Showing papers by "Reza Fazaeli published in 2015"

Monolayer and multilayer adsorption isotherm models for sorption from aqueous media

Abstract: Industrial wastewater polluted with various contaminants, including heavy metals, dyes, etc., endangers human health and the environment. Various separation techniques have been developed for the removal of pollutants from aqueous solutions. Adsorption process has drawn considerable attention due to its simplicity of design, high removal efficiency, even at dilute concentration, and economical aspect. We reviewed the most common two, three, four, and five parameter adsorption isotherm models corresponding to monolayer and multilayer adsorption on the basis of parameters that can be used for exploring novel adsorbents. Thermodynamic assumptions of the models give information about the surface properties, capacity of the adsorbent and adsorption mechanism. Seven error functions were investigated to evaluate the fitness quality of isotherm models with the experimental equilibrium data.

The study of CaO and MgO heterogenic nano-catalyst coupling on transesterification reaction efficacy in the production of biodiesel from recycled cooking oil.

Abstract: Fossil fuels’ pollution and their non-renewability have motivated the search for alternative fuels. Some common example of seed oils are sunflower oil, date seed oil, soy bean oil. For instance, soy methyl and soy-based biodiesel are the main biodiesel. Biodiesel is a clean diesel fuel that can be produced through transesterification reaction. Recycled cooking oil, on the other hand, is one of the inexpensive, easily available sources for producing biodiesel. This article is aimed at production of biodiesel via trans-esterification method, Nano CaO synthesis using sol-gel method, and Nano MgO synthesis using sol-gel self-combustion. Two catalysts’ combination affecting the reaction’s efficacy was also discussed. Optimum conditions for the reaction in the presence of Nano CaO are 1.5 % weight fracture, 1:7 alcohol to oil proportion and 6 h in which biodiesel and glycerin (the byproduct) are produced. Moreover, the optimum conditions for this reaction in the presence of Nano CaO and Nano MgO mixture are 3 % weight fracture (0.7 g of Nano CaO and 0.5 g of Nano MgO), 1:7 alcohols to oil proportion and 6 h. Nano MgO is not capable of catalyzing the transesterification by itself, because it has a much weaker basic affinity but when used with Nano CaO due to its surface structure, the basic properties increase and it becomes a proper base for the catalyst so that CaO contact surface increases and transesterification reaction yield significantly increases as well. This study investigates the repeatability of transesterification reaction in the presence of these Nano catalysts as well.

Computational simulation of CO2 removal from gas mixtures by chemical absorbents in porous membranes

Abstract: In this study chemical absorption of CO2 from a N2/CO2 gas mixture in tetramethylammonium glycinate ([N1111][Gly]) solution using hollow-fiber membrane contactors by employing the CFD (computational fluid dynamics) method was investigated. A two dimensional mathematical model was developed to describe diffusion in axial and radial directions of the HFMC (hollow-fiber membrane contactor). Also, the model gives an account of convection in the tube and the shell sides with chemical reaction between CO2 and the absorbent. Results of simulation showed good agreement with experimental data which reveals the validity of the model. CO2 absorption from the gas mixture increases as the flow rate and the concentration of the absorbent goes up. On the other hand, increase of gas flow rate decreases removal of CO2. The proposed model can predict CO2 capture from gas mixtures in HFMCs.

Determination of axial dispersion and overall mass transfer coefficients for Ni (II) adsorption on nanostructured γ-alumina in a fixed bed column: experimental and modeling studies

Abstract: In this study, nanostructured γ-alumina is used as an adsorbent for the removal of nickel from aqueous solutions using a fixed-bed column and batch experiments. Different parameters, including the initial nickel solution concentration, contact time, and pH were analyzed to determine their optimum values. The results showed that adsorption efficiency increased as contact time increased; optimum contact time was observed to be 150 min. The efficiency of removing metal ions from an aqueous solution increased as pH increased from 2.5 to 4.5, but decreased as pH rose higher, thus, optimum pH was determined to be 4.5. The Langmuir isotherm model showed better agreement with the experimental data than the Freundlich and Tempkin isotherm models. The maximum capacity of the adsorbent in the Langmuir equation was 78.74 mg/g. In the present study, adsorbent bed performance breakthrough curves for different adsorbent bed heights, influent flow rates, and concentrations were analyzed. The experimental data sho...

