Analysis of the Pyrolytic Behaviour of Birch, Maple, and Rowan Leaves

Abstract

A research study was conducted on the thermal behaviour of leaves of urban greenery (birch, maple, and rowan) and the products of their pyrolysis and extraction as assisted by microwaves. The obtained products of pyrolysis and extraction were investigated with the use of FT-IR and UV spectroscopies and XRD techniques. A contractive analysis of samples of chars, condensates, after-extraction residue, and extracts showed that the changes in structural-chemical parameters of leaves of different types of trees during pyrolysis and extraction take place in distinct ways. About 22% of material was removed from birch leaves during extraction, and more than 17% of material was extracted from maple and rowan leaves. It was determined that, during pyrolysis of after-extraction residue of leaves, many fewer PAH compounds with carbonyl groups along with alcohols and phenols are emitted than during pyrolysis of non-extracted leaves. Taking into account that pyrolysis is the first stage of combustion, a decrease in the amount of dangerous compounds in the volatile products of pyrolysis leads to a lower contribution of such compounds in combustion products. This indicates that leaves of urban greenery can be subjected to combustion after extraction, and the obtained extracts can be used as a source of phytochemicals and chemical reagents.