Environmental Engineering,
behnam mousazadeh; nima . mohammadi; touba hamoule
Abstract
Ziziphus nuts are abundant in Khuzestan province, Iran, and are considered as an unwanted natural biomass waste. The present study aimed to develop low-cost activated carbon from Ziziphus nuts as a new precursor for phosphate removal from the water environment. Iron oxide modification was performed to ...
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Ziziphus nuts are abundant in Khuzestan province, Iran, and are considered as an unwanted natural biomass waste. The present study aimed to develop low-cost activated carbon from Ziziphus nuts as a new precursor for phosphate removal from the water environment. Iron oxide modification was performed to simultaneously facilitate adsorbent separation via a simple magnetic process and increase phosphate removal capacity. The iron oxide/activated carbon composite (IOAC) was characterized using XRD, EDX, SEM, and BET methods. The specific surface area for IOAC reached 569.41 m2/g, comparable to that of commercial activated carbon. While other similar biomass-derived activated carbons reached phosphate removal capacity around 15 mg/g, IOAC demonstrated excellent phosphate removal performance as high as 27 mg/g. Also, IOAC showed fast adsorption kinetics, achieving equilibrium in only 60 minutes. On the basis of the results, the pseudo-second-order kinetic model was more consistent with the phosphate adsorption data onto the adsorbent than the pseudo-first-order model. The adsorption results were interpreted using Langmuir, Freundlich, and Webber-Morris diffusion models. The maximum Langmuir adsorption capacity was calculated to be 27 mg/L. The adsorbent was removed from the aqueous solution via a simple magnetic process.
E. Tohfegar; J.S. Moghaddas; E. Sharifzadeh; S. Esmaeilzadeh-Dilmaghani
Abstract
In this work, hydrophobic silica aerogels were synthesized using sol-gel method and drying at ambient pressure. The surface morphology, pore size, and the presence of functional groups on the surface of the nanoparticles were analyzed using FE-SEM, TGA, FT-IR, and EDX, respectively. After calcination ...
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In this work, hydrophobic silica aerogels were synthesized using sol-gel method and drying at ambient pressure. The surface morphology, pore size, and the presence of functional groups on the surface of the nanoparticles were analyzed using FE-SEM, TGA, FT-IR, and EDX, respectively. After calcination at 500 °C, the hydrophilic property of the adsorbents was evaluated by water contact angle measurements. The calcinated silica aerogels were used for adsorption of nitrate from aqueous solution in both batch and continuous processes. In the batch process, the effect of initial nitrate concentration, contact time, pH level, and adsorbent dosage were investigated. Results showed that the nitrate removal percentage increased with the decrement of the pH level and the initial nitrate concentration. On the other hand, increasing the contact time and the adsorbent dosage resulted in higher removal percentage. Accordingly, process optimization resulted in a nitrate removal of 92.2 %. Furthermore, it was found that the equilibrium results were in agreement with the Langmuir isotherm model better than with the Freundlich model and also the adsorption kinetics followed the pseudo-second-order model. In the continuous process, the effects of the input flow rate, the bed height, and the initial nitrate concentration were investigated.
Modeling and Simulation
M. Khajeh Amiri; A. Ghaemi; H. Arjomandi
Volume 16, Issue 1 , March 2019, , Pages 54-64
Abstract
In this work, zeolite 13X with porosity structure has been used as an adsorbent for adsorption of CO2 flue gas. The effect of operating conditions including pressure and time on adsorption capacity were investigated. The experiments conditions are constant temperature, the range of pressure 1 - 9 bar ...
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In this work, zeolite 13X with porosity structure has been used as an adsorbent for adsorption of CO2 flue gas. The effect of operating conditions including pressure and time on adsorption capacity were investigated. The experiments conditions are constant temperature, the range of pressure 1 - 9 bar and the registration of adsorption capacity with passing of time. Experimental data were adjusted with adsorption isotherm models including two and three parameters isotherm. Also the process was studied in terms of kinetic models and after the implementation of the experimental data with kinetic models, the speed of this process equations were obtained. The best kinetic model for this process was selected first order equation. The results showed that adsorption capacity of 13X is 71.5 mg/g at pressure of 8 bars. Also the result indicate that 13x has high capacity at low pressures. With regard to achieved results for adsorption isotherm modeling, the adsorption isotherm followed of the three-parameter and among three-parameter models, Toth isotherm can be interpreted the process. Also the results of the fixed bed indicate a very high adsorbent selectivity to carbon dioxide adsorption and there was little oxygen and nitrogen adsorption.
