Characterization of feedstock and biochar from energetic tobacco seed waste pyrolysis and potential application of biochar as an adsorbent

Abstract

In this study, a material with great adsorption potential was obtained from the residual cake from the extraction of energetic tobacco seeds. This residual cake seed was characterized and subjected to pyrolysis in nitrogen flow, resulting in bio-oil and biochar. The biochar and the feedstock (waste cake of tobacco seeds) were characterized by several techniques (thermogravimetric analysis (TGA), elemental analysis infrared spectroscopy, scanning electron microscopy, inductively coupled plasma optical emission spectrometry (ICP-OES), the Brunauer Emmet Teller (BET) method, the Barret, Joyner, and Halenda (BJH) method and functional density theory (DFT)) for comparison and subsequent possible application of the biochar. The results of the ICP-OES analyses indicate that nitrogen, potassium and phosphorus are the most abundant elements in the biomass and biochar. The metals analysis indicated no toxicological effects for animal feed. IR analysis results show that the pyrolysis led to conversion and/or removal of the vast majority of functional biomass groups, resulting in inorganic matter and inert carbon. The XPS analysis of the biochar indicates nitrogenous heteroaromatic structures which are formed during the pyrolysis process. In this way, can contribute to the cation exchange capacity in soils and adsorption of contaminants. Lastly, this biochar has great potential for use as an adsorbent for small molecules (due to the presence of micropores) after its activation, with a specific area of 1800 m2 g−1, surprisingly high compared with other solids of this type. Thus, a high value-added material can be obtained from the residue.