Utilização de nanotubos de carbono na eletrossíntese de hidrogênio a partir da fermentação de frutas tropicais

Abstract

The The use of fossil fuels, especially oil and gas, has accelerated in recent years, resulting in the global energy crisis. The fermentative biological process is a sustainable way to produce hydrogen because it can use as a substrate various types of carbohydrate-rich industrial and household waste such as fruit, minimizing the problems caused by improper disposal of this material. From a perspective of energy conservation and use of renewable sources for energy generation, this work proposed the identification of the use of a portion of energy, not used today, optimizing the electrosynthesis conditions of hydrogen produced from the fermentation of tropical fruits. For the electrosynthesis process was used an electrolytic cell manufactured by a glassmaker, coupled to two burettes and two decantation funnels, with two passages for the output of the biogas produced. The sample analyzed was a fermented tropical fruit liqueur (strawberry, acerola and pitanga). The main electrodic nanomaterial analyzed in the electrosynthesis was the commercially obtained carbon nanotube (NTC) modified carbon felt (CF). Cyclic voltammetry studies were also performed in three-electrode systems: glassy carbon electrode as working electrode, platinum electrode as auxiliary electrode and Ag/AgCl/Cl- as reference electrode. Surface characterization of electrode materials was performed by scanning electron microscopy (SEM) and electron microscopy (TEM). Carbohydrate analyzes were also performed in the sample before and after the fermentation process to confirm it, as well as gas chromatographic analyzes coupled to GC/MS mass spectrometry after electrosynthesis to verify the compounds present in the sample. Before starting the electrolysis experiments, an experimental design was done using the full factorial design technique to analyze the influence of the variables selected for this study. The independent variables selected were: Tropical fruit liqueur concentration in% v / v, working electrode type, electrolysis time and pH of the electrolyte medium. The dependent variable observed, which corresponds to the response of the present work, was the volumetric fraction (% v/v) of hydrogen gas obtained from tropical fruit liquor electrolysis. After the test results it was concluded that carbon nanotubes can be used as a working electrode with great success in the hydrogen production process and that the pH of the electrolytic medium has a strong influence on this process. The present work was concluded by presenting an alternative route in the production of a renewable energy source.