Obtaining Mathematical Models Combined with Infrared Spectroscopy Data and the Use of Artemia salina as a Biological Indicator to Predict the Toxicity of the Biochars

Resumo

The simple analytical method described herein involves the use of infrared spectroscopy to analyze
residues, consisting of biochar (C) and pyroligneous acid (PA), obtained from Pinus. The values for the
concentration which is lethal to 50% of a sample of brine shrimp (Artemia salina) organisms (LC50) were
determined. For the chars produced at 400, 450 and 500 °C the LC50 values were > 5000 ppm. The LC50
value for PA is related to an increase in the intensity of the absorption bands of phenolic compounds
at 1389 cm-1 and the C=C bands of aromatics at 1492 cm-1. Pyrolysis temperatures of 250 and 300 °C
are associated with the production of PA with LC50 ≥ 715 ppm, accompanied by a lower intensity of the
bands associated with the C-H of aromatic compounds (vibrational frequencies for C-H bending mode
of benzene derivatives are observed from around 720 to 850 cm-1). The biomodel results show that it is
possible to predict the LC50 value through the application of mathematical models obtained from infrared
spectroscopy data. The proposal explores the use of infrared spectroscopy combined with mathematical
models (speed of analysis) and the use of Artemia salina as a biological indicator (low cost).