38 documents found, page 1 of 4
Chitosan-hydroxyapatite composites made from sustainable sources: a morphology ...
Scalera, F.; Pereira, S. I. A.; Bucciarelli, A.; Tobaldi, D. M.; Quarta, A.; Gervaso, F.; Castro, P. M. L.; Polini, A.; Piccirillo, C.Chitosan (Cs) and hydroxyapatite (HA) 3D scaffolds/composites were prepared with a sustainable process, as HA was obtained using CaCO3 derived from cork, a natural material used as a template agent. The HA@Cs composites were prepared with HA in situ formation in a Cs solution, with a dissolution-precipitation mechanism. Different reaction times were considered, with time of 72 h leading to the best materials (s...
Effect of preparation and processing conditions on UV absorbing properties of h...
Teixeira, M. A. C.; Piccirillo, C.; Tobaldi, D. M.; Pullar, R. C.; Labrincha, J. A.; Ferreira, M. O.; Castro, Paula M. L.; Pintado, M. M. E.The development of innovative, safe and non-photocatalytic sunscreens is urgently needed, as it is essential to have sunscreen filters offering appropriate UV protection without damaging the environment and/or generating free radicals when in contact with the skin. Hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp) when substituted with iron has UV protection properties and is not photocatalytic; HAp was used to make a...
Surface modified hydroxyapatites with various functionalized nanostructures: co...
Bystrova, V. S.; Paramonova, E. V.; Bystrova, A. V.; Pullar, R. C.; Kopyl, S.; Tobaldi, D. M.; Piccirillo, C.; Avakyan, L. A.; Coutinho, J.Hydroxyapatite (HAp) has structural features that define its basic physical properties, which have an important role at the surface, and it is one of the most used materials in bone implants. In this work, we present a density functional modeling (DFT) study of HAp both as bulk and with special HAp models with various defects, especially oxygen vacancies in HAp surface layers, which can also determine photocata...
Effects of Cu, Zn and Cu-Zn addition on the microstructure and antibacterial an...
Tobaldi, D. M.; Piccirillo, C.; Rozman, N.; Pullar, R. C.; Seabra, M. P.; Škapin, A. Sever; Castro, Paula M. L.; Labrincha, J. A.Titanium dioxide (TiO2) is well established as one of the most common photocatalysts used for many environmental, anti-pollution and antibacterial applications. However, in this work, novel photocatalytic TiO2 nanopowders were modified with additions of 1 mol% copper, zinc or copper + zinc (with various Cu: Zn ratios). These were prepared via a green sol–gel route and thermally treated at 450 C. For the first t...
Oxygen vacancies, the optical band gap (Eg) and photocatalysis ofhydroxyapatite...
Bystrov, V. S.; Piccirillo, C.; Tobaldi, D. M.; Castro, P. M. L.; Coutinho, J.; Kopyl, S.; Pullar, R.Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is a calcium phosphate employed both in biomedicine and forenvironmental remediation. It is known that HAp can also be photocatalytic under UV light, probablydue to oxygen deficiencies, but the mechanism is unclear, and reported optical band gap energies varygreatly. For the first time we propose the mechanisms and precise kinds of vacancies which may causethe photocatalyti...
Effects of Cu, Zn and Cu-Zn addition on the microstructure and antibacterial an...
Tobaldi, D. M.; Piccirillo, C.; Rozman, N.; Pullar, R. C.; Seabra, M. P.; Skapin, A. Sever; Castro, P. M. L.; Labrincha, J. A.Titanium dioxide (TiO2) is well established as one of the most common photocatalysts used for many environmental, anti-pollution and antibacterial applications. However, in this work, novel photocatalytic TiO2 nanopowders were modified with additions of 1 mol% copper, zinc or copper+ zinc (with various Cu: Zn ratios). These were prepared via a green sol-gel route and thermally treated at 450 degrees C. For the ...
Oxygen vacancies, the optical band gap (E-g) and photocatalysis of hydroxyapati...
Bystrov, V. S.; Piccirillo, C.; Tobaldi, D. M.; Castro, P. M. L.; Coutinho, J.; Kopyl, S.; Pullar, R. C.Hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp) is a calcium phosphate employed both in biomedicine and for environmental remediation. It is known that HAp can also be photocatalytic under UV light, probably due to oxygen deficiencies, but the mechanism is unclear, and reported optical band gap energies vary greatly. For the first time we propose the mechanisms and precise kinds of vacancies which may cause the phot...
Truncated tetragonal bipyramidal anatase nanocrystals formed without use of cap...
Tobaldi, D. M.; Pullar, R. C.; Duraes, L.; Matias, T.; Seabra, M. P.; Labrincha, J. A.Titanium dioxide (TiO2) nanoparticles are extremely attractive materials for numerous applications, especially in the anatase form. We have made these shaped, <10 nm anatase nanoparticles (NPs) via the super-critical (SC) drying of a titania sol, made by a \"green\" aqueous sol-gel nanosynthesis route. The SC drying was carried out in alcohol at 255-260 degrees C, and no further heating or processing of the NPs...
Sensing properties and photochromism of Ag-TiO2 nano-heterostructures
Tobaldi, D. M.; Leonardi, S. G.; Pullar, R. C.; Seabra, M. P.; Neri, G.; Labrincha, J. A.Achieving advanced multifunctional materials displaying several coexisting properties is currently one of the most exciting and innovative research topics. In this study, we report the engineering of a multifunctional material exhibiting, at the same time, tuneable photochromic behaviour and gas-sensing properties for acetone detection. The photochromic property of silver modified (1-10 mol% Ag) titanium dioxid...
Effective removal of anionic and cationic dyes by kaolinite and TiO2/kaolinite ...
Hajjaji, W.; Andrejkovicova, S.; Pullar, R. C.; Tobaldi, D. M.; Lopez-Galindo, A.; Jammousi, F.; Rocha, F.; Labrincha, J. A.The present study investigated the removal of methylene blue (MB) and orange II (OII) dyes from synthetic wastewater by means of adsorption and photocatalysis using natural kaolins. For MB adsorption, the raw kaolinite-rich samples showed the greatest adsorption capacity, with rapid uptake (90% after 20 min). The experimental results were fitted better using the Langmuir isotherm model parameters compared to th...