The Nanopore Inner Sphere Enhancement Effect on Cation Adsorption: Sodium and Nickel

Schulthess, Cristian P.; Taylor, Richard W.; Ferreira, Daniel R.

doi:10.2136/sssaj2010.0129nps

Cited by 25 publications

(30 citation statements)

References 21 publications

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“…For instance, the H + selectivity was higher in X than in Y due to the variations in Si/Al ratios [12]. Schulthess et al [15] reported the adsorption strength of Na + was weak with zeolite Y but strong with mordenite zeolite. Differences in Si/Al ratios within and among zeolite species resulted in significant variations in their H + adsorption selectivity.…”

Section: Resultsmentioning

confidence: 99%

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Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites

et al. 2014

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In addition to their well-known uses as catalysts, zeolites are utilized to adsorb and remove various cations from aqueous system. The adsorption of the cations is ascribed to the negative charge of zeolites derived from isomorphous substitution of Si by Al. The amount of Na+ adsorption on 4A, X, Y, Na-P1 and mordenite type zeolites were determined in aqueous media, in a two-cation (Na+ and H+) system. Although each zeolite has a constant amount of negative charge, the amount of Na+ adsorption of each zeolite decreased drastically at low pH-pNa values, where pH-pNa is equal to log{(Na+)/(H+)}. By using the plot of the amount of Na+ adsorption versus pH-pNa, an index of the H+ selectivity, which is similar to the pKa of acids, of each zeolite was estimated, and the index tended to increase with decreasing Si/Al ratio of zeolites. These indicate that zeolites with lower Si/Al and higher negative charge density have higher H+ adsorption selectivity, and in fact, such a zeolite species (4A and X) adsorbed considerable amount of H+ even at weakly alkaline pH region. The adsorption of H+ results in the decrease of cation adsorption ability, and may lead to the dissolution of zeolites in aqueous media.

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Section: Resultsmentioning

confidence: 99%

“…Usually such factors affect the cation retention behavior and acid strength of the Si(OH)Al group in various zeolites [14]. It has been shown that the adsorption or selectivity of some cations such as Na + , Ni 2+ varies significantly among different zeolites [15].…”

Section: Introductionmentioning

confidence: 99%

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites

et al. 2014

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“…Estos resultados están relacionados con la elevada proporción de Na y K intercambiables presentes en dicho mineral (Palmer y Gunter 2000). Estos cationes se encuentran débilmente adsorbidos y pueden ser fácilmente desplazados o sustituidos por otros en función del potencial iónico (Schulthess et al 2011). Consecuentemente, la incorporación de zeolitas en los suelos incrementó significativamente los valores de CE en SZ con relación a S.…”

Section: Ph Y Ceunclassified

Efecto De Las Zeolitas Sobre Ciertas Propiedades De Un Suelo Enmendado Con Biosólidos

Torri

Amaturo

Sánchez

et al. 2021

RICA

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La aplicación de biosólidos como enmienda orgánica para restaurar suelos degradados constituye una alternativa para su eliminación. Sin embargo, los biosólidos pueden presentar concentraciones variables de elementos traza potencialmente tóxicos (EPT) que se acumulan en los suelos alterando la actividad microbiana. Las zeolitas son minerales que tienen espacios porosos y canales internos con una elevada capacidad de intercambio catiónico. El objetivo de este trabajo fue determinar la influencia del agregado de zeolitas sobre la actividad microbiana, pH, conductividad eléctrica (CE), carbono oxidable y disponibilidad de fósforo (P) en un suelo remediado con biosólidos. Se realizó un ensayo de incubación a temperatura ambiente. Se observó que la incorporación de zeolitas no modificó significativamente la actividad microbiana de los suelos sin remediar o remediados con biosólidos; sin embargo, incrementó de manera importante los valores de pH (en 2.89 y 1.18 unidades) y CE (en 4374 y 1459 µS/cm) en los suelos sin enmendar o enmendados con biosólidos, y produjo una reducción significativa en la concentración de fósforo extraíble. Dado el incremento en los valores de pH y CE observados, la proporción de biosólidos y zeolitas o el empleo de riego suplementario deben evaluarse cuidadosamente cuando estas remediaciones se incorporan de forma conjunta en el suelo, para evitar salinización si el objetivo es emplear ambas remediaciones de manera conjunta con fines de restauración de suelos.

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“…The NISE theory proposed by Schulthess et al (2011) explains this counterintuitive and atypical selectivity by incorporating the dehydration potential of the ions involved. Because divalent ions tend to have higher hydration energies than monovalent ions (Collins, 1997), it is more difficult for them to dehydrate.…”

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confidence: 99%

Calorimetric Evidence in Support of the Nanopore Inner Sphere Enhancement Theory on Cation Adsorption

Ferreira

Schulthess

Kabengi

2012

Soil Science Soc of Amer J

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Soil Chemistry S chulthess and Taylor (2007) proposed a new theory of cation adsorption to describe the adsorption of Na and Ni within zeolite minerals. This theory, called the nanopore inner sphere enhancement (NISE) theory, explains the unusual adsorption selectivity patterns observed for Na and Ni for Na, K, and Ca (Ferreira and. The NISE theory states that ions can dehydrate to fit into confining nanopore channels that are smaller than their hydrated diameters. In such a case, ions with lower hydration energies are more easily stabilized in their dehydrated states on adsorption than ions with higher hydration energies. Accordingly, in certain nanopore channels, monovalent ions are able to outcompete divalent ions because monovalent ions tend to have lower hydration energies than divalent ones (Collins, 1997). While hydration energy generally correlates well with the dehydration potential needed by the NISE theory, there are cases (such as Cu) where ions with high hydration energies can also dehydrate easily (Ferreira et al., 2012b).On zeolite Y, which contained the largest nanopore channels (0.74-nm limiting diameter), Ferreira and Schulthess (2011) observed that all three cations (Na, K, and Ca) adsorbed weakly and in similar amounts. On mordenite, with the smallest nanopore channels (0.26-nm limiting diameter), all three cations adsorbed strongly and in similar amounts. It is important to point out that the monovalent cations competed equally with a divalent cation at equimolar concentrations in these ion exchange reactions, which is very unusual. The most interesting results, however, The nanopore inner sphere enhancement (NISE) theory provides a new theoretical model of cation adsorption within confining nanopore channels. Inside nanopore channels, hydrated ions can dehydrate and more easily adsorb via an inner sphere mechanism. Adsorption data showed that in certain nanopores, weakly hydrated monovalent cations adsorbed more strongly than divalent cations, which tend to be strongly hydrated. Flow adsorption calorimetry is a valuable tool for directly measuring the heats of the ion exchange process and was used to measure the heats of Na and Ca exchange on three zeolite minerals: zeolite Y, mordenite, and ZSM-5. The data collected showed equal and reversible exchange reactions on mordenite but a strong endothermic Na adsorption and weak exothermic Ca adsorption on ZSM-5. On zeolite Y, the calorimetric signal was below the instrument detection limit of 5 to 7.5 mV. These differences coincide with the adsorption mechanisms and relative competitiveness predicted by the NISE theory for these two ions on the three zeolites studied. These data elucidate an exchange reaction where Ca is outcompeted by Na, which is often considered to be a weak background electrolyte.

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The Nanopore Inner Sphere Enhancement Effect on Cation Adsorption: Sodium and Nickel

Cited by 25 publications

References 21 publications

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites

Efecto De Las Zeolitas Sobre Ciertas Propiedades De Un Suelo Enmendado Con Biosólidos

Calorimetric Evidence in Support of the Nanopore Inner Sphere Enhancement Theory on Cation Adsorption

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