fasihi, J ; Arabieh, M ; Mahani, M ; Sharif University of Technology
    Materials and Energy Research Center 
    Uranium (VI) sorption using an anionic exchanger resin, namely Amberlite IRA910, in the presence of sulfate anions was the subject of current study. Batch sorption experiments were carried out to evaluate the influence of operational parameters such as pH, contact time, initial concentration and existence of various anions (including phosphate, sulfate, chloride, fluoride, and nitrate) in the solution on Amberlite IRA910 sorption behavior. Experiments revealed that uranium adsorption was fulfiled at pH>3 and 50 min to amount of 80%. Kinetics study revealed that the pseudo-second-order model showed better curve-fitting regression of the experimental data than the pseudo-first-order one.... 

    Amino functionalized hierarchically produced porous polyacrylamide microspheres for the removal of chromium(VI) from aqueous solution

    , Article Journal of Porous Materials ; Volume 24, Issue 6 , 2017 , Pages 1705-1715 ; 13802224 (ISSN) Karimi, M ; Nematollahzadeh, A ; Shojaei, A ; Sharif University of Technology
    Porous silica microspheres were used as hard template to produce porous polyacrylamide microspheres. The microspheres were modified with ethylenediamine and used for the removal of hexavalent chromium [Cr(VI)] from aqueous solution. Scanning electron microscopy, thermogravimetry analysis, and Fourier transform infrared spectroscopy were utilized to characterize the adsorbent. Adsorption of Cr(VI) was conducted in batch and dynamic modes, and effect of various parameters including solution pH, adsorbent dose, initial concentration of Cr(VI) and agitation time on the adsorption process was studied. The optimum pH for the maximum adsorption (124 mg Cr(VI)/g dry polymer) was found to be 3.... 

    Aminated-Fe3O4 nanoparticles filled chitosan/PVA/PES dual layers nanofibrous membrane for the removal of Cr(VI) and Pb(II) ions from aqueous solutions in adsorption and membrane processes

    , Article Chemical Engineering Journal ; Volume 337 , 1 April , 2018 , Pages 169-182 ; 13858947 (ISSN) Koushkbaghi, S ; Zakialamdari, A. A ; Pishnamazi, M ; Fasih Ramandi, H ; Aliabadi, M ; Irani, M ; Sharif University of Technology
    Elsevier B.V  2018
    In the present study, dual layers mixed matrix membranes (MMMs) were prepared by incorporating aminated-Fe3O4 nanoparticles into the chitosan/polyvinyl alcohol nanofibers over the polyethersulfone (PES) membrane for the removal of Cr(VI) and Pb(II) ions in batch adsorption and membrane processes. The synthesized aminated-Fe3O4 nanoparticles were characterized using XRD, FESEM and FTIR analysis. The morphology and roughness of membranes were determined using SEM, TEM and AFM analysis. The effect of adsorption operating parameters such as pH (2–7), contact time (0–60 min), initial concentration of metal ions (20–1000 mgL−1) and temperature (30–50 °C) on the Cr(VI) and Pb(II) ions sorption was... 

    Fabrication of novel chitosan-g-PNVCL/ZIF-8 composite nanofibers for adsorption of Cr(VI), As(V) and phenol in a single and ternary systems

    , Article Carbohydrate Polymers ; Volume 224 , 2019 ; 01448617 (ISSN) Bahmani, E ; Koushkbaghi, S ; Darabi, M ; ZabihiSahebi, A ; Askari, A ; Irani, M ; Sharif University of Technology
    Elsevier Ltd  2019
    The chitosan-grafted-poly(N-vinylcaprolactam) (chitosan-g-PNVCL) nanofibers were synthesized via electrospinning method. ZIF-8 metal-organic frameworks nanoparticles were incorporated into the nanofibers for adsorption of Cr(VI), As(V) and phenol from water. The BET, FTIR, XRD and SEM analysis were carrfried out to obtain the characteristics of nanofibers. The optimum parameters of ZIF-8 content, pH, contact time, adsorbent dosage, and initial concentration of adsorbates on the Cr(VI), As(V) and phenol removal were studied. The reusability of synthesized nanofibers for five sorption-desorption cycles was also examined. The maximum experimental adsorption capacity of the... 

    Magnetic polyresorcinol@CoFe2O4@MnS nanoparticles for adsorption of Pb(II), Ag(I), Cr(VI) and bacteria from water solution

    , Article Polymer Bulletin ; Volume 77, Issue 4 , 2020 , Pages 1893-1911 Kaveh, R ; Alijani, H ; Beyki, M. H ; Sharif University of Technology
    Springer  2020
    This study devoted to developing an efficient adsorbent with the excellent adsorption performance of heavy metals and bacteria capturing. Polyresorcinol@CoFe2O4 was synthesized by one-step hydrothermal reaction followed with doping MnS nanoparticles. The composite was characterized with SEM,TEM, BET, EDX, XRD, zeta potential measurement and Raman spectroscopy. Optimization of effective parameters on heavy metal adsorption, i.e., pH, contact time and adsorbent dosage, was performed with response surface methodology using Box–Behnken design. The sorbent showed good performance for Pb(II), Ag(I) and Cr(VI) removal with convenient magnetic separation operation with an adsorption capacity of... 

    Synthesis and characterization of bagasse poly(methyl methacrylate) graft copolymer

    , Article Macromolecular Symposia ; Volume 274, Issue 1 , 2008 , Pages 49-54 ; 10221360 (ISSN) Sarvi, I ; Pourjavadi, A ; Noei Aghaei, M. A ; Sharif University of Technology
    Graft copolymerization of methyl methacrylate (MMA) was carried out on bagasse fibers in an aqueous medium using eerie ammonium nitrate (CAN) as initiator under a neutral atmosphere. In order to obtain the optimum condition for graft copolymerization, the effects of initiator concentration, temperature, time of reaction, and monomer concentration were studied. The maximum grafting percent was found to be 122%. The bagasse grafted poly(methyl methacrylate) was characterized by FTIR and its thermal behavior was characterized by TGA. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA  

    Removal of chlorophenolic derivatives by soil isolated ascomycete of Paraconiothyrium variabile and studying the role of its extracellular laccase

    , Article Journal of Hazardous Materials ; Volume 209-210 , 2012 , Pages 199-203 ; 03043894 (ISSN) Forootanfar, H ; Movahednia, M. M ; Yaghmaei, S ; Tabatabaei Sameni, M ; Rastegar, H ; Sadighi, A ; Faramarzi, M. A ; Sharif University of Technology
    The ability of Paraconiothyrium variabile, a laccase producing ascomycete recently isolated from soil, was studied to eliminate chlorophenol derivatives in submerged culture medium. Among the tested compounds, ρ-chlorophenol (ρ-CP) and pentachlorophenol (PCP) were found to have minimum and maximum toxic effects, respectively, on the growth of the microorganism and at the same time high and low bioelimination percentages. The fungal strain was able to remove 86% of ρ-CP (with initial concentration of 40mgl -1) and 56% of 2,4-dichlorophenol (2,4-DCP; with same concentration as ρ-CP) after 9 days of incubation while no elimination was observed in the presence of 2,4,6-trichlorophenol...