Ion Exchange of Divalent Cobalt and Iron with Na–Y Zeolite: Binary and Ternary Exchange Equilibria

Kim, Jong Sung; Keane, Mark A.

doi:10.1006/jcis.2000.7165

Cited by 26 publications

(15 citation statements)

References 38 publications

(46 reference statements)

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“…19,20 A maximum exchange of 60% of the indigenous Na content (1.0 mmol g À1 ) was recorded for Co, essentially the same as that (62%) achieved for Fe. These levels of exchange are somewhat lower than those obtained at a much higher initial solution concentration (total charge = 100 mequiv dm À3 ) reported previously, 25 …”

Section: Batch Operationcontrasting

confidence: 46%

“…31,32 The increase in Co removal rate with increasing temperature can be attributed to a partial stripping of the hydration sheath from the incoming Co(II) ions, which facilitates entry to the zeolite cage structure and exchange with the indigenous sodium. In a previous study of batch Co/Na-Y exchange, 25 it was observed that the exchange capacity of Na-Y was elevated at higher temperatures where an increase in temperature from 291 K to 373 K raised the Co uptake from 80 to 88 mg per gram of zeolite. Maes and Cremers 10 have reported that an increase in temperature from 298 K to 318 K gave rise to an even more marked increase in Co exchange, ie the percentage exchange of indigenous Na was raised from 80% to 98% at [Co s ] i = 5 mmol dm…”

Section: Semi-batch Operationmentioning

confidence: 94%

“…24 However, the treatment of Fe(III) solutions with Na-Y was unfeasible due to the unavoidable pHinduced precipitation of Fe(OH) 3 and disintegration of the zeolitic structure. 24 Stoichiometric exchange with external Co(II) was readily achieved and found, 25 in contrast to Fe(II) exchange, to be temperature dependent. This paper presents the results generated from the treatment of dilute (less than 2 mmol dm À3 ) iron-and cobalt-containing solutions with Na-Y using both ®xed bed (continuous mode) and differential column (semi-batch mode) reactors; HM removal is compared with that achieved in batch treatment.…”

mentioning

confidence: 96%

“…19±25 In each case, ion exchange was conducted solely in the batch mode and sodium-based zeolite Y (Na-Y) proved 24,25 to be effective in removing divalent cobalt and iron from aqueous media over the concentration range 3±50 mmol dm À3 . In the case of iron treatment, the pH must be carefully controlled to minimize both hydroxide precipitation and zeolite structural breakdown.…”

mentioning

confidence: 99%

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The removal of iron and cobalt from aqueous solutions by ion exchange with Na‐Y zeolite: batch, semi‐batch and continuous operation

Kim

Keane

2002

J of Chemical Tech & Biotech

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The removal of single component and binary mixtures of divalent cobalt and iron from water by ion exchange with synthetic Y zeolite has been studied in batch, semi-batch and continuous modes of operation; the initial metal solution concentration did not exceed 2 mmol dm À3. Binary Co/Na and Fe/Na ion exchange equilibrium isotherms (294 K) are presented wherein exchange site heterogeneity is evident in the case of the iron treatment. Under conditions of stoichiometric ion exchange, removal ef®ciencies for both cobalt and iron decrease with increasing metal concentration (0.2±2 mmol dm À3 ) and the values were similar for both metals. Removal of cobalt under transient conditions was found to be temperature dependent. In the ®xed bed operation, break-through behavior was sensitive to changes in both¯ow rate and inlet concentration. The break-through pro®les for both metals under competitive and non-competitive conditions are presented; iron removal is lower in the presence of cobalt and vice versa. An in situ regeneration of the fully loaded zeolite by back exchange with sodium is considered and the exchange capacity of the regenerated zeolite is reported. The main source of an appreciable iron entry into a municipal water supply is through pipeline corrosion.

