Dependency of Catalytic Reactivity on the Characteristics of Expanded Graphites as Representatives of Carbonaceous Materials
Carbonaceous materials (CMs) have gained great attention as heterogeneous catalysts in water treatment because of their high efficiency and potential contribution to achieving carbon neutrality. Expanded graphite (EG) is ideal for studying CMs because the reactivity in CMs largely depends on graphit...
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MDPI AG
2025-05-01
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| author | Do Gun Kim Seong Won Im Kyung Hwan Ryu Seoung Ho Jo Min Gyeong Choe Seok Oh Ko |
| author_facet | Do Gun Kim Seong Won Im Kyung Hwan Ryu Seoung Ho Jo Min Gyeong Choe Seok Oh Ko |
| author_sort | Do Gun Kim |
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| description | Carbonaceous materials (CMs) have gained great attention as heterogeneous catalysts in water treatment because of their high efficiency and potential contribution to achieving carbon neutrality. Expanded graphite (EG) is ideal for studying CMs because the reactivity in CMs largely depends on graphitic structures, and most surface of EG is exposed, minimizing mass transfer resistance. However, EG is poor in adsorption and catalysis. In this study, EG was modified by simple thermal treatment to investigate the effects of characteristics of graphitic structures on reactivity. Tetracycline (TC) removal rate via activating peroxydisulfate (PDS) by the EG treated at 550 °C (EG550) was more than 10 times that of EG. The thermal modification did not significantly increase surfaces but led to increases in damaged, rough surfaces, graphitization degree, C content, defects, and C=O. Radical and non-radical pathways, such as SO<sub>4</sub><sup>•−</sup>, O<sub>2</sub><sup>•−</sup>, <sup>1</sup>O<sub>2</sub>, and electron transfer, were involved in TC removal in EG550+PDS. TC degradation in EG550+PDS was initiated by hydroxylation, followed by demethylation, dehydroxylation, decarbonylation, and ring-opening. The ions ubiquitous in water systems did not significantly affect the performance of EG550+PDS, except for H<sub>2</sub>PO<sub>4</sub><sup>−</sup> and HCO<sub>3</sub><sup>−</sup>, suggesting the high potential of practical applications. This study demonstrated that graphitic structure itself and surface area are not detrimental in the catalytic reactivity of CMs, which is different from previous studies. Rather, the reactivity is governed by the characteristics, i.e., defects and functional groups of the graphitic structure. It is thought that this study provides valuable insights into the development of highly reactive CMs and the catalytic systems using them. |
| format | Article |
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| institution | DOAJ |
| issn | 1420-3049 |
| language | English |
| publishDate | 2025-05-01 |
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| series | Molecules |
| spelling | doaj-art-aa450eb79984461aa19f5372e2cd34f72025-08-20T03:11:19ZengMDPI AGMolecules1420-30492025-05-013011227510.3390/molecules30112275Dependency of Catalytic Reactivity on the Characteristics of Expanded Graphites as Representatives of Carbonaceous MaterialsDo Gun Kim0Seong Won Im1Kyung Hwan Ryu2Seoung Ho Jo3Min Gyeong Choe4Seok Oh Ko5Department of Environmental Engineering, Sunchon National University, Suncheon 57922, Republic of KoreaDepartment of Environmental Engineering, Sunchon National University, Suncheon 57922, Republic of KoreaDepartment of Chemical Engineering, Sunchon National University, Suncheon 57922, Republic of KoreaDepartment of Environmental Engineering, Sunchon National University, Suncheon 57922, Republic of KoreaDepartment of Environmental Engineering, Sunchon National University, Suncheon 57922, Republic of KoreaDepartment of Civil Engineering, Kyung Hee University, Yongin 57922, Republic of KoreaCarbonaceous materials (CMs) have gained great attention as heterogeneous catalysts in water treatment because of their high efficiency and potential contribution to achieving carbon neutrality. Expanded graphite (EG) is ideal for studying CMs because the reactivity in CMs largely depends on graphitic structures, and most surface of EG is exposed, minimizing mass transfer resistance. However, EG is poor in adsorption and catalysis. In this study, EG was modified by simple thermal treatment to investigate the effects of characteristics of graphitic structures on reactivity. Tetracycline (TC) removal rate via activating peroxydisulfate (PDS) by the EG treated at 550 °C (EG550) was more than 10 times that of EG. The thermal modification did not significantly increase surfaces but led to increases in damaged, rough surfaces, graphitization degree, C content, defects, and C=O. Radical and non-radical pathways, such as SO<sub>4</sub><sup>•−</sup>, O<sub>2</sub><sup>•−</sup>, <sup>1</sup>O<sub>2</sub>, and electron transfer, were involved in TC removal in EG550+PDS. TC degradation in EG550+PDS was initiated by hydroxylation, followed by demethylation, dehydroxylation, decarbonylation, and ring-opening. The ions ubiquitous in water systems did not significantly affect the performance of EG550+PDS, except for H<sub>2</sub>PO<sub>4</sub><sup>−</sup> and HCO<sub>3</sub><sup>−</sup>, suggesting the high potential of practical applications. This study demonstrated that graphitic structure itself and surface area are not detrimental in the catalytic reactivity of CMs, which is different from previous studies. Rather, the reactivity is governed by the characteristics, i.e., defects and functional groups of the graphitic structure. It is thought that this study provides valuable insights into the development of highly reactive CMs and the catalytic systems using them.https://www.mdpi.com/1420-3049/30/11/2275antibioticscatalytic degradationexpanded graphiteperoxydisulfatethermal treatment |
| spellingShingle | Do Gun Kim Seong Won Im Kyung Hwan Ryu Seoung Ho Jo Min Gyeong Choe Seok Oh Ko Dependency of Catalytic Reactivity on the Characteristics of Expanded Graphites as Representatives of Carbonaceous Materials Molecules antibiotics catalytic degradation expanded graphite peroxydisulfate thermal treatment |
| title | Dependency of Catalytic Reactivity on the Characteristics of Expanded Graphites as Representatives of Carbonaceous Materials |
| title_full | Dependency of Catalytic Reactivity on the Characteristics of Expanded Graphites as Representatives of Carbonaceous Materials |
| title_fullStr | Dependency of Catalytic Reactivity on the Characteristics of Expanded Graphites as Representatives of Carbonaceous Materials |
| title_full_unstemmed | Dependency of Catalytic Reactivity on the Characteristics of Expanded Graphites as Representatives of Carbonaceous Materials |
| title_short | Dependency of Catalytic Reactivity on the Characteristics of Expanded Graphites as Representatives of Carbonaceous Materials |
| title_sort | dependency of catalytic reactivity on the characteristics of expanded graphites as representatives of carbonaceous materials |
| topic | antibiotics catalytic degradation expanded graphite peroxydisulfate thermal treatment |
| url | https://www.mdpi.com/1420-3049/30/11/2275 |
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