Characterization of bergamot, grape and olive pomaces using different analytical techniques

In the last years, agrifood processing wastes have been used for the development of multifunctional materials possibly capable of effectively and selectively interacting with organic (pesticide, dyes) and inorganic (metals, anions) pollutants, through adsorption mechanisms1. This contribution presents the preliminary results of an investigation focused on the characterization of bergamot (BP), grape (GP) and olive (OP) pomace samples from different cultivars, representative of various harvesting seasons. The waste biomasses were provided after juice and essential oil extraction, berries pressing for the must production and olive oil extraction, respectively. Aliquots of the pristine pomaces were mechanically ground using a grinder, dried in an oven at T = 333 K until constant weight and blended again to gain a fine powder. The resulting solids (raw) were divided in diverse portions and pretreated for 6 hours at T = 303 K using deionized water and nitric acid solutions, according to procedures reported in literature2. The raw and pretreated samples were characterized by means of BET and SEM-EDX techniques to get information on the superficial area and the particles sizes distribution. The TG-DTA and the FT-IR ATR spectroscopy were used to study the pomaces thermal properties and to confirm the presence of functional groups possibly capable to interact with metal cations, respectively. The acid-base properties of the biomasses active sites were potentiometrically investigated at I = 0.10-1.00 mol dm-3 in NaNO3(aq) and T = 298.15 K. To confirm the obtained results, some checks were also carried out on grape and olive pomaces pretreated with H2O by using the classic volumetric method with calcium acetate3. Lastly, the dependence of protonation constants on ionic strength was modelled using an extended Debye-Hückel type equation. Acknowledgements: we thank MUR: PNRR - Missione 4, Componente 2, Investimento 1.1 - Bando Prin 2022 - Decreto Direttoriale n. 104 del 02-02-2022. Project title: “Wastezilla: Recycled waste biomass for efficient recovery of critical elements”. CUP: J53D23007540006, G53D23002970006, H53D23003860006, project code: PRIN_2022HYH95P_001. References: [1] N. Mahato, K. Sharma, M. Sinha E. R. Baral, R. Koteswararao, A. Dhyani, M. H. Cho, S., Cho, J. Adv. Res. 2020, 23, 61–82. [2] A. Irto, S.G.M. Raccuia, G. Lando, C. De Stefano, K. Arena, T.M.G. Salerno, A. Pettignano, F. Cacciola, L. Mondello, P. Cardiano, Microchem. J. 2023, 193, 109183. [3] M. Eshwar, M. Srilatha, K. Bhanu Rekha, S. Harish Kumar Sharma, Int. J. Curr. Microbiol. App. Sci 2017, 6(10), 1768-1774.