TY - JOUR AU - Dallos, Zsolt AU - Golle-Leidreiter, Philipp AU - Molnár, Zsombor AU - Kristály, Ferenc AU - Kovács Kis, Viktória AU - Dódony, István TI - Structural Changes of Bioapatite during Heat Treatment JF - CRYSTAL GROWTH & DESIGN J2 - CRYST GROWTH DES VL - 24 PY - 2024 IS - 5 SP - 2058 EP - 2063 PG - 6 SN - 1528-7483 DO - 10.1021/acs.cgd.3c01375 UR - https://m2.mtmt.hu/api/publication/34722932 ID - 34722932 LA - English DB - MTMT ER - TY - JOUR AU - Molnár, Zsombor AU - Pekker, Péter AU - Rečnik, Aleksander AU - Pósfai, Mihály TI - Formation and properties of spindle-shaped aragonite mesocrystals from Mg-bearing solutions JF - NANOSCALE J2 - NANOSCALE VL - 16 PY - 2024 IS - 4 SP - 2012 EP - 2021 PG - 10 SN - 2040-3364 DO - 10.1039/D3NR04672A UR - https://m2.mtmt.hu/api/publication/34499208 ID - 34499208 AB - Spindle-shaped aragonite mesocrystals form by the attachment of Mg-bearing amorphous calcium carbonate particles that convert to aragonite nanocrystals through dissolution-reprecipitation. LA - English DB - MTMT ER - TY - CHAP AU - UDDIN, IMRAN AU - Shoaib, Mukhtar AU - Molnár, Zsombor AU - Pósfai, Mihály TI - Low-temperature synthesis of graphene/Ag nanocomposite as a photo-catalyst for the degradation of organic pollutants in wastewater T2 - Műszaki Kémiai Napok 2023 Konferencia PB - Pannon Egyetem CY - Veszprém SN - 9789633962565 PY - 2023 SP - 44 UR - https://m2.mtmt.hu/api/publication/34731769 ID - 34731769 AB - We prepared a composite of graphene (Gr) and silver (Ag) nanoparticles by using chemically exfoliated graphene as the base matrix, and biosynthesized Ag nanoparticles. TEM micrographs show that Gr has a 2D delaminated layered structure with a sheet-like morphology, with a moderate concentration of isometric Ag NPs well dispersed over the basal planes of the Gr nanosheet. UV-visible absorption spectroscopy reveals a hump around 265 nm, which corresponds to π-π* electron resonance transitions owing to aromatic sp2 hybridized C-C bonds in graphene sheets, and a peak at 401 nm, which is attributed to Ag NPs. The photocatalytic potential of Gr/Ag nanocomposites was studied using the degradation of organic dyes (methylene blue, 4-nitrophenol, and cumarin) as models of water pollutants. The experiments show that the methylene blue degradation efficacy of the Gr/Ag nanocomposite catalyst after 2 hours is about 97% and 90% using UV and visible light irradiation, respectively. Furthermore, the Gr/Ag nanocomposite showed significant degradation activity toward 4-nitrophenol, and cumarin dye. This study suggests the nanocomposite synthesized at low temperatures can be used as an efficient adaptable photocatalyst for the photodegradation of organic dyes in industrial wastewater. LA - English DB - MTMT ER - TY - JOUR AU - Nguyen Xuan, Truong AU - Nguyen Thi, Dien AU - Tran Thuong, Quang AU - Nguyen Ngoc, Tue AU - Dang Quoc, Khanh AU - Molnár, Zsombor AU - Mukhtar, Shoaib AU - Szabóné Bárdos, Erzsébet AU - Horváth, Ottó TI - Effect of Copper-Modification of g-C3N4 on the Visible-Light-Driven Photocatalytic Oxidation of Nitrophenols JF - MOLECULES J2 - MOLECULES VL - 28 PY - 2023 IS - 23 SN - 1420-3049 DO - 10.3390/molecules28237810 UR - https://m2.mtmt.hu/api/publication/34403482 ID - 34403482 N1 - WoS:hiba:001117619600001 2024-01-01 11:18 cím nem egyezik AB - Graphitic carbon nitride (g-C3N4) has proved to be a promising