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Zelenka T, Zelená L, Abreu-Jaureguí C, Silvestre-Albero J, Zelenková G, Slovák V. On the Low-Pressure Hysteresis (LPH) in Gas Sorption Isotherms of Porous Carbons. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2311990. [PMID: 38712451 DOI: 10.1002/smll.202311990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 04/08/2024] [Indexed: 05/08/2024]
Abstract
This study investigates the origin of low-pressure hysteresis (LPH) in the adsorption and desorption of three different probe molecules: carbon dioxide, nitrogen, and argon, across various adsorption temperatures (from cryogenic to room temperature), and within five different carbon materials: synthetic carbons (pristine and one post-synthetically oxidized) and natural coal. Significant attention is dedicated to elucidating LPH in oxidized samples outgassed at various temperatures (120-350 °C). Experimental results show that insufficient outgassing temperature can lead to unreliable data due to artificial LPH and significantly underestimated textural properties, primarily caused by porosity blockage from substances like moisture. Conversely, in samples where heteroatoms have a stabilizing effect on texture, such as natural coal, careful consideration of outgassing temperature is crucial due to the risk of thermal degradation. Other factors contributing to LPH are adsorption temperature, and especially, kinetic limitations at cryogenic temperatures for cellulose-based carbons. Minor factors responsible for LPH are the physical state of the sample (monolith vs powder) and the flexibility of the porous system, both studied by carbon dioxide sorption. This study constitutes an important piece in the evaluation of LPH, providing practical recommendations and underlining the importance of experimental design, with implications for further research in this complex field.
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Affiliation(s)
- Tomáš Zelenka
- Department of Chemistry, Faculty of Science, University of Ostrava, 30. dubna 22, Ostrava, CZ-702 00, Czech Republic
| | - Lucie Zelená
- Department of Chemistry, Faculty of Science, University of Ostrava, 30. dubna 22, Ostrava, CZ-702 00, Czech Republic
- Department of Inorganic Chemistry, Faculty of Science, P. J. Šafárik University, Moyzesova 11, Košice, SK-041 01, Slovak Republic
| | - Coset Abreu-Jaureguí
- Laboratorio de Materiales Avanzados, Departamento de Química Inorgánica-Instituto Universitario de Materiales, Universidad de Alicante, San Vicente del Raspeig, E-03690, Spain
| | - Joaquin Silvestre-Albero
- Laboratorio de Materiales Avanzados, Departamento de Química Inorgánica-Instituto Universitario de Materiales, Universidad de Alicante, San Vicente del Raspeig, E-03690, Spain
| | - Gabriela Zelenková
- Department of Chemistry, Faculty of Science, University of Ostrava, 30. dubna 22, Ostrava, CZ-702 00, Czech Republic
| | - Václav Slovák
- Department of Chemistry, Faculty of Science, University of Ostrava, 30. dubna 22, Ostrava, CZ-702 00, Czech Republic
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Rocha RP, Pereira MFR, Figueiredo JL. CHARACTERISATION OF THE SURFACE CHEMISTRY OF CARBON MATERIALS BY TEMPERATURE-PROGRAMMED DESORPTION: AN ASSESSMENT. Catal Today 2023. [DOI: 10.1016/j.cattod.2023.114136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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Revisiting the Effect of Pyrolysis Temperature and Type of Activation on the Performance of Carbon Electrodes in an Electrochemical Capacitor. MATERIALS 2022; 15:ma15072431. [PMID: 35407762 PMCID: PMC8999809 DOI: 10.3390/ma15072431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 01/27/2023]
Abstract
Hierarchical porous carbons are known to enhance the electrochemical features of electrodes in electrochemical capacitors. However, the contribution of surface oxygen and the resulting functionalities and wettability, along with the role of electrical conductivity and degree of amorphous or crystalline nature in the micro-mesoporous carbons, are not yet clear. This article considers the effect of carbonisation temperature (500–900 °C) and the type of activation (CO2, KOH) on the properties mentioned above in case of carbon xerogels (CXs) to understand the resulting electrochemical performances. Depending on the carbonisation temperature, CX materials differ in micropore surface area (722–1078 m2 g−1) while retaining a mesopore surface area ~300 m2 g−1, oxygen content (3–15%, surface oxygen 0–7%), surface functionalities, electrical conductivity (7 × 10−6–8 S m−1), and degree of amorphous or crystalline nature. Based on the results, electrochemical performances depend primarily on electrical conductivity, followed by surface oxygen content and meso-micropore connectivity. The way of activation using a varied extent of CO2 exposure and KOH concentrations played differently in CX in terms of pore connectivity from meso- to micropores and their contributions and degree of oxidation, and resulted in different electrochemical behaviours. Such performances of activated CXs depend solely on micro-mesopore features.
