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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.


Effect of pH on the MB adsorption capacity (g.g−1) and efficiency (%) of membrane was plotted. In these experiments, 0.06 g of membrane adsorbed dye molecules from a 0.3 g.L−1 dye solution (250 ml) at 20°C for 8 hours.
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Fig5: Effect of pH on the MB adsorption capacity (g.g−1) and efficiency (%) of membrane was plotted. In these experiments, 0.06 g of membrane adsorbed dye molecules from a 0.3 g.L−1 dye solution (250 ml) at 20°C for 8 hours.

Mentions: The pH value of the solution plays a significant role in the adsorption capacity of the adsorbate onto the adsorbent. As can be seen in Figure 5, with an increase in the initial pH of the MB solution from 3 to 8, adsorption capacity and efficiency increases rapidly and then increases slowly with a further increase in the pH. The maximum adsorption capacity was obtained at 1.245 g.g−1, with 99.64% efficiency at pH 11. This result can be explained by the electrostatic interaction between the cationic MB species and the surface of the adsorbent, which should be a negatively charged species. The lower adsorption at acidic pH levels was probably due to the presence of an excess of H+ ions competing with the dye cations for adsorption sites [19]. In order to confirm these results, the pHzpc of the onion membrane was determined. In this study, pHzpc value was 5.9, which at this pH the adsorbent surface has net electrical neutrality. At a pH below the pHzpc, the surface of the adsorbent is positive, and at a pH above the pHzpc, the surface of the adsorbent becomes more negatively charged by losing protons. Therefore, the adsorption of the MB reached its maximum value in the higher pH because of strong electrostatic attractions between the negatively charged surface of the onion membrane and the cationic MB.Figure 5


Onion membrane: an efficient adsorbent for decoloring of wastewater.

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

Effect of pH on the MB adsorption capacity (g.g−1) and efficiency (%) of membrane was plotted. In these experiments, 0.06 g of membrane adsorbed dye molecules from a 0.3 g.L−1 dye solution (250 ml) 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

Fig5: Effect of pH on the MB adsorption capacity (g.g−1) and efficiency (%) of membrane was plotted. In these experiments, 0.06 g of membrane adsorbed dye molecules from a 0.3 g.L−1 dye solution (250 ml) at 20°C for 8 hours.
Mentions: The pH value of the solution plays a significant role in the adsorption capacity of the adsorbate onto the adsorbent. As can be seen in Figure 5, with an increase in the initial pH of the MB solution from 3 to 8, adsorption capacity and efficiency increases rapidly and then increases slowly with a further increase in the pH. The maximum adsorption capacity was obtained at 1.245 g.g−1, with 99.64% efficiency at pH 11. This result can be explained by the electrostatic interaction between the cationic MB species and the surface of the adsorbent, which should be a negatively charged species. The lower adsorption at acidic pH levels was probably due to the presence of an excess of H+ ions competing with the dye cations for adsorption sites [19]. In order to confirm these results, the pHzpc of the onion membrane was determined. In this study, pHzpc value was 5.9, which at this pH the adsorbent surface has net electrical neutrality. At a pH below the pHzpc, the surface of the adsorbent is positive, and at a pH above the pHzpc, the surface of the adsorbent becomes more negatively charged by losing protons. Therefore, the adsorption of the MB reached its maximum value in the higher pH because of strong electrostatic attractions between the negatively charged surface of the onion membrane and the cationic MB.Figure 5

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.