Time filter

Source Type

Ghaedi M.,Yasouj University | Sharifpour E.,Islamic Azad University at Gachsaran
Desalination and Water Treatment

A new selective solid phase extractor was prepared based on modification of silica gel with 2-((3silylpropylimino) methyl)-2-hydroxy-1-naphthol (SPIMHN). The solid phase extractor is stable in 6 mol/L HCl, common organic solvents, and buffer solutions at pH 2.0-8.0. This new sorbent was successfully applied for the enrichment of trace amount of Fe3+, Pb2+, Cu2+, Ni2+, Co2+, and Zn2+ ions subsequent their determination by flame atomic absorption spectrometry. The influences of the analytical parameters including pH, ratio of aminopropylsily late to 2-hydroxy-1-naphthaldehyde and amount of solid phase, sample flow rate, eluent solution conditions (type, concentration, and volume), and sample volume on the metal ions recoveries were investigated. The method has high sorption-preconcentration efficiency even in the presence of various interfering ions (recoveries between 98 and 99.4 and detection limits in the range of 1.3-2.8). The proposed method is applicable for understudied analytes with recoveries more than 95% and relative standard deviation < 4.2%, especially for real sample analysis. © 2012 Desalination Publications. All rights reserved. Source

Mansourizadeh A.,Islamic Azad University at Gachsaran | Mansourizadeh A.,University of Technology Malaysia | Ismail A.F.,University of Technology Malaysia

Wetting resistance and gas permeability are the main factors for membrane contactor applications, which can be optimized according to the membrane morphology. In present study, three different types of the membrane morphology were obtained via a dry-wet spinning technique. By measuring cloud point data and viscosity, the polymer dope composition was adjusted to produce the different morphologies. The membranes with large finger-like, small finger-like and almost sponge-like morphology were obtained. The plain PVDF membrane with large finger-likes morphology presented the higher N 2 permeance, lower wetting pressure and larger mean pore size (0.08μm). By addition of phosphoric acid into the spinning dope, the prepared sponge-like morphology resulted in the high surface porosity with small pore sizes, which demonstrated good permeability and wetting pressure. It was found that the mean pore size measured by gas permeation method was approximately three times larger than those from FESEM examination. CO 2 stripping from water was conducted through the gas-liquid membrane contactors. The membranes with smaller pore sizes and higher wetting pressure presented higher stripping performance. In conclusion, a structurally developed PVDF hollow fiber membrane for gas-liquid contactor applications can be achieved by controlling the membrane morphology. © 2011 Elsevier B.V. Source

Mansourizadeh A.,Islamic Azad University at Gachsaran
Chemical Engineering Research and Design

Gas-liquid hollow fiber membrane contactor can be a promising alternative for the CO 2 absorption/stripping due to the advantages over traditional contacting devices. In this study, the structurally developed hydrophobic polyvinylidene fluoride (PVDF) hollow fiber membranes were prepared via a wet spinning method. The membranes were characterized in terms of morphology, permeability, wetting resistance, overall porosity and mass transfer resistance. From the morphology analysis, the membranes demonstrated a thin outer finger-like layer with ultra thin skin and a thick inner sponge-like layer without skin. The characterization results indicated that the membranes possess a mean pore size of 9.6nm with high permeability and wetting resistance and low mass transfer resistance (1.2×10 4s/m). Physical CO 2 absorption/stripping were conducted through the fabricated gas-liquid membrane contactor modules, where distilled water was used as the liquid absorbent. The liquid phase resistance was dominant due to significant change in the absorption/stripping flux with the liquid velocity. The CO 2 absorption flux was approximately 10 times higher than the CO 2 stripping flux at the same operating condition due to high solubility of CO 2 in water as confirmed with the effect of liquid phase pressure and temperature on the absorption/stripping flux. © 2011 The Institution of Chemical Engineers. Source

Hosseini Nia R.,Islamic Azad University at Science and Research of Fars | Ghaedi M.,Yasouj University | Ghaedi A.M.,Islamic Azad University at Gachsaran
Journal of Molecular Liquids

This work devoted to the investigation of adsorption of reactive orange 12 (RO-12) by gold nanoparticles loaded with activated carbon (Au-NP-AC), which in high efficiency by routine manner was synthesized in our laboratory. Generally, in batch adsorption procedure, the effect of variables, including adsorbent mass, initial RO-12 concentration, and contact time on its removal percentage was optimized by the application of artificial neural networks and based on an imperialist competitive algorithm. This novel adsorbent by small amount (0.02 g) really is applicable to the removal of the high amount of dye (RO 12) in a short time (< 20 min). The optimum variables for adsorption of RO 12 onto gold nanoparticle-activated carbon were 0.02 g adsorbent mass, 10 mg L - 1 initial RO-12 concentration, 20 min contact time and pH 1. The kinetic of proposed adsorption processes efficiently followed, pseudo-second-order and intra-particle diffusion kinetic models. The equilibrium data of the removal process strongly follow the Langmuir monolayer adsorption with high adsorption capacity. The adsorption capacity of Au-NP-AC for the removal of RO-12 was found to be 714.3 mg g- 1. The comparison of the results obtained using the proposed models showed that the ANN model is better than the MLR model for the prediction of reactive orange 12 adsorption onto gold nanoparticles loaded on activated carbon. The coefficient of determination (R2) and mean squared error (MSE) for the optimal ANN model with 9 neurons at hidden layer were obtained to be 0.9720 and 0.0007, respectively. © 2014 Elsevier B.V. Source

Mansourizadeh A.,Islamic Azad University at Gachsaran | Mansourizadeh A.,University of Technology Malaysia | Ismail A.F.,University of Technology Malaysia
International Journal of Greenhouse Gas Control

Carbon dioxide (CO2), the main greenhouse gas, has been associated with global climate change. Therefore, it is important to develop technologies to mitigate this issue. In present study, porous hydrophobic polyvinylidene fluoride (PVDF) hollow fiber membranes with developed structure for CO2 absorption were prepared via a wet spinning process. The prepared membranes were characterized in terms of morphology examination, gas permeability, critical water entry pressure (CEPw) and mass transfer resistance. From the morphology examination, the membrane showed an almost sponge-like structure with inner skinless layer and ultra-thin outer skin layer. Results of gas permeation test indicated that the membrane possess very small mean pore size (3.96nm) with high surface porosity. The CO2 absorption experiment demonstrated a significant improvement in the CO2 flux of the prepared PVDF membrane compared to the commercial porous polytetrafluoroethylene (PTFE) hollow fiber membrane. At the absorbent flow rate of 200ml/min, CO2 flux of the PVDF membrane (4.10×10-4mol/m2s) was approximately 68% higher than the CO2 flux of the PTFE membrane. In addition, the results indicated that an approximate 25% CO2 flux reduction was gradually occurred at initial 26h, then the CO2 flux maintained constant over 140h of the operation. © 2010 Elsevier Ltd. Source

Discover hidden collaborations