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Dittmann D, Eisentraut P, Goedecke C, Wiesner Y, Jekel M, Ruhl AS, Braun U. Specific adsorption sites and conditions derived by thermal decomposition of activated carbons and adsorbed carbamazepine. Sci Rep 2020; 10:6695. [PMID: 32317741 PMCID: PMC7174341 DOI: 10.1038/s41598-020-63481-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 03/30/2020] [Indexed: 12/07/2022] Open
Abstract
The adsorption of organic micropollutants onto activated carbon is a favourable solution for the treatment of drinking water and wastewater. However, these adsorption processes are not sufficiently understood to allow for the appropriate prediction of removal processes. In this study, thermogravimetric analysis, alongside evolved gas analysis, is proposed for the characterisation of micropollutants adsorbed on activated carbon. Varying amounts of carbamazepine were adsorbed onto three different activated carbons, which were subsequently dried, and their thermal decomposition mechanisms examined. The discovery of 55 different pyrolysis products allowed differentiations to be made between specific adsorption sites and conditions. However, the same adsorption mechanisms were found for all samples, which were enhanced by inorganic constituents and oxygen containing surface groups. Furthermore, increasing the loadings led to the evolution of more hydrated decomposition products, whilst parts of the carbamazepine molecules were also integrated into the carbon structure. It was also found that the chemical composition, especially the degree of dehydration of the activated carbon, plays an important role in the adsorption of carbamazepine. Hence, it is thought that the adsorption sites may have a higher adsorption energy for specific adsorbates, when the activated carbon can then potentially increase its degree of graphitisation.
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Affiliation(s)
- Daniel Dittmann
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin, 12205, Germany.
- Technische Universität Berlin, Water Quality Control, Straße des 17. Juni 135, Berlin, 10623, Germany.
| | - Paul Eisentraut
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin, 12205, Germany
| | - Caroline Goedecke
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin, 12205, Germany
| | - Yosri Wiesner
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin, 12205, Germany
| | - Martin Jekel
- Technische Universität Berlin, Water Quality Control, Straße des 17. Juni 135, Berlin, 10623, Germany
| | - Aki Sebastian Ruhl
- Technische Universität Berlin, Water Quality Control, Straße des 17. Juni 135, Berlin, 10623, Germany
- German Environment Agency (UBA), Section II 3.1, Schichauweg 58, Berlin, 12307, Germany
| | - Ulrike Braun
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin, 12205, Germany
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Hotová G, Slovák V, Zelenka T, Maršálek R, Parchaňská A. The role of the oxygen functional groups in adsorption of copper (II) on carbon surface. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 711:135436. [PMID: 31852589 DOI: 10.1016/j.scitotenv.2019.135436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 11/02/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
The effect of carbon surface oxidation on the adsorption of Cu(II) ions from aqueous solution was studied in order to explain the role of the oxygen functional groups in the binding of copper ions. Pristine carbonaceous adsorbent was oxidized to a various extent of oxygen uptake (Fenton-like oxidation < persulphate in H2SO4 < H2O2 in HNO3). Equilibrium adsorption tests were performed in acetate buffer at pH ≈ 5. The results show that the adsorption capacity of pristine adsorbent is expectable low (~0.1 mmol g-1). The oxidized samples adsorb Cu(II) at a considerably higher level of ~1.4 mmol g-1 despite the degree of surface oxidation. Analysis of the surface groups (FTIR, TPD) and surface charge (zeta potential) of used adsorbents and their Cu(II) saturated counterpart lead to the finding that Cu(II) ions are mostly bonded by complexation with the dissociated carboxylic groups (partly formed by anhydrides hydrolysis) probably in the form of Cu(Ac)+ formed in the acetate buffer. The extent of dissociation is given by equilibrium pH during the adsorption and does not depend on the total amount of the surface groups. Thus, the content of active sites and consequently adsorption capacity is independent on the degree of oxidation when pH is kept constant. The results indicate that even moderate oxidation treatment of carbonaceous materials can produce highly effective adsorbents for Cu(II) immobilization.