Separation Technology,
M. Shafiee; A. Akbari; B. Ghiassimehr
Volume 15, Issue 4 , November 2018, , Pages 17-26
Abstract
At this work, removal of Pb (II) using Lawsonia inermis (Henna) was studied. In recent years, use of low price adsorbent is taken into consideration. Adsorption experiments were performed in batch system at ambient temperature (25℃). The influence of some parameters such as time, initial metal concentration, ...
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At this work, removal of Pb (II) using Lawsonia inermis (Henna) was studied. In recent years, use of low price adsorbent is taken into consideration. Adsorption experiments were performed in batch system at ambient temperature (25℃). The influence of some parameters such as time, initial metal concentration, pH and adsorbent dose were investigated. The optimum conditions was obtained at pH of 6, 10 ppm of initial metal concentration, 80 min of contact time and 0.75 g/L of adsorbent dose. To study the adsorbent morphology, Scanning Electron Microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) was used before and after adsorption of Pb (II) ions. Sorption of Pb (II) was evaluated by Freundlich and Langmuir isotherms. The results indicate that the Freundlich isotherm model is better described the adsorption of Pb (II) than Langmuir isotherm model. Also, it is observed that, the pseudo-second-order kinetic model well fitted to experimental data .
Separation Technology,
N. Mostafazadeh; A.A. Ghoreyshi; K. Pirzadeh
Volume 15, Issue 4 , November 2018, , Pages 27-47
Abstract
In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum ...
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In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum condition was revealed as solvent: metal ion molar ratio of 4.6:1, ligand: metal ion molar ratio of 318:1 and temperature of 23℃. The physio-chemical properties of as-synthesized ZIF-67 were investigated by BET, XRD, FTIR and FESEM analyses. Effect of adsorption pH, adsorbent dosage, initial concentration and contact time on adsorption process was investigated. Based on the results, the maximum adsorption capacity of Cr(VI) was 26.27 mg/g which was obtained at 35℃, pH= 5, adsorbent dosage of 3 g/l and initial concentration of 107.82 mg/l. The equilibrium time for Cr(VI) adsorption varied from 180 min for low initial concentration of 9 mg/L to 240 min for a high initial concentration of 90 mg/L. For the synthesized ZIF-67, maximum uptake capacity was reported 26.27 mg/g at initial concentration of 107.82 mg/l. The equilibrium data were described better by Langmuir-Freundlich isotherm model than the other models at three different temperatures. Pseudo-second-order model fitted the experimental data better than pseudo-first-order one. Adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous in nature. The regenerability of ZIF-67 was also studied in three sequential cycles and the Cr(VI) adsorption was almost retained after two cycles.
Separation Technology,
N. Kakoui; M. Nikzad; A. A. Ghoreyshi; M. mohammadi
Volume 15, Issue 2 , May 2018, , Pages 3-21
Abstract
The present study investigates the potential applicability of the extracted pectin from sour orange pomace as adsorbent for Ni (II) removal from aqueous solution. Pectin extraction from the pomace was carried out using HCl and the highest pectin extraction yield of 26.75% was obtained. The Fourier transform ...
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The present study investigates the potential applicability of the extracted pectin from sour orange pomace as adsorbent for Ni (II) removal from aqueous solution. Pectin extraction from the pomace was carried out using HCl and the highest pectin extraction yield of 26.75% was obtained. The Fourier transform infrared (FTIR) spectroscopy analysis confirmed that the structure of the extracted pectin was similar to the commercial one. The morphology and chemical characteristics of pectin beads were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) techniques. The influence of several parameters including pH, initial metal concentration, adsorption temperature and time was studied to optimize nickel removal. The maximum Ni (II) removal of 85.1% was obtained at initial concentration of 20 mg/L and the highest adsorption capacity of 19.76 mg/g was achieved at nickel concentration of 100 mg/L. Kinetic and equilibrium studies were done to evaluate Ni (II) sorption from aqueous solution by the synthesized beads. Results showed that the sorption process follows a pseudo- second- order kinetic model. The equilibrium data were well correlated with Langmuir and Redlich-Peterson models by high regression coefficients.
Separation Technology,
M. Jadidi; N. Etesami; M. Nasr Esfahany
Volume 14, Issue 3 , August 2017, , Pages 31-40
Abstract
In this study adsorption of Cr(VI) from aqueous solution by Fe3O4 nanoparticles was investigated. Desorption process and recovery of nanoparticles using different solutions were then carried out, and it was observed that NaOH (0.5M) can remove 90% of adsorbed chromium ions. Following the completion of ...
