RESUMO
Arabic gum-based composite hydrogels reinforced with eucalyptus and pinus residues were synthesized via free-radical reaction aiming to controlled phosphorus release. All hydrogels were characterized by swelling kinetics (SK), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical assays (MA). The water and solute transports through the hydrophilic three-dimensional networks of the hydrogels occur preferably by diffusion processes and macromolecular relaxation. Hemicellulose, lignin and cellulose fibers contained in eucalyptus and pinus residues affected the crosslinking density, crystalline structure, and water/solute diffusion due to reduction of free hydroxyl and amine groups in the hydrogel networks. Hence, the eucalyptus and pinus residues improved the mechanical and thermal resistances of the composite hydrogels. Finally, the Arabic gum-based hydrogel and Arabic gum-based composite hydrogels reinforced with eucalyptus and pinus residues demonstrated to be excellent alternatives for the controlled phosphorus release in agricultural nutrient-poor soils.
