Publicatlon costs assisted by Universidad de SevillaA statistical-mechanic study of the surface dehydration of y-alumina is made. The surface monolayer is considered as a monomer-asymmetrical dimer system on a square lattice, so that only nearest neighbors interact. The evolution of a wide set of surface ionic groups is studied. The results explain successfully the experimental data of thermogravimetric analysis, infrared spectra, and mobility of surface ions at T > 600 "C. The contributions to the activation energy of the different surface interactions have been estimated, giving eoo N 2 kcal/mol (oxide-oxide interaction), eHO = 1 kcal/mol (hydroxyl-oxide interaction), and e " N 0 (hydroxyl-hydroxyl interaction). The adsorbed water molecule energy is a surface coverage function and falls between -26 and -89 kcal/mol, within the expected range.
Boron (B) is an essential micronutrient for nutrition and growth of the plants, it is associated to the productivity of crops and quality of agricultural products. However, an excess of B produces toxicity and negative impacts on the plants affecting different shackles of the productive chain of many crops. From the above it is concluded that the correct diagnosis of phytoavailable B amounts in the soils, as well as, its correct incorporation during the fertilization process, are essential stages for the development of sustainable crops. The aim of this study was to develop new polymer materials based in polyurethanes (PUs), for the building of fertilization smart systems for B which will permit to proceed towards the implementation of new technologies with potential agricultural applications. For that, different methodologies were evaluated for the construction of boron-retaining polymers: (i) urethanization of high molecular weight polyols, (ii) making of interpenetrating polymer networks and (iii) urethane-based grafting polymers. Polymers were synthesized and characterized by different techniques and the B amounts Boron Smart polymer Polymer network Grafting polymer Boro Polímeros inteligentes Redes poliméricas Polímeros de injerto
A wide variety of materials, strategies, and methods have been proposed to face the challenge of wastewater pollution. The most innovative and promising approaches include the hybrid materials made of polymeric nanofibers and photocatalytic nanoparticles. Electrospun nanofibers with unique properties, such as nanosized diameter, large specific surface area, and high aspect ratio, represent promising materials to support and stabilize photocatalytic nanosized semiconductors. Additionally, the role performed by polymer nanofibers can be extended even further since they can act as an active medium for the in situ synthesis of photocatalytic metal nanoparticles or contribute to pollutant adsorption, facilitating their approach to the photocatalytic sites and their subsequent photodegradation. In this paper, we review the state of the art of electrospun polymer/semiconductor hybrid nanofibers possessing photocatalytic activity and used for the remediation of polluted water by light-driven processes (i.e., based on photocatalytic activity). The crucial role of polymer nanofibers and their versatility in these types of procedures are emphasized.
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