Dynamics of Pb(II) adsorption on nanostructured γ-alumina: calculations of axial dispersion and overall mass transfer coefficients in the fixed-bed column

Abstract: In the present study, the removal of metal ions Pb(II) using nanostructured γ-alumina was investigated by tests on batch operations and fixed-bed columns. Optimization was determined for factors effective on adsorption such as pH, contact time of metal solution with adsorbent and initial solution concentration. The optimum pH level was determined at 4.5 and the maximum adsorption percentage was achieved at 150 minutes. pHpzc was measured 8.3 for nanostructured γ-Al2O3. The Langmuir, Freundlich and Temkin isotherms were used to analyze the experimental data. The Langmuir isotherm model showed the best agreement with the experimental data. The model showed evaluations for maximum adsorption capacity of adsorbent at 119.04 mg/g and adsorbent bed performance for different flow rates, bed heights and influent concentrations were also investigated. The lumped method was used to solve the bed equations, to predict the breakthrough curve and model overall mass transfer coefficient (Koverall) and axial dispersion coefficient (Dz) parameters to make comparisons with experimental results.

Microwave Absorption Properties of Low Density Polyethelene-Cobalt Ferrite Nanocomposite

Abstract: Low density polyethylene (LDPE) nanocomposites with 3, 5 and 7 wt. % cobalt ferrite (CoFe2O4) nanopowder fabricated with extrusion mixing and followed up by hot press to reach compact samples. The transmission/reflection measurements were carried out with a network analyzer in the frequency range of 8-12 GHz. By increasing the percent of CoFe2O4 nanopowder, reflection loss (S11) increases, while transferring loss (S21) decreases. Reflectivity (R) calculations made using S11 and S21. Increase in percent of CoFe2O4 nanopowder up to 7 wt. % in composite leaded to higher reflectivity amount, and revealed that increasing the percent of CoFe2O4 nanopowder up to 7 wt. % leads to further microwave absorption in 8-12 GHz range. Keywords—Nanocomposite, Cobalt Ferrite, Low Density Polyethylene, Microwave Absorption.

Investigation of effect of using organic surfactant in structural properties of CuFe 2 O 4 nanoparticles

Abstract: CuFe2O4 have been widely investigated and used in variety of applications such as magnetic material, anode material, catalyst, and so on, because of their attractive magnetic, electronic, thermal and catalytic properties. Among methods to synthesize nanoferrites, the combustion synthesis is an easy, safe, rapid and economic method used to synthesise various oxides or to prepare multi-component ceramics. The process is based on a rapid redox reaction between a fuel (urea, citric acid, glycine, etc.) and oxidisers (generally metal nitrates), which starts under a moderated heating. This exothermic reaction can produce some fumes and/or a flame. Applying surfactants, which are composed from molecules along with sol–gel method can improve the properties of the synthesized powders. In the presence of surfactant, surface tension of solution is reduced and this facilitates nucleation and formation of the new phases. The formation of reverse micelles in gel can be effective in controlling the particles growth and the distance between particles. It has been found that the surfactant prevents the agglomeration of the ferrite nanoparticles. In this present study, the sol–gel auto-combustion method is applied for synthesizing the CuFe2O4/CTAB and CuFe2O4/SDS nanocomposite, using nickel nitrate, iron nitrate, ammonia, citric acid and CTAB and SDS as surfactant. The nanoparticles were characterized by XRD, SEM and FT-IR. Powder XRD analysis and FT-IR spectroscopy confirmed formation of CuFe2O4 spinel phase. SEM images show the effect of surfactants on morphology of nanoparticles.

Synthesis of NiFe2O4 nanoparticles by organic surfactants-assisted sol-gel auto-combustion method, characterization and determination of band gap

Abstract: Recently, nickel ferrite has attracted attention due to its multiple applications in storage devices, microwave devices, gas sensors, ferrofluids and catalysts. Nickel ferrites have excellent optical properties owing to their small band gap, which makes them suitable as a photocatalyst. Among methods to synthesize nanocrystalline NiFe2O4, combustion method seems to be one of the facile and one step methods, since it allows the preparation of nanocrystalline NiFe2O4 with an equiaxial shape and narrow size distribution. Applying surfactants, which are composed from molecules along with sol–gel method can improve the properties of the synthesized powders. In this present study, the sol–gel auto-combustion method is applied for synthesizing the NiFe2O4/CTAB and NiFe2O4/SDS nanocomposite, using nickel nitrate, iron nitrate, ammonia, citric acid and CTAB and SDS as surfactant. The nanoparticles were characterized by XRD, SEM, FT-IR and DRS. Powder XRD analysis and FT-IR spectroscopy confirmed formation of NiFe2O4 spinel phase. The particles size was estimated from SEM data. The energy band gaps were calculated by Kubelk-Munk model from UV–Vis absorption.