Carbon dots derivados das cascas de maracujá sintetizados via micro-ondas e sua aplicação na confecção de filmes fluorescentes

Abstract

The search for methods that make it possible to use biomass for profitable purposes is growing, since using waste to synthesize new products gives them a more noble and sustainable destination. Among the various products obtained from biomass are carbon dots (C-Dots). These luminescent carbon nanoparticles have been attracting attention due to their low toxicity, high dispersion in water, biocompatibility, tunable light emission and low cost, thus providing a wide range of applications. In view of the above, in this work passion fruit peels were used as a precursor material to synthesize C-Dots via the microwave method with a view to their application in the production of fluorescent films based on polyvinyl alcohol (PVA) and carboxymethylcellulose. The synthesis was carried out with variations in time and power in order to evaluate the effects on optical and structural properties.In general, the syntheses carried out at higher power had higher yields. The C-Dots synthesized showed absorptions characteristic of the π - π* transitions (230 nm) of the core C=C bonds and the n - π* transitions (286 nm) of the surface groups, such as C=O. The C-Dots exhibited vibrational stretching typical of esters, carboxylic acids and alcohols, as expected, since these groups are present in the fruit. The CDots showed excitation wavelength-dependent emission with a blue emission maximum at 450 nm under excitation at 340 or 360 nm. The aforementioned structural and optical properties were generally not altered by changing the time and power during the synthesis process. In addition, the films were synthesized from the sample with the highest yield, which showed high blue luminescence, flexibility and transparency. Finally, the C-Dots were synthesized in a fast and economical way, proving to be highly viable in the production of promising fluorescent films for various applications, including optical sensors.