heterogeneous photocatalyst in the visible range. It can be used, among others, for the oxidative conversion of environmentally harmful nitrophenols occurring in wastewater. However, its photocatalytic activity needs to be enhanced, which can be achieved by modification with various dopants. In our work, copper-modified g-C3N4 was prepared by ultrasonic impregnation of the pristine g-C3N4 synthesized from thiourea. The morphology, microstructure, and optical properties of the photocatalysts were characterized by XRD, FT-IR, DRS, SEM, XPS, and TEM. DRS analysis indicated a slight change in both the CB and the VB energies of Cu/g-C3N4 compared to those of g-C3N4. The efficiency of the photocatalysts prepared was tested by the degradation of nitrophenols. Copper modification caused a sevenfold increase in the rate of 4-nitrophenol degradation in the presence of H2O2 at pH = 3. This dramatic enhancement can be attributed to the synergistic effect of copper and H2O2 in this photocatalytic system. A minor Fenton reaction role was also detected. The reusability of the Cu/g-C3N4 catalyst was demonstrated through five cycles. Copper-modified g-C3N4 with H2O2 proved to be applicable for efficient visible-light-driven photocatalytic oxidative degradation of nitrophenols. LA - English DB - MTMT ER - TY - THES AU - Molnár, Zsombor TI - Kalcium-karbonát polimorfok heterogén nukleációja PY - 2023 SP - 162 DO - 10.18136/PE.2023.841 UR - https://m2.mtmt.hu/api/publication/34130643 ID - 34130643 LA - Hungarian DB - MTMT ER - TY - CONF AU - Molnár, Zsombor AU - Pekker, Péter AU - Pósfai, Mihály TI - The roles of precursor (Mg)-ACC in the formation of aragonite T2 - Goldschmidt 2023 Conference: abstracts PB - European Association of Geochemistry PY - 2023 UR - https://m2.mtmt.hu/api/publication/33879103 ID - 33879103 AB - Amorphous calcium carbonate (ACC) is often referred to as a phase that can transform into either of the three anhydrous crystalline CaCO3 forms (calcite, aragonite and vaterite). Here, we examined the conditions that make ACC transform into aragonite. Even though aragonite is the stable anhydrous crystalline CaCO3 polymorph at high pressure (4–40 GPa), it is also widespread on Earth’s surface. Nevertheless, the mechanism of its formation and the roles of solid precursors (such as ACC) in the process have not been studied as extensively as in the case of calcite. We studied aragonite formation by synthesizing it under laboratory conditions, focusing on the two, environmentally most relevant factors that are known to enhance its formation: (i) the presence of dissolved Mg2+ ions and (ii) the temperature of the mother solution (up to 80 °C). We used different experimental approaches in the two cases, and studied the precipitated materials with various scanning transmission electron microscopy (STEM) techniques. In Mg-rich solutions the first solid product was Mg-bearing ACC that transformed into aragonite aggregates with a typical, spindle-like appearance. Each spindle was an aggregate of crystallographically oriented nanocrystals, and two or more spindles could form star-like assemblies, with their members in twin orientation. Whereas the remarkable hierarchical structure suggested a growth mechanism by nanoparticle attachment, chemical differences observed between Mg-bearing ACC and aragonite indicated that the process must have involved