Electrochemistry for biofuels waste valorization: Vinasse as a reducing agent for Pt/C and its application to the electrolysis of glycerin and vinasse

Abstract

Waste vinasse has been used, for the first time, as a reducing agent to prepare a 20 wt% Pt/C electrocatalyst. After alkalization and subsequent filtration, abundant cations such as Ca, Mg and Fe were effectively removed, precipitating as hydroxides and insoluble phosphates. Pt chemical reduction was carried out under reflux in the presence of Vulcan XC-72R carbon by the action of reductive species such as sugars and phenols present. Reduction was confirmed by thermal analysis and X-ray diffractograms displaying the typical Pt fcc structure formed by nanocrystals. In the transmission images, an irregular dispersion of the Pt nanoparticles was observed on the carbon support, with the presence of large agglomerations with a cotton-like structure. This structure was found to be very active for glycerol electrolysis in an alkaline membrane electrolysis cell, comparable to commercial materials. Finally, results for electrolysis of the vinasse were also presented, demonstrating the possibility of valorizing this residue by the production of hydrogen. Keywords: Waste valorization, Vinasse, Glycerin, Electrochemical reforming, Hydrogen, Electrocatalyst