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On the optimization of sphalerite bioleaching; the inspection of intermittent irrigation, type of agglomeration, feed formulation and their interactions on the bioleaching of low-grade zinc sulfide ores
, Article Chemical Engineering Journal ; Volume 187 , 2012 , Pages 217-221 ; 13858947 (ISSN) ; Azad, R. R ; Arabian, D ; Molaie, A ; Nemati, F ; Sharif University of Technology
2012
Abstract
In this study, we have investigated the bioleaching potential of a native strain of Acidithiobacillus ferrooxidans isolated from zinc and lead sulfide mines under varied ambient conditions of growth and substrate consumption. The effects of intermittent irrigation, type of agglomeration, feed formulation in terms of acid, enriched salt solution, initial number of microorganism, and their interactions on the bioleaching of low-grade zinc sulfide ores (containing 5.78% zinc) on growth and biooxidation efficiency of the bacteria have been evaluated. Bioleaching capacities of the isolate were optimized by the utilization the Taguchi method (e-qualitic-4) for design of experiments. As a result,...
Determination of 2,4-D in environmental samples by three phases directly suspended LPME combined with HPLC-UV
, Article Analytical Methods ; Volume 3, Issue 10 , 2011 , Pages 2261-2267 ; 17599660 (ISSN) ; Roshan, S ; Asgharinezhad, A. A ; Najafi, E ; Abedi, H ; Tavassoli, N ; Lotfi Zadeh Zhad, H. R ; Sharif University of Technology
Abstract
Experimental design of directly suspended droplet liquid-liquid-liquid microextraction has been used to determine residue of 2,4-D, in environmental water samples. A free suspended droplet of 5.5 μL of receiving phase is delivered to the top-center position of 1-Octanol, which is an immiscible organic solvent, floating on the top of a 2.5 mL aqueous sample while being agitated by a stirring bar to create a mild vortex at the center of the vial. Central composite rotatable design has been used for studying the effect of the parameters, the factors interacting with each other and finding the optimum condition. The chromatographic separation was accomplished on a shim-Pak C18 column using a...
Thermal characteristics of closed loop pulsating heat pipe with nanofluids
, Article Journal of Enhanced Heat Transfer ; Volume 18, Issue 3 , 2011 , Pages 221-237 ; 10655131 (ISSN) ; Arabnejad, S ; Shafii, M. B ; Saboohi, Y ; Sharif University of Technology
2011
Abstract
In this paper, the effect of different parameters on the thermal operation of a Closed Loop Pulsating Heat Pipe (CLPHP) has been investigated. These parameters include the working fluid, the inclination angle, the filling ratio, and the input heat flux. The effect of nanoparticle mass concentrations has been analyzed as well. It was observed that the CLPHP can decrease thermal resistance up to 11.5 times compared to the same empty copper tube with thermal resistance of 9.4 K/W. Optimum thermal operation for a system with the water-silver nanofluid was achieved at conditions of the 50% filling ratio with thermal resistance of 0.9 K/W, and for the water-titanium oxide system, the optimal...
Bacterial leaching of a spent Mo-Co-Ni refinery catalyst using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans
, Article Hydrometallurgy ; Volume 106, Issue 1-2 , February , 2011 , Pages 26-31 ; 0304386X (ISSN) ; Borghei, S. M ; Mousavi, S. M ; Sharif University of Technology
2011
Abstract
A spent processing catalyst from an Iranian oil refinery was initially characterized physically and chemically. Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used to mobilize Al, Co, Mo and Ni from the spent catalysts under optimized conditions in batch cultures. The characteristics of the bioleach solution (pH, Eh, cell concentration and Fe(II)/Fe(III) concentration) were determined along with the concentration of metal values extracted from the catalyst. The results showed that after bioleaching using A. ferrooxidans in the presence of ferrous sulfate, maximum extractions of 63% Al, 96% Co, 84% Mo and 99% Ni were achieved after 30 days at pH 1.8-2.0. However, the...
