TY - JOUR AU - Fazekas, Ákos Ferenc AU - Gyulavári, Tamás AU - Ágoston, Áron AU - Janovák, László AU - Heszlerné Kopniczky, Judit AU - László, Zsuzsanna AU - Veréb, Gábor TI - Enhanced Photocatalytic and Filtration Performance of TiO2-Ag Composite-Coated Membrane Used for the Separation of Oil Emulsions JF - SEPARATIONS J2 - SEPARATIONS VL - 11 PY - 2024 IS - 4 SP - 112 SN - 2297-8739 DO - 10.3390/separations11040112 UR - https://m2.mtmt.hu/api/publication/34823133 ID - 34823133 AB - Polyvinylidene fluoride (PVDF) membranes were coated with TiO2 and TiO2-Ag to enhance their efficiency for oil-in-water emulsion separation. The photocatalytic activities of the two modified membranes and their filtration performances were compared in detail. The significantly enhanced photocatalytic activity of the TiO2-Ag composite was proved using a methyl orange (MO) solution (c = 10−5 M) and a crude oil emulsion (c = 50 mg·L−1). The TiO2-Ag-coated membrane reduced the MO concentration by 87%, whereas the TiO2-modified membrane reached only a 46% decomposition. The photocatalytic reduction in the chemical oxygen demand of the emulsion was also ~50% higher using the TiO2-Ag-coated membrane compared to that of the TiO2-coated membrane. The photoluminescence measurements demonstrated a reduced electron/hole recombination, achieved by the Ag nanoparticle addition (TiO2-Ag), which also explained the enhanced photocatalytic activity. A significant improvement in the oil separation performance with the TiO2-Ag-coated membrane was also demonstrated: a substantial increase in the flux and flux recovery ratio (up to 92.4%) was achieved, together with a notable reduction in the flux decay ratio and the irreversible filtration resistance. Furthermore, the purification efficiency was also enhanced (achieving 98.5% and 99.9% COD and turbidity reductions, respectively). Contact angle, zeta potential, scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements were carried out to explain the results. SEM and AFM images revealed that on the TiO2-Ag-coated membrane, a less aggregated, more continuous, homogeneous, and smoother nanolayer was formed due to the ~50% more negative zeta potential of the TiO2-Ag nanocomposite compared to that of the TiO2. In summary, via Ag addition, a sufficiently hydrophilic, beneficially negatively charged, and homogeneous TiO2-Ag-coated PVDF membrane surface was achieved, which resulted in the presented advantageous filtration properties beyond the photocatalytic activity enhancement. LA - English DB - MTMT ER - TY - GEN AU - Gyulavári, Tamás AU - Kata, Kovács AU - Zoltán, Kovács AU - Veréb, Gábor AU - Hernádi, Klára AU - Pap, Zsolt TI - Titanium dioxide hollow spheres for water treatment utilizing enhanced light trapping capability PY - 2023 UR - https://m2.mtmt.hu/api/publication/34409056 ID - 34409056 LA - English DB - MTMT ER - TY - CONF AU - Miklós, Tímea AU - Gyulavári, Tamás AU - Hodúr, Cecilia AU - Hernádi, Klára AU - László, Zsuzsanna AU - Veréb, Gábor ED - Majdik, Cornelia TI - Development of TiO2 and TiO2/CNT nanocomposite blended and grafted PVDF membranes used for membrane separation of oil emulsions T2 - XXIX. Nemzetközi Vegyészkonferencia / 29th International Conference on Chemistry PB - Erdélyi Magyar Műszaki Tudományos Társaság (EMT) C1 - Kolozsvár T3 - Nemzetközi Vegyészkonferencia, ISSN 1843-6293 PY - 2023 SP - 1 EP - 1 PG - 1 UR - https://m2.mtmt.hu/api/publication/34407490 ID - 34407490 LA - English DB - MTMT ER - TY - CONF AU - Fazekas, Ákos Ferenc AU - Gyulavári, Tamás AU - Pap, Zsolt AU - Bodor, Attila AU - Laczi, Krisztián AU - Perei, Katalin AU - Nyergesné Illés, Erzsébet AU - László, Zsuzsanna AU - Veréb, Gábor ED - Majdik, Cornelia TI - Effects of oil composition and CNT functionalizaton on the membrane filtration of oily wastewaters with TiO2/(f)CNT composite-coated PVDF membranes T2 - XXIX. Nemzetközi Vegyészkonferencia / 29th International Conference on Chemistry PB - Erdélyi Magyar Műszaki Tudományos