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Simultaneous removal of arsenic and mercury from natural-gas-co-produced water from the Gulf of Thailand using synergistic extractant via HFSLM
(2011-03-01)
Lothongkum, Anchaleeporn Waritswat
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Suren, Sira
;
Chaturabul, Srestha
;
Thamphiphit, Nopphawat
;
Pancharoen, Ura
The simultaneous separation of arsenic and mercury ions from natural-gas-co-produced water was well achieved by a synergistic extractant through a hollow fiber supported liquid membrane (HFSLM). Aliquat 336, Bromo-PADAP, Cyanex 923 and Cyanex 471 dissolved in toluene were used as the organic extractants or carriers. The transport system was studied on several variables: types of the extractants, concentration of the synergistic extractant, concentration of H<inf>2</inf>SO<inf>4</inf> (a co-extractant) in feed solution, types of stripping solutions (NaOH, DI water, HNO<inf>3</inf>, H<inf>2</inf>SO<inf>4</inf> and thiourea), and the number of separation cycles. The results indicated the superior performance of mercury removal to arsenic by every single extractant in this study. The synergistic effect on arsenic removal was observed by adding Cyanex 471 in Aliquat 336 resulting in the synergistic coefficient of 2.8. The regulate mercury discharge to the environment not higher than 5ppb was attained within 1-cycle separation by using the mixture of 0.22M Aliquat 336 and 0.06M Cyanex 471 as the synergistic extractant and 0.1M thiourea as the stripping solution with 0.2M H<inf>2</inf>SO<inf>4</inf> in feed solution. By 3-cycle separation, 94% arsenic extraction, which was below the legislation limit of 250ppb, was obtained. © 2010 Elsevier B.V.
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Selective removal of mercury as HgCl42- from natural gas well produced water by TOA via HFSLM
(2010-01-07)
Pancharoen, Ura
;
Somboonpanya, Sawatpop
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Chaturabul, Srestha
;
Lothongkum, Anchaleeporn Waritswat
Handling produced waters from oil and gas production is an important aspect of making future oil and gas operations more environmentally acceptable since produced waters generally contain trace heavy and toxic metals, radioactive elements and chemicals. This research shows the selective removal of mercury ions (Hg(II)) as HgCl<inf>4</inf><sup>2-</sup> from produced water of natural gas well in the Gulf of Thailand, in which the concentrations of arsenic and mercury are high, by using a lab-scale hollow fiber supported liquid membrane (HFSLM). Emulsion liquid membrane (ELM) with different types of extractants and solvents was initially used to select the extractant of high mercury ions selectivity and extractability for the HFSLM system. Tri-n-octylamine (TOA) in toluene was found to be the most suitable extractant. The study parameters were pH of feed solution or produced water, concentration of extractant in liquid membrane, concentration of stripping or recovery solution (sodium hydroxide), volumetric flow rates of feed and stripping solutions, numbers of separation cycles, and stability of HFSLM. The increase in numbers of separation cycles, significantly increased the extraction and stripping of mercury ions. For 300 min at 6-cycle operation, the highest percentages of extraction and stripping of 99.8% and 62%, respectively, were achieved at the pH of feed solution of 2.5, 2% (v/v) TOA, 0.5 M NaOH and 50 ml/min of feed and stripping solutions. Furthermore, the mass transfer coefficients of aqueous phase (k<inf>i</inf>) and organic phase (k<inf>m</inf>) were 0.011 and 0.413 cm/s, respectively. Because the mass transfer coefficient of the organic phase was much higher than that of the aqueous phase implying that the rate controlling step was the diffusion of mercury ions through the film layer between feed solution and liquid membrane. © 2009.
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Performance of hollow fiber supported liquid membrane on the extraction of mercury(II) ions
(2008-11-01)
Uedee, Ekapong
;
Ramakul, Prakorn
;
Pancharoen, Ura
;
Lothongkum, Anchaleeporn W.
The extraction and recovery or stripping of mercury ions from chloride media using microporous hydrophobic hollow fiber supported liquid membranes (HFSLM) has been studied. Tri-n-octylamine (TOA) dissolved in kerosene was used as an extractant. Sodium hydroxide was used as a stripping solution. The transport system was studied as a function of several variables: the concentration of hydrochloric acid in the feed solution, the concentration of TOA in the liquid membrane, the concentration of sodium hydroxide in the stripping solution, the concentration of mercury ions in the feed solution and the flow rates of both feed and stripping solutions. The results indicated that the maximum percentages of the extraction and recovery of mercury ions of 100% and 97% were achieved at the concentration of hydrochloric acid in the feed solution of 0.1 mol/l, the concentration of TOA at 3% v/v, the concentration of sodium hydroxide at 0.5 mol/l and the flow rates of the feed and stripping solutions of 100 ml/min. However, the concentration of mercury ions from 1-100 ppm in the feed solution had no effect on the percentages of extraction and recovery of mercury ions. Thus, these results have identified that the hollow fiber supported liquid membrane process has high efficiency on both the extraction and recovery of mercury (II) ions. Moreover, the mass transfer coefficients of the aqueous phase (k <inf>i</inf> ) and membrane or organic phase (k <inf>m</inf> ) were calculated. The mass transfer coefficients of the aqueous phase and organic phase are 0.42 and 1.67 cm/s, respectively. The mass transfer coefficient of the organic phase is higher than that of the aqueous phase. Therefore, the mass transfer controlling step is the diffusion of the mercury ions through the film layer between the feed solution and the liquid membrane. © 2008 Springer.
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Purely separation of mixture of mercury and arsenic via hollow fiber supported liquid membrane
(2007-09-01)
Sangtumrong, Seewalee
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Ramakul, Prakom
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Satayaprasert, Chairit
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Pancharoen, Ura
;
Lothongkum, Anchaleeporn W.
The separation of mercury(II) and arsenic(III) ions from chloride media has been examined through a hollow fiber supported liquid membrane using tri-n-octylamine (TOA) as an extractant dissolved in toluene. The transport system was studied as a function of several variables: the concentration of the hydrochloric acid feed solutions, the concentration of TOA in the liquid membrane, the concentration of sodium hydroxide in the recovery solutions. According to the system, mercury(II) ions were extracted using TOA by rejecting arsenic (III) ions into raffinate because of the different forms of the mercury(II) and arsenic(III) ions in hydrochloric acid solutions. The maximum percentage of recovery for mercury(II) was 95 %; 100 % selectivity was obtained.

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