Development of block copolymer-templated crack-free mesoporous anatase-TiO2 film: tailoring sol–gel and EISA processing parameters and photovoltaic characteristics
, Article Journal of Materials Science: Materials in Electronics ; Volume 26, Issue 3 , March , 2015 , Pages 1543-1553 ; 09574522 (ISSN) ; Mohammadi, M. R ; Faghihi Sani, M. A ; Sharif University of Technology
Springer New York LLC
2015
Abstract
A new facile strategy for preparation of mesoporous anatase-TiO2 films by a combination of sol–gel and evaporation-induced self-assembly (EISA) processes aided by tri-block Pluronic F127 is reported. Two major parameters, sol preparation and EISA processing parameters, are identified for preparation of mesoporous crack-free films with desired thickness. The mesoporous crack-free films with thickness of 650 nm can be obtained with low water: precursor molar ratio (e.g., 2.5:1) under aging in 10 % relative humidity for 72 h at the low temperature of 5 °C. Although template: precursor molar ratio and annealing temperature show little influence on preparation of crack-free films the optimum...
Biodiesel production using CaO/γ-Al2 O3 catalyst synthesized by sol-gel method
,
Article
Canadian Journal of Chemical Engineering
;
Volume 93, Issue 9
,
July
,
2015
,
Pages 1531-1538
;
00084034 (ISSN)
; Mohadesi, M
; Rezaei, R
; Moradi, R
;
Sharif University of Technology
Wiley-Liss Inc
2015
Abstract
In this study, 40% CaO/γ-Al2 O3 catalyst was used for biodiesel production from corn oil. A transesterification reaction was done for 5h at a temperature of 65°C in the presence of corn oil, methanol (methanol to oil molar ratio of 12:1), and CaO/γ-Al2 O3 catalyst (0.06g/g (6wt%)). Catalyst used in this study was synthesized using the sol-gel method. In this method, two parameters of gelation temperature and nitric acid concentration were used as variables in the catalyst synthesis step, and experiments were designed using central composite design (CCD). The results indicate that the optimal point is achieved at a gelation temperature of 70°C and...
Response surface methodology as an approach to optimize growth medium of indigenous strain of Bacillus mycoides for production of biosurfactant
, Article ICBEE 2010 - 2010 2nd International Conference on Chemical, Biological and Environmental Engineering, Proceedings, 2 November 2010 through 4 November 2010 ; 2010 , Pages 146-152 ; 9781424487479 (ISBN) ; Rahimpour, M. R ; Jahanmiri, A. H ; Roostaazad, R ; Arabian, D ; Soleimani, M ; Sharif University of Technology
Abstract
In this study, we have investigated the potential of a native bacterial strain isolated from an Iranian oil field for the production of biosurfactant. The bacterium was identified to be Bacillus mycoides by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to reduce the surface tension of media to 34 mN/m. Biosurfactant production was optimized by the combination of central composite design (CCD) and response surface methodology (RSM). The factor selected for optimization of growth conditions were pH, temperature, glucose and salinity concentrations. The empirical model developed through RSM in terms of effective operational factors...
Enzymatic synthesis of amoxicillin with immobilized penicillin G acylase
, Article Scientia Iranica ; Volume 17, Issue 1 C , 2010 , Pages 106-113 ; 10263098 (ISSN) ; Borghei, G ; Vafi, L ; Roostaazad, R ; Sharif University of Technology
2010
Abstract
The synthesis of amoxicillin with immobilized penicillin G acylase (PGA) in aqueous medium was investigated. The parameters studied were: time course of amoxicillin production, concentration of substrates: hydroxyphenylglycine methyl ester (HPGM) and 6-aminopeicillanic acid (6-APA) and the. effect of enzyme (PGA) content and pH, under variable and constant conditions and temperature variations. In the study of two substrate concentration on amoxicillin production, impressive results were obtained for a 1/3 ratio of 6-amino penicillanic acid (6-APA) and hydroxyl-phenylglycine methyl ester (HPGM). The. synthesis of amoxicillin was preferable at constant pH rather than a variable one. Other...
