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001-es BibID:	BIBFORM133653
035-os BibID:	(Scopus)105020571877
Első szerző:	Bulátkó Anna (phd candidate)
Cím:	Role of texture and surface chemistry in interaction of graphene oxides with water / Anna Bulátkó, Lajos Höfler, Mónika Kéri, Tamás István Majzik, Miklós Mohai, György Sáfrán, Zoltán Sebestyén, Krisztina László
Dátum:	2025
ISSN:	0167-7322
Megjegyzések:	Hydrophilic graphene oxide (GO) has deservedly attained wide recognition in materials science. Its hydrophilic character, which facilitates its processability, opens new avenues in a wide range of applications. In membranes employed in water treatment or in electrical devices, for example, the solid surface - water interaction plays a key role in its performance. Major characteristic features of graphene that are sacrificed during wet exfoliation were at least partially restored by a mild thermal and green chemical reduction process to yield two reduced GOs with significantly different textures but apparently similar chemical composition. The samples were comprehensively characterised with multiple techniques including microscopic imaging, N2 adsorption, powder X-ray diffraction, Raman and X-ray photoelectron spectroscopy. To reveal how the textural and chemical differences observed in "dry" conditions are manifested in the presence of water, the samples were exposed to water in the vapor and liquid state, respectively. The results reveal a synergy of surface chemistry and relative humidity. In contact with liquid water the pore texture overcomes the effect of surface chemistry in the melting/freezing transition, while surface chemistry dominates the surface charge and thus the performance against charged dissolved species: lower O/C ratios lead to higher pHPZC. Electrochemical impedance spectroscopy reveals that samples with a high concentration of surface functional groups are more efficient in reducing charge transfer resistance. These findings show the importance of controlling the reduction method to optimize the performance of graphite oxide-based materials in an aqueous environment.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Journal Of Molecular Liquids. - 438 (2025), p. 1-12. -
További szerzők:	Höfler Lajos Kéri Mónika (1984-) (környezetkutató vegyész) Majzik Tamás István Mohai Miklós Sáfrán György Sebestyén Zoltán László Krisztina
Pályázati támogatás:	K143571 OTKA Horizon-MSCA-2022-SE-01-01 Egyéb TKP2021-NVA-02 Egyéb Bolyai János Kutatási Ösztöndíj MTA DETKA Egyéb
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001-es BibID:	BIBFORM113891
035-os BibID:	(WoS)001053307800001 (Scopus)85166955717
Első szerző:	Papp Vanda (vegyész, biomérnök)
Cím:	State and role of water confined in cement and composites modified with metakaolin and additives / Vanda Papp, Róbert Janovics, Tamás Péter Kertész, Zoltán Nemes, Tamás Fodor, István Bányai, Mónika Kéri
Dátum:	2023
ISSN:	0167-7322
Megjegyzések:	Cement as a porous material contains pores and cracks on the whole nanoscale forming an interconnected pore structure. Its interaction with water during the rehydration of cement plays a key role in every application, such as in nuclear waste treatment, where cement binders are commonly used for conditioning liquid radioactive waste. In the prediction of the long-term disposal the knowledge of water mobility and distribution in the formed porous cement matrix is essential. In this study we systematically investigate the effects of metakaolin and several components of the liquid phase (complexing agents, model ions, boric acid, etc.) on the hydrated solid structure by various nuclear magnetic resonance (NMR) methods. The novelty lies in the complex use of such non-conventional techniques that separately provide only partial information of the cement structure; however, the gained results complete each other to offer a new approach in the structural study under several conditions. Water mobility is deduced from NMR T2 relaxation distributions and D2O-H2O exchange diffusion measurements, and the conclusion on structural properties is supported by the macropore structure revealed from NMR cryoporometry and SEM (scanning electron microscopy) images, as well as by following the formation of pores and water domains in the curing process with NMR relaxometry. The results confirm that metakaolin was built into the CSH (calcium silicate hydrate) gel region without altering its mesoporous structure, however, it significantly decreased the capillary pore size and the diffusion coefficient of water. Complexing agent concentration between 2 and 20 g/l and the presence of model ions did not cause significant structural changes, while the rehydration decreased the size of capillary pores due to swelling.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Journal Of Molecular Liquids. - 388 (2023), p. 1-10. -
További szerzők:	Janovics Róbert (1984-) (környezetkutató) Kertész Tamás Péter (2001-) (egyetemi hallgató) Nemes Zoltán (1976-) Fodor Tamás (1987-) (vegyész) Bányai István (1953-) (vegyész) Kéri Mónika (1984-) (környezetkutató vegyész)
Pályázati támogatás:	OTKA-135169 OTKA OTKA-131989 OTKA KDP-2021 Egyéb GINOP-2.3.4-15-2020-00007 GINOP 2019-2.1.7-ERA-NET-2021-00021 Egyéb
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