Limits...
Onion membrane: an efficient adsorbent for decoloring of wastewater.

Saber-Samandari S, Heydaripour J - J Environ Health Sci Eng (2015)

Bottom Line: Recently, researchers have tried to design synthetic materials by replicating natural materials as an adsorbent for removing various types of environmental pollutants, which have reached to the risky levels in nature for many countries in the world.In this research, the potential of onion membrane obtained from intermediate of onion shells for adsorption of methylene blue (MB) as a model cationic dye was exhibited.Evidently, the high efficiency and fast removal of methylene blue using onion membrane suggest the synthesis of polymer-based membranes with similar physical and chemical properties of onion membrane as a valuable and promising wastewater decoloring agents in water treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Eastern Mediterranean University, TRNC via Mersin 10, Gazimagusa, Turkey.

ABSTRACT

Background: Recently, researchers have tried to design synthetic materials by replicating natural materials as an adsorbent for removing various types of environmental pollutants, which have reached to the risky levels in nature for many countries in the world. In this research, the potential of onion membrane obtained from intermediate of onion shells for adsorption of methylene blue (MB) as a model cationic dye was exhibited.

Methods: Before and after adsorption, the membrane was characterized by Fourier transform infrared spectroscopy (FTIR) and optical and scanning electron microscopy in order to prove its dye adsorption capability. The various experimental conditions affecting dye adsorption were explored to achieve maximum adsorption capacity.

Results: The dye adsorption capacity of the membrane was found to be 1.055 g.g(-1) with 84.45% efficiency after one hour and 1.202 g.g(-1) with 96.20% efficiency after eight hours in contact with the dye solution (0.3 g.L(-1)). Moreover, the kinetic, thermodynamic and adsorption isotherm models were employed to described the MB adsorption processes. The results show that the data for adsorption of MB onto the membrane fitted well with the Freundlich isotherm and pseudo-second-order kinetic models. In addition, the MB adsorption from room temperature to ~50°C is spontaneous and thermodynamically favorable.

Conclusions: Evidently, the high efficiency and fast removal of methylene blue using onion membrane suggest the synthesis of polymer-based membranes with similar physical and chemical properties of onion membrane as a valuable and promising wastewater decoloring agents in water treatment.

No MeSH data available.


Adsorption isotherm of MB on onion membrane by Langmuir and Freundlich were plotted. In these experiments, 0.06 g of the membrane adsorbed dye molecules from a dye solution (250 ml) with a pH of 7.1 at 20°C for 8 hours.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4374185&req=5

Fig9: Adsorption isotherm of MB on onion membrane by Langmuir and Freundlich were plotted. In these experiments, 0.06 g of the membrane adsorbed dye molecules from a dye solution (250 ml) with a pH of 7.1 at 20°C for 8 hours.

Mentions: The adsorption isotherm generally illustrates the interaction of an adsorbate with the adsorbent and also it can indicates the adsorption capacity of the adsorbent. Therefore, two isotherm models, Langmuir and Freundlich were investigated to find a more suitable model for the design process. The Langmuir model, the most popular, has been widely used to describe single-solute systems. The Langmuir model is based on the assumption that adsorbates produce monolayer coverage on the outer surface with uniform energies of adsorption, which is structurally homogeneous [30]. In the Freundlich model, the adsorption of an adsorbate occurs on a heterogeneous surface via multilayer adsorption with non-uniform distribution of heat of adsorption. The theoretical Langmuir and Freundlich isotherm models are represented by the following equations:8\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \frac{{\mathrm{C}}_{\mathrm{e}}}{{\mathrm{q}}_{\mathrm{e}}}=\frac{{\mathrm{C}}_{\mathrm{e}}}{{\mathrm{q}}_{\mathrm{m}}}+\frac{1}{{\mathrm{q}}_{\mathrm{m}}{\mathrm{k}}_{\mathrm{L}}} $$\end{document}Ceqe=Ceqm+1qmkL9\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\mathrm{logq}}_{\mathrm{e}}={\mathrm{logk}}_{\mathrm{F}}+\frac{1}{\mathrm{n}}{\mathrm{logC}}_{\mathrm{e}} $$\end{document}logqe=logkF+1nlogCewhere qe (g.g−1) is the amount of dye adsorbed at equilibrium time, qm (g.g−1) is the maximum adsorption capacity, and Ce (g.L−1) is the equilibrium dye concentration. kL and kF (L.g−1) are the Langmuir and Freundlich adsorption equilibrium constant. 1/n is the empirical Freundlich constant. As it is clear from Figure 9, the calculated values of qe belong to the Freundlich model is in agreement with the experimental value, which revealed that the Freundlich model is more suitable than the Langmuir model for describing the adsorption. This is confirmed by the correlation coefficient (R2) of the Freundlich isotherm model (0.9922), which is greater than R2 (0.9878) of the Langmuir model (Table 2). The empirical Freundlich constant (1/n) which can be obtained from the linear plot of logqe versus logCe, is an indicator of the favorability and surface affinity for the solute. When the 1/n values are in the range 0.1-1, the adsorption process is favorable. In addition, if the n is below one, then the adsorption is a chemical process; otherwise, the adsorption is a physical process. In this study, the value of 1/n is 0.24, lying between 0.1 and 1, indicating that adsorption of MB ions by an onion membrane is favorable with physisorption.Figure 9


Onion membrane: an efficient adsorbent for decoloring of wastewater.

