From Agricultural Waste to Functional Materials: Modified Carbonaceous Adsorbents From Corn Biomass

The aim of this study was to produce biochars and activated biocarbons from corn postharvest residues (stalks and cobs) and to evaluate their physicochemical properties. The carbonaceous materials were prepared via simple thermochemical conversion methods, including microwave-assisted pyrolysis, impregnation with urea or calcium carbonate followed by thermal treatment at 400°C, or direct activation of the precursor with CO₂. The resulting materials were characterized in terms of elemental composition, textural properties, surface acid-base characteristics, and thermal stability. Their effectiveness in removing model organic and inorganic contaminants from aqueous solutions was also evaluated. In addition, their usefulness as a soil additive supporting the growth of corn seedlings was tested. The results demonstrated that corn crop residues are a highly promising precursor for low-cost adsorbents. Various thermochemical treatment methods enabled the synthesis of a wide range of carbonaceous materials with favorable physicochemical properties and high sorption capacity. The properties of the adsorbents were influenced not only by the thermochemical treatment method but also by the specific plant fraction used in their production. The study also demonstrated that the resulting biochars can be used as an effective soil amendment in corn cultivation, and calcium carbonate-modified materials exhibiting particularly favorable properties in this regard.