Synthesis of new carbon-nitrogen composites based on waste sweet drinks

The materials under investigation were new carbon-nitrogen composites obtained via pyrolysis and CO₂ activation of sweet drinks destined for utilization. Waste Pepsi Cola® has been examined as an alternative and renewable carbon source for composite materials. Nitrogen was introduced into the Pepsi Cola® solution via the addition of guanidine carbonate, before the pyrolysis process. The physicochemical properties of the materials studied were characterized by low- temperature nitrogen adsorption (using BET and BJH methods), elemental analysis, FTIR spectroscopy, scanning electron microscopy (SEM) as well as determination of pH_PZC and the number of surface functional groups. Additionally, thermal properties of the samples were investigated by thermogravimetric analysis (TG) and differential thermogravimetry (DTG). The final products were new carbon-nitrogen composites characterized by a very high content of nitrogen (11.2 - 21.6 wt.%) as well as relatively low surface area and pore volume reaching 198 m²/g and 0.16 cm³/g, respectively. Results of FT-IR study and Boehm titration indicated that the composites surface has clearly basic character, which was confirmed by pH_pzc values above 8.0.