Solubility-normalized Dubinin–Astakhov adsorption isotherm for ion-exchange systems

Inglezakis, Vassilis J.

doi:10.1016/j.micromeso.2007.01.039

Cited by 79 publications

(75 citation statements)

References 54 publications

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“…The value of the heterogeneity factor "n D " was 1.9, which was consistent with a material with a relatively disordered pore structure [30]. The magnitude of the sorption energy was higher than typical values of 8-16 kJ/mol described in the ion exchange literature, but consistent with data reported for exchange of "2+" cations with zeolites [51]. Additionally, Dron and Dodi [52] noted that the stronger the affinity for the exchanging ion in solution for the resin surface site the greater the sorption energy was calculated to be, with values up to 24.5 kJ/mol for R-OH/SO 4 2À anion exchange.…”

Section: Isotherm Model Equationsupporting

confidence: 85%

“…For the purposes of this study it was deemed sufficient to employ a selection of empirical equations as these were conducive to provision of clear illustration of the key aspects of the interaction of iron ions with strong acid cation resin. The following isotherm expressions were chosen: Langmuir-Vageler [46,47]; Competitive Langmuir [48]; Freundlich [49]; Temkin [50]; Dubinin-Astakhov [51,52]; Sips [53] and Brouers-Sotolongo [54,55]. A summary of these latter models is shown in Table 2.…”

Section: Background Theorymentioning

confidence: 99%

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Equilibrium and column studies of iron exchange with strong acid cation resin

Millar

Schot

Couperthwaite

et al. 2015

Journal of Environmental Chemical Engineering

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A B S T R A C TThe exchange of iron species from iron(III) chloride solutions with a strong acid cation resin has been investigated in relation to a variety of water and wastewater applications. A detailed equilibrium isotherm analysis was conducted wherein models such as Langmuir-Vageler, Competitive Langmuir, Freundlich, Temkin, Dubinin-Astakhov, Sips and Brouers-Sotolongo were applied to the experimental data. An important conclusion was that both the bottle-point method chosen and solution normality used to generate the ion exchange equilibrium isotherm influenced which sorption model fitted the isotherm profiles optimally. Invariably, the calculated value for the maximum loading of iron on strong acid cation resin was substantially higher than the value of 47.1 g/kg of resin which would occur if one Fe 3 + ion exchanged for three "H + " sites on the resin surface. Consequently, it was suggested that above pH 1, various iron complexes sorbed to the resin in a manner which required less than 3 sites per iron moiety. Column trials suggested that the iron loading was 86.6 g/kg of resin when 1342 mg/L Fe(III) ions in water were flowed at 31.7 BV/h. Regeneration with 5-10% HCl solutions reclaimed approximately 90% of exchange sites.2014 Elsevier Ltd. All rights reserved. IntroductionMetal pollution of our water resources remains a major concern [1-3]. Several methods have been employed to remediate contaminated solutions including precipitation [4], coagulationflocculation [5], adsorption [6-8], ion exchange [9,10], membrane filtration [11], flotation [12,13] and electrochemical means [14]. Physico-chemical techniques are attractive due to a variety of reasons such as process economics, reliability and ease of use [15]. Ion exchange is of particular interest as not only can the metals potentially be recovered but also the technology is well developed, simple and effective [16]. Iron is a common contaminant in natural waters [17], mining effluents [18], hydrometallurgical solutions [19] and a range of other industrial wastes [20]. Demineralization of water and wastewater solutions is widely practiced in industry, usually with a combination of cation and anion resins to remove the dissolved ions [21]. Kaya et al. [22] have shown that the presence of iron even at low concentration can significantly reduce the operating capacity of synthetic strong acid cation resins. Victor-Ortega Abbreviations: A, Temkin isotherm parameter (L/mmol or L/mg); a s , Sips equilibrium isotherm coefficient; a, exponent which represents the inherent energy heterogeneity of the sorbent surface; AIC, Akaike information criterion; ARE, average relative error; b T , Temkin constant related to the heat of adsorption (J/mol); BV, bed volumes; C e , equilibrium concentration of iron ions in solution (mg/L); C o , initial concentration of iron ions in solution (mg/L); e, adsorption potential (J/mol); E, energy of adsorption (J/mol); eq, equivalents; EABS, sum of the absolute errors; HYBRID, hybrid fractional error function; K CL , Competitive Lan...

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Section: Isotherm Model Equationsupporting

confidence: 85%

Section: Background Theorymentioning

confidence: 99%

Equilibrium and column studies of iron exchange with strong acid cation resin

Millar

Schot

Couperthwaite

et al. 2015

Journal of Environmental Chemical Engineering

View full text Add to dashboard Cite

show abstract

“…The Dubinin-Radushkevich (D-R) and Dubinin-Astakhov (D-A) models are based on the Polanyi adsorption potential theory which defines an adsorption potential ε related to the free energy of change of a substance from the liquid to the resin phase [20,33,34]. In contrast to the Langmuir and Freundlich models, the Dubinin isotherms consider a micropore volume filling adsorption process [20,35,36], and are temperature dependent.…”

Section: Dubinin Equationsmentioning

confidence: 99%

“…Langmuir, Freundlich, and Dubinin-Radushkevich. In addition, the DubininAstakhov isotherm integrating a potentially relevant parameter related to the nature of the sorbent surface is also applied [20]. To our knowledge, this latter model is applied for the first time to anion exchange systems involving an ion exchange resin.…”

Section: Introductionmentioning

confidence: 99%

Comparison of adsorption equilibrium models for the study of CL−, NO3− and SO42− removal from aqueous solutions by an anion exchange resin

Dron¹,

Dodi²

2011

Journal of Hazardous Materials

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“…So significance of parameters A, n and E is somewhat unknown for sorption from aqueous solutions onto sorbents with polymodal pore distribution and heterogeneous surface. Some authors [5,34,35] define calculated values of parameters E as adsorption energy values. In our view this parameter E in a greater degree expresses an energy (chemical) potential of an adsorbate, while parameter A characterizes adsorption energy.…”

Section: Sorption Isothermsmentioning

confidence: 99%