Desenvolvimento de carbonos porosos sustentáveis à partir de biomassas: aplicações em adsorção de contaminantes emergentes e baterias de lítio-enxofre.

Abstract

This work reports the production of high-value sustainable porous carbons with potential technological applications from low-value products (biomass and biomass waste). The porous carbons developed in this study, especially hierarchical porous carbons (micro/meso/macroporous) and mesoporous carbons, were obtained through the following routes: without the use of templates, and via a mechanochemical route using biomass sources such as bio-oil, coffee grounds, and tannin as sustainable carbon sources. The hierarchical porous carbons were produced at temperatures between 700 – 900 °C and activated with zinc chloride in a single step. The mesoporous carbons were produced at 800 °C using a new cross-linking agent that is much more economical and sustainable than the conventional ones described in the literature. The materials obtained were characterized by elemental analysis, X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM/TEM), energy-dispersive X-ray fluorescence spectroscopy (EDS), nitrogen adsorption/desorption isotherms, X-ray photoelectron spectroscopy (XPS), and point of zero charge (PZC). The produced porous carbons exhibited high carbon contents (> 80%), specific surface areas ranging from 249 to 919 m².g-1, pore diameters between 0.6 – 12 nm, with variations in pore morphology and arrangement (ordered and disordered), as well as magnetic properties. The porous carbons derived from bio-oil, spent coffee grounds, and tannin biomasses were used as adsorbents for the removal of contaminants such as 17α-ethinylestradiol, amoxicillin, ibuprofen, tenofovir, caffeine, and paracetamol from aqueous media. Preliminary contact tests demonstrated removal rates above 70% for all contaminants used. Kinetic and adsorption isotherm studies of caffeine and paracetamol using the produced porous carbons showed pseudo-second-order kinetics and maximum removal capacities obtained by the adsorption of 376 mg.g-1 and 310 mg.g-1, for CpBC800 and CpBO800 respectively. The porous carbons were also applied as potential cathodes in lithium-sulfur batteries (Li–S) with capacities between 697 – 778 mAhg-1 at 0.1C. Thus, we demonstrated the production of high-value porous carbons obtained from biomass and biomass waste, which can be applied as excellent adsorbents for emerging contaminants (caffeine and paracetamol), and as potential cathodes in lithium-sulfur batteries.