Author: Beatriz Escobar Morales
Tubular fibers (raw and wax-free) from Ceiba pentandra (CP) were cross-linked with butane-1,2,3,4-tetracarboxylic acid (BTCA) at different concentrations to obtain a porous biodegradable medium for drug release applications. Chlorhexidine diacetate (CHX) was added to the cross-linked fibers for drug release studies. The Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy results indicated that the cross-linked fibers with a 5:1 fiber:BTCA ratio presented the higher cross-linking density. CHX was added at different concentrations (8% and 16% wt/wt); the elemental analysis indicated that CHX was loaded up to 7.99 wt%. In vitro studies showed a burst release of CHX within the first 3 h. CHX release kinetics was described using several models, with the Korsmeyer–Peppas equation, which adjusted better to the experimental data. The results indicated that the CP fibers are a feasible material for drug release applications.
Water electrolysis is an electrochemical process capable of producing high-purity hydrogen (H2 ≈ 100%). However, due to high anodic operating potentials, which are greater than 1.8 V in acidic media, they tend to degrade the components that are currently designed. One of the main components is the gas diffusion layer (GDL) of a proton exchange membrane water electrolyzer (PEMWE). A commonly used carbon GDL is coal. However, the acid medium increases the potential to 1.4 V, which causes the GDL to become oxidized and degrade; the above result is due to the generation of carbon products that poison the electrode and the blocking of active sites, all of which decrease the performance of the cell. In this work, the results of a morphological study on a modified titanium porous matrix are presented. The analysis includes the determination of the microstructural influence on mass transport through numerical simulation and statistical electrochemical characterization techniques. Two different microstructural attacks are performed to modify the porous matrix. These attacks consist of an acidic mixture of 17 and 27% v/v HCl/H2SO4 and an attack by a 0.1 M oxalic acid solution; these attacks were performed at different times. Afterward, the GDLs were characterized by scanning electron microscopy (SEM) at different magnifications to determine significant microstructural differences between the three matrices (the two that are modified and the one without modification) and their stochastic reconstruction. Subsequently, a surface area characterization is performed by the BET absorption technique to calculate the porosity of the different matrices.
WATER ELECTROLYSIS MICROSTRUCTURAL ANALYSIS GAS DIFFUSION LAYER POROUS MATRIX MICROSTRUCTURAL ATTACK CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO HIDROLOGÍA CALIDAD DE LAS AGUAS CALIDAD DE LAS AGUAS