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In this study adsorption of Cr(VI) from aqueous solution by Fe3O4 nanoparticles was investigated. Desorption process and recovery of nanoparticles using different solutions were then carried out, and it was observed that NaOH (0.5M) can remove 90% of adsorbed chromium ions. Following the completion of adsorption/ desorption cycles, it was determined that nanoparticles have still had a high ability of chromium ions adsorption after 4 cycles. In addition, it was found that when iron oxide nanoparticles were washed with NaOH solution, the adsorption efficiency increases in the next cycle. FTIR spectra and zeta potential analysis, demonstrated the increased in surface positively charged of nanoparticles leads to increased electrostatic attraction forces between the iron oxide nanoparticles and chromium ions which finally resulted in adsorption increasing. So in this research, pretreatment of nanoparticles with NaOH solution modifies the surface of Fe3O4 nanoparticles by increasing surface positively charged mechanism and the adsorption efficiency has improved in the next cycle.
Separation Technology,
M. Delavar; Gh. Bakeri; M. Hosseini
Volume 14, Issue 2 , 2017, , Pages 59-73
Abstract
In this study, novel polycarbonate-titanium oxide nanotubes (PC-TNT) ultrafiltration mixed matrix membranes (MMMs) were fabricated for decontamination of Cd2+ and Cu2+ metal ions from aqueous solution. The weight percent of TNTs in the polycarbonate membrane matrix was changed from 0 to 15. The synthesized ...
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In this study, novel polycarbonate-titanium oxide nanotubes (PC-TNT) ultrafiltration mixed matrix membranes (MMMs) were fabricated for decontamination of Cd2+ and Cu2+ metal ions from aqueous solution. The weight percent of TNTs in the polycarbonate membrane matrix was changed from 0 to 15. The synthesized neat PC membrane and PC-TNTs MMMs were characterized with respect to structural morphology and hydrophilicity using scanning electron microscopy (SEM) and water contact angle, respectively. The effects of TNTs loadings on the pure water flux, mean pore size, porosity and water contact angle of fabricated membranes and Cd2+ and Cu2+ heavy metal ion rejection were also studied. By increasing the loading of TNTs nanoparticles in the membrane matrix, the membrane mean pore size tended to increase, while the porosity decreased. Also, the increase in TNTs loading resulted in an increase in membrane water flux which was mainly attributable to the enhancement in mean pore size and partly caused by the decreased contact angle value (more hydrophilic). Of all the membranes studied, it was found by UF experiments that PC-TNT MMM was the most efficient material in heavy metal ions removal due to the superior adsorption capacity of TNTs material. The generic results revealed that TNTs material can be favorite candidates for MMMs preparation in order to be conveniently used in the Cd2+ and Cu2+ heavy metal ions decontamination from polluted water resources.
Reaction Engineering, Kinetics and Catalysts,
Z. Shojaei; E. Iravani; M.A. Moosavian; M. Torab-Mostaedi
Volume 13, Issue 2 , April 2016, , Pages 3-21
Abstract
Adsorption of Ce(III) from aqueous solution by amino phosphate modified nano TiO2 was investigated. Effects of pH of solution, adsorbent dose, contact time, initial metal concentration and temperature were examined. Experimental data were fitted well by the pseudo second order model. Adsorption was well ...
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Adsorption of Ce(III) from aqueous solution by amino phosphate modified nano TiO2 was investigated. Effects of pH of solution, adsorbent dose, contact time, initial metal concentration and temperature were examined. Experimental data were fitted well by the pseudo second order model. Adsorption was well described by Freundlich isotherm model with a maximum adsorption capacity of 25 mg g-1. According to the obtained thermodynamic parameters, the adsorption was a spontaneous and endothermic process. Effect of interfering cations was studied. The presence of Ca and Mg ions up to 150 mg L-1 showed no considerable effect on the adsorption of Ce(III). Regeneration of adsorbent was performed using HNO3 with efficiency greater than 84%. The quantities of distribution coefficient (Kd), the affinity of metal for retention onto solid phase, was the higher for Ce(III) than La(III). Due to the high sorption capacity, being plentiful and low cost it is concluded that the use of amino phosphate mofified nano titania as an appropriate adsorbent is promising for the removal of lanthanides especially Ce(III) from contaminated sites.
Materials synthesize and production
M. Ghasemi; A. A. Ghoreyshi; H. Younesi; S. Khoshhal Khoshhal
Volume 12, Issue 4 , October 2015, , Pages 28-51
Abstract
A high performance activated carbon was synthesized using walnut shell as a solid waste through a two-step zinc chloride chemical activation-thermal pyrolysis process. Characterization results demonstrated its porous structure with very good textural properties such as high BET surface area (1223 m2/g) ...
