Theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbons
The aim of this study was to analyze various theoretical models (clusters, systems with periodic boundary conditions) and methods, which could be applied to investigate the adsorption phenomena and for better interpretation of the experimental data. The density functional theory (DFT) and semiempir...
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Chuiko Institute of Surface Chemistry of NAS of Ukraine
2019-11-01
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| Series: | Хімія, фізика та технологія поверхні |
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| Online Access: | https://cpts.com.ua/index.php/cpts/article/view/519 |
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| author | V. M. Gun'ko |
| author_facet | V. M. Gun'ko |
| author_sort | V. M. Gun'ko |
| collection | DOAJ |
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The aim of this study was to analyze various theoretical models (clusters, systems with periodic boundary conditions) and methods, which could be applied to investigate the adsorption phenomena and for better interpretation of the experimental data. The density functional theory (DFT) and semiempirical (PM7) methods were used to model the adsorption phenomena at a surface of fumed nanooxides, silica gels, activated carbons, etc. The main idea is that appropriate theoretical analysis allows a deeper insight into interfacial phenomena related to the structure & properties of the adsorption layers vs. the textural and other characteristics of adsorbents. Comparison of the theoretically calculated characteristics with experimental ones can allow more accurate interpretation of the effects observed in various experiments on the adsorption phenomena. It was established that polarization of nonpolar and polar molecules adsorbed onto a polar surface and charge (& proton) transfer play an important role, as well as confined space effects. It enhances the interaction energy of adsorbed molecules bound to a solid surface and affects the surface orientation of adsorbed molecules, as well the behavior of the adsorption layer vs. temperature, pressure or concentration, as well other conditions. Surface hydrophobization reduces the interaction energy for both polar and nonpolar adsorbates. Adsorbates clusterization reduces the average energy of interaction of the adsorption layer with a surface per a molecule. The charge transfer is observed for both polar and nonpolar molecules interacting with polar surface functionalities. The mostly strong interfacial effects changing the behavior of the adsorption layer are observed upon proton transfer to the adsorbed molecules or vice versa. Variation in orientation of adsorbed molecules results in overestimation of the specific surface area estimated using a fixed value of surface area occupied by a probe molecule (e.g. 0.162 nm2 for N2).
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| format | Article |
| id | doaj-art-93db005c86ea4ce596bd8fe6f154e037 |
| institution | DOAJ |
| issn | 2079-1704 2518-1238 |
| language | English |
| publishDate | 2019-11-01 |
| publisher | Chuiko Institute of Surface Chemistry of NAS of Ukraine |
| record_format | Article |
| series | Хімія, фізика та технологія поверхні |
| spelling | doaj-art-93db005c86ea4ce596bd8fe6f154e0372025-08-20T03:08:22ZengChuiko Institute of Surface Chemistry of NAS of UkraineХімія, фізика та технологія поверхні2079-17042518-12382019-11-0110410.15407/hftp10.04.340Theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbonsV. M. Gun'ko0Chuiko Institute of Surface Chemistry of National Academy of Sciences of Ukraine The aim of this study was to analyze various theoretical models (clusters, systems with periodic boundary conditions) and methods, which could be applied to investigate the adsorption phenomena and for better interpretation of the experimental data. The density functional theory (DFT) and semiempirical (PM7) methods were used to model the adsorption phenomena at a surface of fumed nanooxides, silica gels, activated carbons, etc. The main idea is that appropriate theoretical analysis allows a deeper insight into interfacial phenomena related to the structure & properties of the adsorption layers vs. the textural and other characteristics of adsorbents. Comparison of the theoretically calculated characteristics with experimental ones can allow more accurate interpretation of the effects observed in various experiments on the adsorption phenomena. It was established that polarization of nonpolar and polar molecules adsorbed onto a polar surface and charge (& proton) transfer play an important role, as well as confined space effects. It enhances the interaction energy of adsorbed molecules bound to a solid surface and affects the surface orientation of adsorbed molecules, as well the behavior of the adsorption layer vs. temperature, pressure or concentration, as well other conditions. Surface hydrophobization reduces the interaction energy for both polar and nonpolar adsorbates. Adsorbates clusterization reduces the average energy of interaction of the adsorption layer with a surface per a molecule. The charge transfer is observed for both polar and nonpolar molecules interacting with polar surface functionalities. The mostly strong interfacial effects changing the behavior of the adsorption layer are observed upon proton transfer to the adsorbed molecules or vice versa. Variation in orientation of adsorbed molecules results in overestimation of the specific surface area estimated using a fixed value of surface area occupied by a probe molecule (e.g. 0.162 nm2 for N2). https://cpts.com.ua/index.php/cpts/article/view/519quantum chemical methodsab initio and DFT methodssemiempirical methodssilica modelsactivated carbon modelsadsorption models |
| spellingShingle | V. M. Gun'ko Theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbons Хімія, фізика та технологія поверхні quantum chemical methods ab initio and DFT methods semiempirical methods silica models activated carbon models adsorption models |
| title | Theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbons |
| title_full | Theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbons |
| title_fullStr | Theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbons |
| title_full_unstemmed | Theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbons |
| title_short | Theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbons |
| title_sort | theoretical analysis of adsorption of various compounds onto hydrophilic and hydrophobic silicas compared to activated carbons |
| topic | quantum chemical methods ab initio and DFT methods semiempirical methods silica models activated carbon models adsorption models |
| url | https://cpts.com.ua/index.php/cpts/article/view/519 |
| work_keys_str_mv | AT vmgunko theoreticalanalysisofadsorptionofvariouscompoundsontohydrophilicandhydrophobicsilicascomparedtoactivatedcarbons |