Selective voltammetric determination of d-penicillamine in the presence of tryptophan at a modified carbon paste electrode incorporating TiO2 nanoparticles and quinizarine
, Article Journal of Electroanalytical Chemistry ; Volume 644, Issue 1 , Jan , 2010 , Pages 1-6 ; 15726657 (ISSN) ; Beitollahi, H ; Taleat, Z ; Naeimi, H ; Taghavinia, N ; Sharif University of Technology
2010
Abstract
A carbon paste electrode (CPE) chemically modified with TiO2 nanoparticles and quinizarine (QZ) was used as a selective electrochemical sensor for the simultaneous determination of minor amounts of d-penicillamine (D-PA) and tryptophan (Trp). This modified electrode showed very efficient electrocatalytic activity for anodic oxidation of both d-PA and Trp. Substantial decreases of anodic overpotentials for both compounds made this analysis possible. Results of square wave voltammetry (SWV) using this modified electrode showed two well-resolved anodic waves for the oxidation of d-PA and Trp, which makes the simultaneous determination of both compounds possible. The peak potential for the...
A bi-level approach for optimal contract pricing of independent dispatchable DG units in distribution networks
, Article International Transactions on Electrical Energy Systems ; Volume 26, Issue 8 , 2016 , Pages 1685-1704 ; 20507038 (ISSN) ; Rajabi Ghahnavieh, A ; Haghighat, H ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
Distributed generation (DG) units are increasingly installed in the power systems. Distribution companies (DisCo) can opt to purchase the electricity from DG in an energy purchase contract to supply the customer demand and reduce energy loss. This paper proposes a framework for optimal contract pricing of independent dispatchable DG units considering competition among them. While DG units tend to increase their profit from the energy purchase contract, DisCo minimizes the demand supply cost. Multi-leader follower game theory concept is used to analyze the situation in which competing DG units offer the energy price to DisCo and DisCo determines the DG generation. A bi-level approach is used...
Medium-term retailer's planning and participation strategy considering electricity market uncertainties
, Article International Transactions on Electrical Energy Systems ; Volume 26, Issue 5 , 2016 , Pages 920-933 ; 20507038 (ISSN) ; Kazemi, M ; Ehsan, M ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
This paper presents a risk-constrained programming approach to solve a retailer's medium-term planning problem. A retailer tries to maximize its profit via determining the optimal price offered to the customers as well as optimal strategy of participating in futures and pool markets. The uncertainty of pool prices is modeled by an envelope-bound information-gap model. Another source of uncertainty in this problem is the clients' demand, which is considered via a scenario generation method. The proposed method is formulated as a bi-level stochastic programming problem based on the information-gap decision theory. The Karush-Kuhn-Tucker optimality conditions are used to convert the bi-level...
Experimental investigation of closed loop pulsating heat pipe with nanofluids
, Article Proceedings of the ASME Summer Heat Transfer Conference 2009, HT2009 ; Volume 1 , 2009 , Pages 675-683 ; 9780791843567 (ISBN) ; Arabnejad, S ; Behshad Shafii, M ; Saboohi, Y ; Rasoulian, R ; Sharif University of Technology
Abstract
In this paper, the effect of several different parameters on the thermal resistance of a Closed Loop Pulsating Heat Pipe (CLPHP) has been investigated. These parameters include the working fluid, the inclination angle, the filling ratio and the heat influx. Also, the impact of using nanofluids with different nano-particle concentrations has been analyzed. It was observed that a CLPHP can increase the heat transfer up to 11.5 times compared to an empty pipe. Optimum performance for a system with the water-silver nanofluid was achieved at conditions of 50% filling ratio and 0.9 K/W of thermal resistance, and for the water-titanium oxide system, these optimal conditions were found to be 40%...
