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Author: search.filters.author.Chaturabul, SresthaSubject: search.filters.subject.Mercury

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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
    ;
    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
    ;
    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.