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Author: search.filters.author.Chaturabul, Srestha

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    Arsenic removal from natural gas condensate using a pulsed sieve plate column and mass transfer efficiency
    (2012-02-01)
    Chaturabul, Srestha
    ;
    Wannachod, Pharannalak
    ;
    Rojanasiraprapa, Bongkotch
    ;
    Summakasipong, Supat
    ;
    Lothongkum, Anchaleeporn W.
    This work applied a pulsed sieve plate column in conjunction with liquid-liquid extraction technique to remove arsenic from natural gas condensate. The relevant parameters, that is the type and concentration of the extractant, pulse velocity, volumetric-flow rate ratio of the condensate to the extractant, operating time, and extraction cycle were investigated. Mass transfer efficiency in terms of the overall height of transfer unit (HTU <inf>oy</inf>cm) and the interfacial area (m <sup>2</sup>/m <sup>3</sup>) were calculated. The highest percentage of arsenic removal in this study was 94% corresponding to the calculated HTU <inf>oy</inf> of 26 cm and the calculated interfacial area of 118 m <sup>2</sup>/m <sup>3</sup> at the optimum conditions: the mixture of the extractant (1 M hydrochloric acid and 20% (v/v) methanol), pulse velocity of 20 mm/s, and volumetric-flow rate ratio of the condensate to the extractant of 1:4. By using continuous operation in the cycle mode, the percentages of arsenic removal were observed at 94, 85, and 80 from the respective 1st, 2nd, and 3rd cycles. The operation was based on the condition that fresh feed was introduced in each cycle while the extractant was reused. © Taylor and Francis Group, LLC.
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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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    The effective recovery of praseodymium from mixed rare earths via a hollow fiber supported liquid membrane and its mass transfer related
    (2011-01-12)
    Wannachod, Pharannalak
    ;
    Chaturabul, Srestha
    ;
    Pancharoen, Ura
    ;
    Lothongkum, Anchaleeporn W.
    ;
    Patthaveekongka, Weerawat
    The recovery of praseodymium from mixed rare earths via a hollow fiber supported liquid membrane (HFSLM) was examined. Bis(2,4,4-trimethylpentyl) phosphinic acid - known as Cyanex 272 - was used as an extractant carrier. The stripping solution was hydrochloric acid solution. The experiments examined in functions of the concentrations of the carrier in liquid membrane, the (initial) pH's of initial feed solution within the acidic-pH range, the concentrations of hydrochloric acid, the flow rates of feed and stripping solution, and the operation mode of runs through the hollow fiber module. In addition, the influence of circulation of the stripping solution at various numbers of runs through the HFSLM on the outlet concentration of praseodymium ions in the stripping solution was observed. Mass transfer mechanism in the system was investigated. Extraction equilibrium constant (K<inf>ex</inf>), distribution ratio (D), permeability (P) and mass transfer coefficients were determined. The aqueous-phase mass-transfer coefficient (k<inf>i</inf>) and organic-phase mass-transfer coefficient (k<inf>m</inf>) were reported to 0.0103 and 0.788 cm s<sup>-1</sup>, respectively, in which k<inf>m</inf> is much higher than the k<inf>i</inf>. Thus it suggests the rate-controlling step is the diffusion of praseodymium ions through the film layer between the feed solution and the liquid membrane. Model prediction of the dimensionless concentrations and separation factors were also put on trial in this paper. The results showed promising agreement with the experimental data. © 2010 Elsevier B.V. All rights reserved.
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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.