Társaság (EMT) C1 - Kolozsvár T3 - Nemzetközi Vegyészkonferencia, ISSN 1843-6293 PY - 2023 SP - 1 EP - 1 PG - 1 UR - https://m2.mtmt.hu/api/publication/34407456 ID - 34407456 LA - English DB - MTMT ER - TY - JOUR AU - Fazekas, Ákos Ferenc AU - Gyulavári, Tamás AU - Pap, Zsolt AU - Bodor, Attila AU - Laczi, Krisztián AU - Perei, Katalin AU - Nyergesné Illés, Erzsébet AU - László, Zsuzsanna AU - Veréb, Gábor TI - Effects of Different TiO2/CNT Coatings of PVDF Membranes on the Filtration of Oil-Contaminated Wastewaters JF - MEMBRANES (BASEL) J2 - MEMBRANES-BASEL VL - 13 PY - 2023 IS - 10 PG - 17 SN - 2077-0375 DO - 10.3390/membranes13100812 UR - https://m2.mtmt.hu/api/publication/34166716 ID - 34166716 N1 - Funding Agency and Grant Number: Hungarian National Research, Development and Innovation Office-NKFIH [NKFI_FK_20_135202] Funding text: This research was funded by the Hungarian National Research, Development and Innovation Office-NKFIH in the framework of the "Development and application of nanoparticle modified membranes for the efficient treatment of oil-contaminated waters" project (NKFI_FK_20_135202). AB - Six different TiO2/CNT nanocomposite-coated polyvinylidene-fluoride (PVDF) microfilter membranes (including –OH or/and –COOH functionalized CNTs) were evaluated in terms of their performance in filtering oil-in-water emulsions. In the early stages of filtration, until reaching a volume reduction ratio (VRR) of ~1.5, the membranes coated with functionalized CNT-containing composites provided significantly higher fluxes than the non-functionalized ones, proving the beneficial effect of the surface modifications of the CNTs. Additionally, until the end of the filtration experiments (VRR = 5), notable flux enhancements were achieved with both TiO2 (~50%) and TiO2/CNT-coated membranes (up to ~300%), compared to the uncoated membrane. The irreversible filtration resistances of the membranes indicated that both the hydrophilicity and surface charge (zeta potential) played a crucial role in membrane fouling. However, a sharp and significant flux decrease (~90% flux reduction ratio) was observed for all membranes until reaching a VRR of 1.1–1.8, which could be attributed to the chemical composition of the oil. Gas chromatography measurements revealed a lack of hydrocarbon derivatives with polar molecular fractions (which can act as natural emulsifiers), resulting in significant coalescent ability (and less stable emulsion). Therefore, this led to a more compact cake layer formation on the surface of the membranes (compared to a previous study). It was also demonstrated that all membranes had excellent purification efficiency (97–99.8%) regarding the turbidity, but the effectiveness of the chemical oxygen demand reduction was slightly lower, ranging from 93.7% to 98%. LA - English DB - MTMT ER - TY - JOUR AU - Sisay, Elias Jigar AU - Fazekas, Ákos Ferenc AU - Gyulavári, Tamás AU - Heszlerné Kopniczky, Judit AU - Hopp, Béla AU - Veréb, Gábor AU - László, Zsuzsanna TI - Investigation of Photocatalytic PVDF Membranes Containing Inorganic Nanoparticles for Model Dairy Wastewater Treatment JF - MEMBRANES (BASEL) J2 - MEMBRANES-BASEL VL - 13 PY - 2023 IS - 7 PG - 21 SN - 2077-0375 DO - 10.3390/membranes13070656 UR - https://m2.mtmt.hu/api/publication/34059475 ID - 34059475 AB - Membrane separation processes are promising methods for wastewater treatment. Membrane fouling limits their wider use; however, this may be mitigated using photocatalytic composite materials for membrane preparation. This study aimed to investigate photocatalytic polyvinylidene fluoride (PVDF)-based nanocomposite membranes for treating model dairy wastewater containing bovine serum albumin (BSA). Membranes were fabricated via physical coating (with TiO2, and/or carbon nanotubes, and/or BiVO4) and blending (with TiO2). Another objective of this study was to compare membranes of identical compositions fabricated using different techniques, and to examine how various