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Author: search.filters.author.Sunsandee, NitiSubject: search.filters.subject.Silver ions

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    The role of organic diluents in the aspects of equilibrium, kinetics and thermodynamic model for silver ion extraction using an extractant D2EHPA
    (2015-02-05)
    Wongsawa, Thidarat
    ;
    Sunsandee, Niti
    ;
    Lothongkum, Anchaleeporn Waritswat
    ;
    Pancharoen, Ura
    ;
    Phatanasri, Suphot
    The effects of organic diluents regarding the aspects of equilibrium data, kinetics of extraction behavior and thermodynamic model are of great importance in the extraction processes. Therefore, these effects were investigated for silver ion extraction by a liquid-liquid extraction process using D2EHPA as an extractant. Various organic diluents that have different dielectric constants like kerosene, cyclohexane, chloroform and 1-octanol were selected for use in this work. The equilibrium data of solubility and tie-lines for the ternary systems of water. +. D2EHPA. +. organic diluents exhibited type-2 LLE behavior at a temperature of 298.2. K and atmospheric pressure. Moreover, the uncertainty propagation calculation was determined to validate the reliability of the data. The extraction efficiency of silver ions for each organic diluent was also investigated; maximum extraction of 94% was obtained for 1-octanol. The extraction behaviors of silver ion with D2EHPA in the different organic diluents were reported as regards their reaction stoichiometry. They were also analyzed by spectroscopic analysis. Results of the thermodynamic NRTL model were obtained and a very good correlation with the experimental LLE data was confirmed by the root-mean square deviation (. rmsd) values of 1%.
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    High-efficiency HFSLM for silver-ion pertraction from pharmaceutical wastewater and mass-transport models
    (2014-11-01)
    Wongsawa, Thidarat
    ;
    Sunsandee, Niti
    ;
    Pancharoen, Ura
    ;
    Lothongkum, Anchaleeporn Waritswat
    Hollow fiber supported liquid membrane (HFSLM) is a favorable technique for the pertraction of metal ions, especially at very low metal concentration. In this work, the pertraction of silver ions from acidic pharmaceutical wastewater via HFSLM was investigated. Pharmaceutical wastewater containing 30mg/dm<sup>3</sup> of silver ions and 120mg/dm<sup>3</sup> of ferric ions was subjected to HFSLM as a feed solution. LIX 84-I dissolved in organic solvent together with Na<inf>2</inf>S<inf>2</inf>O<inf>3</inf>5H<inf>2</inf>O solution was selected for use as a liquid membrane and a receiving solution, respectively. The influence of ferric ions on the pertraction of silver ions was studied firstly using wastewater with normal ferric ion concentration and secondly using wastewater with ferric ion precipitation by phosphoric acid solution. The highest pertraction of silver ions was achieved by using 0.1M of LIX 84-I and 0.5M of Na<inf>2</inf>S<inf>2</inf>O<inf>3</inf>·5H<inf>2</inf>O solution at pH of feed and receiving solutions of 3.5 and 2. The flow rates of feed and receiving solutions were 0.2dm<sup>3</sup>/min. 0.6mg/dm<sup>3</sup> of silver ions that remained in the wastewater was below the mandatory discharge limit. No effect of normal ferric ion concentration in the wastewater on silver ion pertraction was observed. The crucial parameters were defined to confirm the efficiency and reliability of the system. Finally, the controlling transport regime of silver ion pertraction across HFSLM was determined by the diffusion flux and reaction flux models.