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A high performance activated carbon was synthesized using walnut shell as a solid waste through a two-step zinc chloride chemical activation-thermal pyrolysis process. Characterization results demonstrated its porous structure with very good textural properties such as high BET surface area (1223 m2/g) and high total pore volume (0.85 cm3/g). The final adsorbent was used for adsorption of Fe (II) and Cr (VI) from aqueous solution. Effect ofpH, initial concentration of metal ions, temperature, and contact time on adsorption capacity of the adsorbent was investigated. Adsorption results revealed that the maximum removal of Fe (II) and Cr (VI) ions, occurred at pH 4. 5 and 2 respectively, were 96.2% and 99% at 313K. The equilibrium and kinetics data for adsorption of single-component ions were well described by the Sips isotherm and the pseudo-nth-order models, respectively. The impact of competing ions was studied by adsorption of a binary solution of Fe (II) and Cr (VI) ions. The binary adsorption isotherm was described by the modified Langmuir model and model parameters were found following an optimization procedure by genetic algorithm. Finally, the developed walnut-shell based activated carbon showed higher adsorption efficiency compared to other activated carbons at similar conditions.
Separation Technology,
Volume 3, Issue 3 , July 2006, , Pages 44-50
Abstract
Surfactants are one of the major components (10- 18%) of detergents and household cleaning products and are used in high volumes in developed countries. In the present research work, the ability of rice husk as a low cost adsorbent for anionic and nonionic surfactants in wastewater has been studied. ...
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Surfactants are one of the major components (10- 18%) of detergents and household cleaning products and are used in high volumes in developed countries. In the present research work, the ability of rice husk as a low cost adsorbent for anionic and nonionic surfactants in wastewater has been studied. The maximum removal efficiency for anionic surfactants was 97%, in an aqueous solution that contains 10mg/lit sodium linear alkyl benzene sulphonate in pH 2 and for nonionic surfactants was up to 75% in an aqueous solution that contains 20mg/lit nonyl phenol ethoxylate in pH 6-7. The mechanism of surfactant removal by rice husk was attributed to the physicochemical characteristics of rice husk. In addition, the size of micelles and critical micelle concentration are two important factors in the removal yield.
Modeling and Simulation
Volume 3, Issue 3 , July 2006, , Pages 51-64
Abstract
In this research, Fischer Tropsch synthesis (FTS) has been modeled in the fixed bed chromatographic reactor for the first time by applying a rather complex dispersed plug flow model for fluid phase and linear driving force (LDF) model for adsorbent. Model equations are dynamic, multi-component, non-linear ...
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In this research, Fischer Tropsch synthesis (FTS) has been modeled in the fixed bed chromatographic reactor for the first time by applying a rather complex dispersed plug flow model for fluid phase and linear driving force (LDF) model for adsorbent. Model equations are dynamic, multi-component, non-linear and heterogeneous including reaction and adsorption simultaneously Complex kinetics for FTS and water-gas shift (WGS) reaction and the multicomponent Langmuir adsorption isotherm is used in the model. A set of partial differential and ordinary differential equations with algebraic equations have been converted into a set of ordinary differential equations by using the orthogonal collocation technique. Then this set of equations has been solved by multi-step methods of Numerical Differentiation Formulae (NDF) or Backward Dif-ferentiation Formulae (BDF) Known as the Gear’s method. Consequently, results for dynamic model and effects of modeling parameters have been analyzed. Through this fixed bed chromatographic reactor model, one may develop a suitable configuration of simulated moving bed chromatographic reactors.
Separation Technology,
Volume 1, Issue 2 , July 2004, , Pages 39-44
Abstract
Recently, use of naturally-occurring low-cost and harmless material for removal of trace contaminants from colored wastewater has attracted extensive attention. In this study, silkworm pupa has been used as a basic dye adsorbent. Adsorption capacity and isotherms have been assessed. Results show that ...
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Recently, use of naturally-occurring low-cost and harmless material for removal of trace contaminants from colored wastewater has attracted extensive attention. In this study, silkworm pupa has been used as a basic dye adsorbent. Adsorption capacity and isotherms have been assessed. Results show that adsorption isotherms can be expressed well by Langmuir equation. The effects of parameters such as pH, temperature, agitation time and speed on the adsorption efficiency were investigated. It was found that among those factors the pH is the most pronounced one. Also the adsorption capacity of pupa towards the various cationic dyes is changed as follows: basic blue >basic yellow >basic red.