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Mechanisms of mercury ions separation by non-toxic organic liquid membrane via DFT, thermodynamics, kinetics and mass transfer model
(2023-01-25)
Traiwongsa, Natthapol
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Suren, Sira
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Pancharoen, Ura
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Nootong, Kasidit
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Maneeintr, Kreangkrai
This work focuses on the separation of mercury ions from synthetic produced wastewater via hollow fiber supported liquid membrane (HFSLM). Standard sunflower oil is used as a non-toxic extractant and solvent for mercury ions separation from wastewater. Under optimal conditions: 20 ppm NaCl in wastewater, 0.1 M thiourea in 0.5 M HCl as stripping solution, flow rates of feed and stripping solutions of 100 mL/min, and temperature 323 K, percentages of extraction and stripping reach 98% and 81%, respectively. The mechanisms of extraction and stripping reactions were investigated via the density functional theory (DFT). For the extraction, a linoleic acid extracted HgCl<inf>2</inf> and formed halogen bond. For the stripping, two protonated thiourea stripped HgCl<inf>2</inf> and formed covalent and halogen bonds. According to the thermodynamics study, extraction reaction is found to be endothermic (ΔH<inf>Ex</inf>0 = 1,001.00 J/mol), irreversible (ΔS<inf>Ex</inf>0 = 3.45 J/mol K), and spontaneous, (ΔG<inf>Ex@323K</inf>0 = −112.65 J/mol). Finally, the mathematical model including conservation, convection, diffusion, reaction, and accumulation was developed. The differences of mercury ions concentration in feed and stripping phases from the experiments and the predicted data from the mathematical model were 5% and 2%, respectively indicating that the model is acceptable.
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Separation of platinum(IV) across hollow fiber supported liquid membrane using non-toxic diluents: Mass transfer and thermodynamics
(2017-10-25)
Wongkaew, Krirkratthawit
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Mohdee, Vanee
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Pancharoen, Ura
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Arpornwichanop, Amornchai
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Lothongkum, Anchaleeporn W.
Non-toxic diluents were studied and compared with toxic diluents for separation of platinum(IV) across hollow fiber supported liquid membrane. 91.41% extraction and 81% stripping of platinum(IV) was observed for sunflower oils at 328.15 K. Overall mass transfer resistance (R) was 146.612 × 104 s/cm. The separation process was exothermic (ΔH<inf>ex</inf> 0 = −975.20 kJ/mol) and spontaneous (ΔG<inf>ex</inf> 0 = −326.447 J/mol). The E<inf>a</inf> of 1.673 kJ/mol indicated that the diffusion of complex species across the liquid membrane controlled the mass transfer step. Moreover, a modified Apelblat model gave an excellent match for predicting the extraction behavior of platinum(IV) at 1.2818% RMSD.
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Effect of diluent polarity on membrane stability in the separation of trace Pd(II) from wastewater by HFSLM using LIX84-I
(2015-01-25)
Wongkaew, Kraiwith
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Pancharoen, Ura
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Phatanasri, Suphot
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Leepipatpiboon, Natchanun
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Lothongkum, Anchaleeporn W.
In a liquid membrane, the type of diluents for the selected extractant plays an important role in membrane stability and separation efficiency. High Pd(II) extraction and stripping of 96% and 91%, respectively, were observed by HFSLM under a feed pH 2, 5% (v/v) LIX84-I dissolved in kerosene and a mixture of 0.8M NH<inf>2</inf>CSNH<inf>2</inf> with 1M HCl as a stripping solution. The highest stability was attained at 350min by using hexane as a diluent. Finally, the calculated activation energy (E<inf>a</inf>) of 30 kJ/mol implied that the separation of Pd(II) was controlled by the diffusion and chemical reaction.
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High-efficiency HFSLM for silver-ion pertraction from pharmaceutical wastewater and mass-transport models
(2014-11-01)
Wongsawa, Thidarat
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Sunsandee, Niti
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Pancharoen, Ura
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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/dm3 of silver ions and 120mg/dm3 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 0.2dm3/min. 0.6mg/dm3 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.
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Fluid-flow models operating on linear algebra for extraction and stripping of silver ions from pharmaceutical wastewater by HFSLM
(2013-04-05)
Wongsawa, Thidarat
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Leepipatpiboon, Natchanun
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Thamphiphit, Nopphawat
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Pancharoen, Ura
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Lothongkum, Anchaleeporn Waritswat
The extraction and stripping of silver ions by hollow fiber supported liquid membrane (HFSLM) was examined. Pharmaceutical wastewater containing 30mg/dm3 of silver ions was used as the feed solution. LIX 84-I dissolved in kerosene, and sodium thiosulfate pentahydrate solution were used as the liquid membrane and stripping solution, respectively. The influences of several variables on the extraction and stripping of silver ions were investigated. Fluid-flow models for greater accuracy in describing the transport of silver ions from feed phase to stripping phase were developed. The models were calculated by linear algebra. The investigated parameters in the models were axial convections and axial diffusions on both sides, chemical reactions at the feed-liquid membrane and liquid membrane-stripping interfaces as well as the accumulation of silver ions in the system. The mass transfer coefficient in the liquid membrane (k<inf>m</inf>) was determined for use in the models. The final predicted concentrations of silver ions in feed and stripping phases were successfully in agreement with the experimental data. It indicates that the fluid-flow model can accurately estimate the transport of silver ions inside and outside the hollow fibers corresponding to the axial convections, axial diffusions, reactions at the feed-liquid membrane and liquid membrane-stripping interfaces. In accordance with this investigation, the HFSLM shows a practical implication for the use in pharmaceutical wastewater treatment. © 2013 Elsevier B.V.
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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
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Chaturabul, Srestha
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Thamphiphit, Nopphawat
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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
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Chaturabul, Srestha
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Pancharoen, Ura
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Lothongkum, Anchaleeporn W.
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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-1, 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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