Nanostructured TiO2 thick films aided by new viscous gels for dye-sensitized solar cell applications
, Article Journal of Sol-Gel Science and Technology ; Volume 82, Issue 2 , 2017 , Pages 541-550 ; 09280707 (ISSN) ; Mohammadi, M. R ; Sharif University of Technology
Springer New York LLC
2017
Abstract
We develop a facile route for deposition of mesoporous TiO2 thick films over several micrometers by sol–gel and evaporation-induced self-assembly processes using Pluronic F127. The light harvesting of deposited films by two different methods (i.e., using a viscous gel and a paste) is studied by controlling their mesoscopic characteristics, phase composition and thickness for dye-sensitized solar cells applications. It is revealed that the mesoscopic films have mixtures of anatase and rutile crystal structures with surface area in the range 50.6–94.6 m2/g. We observe that the mesoporous TiO2 films prepared under optimized conditions improve light harvesting and dye loading of photoelectrodes....
Thermal optimization of the continuous casting process using distributed parameter identification approach—controlling the curvature of solid-liquid interface
, Article International Journal of Advanced Manufacturing Technology ; Volume 94, Issue 1-4 , 2018 , Pages 1101-1118 ; 02683768 (ISSN) ; Sharif University of Technology
Springer London
2018
Abstract
Thermal optimization of the vertical continuous casting process is considered in the present study. The goal is to find the optimal distribution of the temperature and interfacial heat transfer coefficients corresponding to the primary and secondary cooling systems, in addition to the pulling speed, such that the solidification along the main axis of strand approaches to the unidirectional solidification mode. Unlike many thermal optimization of phase change problems in which the desirable (target) temperature, temperature gradient, or interface position are assumed to be a priori known, a desirable shape feature of the freezing interface (not its explicit position) is assumed to be known in...
A competitive error in variables approach and algorithms for finding positive definite solutions of linear systems of matrix equations
, Article Springer Proceedings in Mathematics and Statistics, 2 January 2017 through 5 January 2017 ; Volume 235 , 2018 , Pages 45-66 ; 21941009 (ISSN); 9783319900254 (ISBN) ; Mahdavi Amiri, N ; Sharif University of Technology
Springer New York LLC
2018
Abstract
Here, we refine our recent proposed method for computing a positive definite solution to an overdetermined linear system of equations with multiple right-hand sides. This problem is important in several process control contexts including quadratic models for optimal control. The coefficient and the right-hand side matrices are, respectively, named data and target matrices. In several existing approaches, the data matrix is unrealistically assumed to be error free. We have recently presented an algorithm for solving such a problem considering error in measured data and target matrices. We defined a new error in variables (EIV) error function considering error for the variables, the necessary...
Optimal bidding strategy of coordinated wind power and gas turbine units in real-time market using conditional value at risk
, Article International Transactions on Electrical Energy Systems ; Volume 29, Issue 1 , 2019 ; 20507038 (ISSN) ; Goodarzi, H ; Ranjbar, A ; Sharif University of Technology
John Wiley and Sons Ltd
2019
Abstract
Nowadays, the incorporation of wind power in electrical grids and electricity markets is grown. Due to the fluctuation of wind speed, one of the main challenges of wind power would be selling power directly to the wholesale markets. A method for solving this challenge is coordination of wind power with energy storages, cascaded hydro, or gas turbine units in bidding strategy and operation. By coordinating with gas turbine units, wind power can be incorporated in real-time markets with fewer capital costs. In this paper, a stochastic bi-level optimization is proposed for coordinated wind power and gas turbine units in the real-time market. The uncertainties of wind power, demands, rivals'...