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Affiliation(s)
- Gabriela Hotová
- University of Ostrava, Faculty of Science, Department of Chemistry, 30. dubna 22, 702 00 Ostrava, Czech Republic.
| | - Václav Slovák
- University of Ostrava, Faculty of Science, Department of Chemistry, 30. dubna 22, 702 00 Ostrava, Czech Republic.
| | - Tomáš Zelenka
- University of Ostrava, Faculty of Science, Department of Chemistry, 30. dubna 22, 702 00 Ostrava, Czech Republic.
| | - Roman Maršálek
- University of Ostrava, Faculty of Science, Department of Chemistry, 30. dubna 22, 702 00 Ostrava, Czech Republic.
| | - Alžběta Parchaňská
- University of Ostrava, Faculty of Science, Department of Chemistry, 30. dubna 22, 702 00 Ostrava, Czech Republic.
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Zhang D, Wang J, He C, Wang Y, Guan T, Zhao J, Qiao J, Li K. Rational Surface Tailoring Oxygen Functional Groups on Carbon Spheres for Capacitive Mechanistic Study. ACS APPLIED MATERIALS & INTERFACES 2019; 11:13214-13224. [PMID: 30888151 DOI: 10.1021/acsami.8b22370] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Porous carbons represent a typical class of electrode materials for electric double-layer capacitors. However, less attention has been focused on the study of the capacitive mechanism of electrochemically active surface oxygen groups rooted in porous carbons. Herein, the degree and variety of oxygen surface groups of HNO3-modified samples (N-CS) are finely tailored by a mild hydrothermal oxidation (0.0-3.0 mol L-1), while the micro-meso-macroporous structures are efficiently preserved from the original sample. Thus, N-CS is a suitable carrier for separately discussing the contribution of oxygen functional groups to the electrochemical property. The optimized N-CS shows a high capacitance of 279.4 F g-1 at 1 A g-1, exceeding 52.8% of pristine carbon sphere (CS) (182.8 F g-1 at 1 A g-1) in KOH electrolyte. On further deconvoluting the redox peaks of cyclic voltammetry curves, we find that the pseudocapacitance not only associates with the surface-controlled faradic reaction at high scan rate but also dramatically stems from the diffusion-controlled capacitance through potassium and hydroxyl ion insertion/deinsertion into the underutilized micropores at low scan rate. The assembled supercapacitor based on N-CS presents a stable energy density of 5 Wh kg-1 over a wide range of power density of 250-5000 W kg-1, which is higher than 0.0N-CS in KOH electrolyte. In TEABF4 electrolyte, the N-CS supercapacitor has an energy density of 26.9 Wh kg-1 at the power density of 1350 W kg-1 and exhibits excellent cycling stability with a capacitance retention of 93.2% at 2 A g-1 after 10 000 cycles. These results demonstrate that surface oxygen groups alter the capacitive mechanism and contribution of porous carbons.
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Affiliation(s)
- Dongdong Zhang
- Institute of Coal Chemistry , Chinese Academy of Sciences , 27 Taoyuan South Road , Taiyuan 030001 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 010049 , China
| | - Jianlong Wang
- Institute of Coal Chemistry , Chinese Academy of Sciences , 27 Taoyuan South Road , Taiyuan 030001 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 010049 , China
| | - Chong He
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 010049 , China
| | - Yuzi Wang
- Institute of Coal Chemistry , Chinese Academy of Sciences , 27 Taoyuan South Road , Taiyuan 030001 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 010049 , China
| | - Taotao Guan
- Institute of Coal Chemistry , Chinese Academy of Sciences , 27 Taoyuan South Road , Taiyuan 030001 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 010049 , China
| | - Jianghong Zhao
- Engineering Research Center of Ministry of Education for Fine Chemicals , Shanxi University , 92 Wucheng Road , Taiyuan 030006 , China
| | - Jinli Qiao
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering , Donghua University , 2999 Ren'min North Road , Shanghai 201620 , China
| | - Kaixi Li
- Institute of Coal Chemistry , Chinese Academy of Sciences , 27 Taoyuan South Road , Taiyuan 030001 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 010049 , China
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Zhang N, Li G, Xie T, Li L. Amorphous tantalum oxyhydroxide homojunction: In situ construction for enhanced hydrogen production. J Colloid Interface Sci 2018; 525:196-205. [DOI: 10.1016/j.jcis.2018.04.066] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/16/2018] [Accepted: 04/17/2018] [Indexed: 10/17/2022]
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