TiO2 concentrations affect the antifouling and cleaning performances of the blended membranes. Filtration experiments were performed using a dead-end cell. Filtration resistances, BSA rejection, and photocatalytic cleanability (characterized by flux recovery ratio (FRR)) were measured. The surface characteristics (SEM, EDX), roughness (measured by atomic force microscopy, AFM), wettability (contact angle measurements), and zeta potential of the membranes were also examined. Coated PVDF membranes showed higher hydrophilicity than the pristine PVDF membrane, as evidenced by a decreased contact angle, but the higher hydrophilicity did not result in higher fluxes, unlike the case of blended membranes. The increased surface roughness resulted in increased reversible fouling, but decreased BSA retention. Furthermore, the TiO2-coated membranes had a better flux recovery ratio (FRR, 97%) than the TiO2-blended membranes (35%). However, the TiO2-coated membrane had larger total filtration resistances and a lower water flux than the commercial pristine PVDF membrane and TiO2-blended membrane, which may be due to pore blockage or an additional coating layer formed by the nanoparticles. The BSA rejection of the TiO2-coated membrane was lower than that of the commercial pristine PVDF membrane. In contrast, the TiO2-blended membranes showed lower resistance than the pristine PVDF membrane, and exhibited better antifouling performance, superior flux, and comparable BSA rejection. Increasing the TiO2 content of the TiO2-blended membranes (from 1 to 2.5%) resulted in increased antifouling and comparable BSA rejection (more than 95%). However, the effect of TiO2 concentration on flux recovery was negligible. LA - English DB - MTMT ER - TY - JOUR AU - Gyulavári, Tamás AU - Veréb, Gábor AU - Pap, Zsolt AU - Hernádi, Klára TI - Titán-dioxid fotokatalizátorok fotokatalitikus aktivitásának növelése JF - MAGYAR KÉMIAI FOLYÓIRAT - KÉMIAI KÖZLEMÉNYEK (1997-) J2 - MAGY KÉM FOLY KÉM KÖZL VL - 129 PY - 2023 IS - 1 SP - 39 EP - 44 PG - 6 SN - 1418-9933 DO - 10.24100/MKF.2023.01.39 UR - https://m2.mtmt.hu/api/publication/34039621 ID - 34039621 N1 - "Gyulavári Tamás azonos című PhD értekezése és az ahhoz kapcsolódó tézisfüzet alapján készült." LA - Hungarian DB - MTMT ER - TY - JOUR AU - Márta, Viktória AU - Pap, Zsolt AU - Bárdos, Enikő AU - Gyulavári, Tamás AU - Veréb, Gábor AU - Hernádi, Klára TI - Effect of Urea as a Shape-Controlling Agent on the Properties of Bismuth Oxybromides JF - CATALYSTS J2 - CATALYSTS VL - 13 PY - 2023 IS - 3 PG - 13 SN - 2073-4344 DO - 10.3390/catal13030616 UR - https://m2.mtmt.hu/api/publication/33709488 ID - 33709488 AB - Bismuth oxybromides were prepared via a solvothermal method by applying different urea amounts during synthesis. The effects of the urea ratio on the morpho–structural properties and photocatalytic activity of the samples were investigated. X-ray diffraction, diffuse reflectance spectroscopy, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and surface tension measurements were carried out to characterize the samples. Their photoactivity was evaluated by the photocatalytic degradation of rhodamine B and ibuprofen under UV and visible light irradiations. The urea ratio notably influenced morphology, particle size distribution, and photoactivity. However, it only had a limited effect on the crystalline composition, primary crystallite size, and band gap of bismuth oxybromides. The formation of Bi-based complexes and degraded urea-based products were observed, which were deduced to influence band gap energies and hence, photoactivity. Predominantly, samples prepared at low urea ratios proved to be the best for both rhodamine B and ibuprofen degradations under both irradiations. LA - English DB - MTMT ER - TY - JOUR AU - Sisay, Elias Jigar AU - Kertész, Szabolcs AU - Fazekas, Ákos Ferenc AU - Jákói, Zoltán Péter AU - Kedves, Endre-Zsolt AU - Gyulavári, Tamás AU - Ágoston, Áron AU - Veréb, Gábor AU - László, Zsuzsanna