Arturo Rico-Zavala

The aim of this work is the evaluation of a Sulfonated Poly Ether-Ether Ketone (S-PEEK) polymer modified by the addition of pure Santa Barbara Amorphous-15 (SBA-15, mesoporous silica) and SBA-15 previously impregnated with phosphotungstic acid (PWA) fillers (PWA/SBA-15) in order to prepare composite membranes as an alternative to conventional Nafion^® membranes. This component is intended to be used as an electrolyte in electrochemical energy systems such as hydrogen and methanol Proton Exchange Membrane Fuel Cell (PEMFC) and Electrochemical Hydrogen Pumping (EHP). The common requirements for all the applications are high proton conductivity, thermomechanical stability, and fuel and oxidant impermeability. The morphology of the composite membranes was investigated by Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy (SEM-EDS) analysis. Water Uptake (Wup), Ion Exchange Capacity (IEC), proton conductivity, methanol permeability and other physicochemical properties were evaluated. In PEMFC tests, the S-PEEK membrane with a 10 wt.% SBA-15 loading showed the highest performance. For EHP, the inclusion of inorganic materials led to a back-diffusion, limiting the compression capacity. Concerning methanol permeability, the lowest methanol crossover corresponded to the composites containing 5 wt.% and 10 wt.% SBA-15.

The in-situ generation of hydrogen peroxide in the electro-Fenton process is paramount. For this reason, in this research the electrocatalytic activity of three carbon materials was evaluated in the reaction of oxygen reduction via two electrons. Furthermore, in order to eliminate the use of iron salts in solution (homogeneous process), the iron was electrodeposited on the surface of the carbon material and was applied in a heterogeneous electro-Fenton process for the degradation of methyl orange dye. The largest amount of generated H ₂ O ₂ was achieved with the Carbon Felt (CF) electrode (460 mg L ⁻¹ ) without iron after 60 minutes. The electrodes with electrodeposited iron were characterized by SEM and EDS, which showed that the surface of the Carbon Sponge (CS) electrode had the largest amount of iron (23.84 %). However, the CF electrode showed a greater and faster degradation of the dye (98 %) after 30 minutes of treatment. The CF material was the best and most-viable choice of material compared to the CS and Carbon Cloth (CC) for industrial application in electro-Fenton processes, due to its greater catalytic activity in the production of H ₂ O ₂ , uniform distribution of iron, more efficient TOC removal and lower cost per cm ² of material.