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Section: Batch Operationcontrasting

confidence: 46%

Section: Semi-batch Operationmentioning

confidence: 94%

mentioning

confidence: 96%

mentioning

confidence: 99%

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The removal of iron and cobalt from aqueous solutions by ion exchange with Na‐Y zeolite: batch, semi‐batch and continuous operation

Kim

Keane

2002

J of Chemical Tech & Biotech

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“…Further, the Freundlich model predicts that the cobalt concentration in the zeolite will increase steadily with increasing cobalt concentration in the liquid phase (Hameed et al, 2007). As the Freundlich model was the most representative for the H-USY system, it suggests that initially there is a cobalt exchange with H + ions in the accessible supercages and then an increase of ion exchange with parent ions located in the sodalite units and some less accessible hexagonal prisms at higher external cobalt concentrations (Kim and Keane, 2000). These ion exchange conditions lead to a favorable behavior that is represented by an exponent n higher than 1 for zeolite H-USY (Rengaraj and Moon, 2002).…”

Section: Resultsmentioning

confidence: 99%

Determination of the maximum retention of cobalt by ion exchange in h-zeolites

Zola

Barros

Sousa-Aguiar

et al. 2012

Braz. J. Chem. Eng.

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-This work aimed to determine the maximum content of cobalt that can be incorporated by ion exchange in zeolites H-USY, H-Beta, H-Mordenite, and H-ZSM-5. To reach this goal, batch isotherms at 75ºC were constructed after addition of zeolite samples in flasks filled with cobalt nitrate solution. The equilibrium data were fitted to Langmuir, Freundlich, and Tóth adsorption isotherm models. Langmuir was the best model for zeolites H-Beta, H-Mordenite, and H-ZSM-5, whereas experimental data for H-USY were better fitted to the Freundlich isotherm model. From the isotherms, it was possible to determine the maximum cobalt exchange level (q max ) that can be incorporated in each zeolite through ion exchange. In this sense, H-USY presented the highest q max value (2.40 meq/g zeol ), while H-ZSM-5 showed the lowest one (0.64 meq/g zeol ).These results also show the influence of the zeolite framework related to the channel system, pore opening, presence of cavities and secondary porosity and SiO 2 /Al 2 O 3 ratio (SAR) on the maximum capacity and behavior of cobalt ion exchange in protonic zeolites.

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Relationship between biodegradation and sorption of phthalate esters and their metabolites in natural sediments

Kickham

Otton

Moore

et al. 2012

Enviro Toxic and Chemistry

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Regulatory evaluations of commercial chemicals in Canada, the United States, the European Union, and other countries aim to identify biodegradation rates of chemicals in natural soils and sediments. However, commonly used biodegradation testing methods are limited in their capacity to determine biodegradation rates under natural environmental conditions. As a result, widely varying biodegradation rates have been reported for many very hydrophobic substances. This variability causes difficulties in regulatory evaluations, potentially leading to chemical misclassification. In the present study, the authors developed a model of the relationship between biodegradation, sorption, and hydrophobicity, and tested the model in experiments that measured the biodegradation rates of a range of di-phthalate esters (DPEs) and mono-phthalate esters (MPEs) in natural sediments. The results indicate that DPEs and MPEs have the inherent capacity to be quickly degraded by microbes in sediments at a common rate, but that DPE biodegradation rates in natural sediments decrease with increasing phthalate ester sorption to sediments. The results show that inherently biodegradable substances that are subject to a high degree of sorption can be expected to exhibit long half-lives in natural sediments. The model provides a potential methodology for assessing biodegradation rates in natural sediments from inherent biodegradation rates measured in screening tests by accounting for chemical sorption. The present study indicates that a reduced rate of biodegradation is due to a reduced fraction of freely dissolved chemical concentration in the interstitial water, and that the environmental significance of sorption-reduced biodegradation rates needs to be viewed in the context of risk in chemical evaluations.

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Ion Exchange of Divalent Cobalt and Iron with Na–Y Zeolite: Binary and Ternary Exchange Equilibria

Cited by 26 publications

References 38 publications

The removal of iron and cobalt from aqueous solutions by ion exchange with Na‐Y zeolite: batch, semi‐batch and continuous operation

The removal of iron and cobalt from aqueous solutions by ion exchange with Na‐Y zeolite: batch, semi‐batch and continuous operation

Determination of the maximum retention of cobalt by ion exchange in h-zeolites

Relationship between biodegradation and sorption of phthalate esters and their metabolites in natural sediments

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