Comunicaciones a congresos, Conferencias, … (Fac. de Ciencias)
Permanent URI for this collectionhttps://hdl.handle.net/10171/70279
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4 results
Results
- Visible light-sensitive photocatalytic aditives to render cement-based materials suitable depolluting agents(Universidad de Navarra, 2015-03-26) Sirera-Bejarano, R. (Rafael); Perez-Nicolas, M. (María); Alvarez-Galindo, J.I. (José Ignacio); Duran-Benito, A. (Adrian); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)The presence of NOx in the atmosphere is an environmental challenge that needs to be addressed. Good NOx removal efficiencies have been attained by photocatalytic activity of TiO2 under UV light. TiO2 has been incorporated to cement-based materials to obtain depollutant and self-cleaning building materials. With the aim of broadening the sensitivity of these materials towards the visible light, two doped photocatalytic additives based on TiO2 were synthesized and used. Flame spray pyrolysis (FSP) allowed us to obtain TiO2 doped with either Fe or V, which generated hole-electron pairs with band gaps corresponding to visible light. Fe-TiO2, V-TiO2 and plain TiO2 were added (up to 2.5 wt.%) to different binding matrices: Portland cement (OPC) and air lime. The effect of the three photocatalytic additives on the setting time, consistency and mechanical properties of the cements were assessed.
- Biopolymer-cement composites for building purposes: performance of chitosan and some of its derivatives as cement admixtures(Mahatma Gandhi University, 2010-09-24) Alvarez-Galindo, J.I. (José Ignacio); Navarro-Blasco, I. (Iñigo); Lasheras-Zubiate, M. (María); Fernandez-Alvarez, J.M. (José María)Invited lecture presented on the 2nd ICNP held in Kottayam, India on 24th September 2010.
- Chitosan-cement matrices for solidification-stabilization of heavy metals(University of Birmingham, 2010-09-13) Alvarez-Galindo, J.I. (José Ignacio); Navarro-Blasco, I. (Iñigo); Lasheras-Zubiate, M. (María); Fernandez-Alvarez, J.M. (José María)Cement matrices have been extensively used to solidify-stabilize hazardous wastes containing heavy metals [1]. However, the presence of some heavy metals such as Pb and Zn modify the rheological properties of the cement due to the interaction with different cement phases [2], [3]. These changes in fresh-state properties of the cement materials may have a negative influence on the applicability of these matrices. Moreover, the hardened-state properties could be affected by the fresh-state changes and, consequently, the long-term stability and leaching of the heavy metals would be jeopardized. The use of some polymeric additives may be interesting in order to solve the aforementioned problems. Polysaccharides have been reported to be efficient cement additives behaving as viscosity-enhancing admixtures and set retarders [4].
- An etherified derivative of chitosan as an improved complexing agent for solidification/stabilisation of heavy metals into cementitious matrices(2010-06-20) Alvarez-Galindo, J.I. (José Ignacio); Bessard, B. (Benjamin); Navarro-Blasco, I. (Iñigo); Lasheras-Zubiate, M. (María); Fernandez-Alvarez, J.M. (José María)Book of abstracts of the13th International Conference on Electroanalysis ESEAC, 2010; PIN50:357: Chitosan is a natural widely available biopolymer and increasingly used for most diverse applications. Different chitosans of various molecular weight and deacetylation degrees have been previously checked as for their complexing activity towards selected target heavy metals, such as Zn, Pb, Cd, Cu, Mo and Cr [1,2]. Some rheological properties of cementitious matrices have been seen to improve upon incorporation of those biopolymers, such as water retention, setting time and consistency (through the flow table test). In this paper we report the different complexing patterns found for Zn and Pb when a chitosan derivative is used. These results will be discussed by comparison with the behaviour of the aforementioned non-modified chitosans.