93 documents found, page 1 of 10
Red mud valorization in stoneware pastes: technical and environmental assessment
Vilarinho, I. S.; Dias, A. C.; Carneiro, J.; Pinto, C.; Labrincha, J. A.; Seabra, M. P.Red mud (RM), resulting from alumina production by Bayer process, is classified as hazardous waste and is, nowadays, one of the most abundant industrial waste worldwide. Currently, over 4 billion tons are stored in ponds/dried mounds and is of utmost importance to tackle this problem. This work aims to recycle RM as colouring agent in stoneware products. For this purpose, several proportions of RM (0–10 wt%) we...
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...
Red mud-based geopolymers with tailored alkali diffusion properties and pH buff...
Ascensão, G.; Seabra, M. P.; Aguiar, J. L. Barroso de; Labrincha, J. A.This study develop novel porous red mud (RM) based geopolymers and evaluates their potential to ensure prolonged pH control. Several properties of the novel geopolymers were examined including buffering ability, alkalis leaching behaviour, mineralogical composition, microstructure and physical properties. Two experimental plans were defined to evaluate the influence of porosity and RM content on those propertie...
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...
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 ...
Influence of blowing agent on the fresh- and hardened-state properties of light...
Novais, Rui M.; Ascensao, G.; Buruberri, L. H.; Senff, L.; Labrincha, J. A.The production of lightweight geopolymers is an emergent area, and the influence of the pore forming agent on geopolymer kinetics and the rheology of the pastes has been rather neglected up to now. In this work the influence of the blowing agent content, NaOH molarity and water content on the fresh and hardened-state properties of fly ash-containing geopolymers was evaluated. Results demonstrate that the blowin...
Assessment of the single and combined effect of superabsorbent particles and po...
Senff, L.; Ascensao, G.; Hotza, D.; Ferreira, V. M.; Labrincha, J. A.This article reports an investigation on the development of multifunctional mortars with enhanced potential to passively adjust indoor RH levels and thermal conductivity, while reducing aerial pollutants (NOx) through photocatalysis. Superabsorbent polymer (SAP), Vermiculite (VER) and TiO2 nanoparticles (nT) were used as functional additives for mortars. Single and binary mixtures with 0-0.9 wt.% SAP and 0-15 w...
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...
Novel porous fly ash-containing geopolymers for pH buffering applications
Novais, Rui M.; Buruberri, L. H.; Seabra, M. P.; Bajare, D.; Labrincha, J. A.In this work novel, porous biomass fly ash-containing geopolymers with high pH buffer capacity and tailored alkalis leaching were produced by using hydrogen peroxide as blowing agent. Results demonstrate that the geopolymers leaching rate can be controlled by the hydrogen peroxide content and by the solids-to-liquid ratio during geopolymers preparation. Total leaching of hydroxyl ions from the porous geopolymer...
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...