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Arsenic removal by liquid membranes.

Marino T, Figoli A - Membranes (Basel) (2015)

Bottom Line: The development of different LM configurations has been a matter of investigation by several researching groups, especially for the removal of As(III) and As(V) from aqueous solutions.Most of these LM systems are based on the use of phosphine oxides as carriers, when the metal removal is from sulfuric acid media.For such LM configuration, the most relevant step toward efficiency is the choice of the surfactant type and its concentration.

View Article: PubMed Central - PubMed

Affiliation: Institute on Membrane Technology, ITM-CNR, Via Pietro Bucci 17/c, 87030, Rende (CS), Italy. t.marino@itm.cnr.it.

ABSTRACT
Water contamination with harmful arsenic compounds represents one of the most serious calamities of the last two centuries. Natural occurrence of the toxic metal has been revealed recently for 21 countries worldwide; the risk of arsenic intoxication is particularly high in Bangladesh and India but recently also Europe is facing similar problem. Liquid membranes (LMs) look like a promising alternative to the existing removal processes, showing numerous advantages in terms of energy consumption, efficiency, selectivity, and operational costs. The development of different LM configurations has been a matter of investigation by several researching groups, especially for the removal of As(III) and As(V) from aqueous solutions. Most of these LM systems are based on the use of phosphine oxides as carriers, when the metal removal is from sulfuric acid media. Particularly promising for water treatment is the hollow fiber supported liquid membrane (HFSLM) configuration, which offers high selectivity, easy transport of the targeted metal ions, large surface area, and non-stop flow process. The choice of organic extractant(s) plays an essential role in the efficiency of the arsenic removal. Emulsion liquid membrane (ELM) systems have not been extensively investigated so far, although encouraging results have started to appear in the literature. For such LM configuration, the most relevant step toward efficiency is the choice of the surfactant type and its concentration.

No MeSH data available.


Related in: MedlinePlus

Influence of pH on As(V) transport efficiency after 24 h using SLM and AEM systems. (Feed phase: [As(V)] = 10 mg L–1; SLM: [Aliquat 336] = 0.5 M in dodecane and 4% dodecanol. Stripping phase: [NaCl] = 0.1 M [54].
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membranes-05-00150-f006: Influence of pH on As(V) transport efficiency after 24 h using SLM and AEM systems. (Feed phase: [As(V)] = 10 mg L–1; SLM: [Aliquat 336] = 0.5 M in dodecane and 4% dodecanol. Stripping phase: [NaCl] = 0.1 M [54].

Mentions: Mafu et al. [52] used Aliquat 336 and sodium hydroxide as the extractant and stripping phase, respectively, optimizing the operational conditions and thus obtaining a 78% arsenic removal from real wastewater. In addition, Guell et al. [53] reported on As(V) and As(III) removal using a Aliquat 336 in a SLM system. As organic solvent a dodecane/dodecanole mixture at pH 13 was used. The receiving phase consisted of a 0.1 M HCl solution. The proposed system allowed for As(V) separation from As(III), which was driven by different kinetics, and the removal of the As(V) ions from real aqueous solutions. In particular, using a wastewater model prepared with ultrapure water, a complete recovery of arsenic was registered after 6 h. By contrast, when real tap water was used, a 44% recovery was obtained, demonstrating that the presence of other chemical compounds could negatively influence the As(V) recovery. Successively, a comparison between two membrane-based systems was analyzed [54] using natural water and operating at neutral pH values. The performance of two anion-exchange membranes (AEMs) was compared to that of the SLM previously described [54] and also in this case the effect of pH on the arsenic transport was evaluated. The authors reported the best results when pH 7 was used (Figure 6). Furthermore, a study on the As(III) ions transport under the optimal operational conditions, registered for As(V) at pH 7, was presented. The obtained data revealed that when an AEM system was used, As(III) ion transport was observed, although the process occurred at a lower rate in comparison to that obtained for As(V). On the contrary, the SLM system led to worsen results, due to the formation, at pH 7, of the undissociated H3AsO3 form, which could not be extracted by the Aliquat 336 anion exchanger. In view of the reported results, it can be assumed that the SLM allows for efficient As(III) and As(V) separation.


