Multiple equilibria describe the complete adsorption isotherms of nonporous, microporous, and mesoporous adsorbents

Calzaferri, Gion; Gallagher, Samuel H.; Brühwiler, Dominik

doi:10.1016/j.micromeso.2021.111563

Please use this identifier to cite or link to this item: https://doi.org/10.21256/zhaw-23908

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DC Field	Value	Language
dc.contributor.author	Calzaferri, Gion	-
dc.contributor.author	Gallagher, Samuel H.	-
dc.contributor.author	Brühwiler, Dominik	-
dc.date.accessioned	2022-01-12T15:14:30Z	-
dc.date.available	2022-01-12T15:14:30Z	-
dc.date.issued	2022	-
dc.identifier.issn	1387-1811	de_CH
dc.identifier.uri	https://digitalcollection.zhaw.ch/handle/11475/23908	-
dc.description.abstract	The adsorption of simple gases begins with the formation of a monolayer on the pristine surface, not always followed by the formation of a second or more monolayers. Subsequently, cluster formation or cavity filling occurs, depending on the properties of the surface. The characteristically different shape of the isotherms related to these processes allows to clearly differentiate them. We analyzed argon and N2 adsorption isotherms quantitatively over the entire relative pressure range for adsorbents bearing different properties: the nonporous Stöber-type particles, the microporous zeolite L (ZL) and zeolite L filled with indigo (Indigo-ZL), and three mesoporous silica adsorbents of different pore size. The formal equilibria involved in cluster formation and in cavity filling have been derived and successfully applied to quantitatively describe the isotherms of the adsorbents. No indication regarding formation of a second monolayer on top of the first one was observed for the Stöber-type particles. Instead, cluster generation, which minimizes surface tension, starts early. The behavior of microporous ZL and of Indigo-ZL is different. A second monolayer sets up and cluster formation starts with some delay. The enthalpy of cluster formation is, however, practically identical with that seen for the Stöber-type particles. The difference between the experimental and the calculated inflection points is very small. The shapes of the isotherms seen for the mesoporous adsorbents differ significantly from those seen for the nonporous and for the microporous adsorbents. The quantitative analysis of the data proves that formation of a second monolayer is followed by filling of cavities which ends as soon as all cavity sites are filled. The sum of the individual fractional contributions, namely the monolayer formation ΘmL, the appearance of a second monolayer Θ2L on top of the first one, and the cavity filling, yields a calculated adsorption isotherm Θcalc which describes the experimental data Θexp well. The experimental and the calculated first inflection points are in excellent agreement, which is also the case for the second inflection points. The value of the cavity filling enthalpy is roughly 10% larger than that for the cluster formation seen in the nonporous and the microporous adsorbents. The volume for cavity filling is significantly smaller than the monolayer volume for the mesoporous adsorbent with a pore diameter of 2.7 nm, while it is the same or larger for pore diameters of 4.1 nm and 4.4 nm, respectively. We conclude that understanding the adsorption isotherms as signature of several sequential chemical equilibrium steps provides additional information data for clusters, cavities, and position of the inflection points, not accessible by means of the conventional models. The theory reported herein covers type I, II, IV and to some extent also type VI isotherms.	de_CH
dc.language.iso	en	de_CH
dc.publisher	Elsevier	de_CH
dc.relation.ispartof	Microporous and Mesoporous Materials	de_CH
dc.rights	http://creativecommons.org/licenses/by-nc-nd/4.0/	de_CH
dc.subject	Stöber-type particle	de_CH
dc.subject	Zeolite L	de_CH
dc.subject	MCM-41	de_CH
dc.subject	Type I	de_CH
dc.subject	Type II	de_CH
dc.subject	Type IV	de_CH
dc.subject	Type VI	de_CH
dc.subject	Adsorption isotherm	de_CH
dc.subject	Cluster	de_CH
dc.subject	Cavity	de_CH
dc.subject	Sequential chemical equilibria	de_CH
dc.subject.ddc	540: Chemie	de_CH
dc.title	Multiple equilibria describe the complete adsorption isotherms of nonporous, microporous, and mesoporous adsorbents	de_CH
dc.type	Beitrag in wissenschaftlicher Zeitschrift	de_CH
dcterms.type	Text	de_CH
zhaw.departement	Life Sciences und Facility Management	de_CH
zhaw.organisationalunit	Institut für Chemie und Biotechnologie (ICBT)	de_CH
dc.identifier.doi	10.1016/j.micromeso.2021.111563	de_CH
dc.identifier.doi	10.21256/zhaw-23908	-
zhaw.funding.eu	No	de_CH
zhaw.issue	111563	de_CH
zhaw.originated.zhaw	Yes	de_CH
zhaw.publication.status	publishedVersion	de_CH
zhaw.volume	330	de_CH
zhaw.publication.review	Peer review (Publikation)	de_CH
zhaw.funding.snf	172805	de_CH
zhaw.webfeed	Polymerchemie	de_CH
zhaw.funding.zhaw	Multimodal Porous Particles	de_CH
zhaw.author.additional	No	de_CH
zhaw.display.portrait	Yes	de_CH
Appears in collections:	Publikationen Life Sciences und Facility Management

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Calzaferri, G., Gallagher, S. H., & Brühwiler, D. (2022). Multiple equilibria describe the complete adsorption isotherms of nonporous, microporous, and mesoporous adsorbents. Microporous and Mesoporous Materials, 330(111563). https://doi.org/10.1016/j.micromeso.2021.111563

Calzaferri, G., Gallagher, S.H. and Brühwiler, D. (2022) ‘Multiple equilibria describe the complete adsorption isotherms of nonporous, microporous, and mesoporous adsorbents’, Microporous and Mesoporous Materials, 330(111563). Available at: https://doi.org/10.1016/j.micromeso.2021.111563.

G. Calzaferri, S. H. Gallagher, and D. Brühwiler, “Multiple equilibria describe the complete adsorption isotherms of nonporous, microporous, and mesoporous adsorbents,” Microporous and Mesoporous Materials, vol. 330, no. 111563, 2022, doi: 10.1016/j.micromeso.2021.111563.

CALZAFERRI, Gion, Samuel H. GALLAGHER und Dominik BRÜHWILER, 2022. Multiple equilibria describe the complete adsorption isotherms of nonporous, microporous, and mesoporous adsorbents. Microporous and Mesoporous Materials. 2022. Bd. 330, Nr. 111563. DOI 10.1016/j.micromeso.2021.111563

Calzaferri, Gion, Samuel H. Gallagher, and Dominik Brühwiler. 2022. “Multiple Equilibria Describe the Complete Adsorption Isotherms of Nonporous, Microporous, and Mesoporous Adsorbents.” Microporous and Mesoporous Materials 330 (111563). https://doi.org/10.1016/j.micromeso.2021.111563.

Calzaferri, Gion, et al. “Multiple Equilibria Describe the Complete Adsorption Isotherms of Nonporous, Microporous, and Mesoporous Adsorbents.” Microporous and Mesoporous Materials, vol. 330, no. 111563, 2022, https://doi.org/10.1016/j.micromeso.2021.111563.