Optimal bidding strategy of coordinated wind power and gas turbine units in real-time market using conditional value at risk
, Article International Transactions on Electrical Energy Systems ; Volume 29, Issue 1 , 2019 ; 20507038 (ISSN) ; Goodarzi, H ; Ranjbar, A ; Sharif University of Technology
John Wiley and Sons Ltd
2019
Abstract
Nowadays, the incorporation of wind power in electrical grids and electricity markets is grown. Due to the fluctuation of wind speed, one of the main challenges of wind power would be selling power directly to the wholesale markets. A method for solving this challenge is coordination of wind power with energy storages, cascaded hydro, or gas turbine units in bidding strategy and operation. By coordinating with gas turbine units, wind power can be incorporated in real-time markets with fewer capital costs. In this paper, a stochastic bi-level optimization is proposed for coordinated wind power and gas turbine units in the real-time market. The uncertainties of wind power, demands, rivals'...
Investigating critical parameters for bioremoval of heavy metals from computer printed circuit boards using the fungus Aspergillus niger
, Article Hydrometallurgy ; Volume 197 , 2020 ; Esmaeili, A ; Yaghmaei, S ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this article, bioleaching of computer printed circuit boards (CPCBs) was examined using Aspergillus niger with one-step, two-step, and spent-medium bioleaching methods. Four effective parameters were optimized using response surface methodology (RSM) to achieve maximum recovery of Cu and Ni. Under optimal conditions – pH of 5.15, pulp density of 10 g/l, 1E+007 spores of A.niger, and 4.5 days for the sample adding time − 97% and 74% of Cu and Ni were recovered, respectively. Two-step bioleaching and spent medium bioleaching were respectively identified as the best methods for maximizing Cu and Ni recovery. Fungi deteriorate the sample mainly by it is chemical action like producing acids....
Enhancement of PMS activation in an UV/ozone process for cyanide degradation: a comprehensive study
, Article Pigment and Resin Technology ; Volume 49, Issue 5 , August , 2020 , Pages 409-414 ; ISSN: 03699420 ; Hassani, H ; Torabian, A ; Borghei, S. M ; Sharif University of Technology
Emerald Group Publishing Ltd
2020
Abstract
Purpose: This paper aims to study peroxymonosulfate (PMS) activation in the ultraviolet (UV)/ozone process for toxic cyanide degradation from aqueous solution by a novel and simple method. Design/methodology/approach: Photocatalytic degradation of cyanide (CN-) was carried out using a bench-scale photoreactor. Optimization of the UV/ozone process for the highest removal of cyanide was obtained. The effect of parameters such as ozone concentration, PMS concentration, temperature, cations (Cu2+, Co2+ and Fe2+), cyanide concentration, anions (bicarbonate, carbonate, chloride, nitrite, nitrate and sulfate [SO42−]) and scavengers (ethanol [EtOH], humic acid, TBA and NaN3) was investigated for CN-...
Influence of heat treatment and aging on microstructure and mechanical properties of Mg-1.8Zn-0.7Si-0.4Ca alloy
, Article Materialwissenschaft und Werkstofftechnik ; Volume 50, Issue 2 , 2019 , Pages 187-196 ; 09335137 (ISSN) ; Taheri, K. K ; Taheri, A. K ; Shaeri, M. H ; Sharif University of Technology
Wiley-VCH Verlag
2019
Abstract
In order to optimize the aging treatment of Mg-1.8Zn-0.7Si-0.4Ca alloy, different times and temperatures of solid solution and age hardening were applied to the alloy specimens. Microstructures and mechanical properties of the specimens were investigated using the optical microscopy, field emission scanning electron microscopy equipped with an energy dispersive x-ray spectrometer, x-ray diffraction, hardness, and shear punch tests. The lowest hardness and strength were achieved by solution treating of the alloy at 500 °C for 8 h, presenting the optimal condition for solution treatment of the alloy. The microstructural examinations revealed three different precipitates consisting of CaMgSi,...