Arsenic removal by liquid membranes.

Marino T, Figoli A - Membranes (Basel) (2015)

Influence of pH on As(V) transport efficiency after 24 h using SLM and AEM systems. (Feed phase: [As(V)] = 10 mg L–1; SLM: [Aliquat 336] = 0.5 M in dodecane and 4% dodecanol. Stripping phase: [NaCl] = 0.1 M [54].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496637&req=5

membranes-05-00150-f006: Influence of pH on As(V) transport efficiency after 24 h using SLM and AEM systems. (Feed phase: [As(V)] = 10 mg L–1; SLM: [Aliquat 336] = 0.5 M in dodecane and 4% dodecanol. Stripping phase: [NaCl] = 0.1 M [54].
Mentions: Mafu et al. [52] used Aliquat 336 and sodium hydroxide as the extractant and stripping phase, respectively, optimizing the operational conditions and thus obtaining a 78% arsenic removal from real wastewater. In addition, Guell et al. [53] reported on As(V) and As(III) removal using a Aliquat 336 in a SLM system. As organic solvent a dodecane/dodecanole mixture at pH 13 was used. The receiving phase consisted of a 0.1 M HCl solution. The proposed system allowed for As(V) separation from As(III), which was driven by different kinetics, and the removal of the As(V) ions from real aqueous solutions. In particular, using a wastewater model prepared with ultrapure water, a complete recovery of arsenic was registered after 6 h. By contrast, when real tap water was used, a 44% recovery was obtained, demonstrating that the presence of other chemical compounds could negatively influence the As(V) recovery. Successively, a comparison between two membrane-based systems was analyzed [54] using natural water and operating at neutral pH values. The performance of two anion-exchange membranes (AEMs) was compared to that of the SLM previously described [54] and also in this case the effect of pH on the arsenic transport was evaluated. The authors reported the best results when pH 7 was used (Figure 6). Furthermore, a study on the As(III) ions transport under the optimal operational conditions, registered for As(V) at pH 7, was presented. The obtained data revealed that when an AEM system was used, As(III) ion transport was observed, although the process occurred at a lower rate in comparison to that obtained for As(V). On the contrary, the SLM system led to worsen results, due to the formation, at pH 7, of the undissociated H3AsO3 form, which could not be extracted by the Aliquat 336 anion exchanger. In view of the reported results, it can be assumed that the SLM allows for efficient As(III) and As(V) separation.

Bottom Line: The development of different LM configurations has been a matter of investigation by several researching groups, especially for the removal of As(III) and As(V) from aqueous solutions.Most of these LM systems are based on the use of phosphine oxides as carriers, when the metal removal is from sulfuric acid media.For such LM configuration, the most relevant step toward efficiency is the choice of the surfactant type and its concentration.

View Article: PubMed Central - PubMed

Affiliation: Institute on Membrane Technology, ITM-CNR, Via Pietro Bucci 17/c, 87030, Rende (CS), Italy. t.marino@itm.cnr.it.

ABSTRACT
Water contamination with harmful arsenic compounds represents one of the most serious calamities of the last two centuries. Natural occurrence of the toxic metal has been revealed recently for 21 countries worldwide; the risk of arsenic intoxication is particularly high in Bangladesh and India but recently also Europe is facing similar problem. Liquid membranes (LMs) look like a promising alternative to the existing removal processes, showing numerous advantages in terms of energy consumption, efficiency, selectivity, and operational costs. The development of different LM configurations has been a matter of investigation by several researching groups, especially for the removal of As(III) and As(V) from aqueous solutions. Most of these LM systems are based on the use of phosphine oxides as carriers, when the metal removal is from sulfuric acid media. Particularly promising for water treatment is the hollow fiber supported liquid membrane (HFSLM) configuration, which offers high selectivity, easy transport of the targeted metal ions, large surface area, and non-stop flow process. The choice of organic extractant(s) plays an essential role in the efficiency of the arsenic removal. Emulsion liquid membrane (ELM) systems have not been extensively investigated so far, although encouraging results have started to appear in the literature. For such LM configuration, the most relevant step toward efficiency is the choice of the surfactant type and its concentration.

No MeSH data available.


Related in: MedlinePlus