Functionalization of activated carbon with melamine binder for adsorption of metallic species from aqueous environments

In the face of the increasing exposure to heavy metals in the environmental scenario, there arose the need for further research by the scientific community. In this perspective, the present work reports the application of a material made from Typha sp. leaf, activated and functionalised with molecules of 1,3,5-Triazine-2,4,6-triamine (melamine), for the selective adsorption of metal ions Cu(II), Cd(II), and Pb(II) in aqueous solutions. Confirmation of material functionalization occurred through infrared vibrational spectroscopy, revealing bands at 3467, 3424, and 1338 cm−1 associated with the stretching vibration of -NH2. These results provide evidence of the possible anchoring of the ligand on the material surface. Elemental nitrogen analysis corroborated the results of infrared spectroscopy and showed 2.21% nitrogen in the functionalised material, while 1.30% in activated carbon. X-ray photoelectron spectroscopy showed the modification of the material surface composition after the functionalization reaction. The specific surface area was calculated as 193.876 m2/g. Adsorption studies revealed a rapid kinetics, best described by the pseudo-second-order model. The optimised pH for adsorption was 6.0 (pHPZC = 7.5), aligning with conditions found in natural waters. The maximum adsorption capacity was 0.4388, 0.4025, and 0.2792 mmol g−1 for Cu(II), Pb(II), and Cd(II), respectively, following the Langmuir model. Furthermore, to facilitate practical application, parameters such as mass and flow rate were optimised. The results suggest that the developed material exhibits promising adsorptive properties, emerging as a potential solution for remediating areas contaminated by metallic species.