Stage 1 (2022) of the resarch project „Agricultural waste - complete valorization to biofuels and chemicals” (AgriValBack) was entitled „Collection, stabilization, characterization od agricultural waste”. Samples of vegetable residues were collected in this stage of the project, from a geographical area as small as possible to minimise, as much as possible, the effect of geographical, climaterical and pedological factors that affect the growth and development of vegetal biomass and the properties of the generated materials. Various types of biomass were considered, mainly residues from agricultural activities, with high lignification degree and which are rarely valorified and left unused for natural decay. The vegetal sources were selected from the most representative ones and, in some situations, the same source provided materials for varius classes.

            The studied vegetal residues were as following:

-          pods (corn, sunflower, okra);

-          hulls (walnuts, almonds, chestnuts, okra);

-          shells (walnuts, almonds, hazelnuts, ginko);

-          pits (apricots, cherries, peaches, plums, okra);

-          powderd seeds (walnuts, hemp, pumpkin, flax, sunflower).

Sampled were dried, first in natural conditions then in controlled ones, ground, sorted by dimensions and characterized to determine the proximate and ultimate composition, structure (by FTIR spectroscopy), thermal behaviour (by thermogravimetry) and heat capacity.

Sample characterozation revealed o clear diferentiation of vegetal residues according to the type, as evidenced by the Van Krevelen diagram and by the PCA analysis.

The studied vehetal residues are promising candidates for valorisation by thermal procedures, such as torrefaction and pyrolysis, which will be the subject of research for the following stages of the project.