Zinc(II) phthalocyanines immobilized in mesoporous silica Al-MCM-41 and their applications in photocatalytic degradation of pesticides

In the present study the authors investigated a set of three new zinc(II) phthalocyanines (zinc(II) tetranitrophthalocyanine (ZnTNPc), zinc(II) tetra(phenyloxy)phthalocyanine (ZnTPhOPc) and the tetraiodide salt of zinc(II)tetra(N,N,N-trimethylaminoethyloxy) phthalocyaninate (ZnTTMAEOPcI)) immobilized into Al-MCM-41 prepared via ship-in-a-bottle methodology. The samples were fully characterized by diffuse reflectance-UV–vis spectroscopy (DRS-UV–vis), luminescence, thermogravimetric analysis (TG/DSC), N2 adsorption techniques and elemental analysis. A comparative study was made on the photocatalytic performance upon irradiation within the wavelength range 320–460 nm of these three systems in the degradation of pesticides fenamiphos and pentachlorophenol. ZnTNPc@Al-MCM-41 and ZnTTMAEOPcI@Al-MCM-41 were found to be the most active systems, with the best performance observed with the immobilized cationic phthalocyanine, ZnTTMAEOPcI@Al-MCM-41. This system showed high activity even after three photocatalytic cycles. LC–MS product characterization and mechanistic studies indicate that singlet oxygen (1O2), produced by excitation of these immobilized photosensitizers, is a key intermediate in the photocatalytic degradation of both pesticides

Further works on concrete at early age coordinated within COST TU1404 European Project

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The characterisation by luminescence spectroscopy of uranium(VI) incorporated into zeolites and aluminas

Luminescence spectroscopy of solids at 77 K has been used to characterise the uranium(VI) species incorporated into [alpha]-alumina, [gamma]-alumina and zeolites Y and ZSM-20 by adsorption from solution and into ZSM-5 by chemical synthesis. With uranyl adsorbed from nitrate solutions onto [alpha]- and [gamma]-aluminas, the luminescence measurements show the dominant uranium species is schoepite, UO3·xH2O, in agreement with results from X-ray diffraction and Raman spectroscopy. With uranyl acetate, there are indications that a crystalline acetate species is also present. With zeolite-Y and ZSM-20, the main species is a dimer. In addition, some monomeric [UO2(H2O)5]2+ is also present. With ZSM-5, although this is not observed in X-ray diffraction, the luminescence spectrum shows the presence of a species, similar to the schoepite seen with the aluminas. It is suggested that this may be due both to closely related polymeric species, and to uranyl anions, such as [UO2(OH)4]2- and [UO2(OH)3]-.http://www.sciencedirect.com/science/article/B6TGS-435M5SD-2D/1/1fcff58939e013c8fdee4bba2d901a3

The characterisation by luminescence spectroscopy of uranium(VI) incorporated into zeolites and aluminas

Luminescence spectroscopy of solids at 77 K has been used to characterise the uranium(VI) species incorporated into [alpha]-alumina, [gamma]-alumina and zeolites Y and ZSM-20 by adsorption from solution and into ZSM-5 by chemical synthesis. With uranyl adsorbed from nitrate solutions onto [alpha]- and [gamma]-aluminas, the luminescence measurements show the dominant uranium species is schoepite, UO3·xH2O, in agreement with results from X-ray diffraction and Raman spectroscopy. With uranyl acetate, there are indications that a crystalline acetate species is also present. With zeolite-Y and ZSM-20, the main species is a dimer. In addition, some monomeric [UO2(H2O)5]2+ is also present. With ZSM-5, although this is not observed in X-ray diffraction, the luminescence spectrum shows the presence of a species, similar to the schoepite seen with the aluminas. It is suggested that this may be due both to closely related polymeric species, and to uranyl anions, such as [UO2(OH)4]2- and [UO2(OH)3]-.http://www.sciencedirect.com/science/article/B6TGS-435M5SD-2D/1/1fcff58939e013c8fdee4bba2d901a3

Experimental measurement and modeling of ion exchange equilibrium and kinetics of cadmium(II) solutions over microporous stannosilicate AV-6

Microporous stannosilicate AV-6 was investigated for cadmium(II) removal from aqueous solutions in batch experiments. Ion exchange equilibrium of the Cd2+/K+/AV-6 system was modeled using the mass action law combined with activity coefficient models for the solution (ideal, Debye-Htickel and Pitzer equations) and for the solid (Wilson equation) with absolute average relative deviations (AARDs) between 6.56% and 6.75%. It was concluded that the system embodies strong intraparticle non-idealities, namely solid activity coefficients between 0.2602 and 0.7180 for Cd2+. The kinetics of cadmium(II) sorption was analyzed measuring removal curves and modeling the data with pseudo-first and pseudo-second order expressions, commonly adopted in the literature, and with Maxwell-Stefan (MS) and Nernst-Plank (NP) based models. The best results were achieved by MS and NP approaches, for which AARD was 3.74% and 3.71%, respectively. The kinetic performance of the ion exchange was also discussed taking into account structural aspects of the AV-6 material

Experimental measurement and modeling of ion exchange equilibrium and kinetics of cadmium(II) solutions over microporous stannosilicate AV-6

Microporous stannosilicate AV-6 was investigated for cadmium(II) removal from aqueous solutions in batch experiments. Ion exchange equilibrium of the Cd2+/K+/AV-6 system was modeled using the mass action law combined with activity coefficient models for the solution (ideal, Debye-Htickel and Pitzer equations) and for the solid (Wilson equation) with absolute average relative deviations (AARDs) between 6.56% and 6.75%. It was concluded that the system embodies strong intraparticle non-idealities, namely solid activity coefficients between 0.2602 and 0.7180 for Cd2+. The kinetics of cadmium(II) sorption was analyzed measuring removal curves and modeling the data with pseudo-first and pseudo-second order expressions, commonly adopted in the literature, and with Maxwell-Stefan (MS) and Nernst-Plank (NP) based models. The best results were achieved by MS and NP approaches, for which AARD was 3.74% and 3.71%, respectively. The kinetic performance of the ion exchange was also discussed taking into account structural aspects of the AV-6 material. (C) 2016 Elsevier B.V. All rights reserved

Evaluation of the LDPM elastic and fracture parameters by up-scaling procedure

The heterogeneity of the concrete may be considered on different size scales of observation, ranging from the atomistic scale (10-10m), characterized by the behavior of crystalline particles of hydrated Portland cement, to the macroscopic scale (101 m), where concrete has traditionally been considered homogeneous. The multiscale framework we are proposing in this paper is based on the following models: chemical analyses at the cement paste scale; mechanical lattice model at the cement and mortar scales; geometrical aggregate distribution models at the mortar and concrete scales; and the Lattice Discrete Particle Model (LDPM) at the concrete scale. For that purpose, a set of analysis starting from a known set of parameters of the cement paste. This input is utilized to evaluate the mechanical properties of the mortars (cement and sand), and then these properties are used to evaluate the mechanical properties of the mortar-a4 (mortar-s and aggregate smaller then 4mm). The upscaling in the proposed methodology involved the evaluation of the LDPM concrete parameters based on the mortara4 properties. Here we are suggesting a uni-axial tension "numerical experiments" on the mortar-a4 scale to evaluate the elastic and fracture LDPM mechanical parameters