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Author: search.filters.author.Ramakul, Prakorn

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    Efficient transport and selective extraction of Cr(VI) from waste pickling solution of the stainless steel-cold rolled plate process using Aliquat 336 via HFSLM
    (2009-05-01)
    Usapein, Parnuwat
    ;
    Lothongkum, Anchaleeporn W.
    ;
    Ramakul, Prakorn
    ;
    Pancharoen, Ura
    The selective extraction of Cr(VI) from waste pickling solution of the stainless steel-cold rolled plate process by hydrophobic hollow fiber supported liquid membrane (HFSLM) was investigated. The effects of various parameters- types of organic extractants, i.e., metyl trioctylammonium chloride (Aliquat 336), tri-n-octylamine (TOA), tri-n-butyl phosphate (TBP) and the mixture of Aliquat 336 and TBP, concentration of the selected extractant, types of stripping solutions (NaCl and NaOH), pH and concentration of the selected stripping solution, and the operating temperature-were studied. The feed and stripping solutions flowed countercurrently. The results showed that the coexisting contamination in spent pickling solution of Fe(II) and Ni(II) ions had no significant effect on Cr(VI) extraction. Among the extractants used in this study, Aliquat 336 was a specific carrier to attain the highest percentage of Cr(VI) extraction. About 70% extraction was achieved by using 0.11 M Aliquat 336 and 0.5 M NaCl at pH 7. The percentage of stripping slightly increased when the concentration of NaCl increased. In addition, it was found that the operating temperature of 20, 30, 40, and 50 °C had almost no influence on the percentages of extraction and stripping of Cr(VI). The calculated diffusion energy of Cr(VI) extraction was 15.14 kJ/mol. © 2009 Springer.
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    Synergistic separation of yttrium ions in lanthanide series from rare earths mixture via hollow fiber supported liquid membrane
    (2009-03-01)
    Ramakul, Prakorn
    ;
    Supajaroon, Tossaporn
    ;
    Prapasawat, Tatchanok
    ;
    Pancharoen, Ura
    ;
    Lothongkum, Anchaleeporn W.
    Separation of yttrium ions from the mixture of rare earths in lanthanide series has been examined by a microporous hydrophobic hollow fiber supported liquid membrane. Cyanex 272 and TBP in kerosene are used separately as an extractant. Nitric acid solution is used as a stripping solution. Increasing the concentration of Cyanex 272 increases the percentages of extraction and stripping of yttrium from rare earths but slightly percentages are obtained by TBP. Interestingly, when TBP is added with Cyanex 272, the percentages of extraction and stripping increases. This is due to the synergistic effect of the extractants. Moreover, yttrium can be selectively extracted and stripped more than other lanthanide ions because the equilibrium constant decreases with an increase in atomic number or decreases with the ionic radius of the lanthanides. In other words, yttrium is separated selectively due to the smallest ionic radius while other lanthanides are separated with a decrease in ionic radius or an increase in atomic number. © 2009 The Korean Society of Industrial and Engineering Chemistry.
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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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    Separation of As(III) and As(V) by hollow fiber supported liquid membrane based on the mass transfer theory
    (2008-01-01)
    Prapasawat, Tatchanok
    ;
    Ramakul, Prakorn
    ;
    Satayaprasert, Chairit
    ;
    Pancharoen, Ura
    ;
    Lothongkum, Anchaleeporn W.
    Separation of As(III) and As(V) ions from sulphate media by hollow fiber supported liquid membrane has been examined. Cyanex 923 was diluted in toluene and used as an extractant. Water was used as a stripping solution. The extractability of As(V) was higher than As(III). When the concentration of sulphuric acid in feed solution and Cyanex 923 in liquid membrane increased, more arsenic ions were extracted into liquid membrane and recovered into the stripping solution. The mathematical model was focused on the extraction side of the liquid membrane system. The mass transfer coefficients of the aqueous phase (k <inf>i</inf> ) and organic phase (k <inf>m</inf> ) are 7.15×10 <sup>-3</sup> and 3.45×10<sup>-2</sup> cm/s for As(III), and 1.07×10<sup>-2</sup> and 1.79×10<sup>-2</sup> cm/s for As(V). Therefore, the rate-controlling step for As(III) and As(V) in liquid membrane process is the mass transfer in the aqueous film between the feed solution and liquid membrane. The calculated mass transfer coefficients agree with the experimental results. © 2008 Springer.