Home – Home – Jornals – Chemistry for Sustainable Development 2025 number 4

The effect of ZnCl₂ on the composition of pyrolysis liquid and the solid pyrolysis product, as well as on the electrochemical properties of the carbonisate obtained during pyrolysis of fir bark was studied. It has been found that destruction starts in the mixture of fir bark with ZnCl₂ at lower temperatures and with lower rates of mass loss than the destruction of fir bark without ZnCl₂, and leads to the formation of a highly porous ZnO/C composite with the specific surface area of up to 770 m²/g. Current-voltage measurements of the samples have shown that the ZnO/C composite has a specific capacitance of 394 F/g, which allows using it for making supercapacitors. The charge accumulation dynamics was revealed to be significantly dependent on the potential scanning rate, and specific capacitance noticeably decreases with its increase. Ion accumulation is assumed to proceed over the surface accessible for ions, and the accessible surface area decreases with an increase in scanning rate because of diffusion-related limitations. The composition of the pyrolysis liquid from initial fir bark and a mixture of fir bark with ZnCl₂ was determined using gas chromatography with mass spectrometric detection, which showed a more complex composition of the pyrolysate for the former case, with a high content of phenol and guaiacol homologues, carboxylic acids and their esters. When using a mixture of fir bark with ZnCl₂, the pyrolysis liquid contains mainly carboxylic acids, predominantly hexa- and heptadecanoic acids, while the homologues of phenol and guaiacol are almost completely absent. It is assumed that ZnCl₂ as a catalyst of Lewis acid type promotes the formation of carbonium ions and the synthesis of more stable high-molecular products.