TI - Application of BiVO4/TiO2/CNT Composite Photocatalysts for Membrane Fouling Control and Photocatalytic Membrane Regeneration during Dairy Wastewater Treatment JF - CATALYSTS J2 - CATALYSTS VL - 13 PY - 2023 IS - 2 PG - 13 SN - 2073-4344 DO - 10.3390/catal13020315 UR - https://m2.mtmt.hu/api/publication/33641282 ID - 33641282 AB - This study aimed to investigate the performance of composite photocatalytic membranes fabricated by incorporating multiple nanoparticles (TiO2, carbon nanotubes, BiVO4) into polyvinylidene fluoride membrane material for real dairy wastewater treatment. The composite photocatalytic membranes exhibited superior antifouling behavior, lower filtration resistance, better flux, and higher flux recovery ratio than the pristine membrane. Salinity, pH, and lactose concentration are determinant factors that affect filtration resistance and rejection performance during the ultrafiltration of dairy wastewater. Generally, higher irreversible and total resistances and slightly lower chemical oxygen demand (COD) rejections were found at higher salinity (expressed by electric conductivity values of >4 mS/cm) than lower salinity (<4 mS/cm) levels. The presence of lactose in dairy wastewater increased irreversible resistance and severely reduced COD rejection during ultrafiltration due to the ability of lactose to pass through the membranes. It was ascertained that membranes require further treatment after filtrating such wastewater. Lower resistances and slightly better COD rejections were observed at pH 7.5 and pH 9.5 compared to those observed at pH 4. Photocatalytic membranes fouled during the ultrafiltration of real dairy wastewater were regenerated by visible light irradiation. The membrane containing all constituents (i.e., TiO2, carbon nanotubes, and BiVO4) showed the best regeneration performance, exceeding that of the pristine membrane by 30%. LA - English DB - MTMT ER - TY - JOUR AU - Fekete, Laura AU - Fazekas, Ákos Ferenc AU - Hodúr, Cecilia AU - László, Zsuzsanna AU - Ágoston, Áron AU - Janovák, László AU - Gyulavári, Tamás AU - Pap, Zsolt AU - Hernádi, Klára AU - Veréb, Gábor TI - Outstanding Separation Performance of Oil-in-Water Emulsions with TiO2/CNT Nanocomposite-Modified PVDF Membranes JF - MEMBRANES (BASEL) J2 - MEMBRANES-BASEL VL - 13 PY - 2023 IS - 2 PG - 14 SN - 2077-0375 DO - 10.3390/membranes13020209 UR - https://m2.mtmt.hu/api/publication/33636061 ID - 33636061 AB - Membrane filtration is an effective technique for separating micro- and nano-sized oil droplets from harmful oil-contaminated waters produced by numerous industrial activities. However, significant flux reduction discourages the extensive application of this technology; therefore, developing antifouling membranes is necessary. For this purpose, various titanium dioxide/carbon nanotube (TiO2/CNT) nanocomposites (containing 1, 2, and 5 wt.% multi-walled CNTs) were used for the modification of polyvinylidene fluoride (PVDF) ultrafilter (250 kDa) membrane surfaces. The effects of surface modifications were compared in relation to the flux, the filtration resistance, the flux recovery ratio, and the purification efficiency. TiO2/CNT2% composite modification reduced both irreversible and total filtration resistances the most during the filtration of 100 ppm oil emulsions. The fluxes were approximately 4–7 times higher compared to the unmodified PVDF membrane, depending on the used transmembrane pressure (510, 900, and 1340 L/m2h fluxes were measured at 0.1, 0.2, and 0.3 MPa pressures, respectively). Moreover, the flux recovery ratio (up to 68%) and the purification efficiency (95.1–99.8%) were also significantly higher because of the surface modification, and the beneficial effects were more dominant at higher transmembrane pressures. TiO2/CNT2% nanocomposites are promising to be applied to modify membranes used for oil–water separation and achieve outstanding flux, cleanability, and purification efficiency. LA - English DB - MTMT ER -