dissolution and re-precipitation (DRP) as well. At elevated temperature ACC particles formed in the highly supersaturated (Mg-free) solutions, and their electron diffraction analysis suggested a trend of structural change with increasing temperature. The increasing temperature accelerated the transformation of ACC into crystalline forms (both calcite and aragonite), with aragonite formation favored at 80 °C. Morphological features suggested that the ACC could transform into either calcite or aragonite in solid state (preserving the globular shape of ACC), while simultaneously DRP produced aragonite crystals with aggregate or needle-like appearance. Thus, aragonite formation from ACC involved particle aggregation coupled with DRP in Mg-rich solutions, and solid-state transformation coupled with DRP at elevated temperatures. [1] [1] Support from NKFIH under grants RRF-2.3.1-21-2022-00014 and SNN-139585 is acknowledged. LA - English DB - MTMT ER - TY - CONF AU - Lázár, Anett AU - Karlik, Máté AU - Molnár, Zsombor AU - Demény, Attila AU - Németh, Péter TI - Ikaite (CaCO3*6H2O) -> ACC (amorphous calcium carbonate) -> calcite transformation and its paleoclimatological implication T2 - EGU General Assembly 2023: Abstracts PB - European Geosciences Union (EGU) C1 - München PY - 2023 DO - 10.5194/egusphere-egu23-1133 UR - https://m2.mtmt.hu/api/publication/33828942 ID - 33828942 LA - English DB - MTMT ER - TY - JOUR AU - Meister, P AU - Frisia, S AU - Dódony, István AU - Pekker, Péter AU - Molnár, Zsombor AU - Neuhuber, S AU - Gier, S AU - Kovács, Ivett AU - Demény, Attila AU - Pósfai, Mihály TI - Nanoscale Pathway of Modern Dolomite Formation in a Shallow, Alkaline Lake JF - CRYSTAL GROWTH & DESIGN J2 - CRYST GROWTH DES VL - 23 PY - 2023 IS - 5 SP - 3202 EP - 3212 PG - 11 SN - 1528-7483 DO - 10.1021/acs.cgd.2c01393 UR - https://m2.mtmt.hu/api/publication/33741775 ID - 33741775 LA - English DB - MTMT ER - TY - JOUR AU - Molnár, Zsombor AU - Dódony, István AU - Pósfai, Mihály TI - Transformation of amorphous calcium carbonate in the presence of magnesium, phosphate, and mineral surfaces JF - GEOCHIMICA ET COSMOCHIMICA ACTA J2 - GEOCHIM COSMOCHIM AC VL - 345 PY - 2023 SP - 90 EP - 101 PG - 12 SN - 0016-7037 DO - 10.1016/j.gca.2023.01.028 UR - https://m2.mtmt.hu/api/publication/33628972 ID - 33628972 N1 - University of Pannonia, Research Institute of Biomolecular and Chemical Engineering, Nanolab, Egyetem st. 10, Veszprém, 8200, Hungary ELKH-PE Environmental Mineralogy Research Group, Egyetem st. 10, Veszprém, 8200, Hungary Cited By :7 Export Date: 14 March 2024 Correspondence Address: Molnár, Z.; University of Pannonia, Nanolab, Egyetem st. 10, Hungary; email: molnar.zsombor@mk.uni-pannon.hu LA - English DB - MTMT ER - TY - JOUR AU - Lázár, Anett AU - Molnár, Zsombor AU - Demény, Attila AU - Kótai, László AU - Trif, László AU - Béres, Kende Attila AU - Bódis, Eszter AU - Bortel, Gábor AU - Aradi, László Előd AU - Karlik, Máté AU - Szabó, Máté Zoltán AU - Pekker, Áron AU - Németh, Gergely AU - Kamarás, Katalin AU - Garvie, L.A.J. AU - Németh, Péter TI - Insights into the amorphous calcium carbonate (ACC) → ikaite → calcite transformations JF - CRYSTENGCOMM J2 - CRYSTENGCOMM VL - 25 PY - 2023 IS - 3 SP - 738 EP - 750 PG - 13 SN - 1466-8033 DO - 10.1039/d2ce01444k UR - https://m2.mtmt.hu/api/publication/33606758 ID - 33606758 LA - English DB - MTMT ER -