Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe₂(SO₄)₃ solutions

Abstract

The thermochemical changes taking place in the phase of a Fe(III)‐containing strongly basic anion exchanger (AV‐17) are investigated by using Mössbauer, IR, and EPR spectroscopy. During the heating of Fe(III)‐containing resin in air up to 200°C, redox processes in the polymer phase take place. On boiling in water, the jarosite‐type compounds in the polymer are converted into higher dispersed β‐FeOOH particles. After sorption–boiling in water cycles in the polymer phase, relatively massive and magnetically ordered β‐FeOOH particles are formed. A portion of the β‐FeOOH particles remains in the highly dispersed superparamagnetic state distributed in the narrow pores of the exchanger. It is suggested that the Fe(III) ion sorption from Fe2(SO4)3 solutions by an exchanger takes place through the formation in the polymer phase of solid ultrafine particles of jarosite mineral‐type compounds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 59–64, 2006

Unforseen factors influencing Fe(III)‐containing cations sorption on strongly basic anion exchangers

“…However, in certain conditions, polymers of this type are able to retain metallic cations from solutions of Fe(III), Cr(III), and Al(III) sulfates. [1][2][3] Retaining of the M(III)-containing cations on strongly basic anion exchangers from sulfate solutions as a result of anion exchange or M(OH) 3 compounds formation in the polymer phase is unlikely. 3 We have suggested that the retention of the M(III) þ is a functional group of polymer.…”

“…11 In the phase of strongly basic anion exchangers, when boiling in water media, jarosite compounds may be converted into b-FeOOH in superparamagnetic state or relatively massive magnetically ordered particles. 2,4 Native jarosite mineral is not so stable, partially being transformed into Fe(OH) 3 . 5 It is necessary in order to apply Fe(III)-containing strongly basic anion exchangers as selective sorbents or catalysts to know their behavior in different media and sorption-desorptional features of the Fe(III)-containing cations on such kind of polymers.…”

“…In the organic polymer phase, these compounds are in form of inorganic polymers of solid ultrafine particles. 4,5 Metallic compounds in the polymer phase modify the sorptional, catalytically and thermochemical properties of the strongly basic anion exchangers. 6 The obtaining and transformations of metallic compounds in the polymer phase could expand the utilization of ion exchange materials, particularly in obtaining selective sorbents, [7][8][9] catalysis and modeling of physical and biochemical processes.…”

Some metal compounds in the phase of crosslinked ionic polymer—precursors for new sorbents and catalysts

“…Therefore, theoretically, they are able to retain from solution only anions but not inorganic cations. However, in previous studies1–3 it has been reported that in certain conditions, strongly basic anion exchangers are able to retain Fe(III), Al(III), Cr(III)‐containing cations (hydroxocomplexes) from solutions. These cations are retained by polymers from their sulfates solutions only and not from nitrates or chlorides.…”

“…The retaining of cations takes place through the formation in the polymer phase of jarosite4–6 mineral type compounds: R 4 N[M 3 (OH) 6 (SO 4 ) 2 ] and H 3 O[M 3 (OH) 6 (SO 4 ) 2 ], where R 4 N + is a polymer group, M is Fe 3+ , Al 3+ , or Cr 3+ . In the polymer phase, metallic compounds are in the form of ultra fine particles 1, 7…”