Physicochemical and adsorption properties of carbonaceous sorbents prepared by activation of tropical fruit skins with potassium carbonate

Highlights: • Common tropical fruit peel recycling has been described. • Activated carbons were synthesized in one-step biomass conversion process. • The adsorbents prepared show a high sorption capacity towards organic dyes and iodine. • The adsorbents can be used for purification and decolourisation of drinking water. A series of new carbonaceous adsorbents has been obtained by means of chemical activation of common tropical fruit peels with potassium carbonate. The influence of the precursor on the porous structure development, acidic and basic surface group generation, as well as the sorptive properties of the adsorbents prepared towards liquid pollutants, was tested. The products of thermo-chemical treatment of grapefruit, mandarin, pomelo and banana peels were microporous carbonaceous sorbents with relatively high contribution of mesopores (of diameters within the range of 2–10 nm), characterised by well-developed surface area ranging between 836 and 1198 m²/g, containing mainly acidic surface functional groups. Moreover, the results obtained during the study proved that a proper selection of biomass treatment process allows getting adsorbents with a very high sorption capacity towards methylene blue and methyl red as well as inorganic pollutants of molecules of size similar to that of iodine molecules.