<i>Spondias Tuberosa</i> Seeds as Lignocellulosic Bioadsorbent for Efficient PB (II) Removal: Characterization, Adsorption Modeling, Selectivity, and Reusability

Abstract The objective of this research was to investigate the efficiency of Spondias tuberosa seeds (SST) as a bioadsorbent for Pb (II) ions in aqueous solutions. Adsorption isotherms and kinetics as well thermodynamics were studied in a batch system. The SST residue was collected from pulp manufacturing industries in the Cariri region of Ceará, specifically in the city of Juazeiro do Norte, Ceará, Brazil. For the characterization of the adsorbent material, point of zero charge (PZC), scanning electron microscopy (SEM), and infrared spectroscopy (FTIR) analyses were performed. The pHPZC obtained had an average value of 5.3, which was adjusted to 5.5. SEM images revealed the presence of roughness and porosity typical of fibrous plant materials. With increased magnification, the material showed varying pore shapes and sizes, generally derived from the structure of the plant cell wall of the precursor biomass. It was also observed that the adsorption rate reached equilibrium within 30 min. Thus, it was concluded that the SST bioadsorbent demonstrated satisfactory performance in the adsorption of Pb (II) ions with a maximum adsorption capacity of 46.0 mg. g −1 . These findings support the use of SST as an environmentally friendly low‐cost and efficient biosorbent contributing to sustainable strategies for toxic metals remediation.