Saber-Samandari S, Heydaripour J - J Environ Health Sci Eng (2015)

Adsorption isotherm of MB on onion membrane by Langmuir and Freundlich were plotted. In these experiments, 0.06 g of the membrane adsorbed dye molecules from a dye solution (250 ml) with a pH of 7.1 at 20°C for 8 hours.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4374185&req=5

Fig9: Adsorption isotherm of MB on onion membrane by Langmuir and Freundlich were plotted. In these experiments, 0.06 g of the membrane adsorbed dye molecules from a dye solution (250 ml) with a pH of 7.1 at 20°C for 8 hours.
Mentions: The adsorption isotherm generally illustrates the interaction of an adsorbate with the adsorbent and also it can indicates the adsorption capacity of the adsorbent. Therefore, two isotherm models, Langmuir and Freundlich were investigated to find a more suitable model for the design process. The Langmuir model, the most popular, has been widely used to describe single-solute systems. The Langmuir model is based on the assumption that adsorbates produce monolayer coverage on the outer surface with uniform energies of adsorption, which is structurally homogeneous [30]. In the Freundlich model, the adsorption of an adsorbate occurs on a heterogeneous surface via multilayer adsorption with non-uniform distribution of heat of adsorption. The theoretical Langmuir and Freundlich isotherm models are represented by the following equations:8\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \frac{{\mathrm{C}}_{\mathrm{e}}}{{\mathrm{q}}_{\mathrm{e}}}=\frac{{\mathrm{C}}_{\mathrm{e}}}{{\mathrm{q}}_{\mathrm{m}}}+\frac{1}{{\mathrm{q}}_{\mathrm{m}}{\mathrm{k}}_{\mathrm{L}}} $$\end{document}Ceqe=Ceqm+1qmkL9\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\mathrm{logq}}_{\mathrm{e}}={\mathrm{logk}}_{\mathrm{F}}+\frac{1}{\mathrm{n}}{\mathrm{logC}}_{\mathrm{e}} $$\end{document}logqe=logkF+1nlogCewhere qe (g.g−1) is the amount of dye adsorbed at equilibrium time, qm (g.g−1) is the maximum adsorption capacity, and Ce (g.L−1) is the equilibrium dye concentration. kL and kF (L.g−1) are the Langmuir and Freundlich adsorption equilibrium constant. 1/n is the empirical Freundlich constant. As it is clear from Figure 9, the calculated values of qe belong to the Freundlich model is in agreement with the experimental value, which revealed that the Freundlich model is more suitable than the Langmuir model for describing the adsorption. This is confirmed by the correlation coefficient (R2) of the Freundlich isotherm model (0.9922), which is greater than R2 (0.9878) of the Langmuir model (Table 2). The empirical Freundlich constant (1/n) which can be obtained from the linear plot of logqe versus logCe, is an indicator of the favorability and surface affinity for the solute. When the 1/n values are in the range 0.1-1, the adsorption process is favorable. In addition, if the n is below one, then the adsorption is a chemical process; otherwise, the adsorption is a physical process. In this study, the value of 1/n is 0.24, lying between 0.1 and 1, indicating that adsorption of MB ions by an onion membrane is favorable with physisorption.Figure 9

Bottom Line: Recently, researchers have tried to design synthetic materials by replicating natural materials as an adsorbent for removing various types of environmental pollutants, which have reached to the risky levels in nature for many countries in the world.In this research, the potential of onion membrane obtained from intermediate of onion shells for adsorption of methylene blue (MB) as a model cationic dye was exhibited.Evidently, the high efficiency and fast removal of methylene blue using onion membrane suggest the synthesis of polymer-based membranes with similar physical and chemical properties of onion membrane as a valuable and promising wastewater decoloring agents in water treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Eastern Mediterranean University, TRNC via Mersin 10, Gazimagusa, Turkey.

ABSTRACT

Background: Recently, researchers have tried to design synthetic materials by replicating natural materials as an adsorbent for removing various types of environmental pollutants, which have reached to the risky levels in nature for many countries in the world. In this research, the potential of onion membrane obtained from intermediate of onion shells for adsorption of methylene blue (MB) as a model cationic dye was exhibited.

Methods: Before and after adsorption, the membrane was characterized by Fourier transform infrared spectroscopy (FTIR) and optical and scanning electron microscopy in order to prove its dye adsorption capability. The various experimental conditions affecting dye adsorption were explored to achieve maximum adsorption capacity.

Results: The dye adsorption capacity of the membrane was found to be 1.055 g.g(-1) with 84.45% efficiency after one hour and 1.202 g.g(-1) with 96.20% efficiency after eight hours in contact with the dye solution (0.3 g.L(-1)). Moreover, the kinetic, thermodynamic and adsorption isotherm models were employed to described the MB adsorption processes. The results show that the data for adsorption of MB onto the membrane fitted well with the Freundlich isotherm and pseudo-second-order kinetic models. In addition, the MB adsorption from room temperature to ~50°C is spontaneous and thermodynamically favorable.

Conclusions: Evidently, the high efficiency and fast removal of methylene blue using onion membrane suggest the synthesis of polymer-based membranes with similar physical and chemical properties of onion membrane as a valuable and promising wastewater decoloring agents in water treatment.

No MeSH data available.