Orán y Mazalquivir: una historia de las fortificaciones españolas

Máster en Estudios Avanzados de Historia Moderna: "Monarquía de España" Ss. XVI-XVII

Characterization and application of heat-treated and acid-leached halloysites in the removal of malachite green: adsorption, desorption, and regeneration studies

International audienc

Improving of the adsorption capacity of halloysite nanotubes intercalated with dimethyl sulfoxide

International audienc

Flexural strengthening of finger-jointed Spruce timber beams with CFRP

International audienceThis study describes an experimental and numerical investigation of the use of CFRP material for strengthening finger-jointed Spruce timber beams. The corresponding experimental work was based on a four-point bending test configuration in order to characterise stiffness, ductility and strength. The results show that the external bonding of CFRP increased the ultimate load-bearing capacity of finger-jointed Spruce timber beams under flexure. FE simulations were also carried out, based on the cohesive zone model (CZM) available in Abaqus software to allow an accurate description of the damage evolution of the bond lines within the finger joint until failure. The FE models incorporated the different materials' nonlinear constitutive laws including bond-slip action between finger joints and CFRP-timber interface. The results indicated increases of 33.84% and 16.7% for flexural capacity and initial stiffness, respectively, in comparison with unreinforced finger-jointed Spruce specimens. Besides, comparisons of computed and experimental ultimate loads for all tested specimens showed that the absolute error was around 5%. It is concluded that the developed FE models are able to predict accurately ultimate load and failure mode of finger-jointed Spruce timber beams strengthened with CFRP materials

The Adsorption of Pentachlorophenol from Aqueous Solutions onto Exchanged Al-MCM-41 Materials

The ability of a mesoporous molecular sieve to adsorb chlorinated phenols was studied experimentally. Thus, the adsorption isotherms of pentachlorophenol (PCP) from aqueous solutions were measured on (M)Al-MCM-41 (M = Na + , K + , Cu 2+ , Cr 3+ ) at intervals of 10 K between 303 K and 323 K. The experimental isotherms obtained were of the S-type in terms of the classification of Giles and co-workers. The best fit of the adsorption isotherm data was obtained using the Freundlich model. The adsorption affinity of PCP increased in the order (K)Al-MCM-41 < (Cr)Al-MCM-41 < (Na)Al-MCM-41 < (Cu)Al-MCM-41. At the same temperature, the adsorption of PCP on (Cu)Al-MCM-41 was more pronounced compared to its adsorption on alumina-pillared montmorillonite and mesoporous alumina aluminium phosphates. Analysis of the isosteric curves showed that (Cu)Al-MCM-41 and (Na)Al-MCM-41 presented a heterogeneous profile. In contrast, (K)Al-MCM-41 and (Cr)Al-MCM-41 did not exhibit energetic heterogeneity throughout the entire range of coverage

Development and characterization of a new dolomite-based catalyst: application to the photocatalytic degradation of pentachlorophenol

The development of new catalysts from abundant raw materials, generating attractive photocatalytic activity, constitutes a real challenge in the context of sustainable development concerns. In this setting, a dolomite was treated at 800 degrees C (D800) and then chemically modified by Ca(NO3)(2) (CaD800) using a simple procedure. The resulting materials were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), solid state UV spectroscopy, and used as catalysts of pentachlorophenol (PCP) degradation in aqueous solutions under UV light irradiation. The treatment of dolomite at 800 degrees C enabled a full decarbonation of CaMg(CO3)(2), with formation of CaO, Ca(OH)(2), and MgO. Additional CaO was generated after chemical treatment as revealed by EDS analysis; the Ca/Mg ratio increased from 1.29 (D800) to 1.44 for CaD800. This CaO in aqueous medium hydrates by giving Ca(OH)(2). CaD800 was found to be the best photocatalyst with a PCP degradation rate of 95% after only 1 h of treatment, for a CaD800/D800 degradation rate constant ratio of 1.58. In this regard, we investigated the Fourier transform infrared spectra of CaD800, PCP, and CaD800 loaded with PCP after degradation. We thus evidenced the involvement of Ca(OH)(2) in the PCP degradation process. Catalytic activity was discussed through the contribution of OH radicals and electrodonation

Synergetic effects of Cu-Zn bimetallic ions exchanged in NaX on acid sites of M(

X zeolites were prepared by ion-exchange with Cu2+ and/or Zn2+ cations, at different concentrations of the exchange solution, and characterized by thermal analysis and nitrogen adsorption. The acidity of the samples was investigated by pyridine adsorption–desorption followed by in situ Fourier transform infrared (FTIR) spectroscopy. Desorption was carried out at 150, 250 and 350 °C. The objective is to estimate the nature and concentration of acid sites. A comparison between the binary (Cu(x)X, Zn(x)X) and ternary (CuZn(x)X) exchanges was also established (x = level of exchange) through the Cu(43)X, Zn(48)X and CuZn(50)X samples. Lewis acidity decreases overall with desorption temperature and the level of exchange. As the latter increases, there is a conversion of some Lewis sites into those of Brønsted during thermal treatment. In return, the concentration of Brønsted sites increases with the degree of exchange. The Brønsted acidity of CuZn(50)X at 350 °C is more important than the sum of those of Cu(43)X and Zn(48)X with respectively values of 73, 32 and 15 μmol g−1. Besides, the concentration of Brønsted sites for CuZn(50)X increases with desorption temperature. These features indicate the presence of a synergetic effect amplifying the strength of these sites when Cu2+ and Zn2+ cations compete for the occupancy of sites distributed in zeolite cavities

A new approach about the intercalation of hexadecyltrimethylammonium into halloysite: preparation, characterization, and mechanism

International audienc