RESUMO
Spent coffee grounds are wastes generated annually worldwide in significantly large amounts in the soluble coffee industry and in household and commercial beverage preparation. Although spent coffee grounds are rich in several classes of compounds, predominantly polysaccharides, profitable applications have not yet been effectively implemented for such wastes. Thus, it was the aim of this study to verify the feasibility of producing biopolymeric films from the polysaccharide-rich fraction of spent coffee grounds, obtained by alkaline hydrogen peroxide treatment of the coffee waste. Produced films were characterized for their physicochemical, barrier and mechanical properties and these properties were comparable to those of similar polysaccharides films from the literature.
RESUMO
This paper reports the development of superhydrophobic nanocomposite systems which are also oleophilic. As hydrophobicity is based on low energy surface and surface roughness, the electrospinning technique was selected as the manufacturing technique. N,N' dimethylformamide (DMF) was employed as the polystyrene (PS) solvent. The "Tea-bag" (T-B) nanocomposite system is based on exfoliated graphite surrounded by PS superhydrophobic membranes. The T-B systems were tested regarding its adsorption and absorption rates. To test these properties, it was employed three different water/oil emulsions, i.e., new and used motor oil, which have physical properties (viscosity and specific gravity) similar to heavy crude oil extracted in Brazil, and vacuum pump oil (which does not form oil/water emulsion). It was observed that oil adsorption rate is dependent on oil surface tension, while the absorption rate is mainly dependent on membrane/exfoliated graphite surface area. Experimental data show that oil absorption rates ranged between 2.5g/g and 40g/g, while the adsorption rate oscillated from 0.32g/g/min to 0.80g/g/min. Furthermore, T-B systems were tested as containment barriers and sorbent materials with good results including its recyclability.
