Caracterização química do extrato pirolenhoso obtido a partir de Eucalyptus grandis e testes alelopáticos da fração destilada

Abstract

The pyroligneous extract is a by-product of the charcoal industry, obtained through the condensation of smoke released through charcoal production ovens, which, if properly processed, can reveal several applications. The objective of this work was to evaluate the physicochemical characteristics of crude pyroligneous extract (CE), decanted (DE) and distilled (DSE) obtained on an industrial scale from Eucalyptus grandis wood, as well as to determine the chemical composition of each sample by means of the gas chromatography technique, in addition to performing allelopathic germination and growth tests, of the EDS fraction against recipient plants Bidens pilosa and Eragrostis plana Nees (Capim Annoni-2) which are considered weeds of the dicotyledonous and monocotyledonous classes, respectively. It was possible to identify more than 100 compounds in the three studied pyroligneous extract fractions, including different acids such as benzoic, fumaric, acetic, butanoic and vanillic, in addition to guaiacol, syringol and cresol, which are characteristic compounds to be found in pyroligneous extracts, being the majority 2,6-dimethoxy-phenol (34.67%), 3,5-dimethoxy-4-hydroxy-toluene (23.28%), 5-tert-butyl-pirogalol (12.94%), tetrapentacontane (11.14%), tetratetracontane (12.71%), 4,5-dimethyl-1H-imidazole (26.64%) and phenol (19.41%). CE had in its composition many highly toxic compounds, such as phenolics, furfural delivery, among others, followed by DE. As for the composition of the DSE, those selected are composed in existing ones and/or they are tested, for this reason it was for allelopathic use. The germination tests were carried out with distilled water as a negative control, DSE at 10; 12,5; 15; 17,5 and 20% and glyphosate as a positive control. The results showed a germination inhibition of 100% for BP using 17.5% DSE and 87.5% for CA using 20% DSE. The results obtained are promising and indicate efficacy for the control of germination of the studied plants, besides indicating that the distillation process performs the purification of the crude pyroligneous extract.