Extraction and Separation of Precious Metals by a Column Packed with Divinylbenzene Homopolymeric Microcapsule Containing Tri‐<i>n</i>‐octylamine

Zn(II) sorption from aqueous solutions was studied on polymeric hydrophobic microcapsules (MCs) containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as the extractant (PC-88A). The microcapsules were synthesised by adding this extractant during in situ radical polymerisation using styrene and ethylene glycol dimethacrylate (EGDMA) as starting monomers and benzoyl peroxide as the polymerisation initiator. SEM analysis of the microcapsules indicated that they had a spherical shape and a rough surface. A set of experiments was designed to study Zn(II) sorption behaviour onto MCs using aqueous solutions containing 100 mg/L of Zn(II) with an initial pH of 4.0. A Langmuir isotherm model fitted the experimentally observed equilibrium sorption data well. Results of kinetics experiments conducted between 293 and 323 K were well explained by a pseudo-second order kinetic model with an activation energy of 43.27 kJ mol -1 .Calculated thermodynamic parameters revealed that the chemisorption process was spontaneous and exothermic. The observed negative entropy change indicated that the metal bound to the extractant on the surface of MCs would generate a moderately ordered structure.

Section: Introductionmentioning

confidence: 99%

Zn(II) Sorption From Aqueous Solutions Using Polymeric MicrocapsulesContaining 2-Ethylhexylphosphonic Acid Mono-2-Ethylhexyl Ester

Valenzuela

Ide

Narváez

et al. 2014

“…Microcapsules encapsulating extractants used in solvent extraction systems are expected to be effective separation media for various substances such as metal ions [6][7][8][9][10][11][12][13][14][15], organic acids [16][17][18][19][20], antibiotics [21][22][23], and environmentally hazardous substances [24][25][26], because of the high separation properties of the encapsulated extractants, which have been proven in solvent extraction systems, and because of the high capacity for the extracted chemicals in the interior of the microcapsules. Furthermore, continuous separation is also possible by using a column packed with microcapsules containing extractants [27,28].…”

Section: Introductionmentioning

confidence: 99%

Preparation of Microcapsules Containing PC-88A with Interconnected Spherical Pores and Their Extraction Properties for Zn(II)

Matsushita

Sana

Kiyoyama

et al. 2011

Self Cite

2-Ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A), which is an effective extractant of Zn(II), was microencapsulated by in situ polymerization in a W/O/W emulsion system. Divinylbenzene was used as the wall material and polymerized in the organic phase by free radical polymerization. Microcapsules with large interconnected-spherical pores were successfully prepared. The pore size and the diameter of the microcapsules increased with increasing NaCl concentration in the inner aqueous phase. The diameter of the microcapsules was almost constant at around 230 μm and was independent of the concentration of PC-88A in the organic phase. The entrapment efficiency of PC-88A in the microcapsules was higher than 80% for all preparation conditions. The extraction of Zn(II) using the microcapsules containing PC-88A sharply increased at pH values greater than 2. Zn(II) extracted in the microcapsules was successfully back-extracted at pH values less than 2. It was confirmed that two molecules of PC-88A reacted with one Zn(II) ion by quantitative analysis of the relationship between the maximum amounts of Zn(II) extracted and the amount of PC-88A encapsulated in the microcapsules. The extraction rate of Zn (II) was accelerated by the formation of interconnected-spherical pores inside the microcapsules.

“…To solve these problems, the immobilization of the extractant [2][3][4][5][6][7][8] and microencapsulation [9][10][11][12][13][14][15][16][17][18][19][20][21][22] of the extractant have been investigated. The immobilization of the extractant is achieved using porous polymer particles [2][3][4][5][6] and in some cases using fibers [7,8].…”

Section: Introductionmentioning

confidence: 99%

Extraction Properties of Nickel (II) with Polymeric Particles with Interconnected Spherical Pores Impregnating with LIX84-I

Kitabayashi

Sana

Kiyoyama

et al. 2013

Self Cite

1-(2-hydroxyl-5-nonyphenyl)ethanone oxime (LIX84-I) was impregnated intopolymeric particles with interconnected spherical pores by the solvent evaporation method. Divinylbenzene was used as a wall material and polymerized in the organic phase of a (W/O/W) emulsion by free radical polymerization. The diameter of the polymeric particles was almost constant at around 208±26μm. The impregnated yield of LIX84-I in the polymeric particles was higher than 80% in all preparation conditions. The extraction of Ni(II) with the polymeric particles impregnated with LIX84-I sharply increased at pH values higher than 6. It is confirmed that three molecules of LIX84-I reacted with one Ni(II) ion by quantitative analysis of the relationship between the maximum amounts of Ni(II) extracted and the amount of LIX84-I impregnated in the polymeric particles. The extraction rate of Ni(II) was effectively accelerated by the presence of the interconnected-spherical pores in the inside of the polymeric particles.