Cellulose nanofibrils (CNFs) produced from waste lignocellulosic biomass have emerged as a sustainable source material for high value-added applications. In the current study, previously unreported entangled cellulose nanofibril and nanosheet (CNF/CNS) were obtained using Agave Tequilana Weber var. Azul leaves by means of a microfluidization process. These nanomaterials were investigated as potential biosorbents of Pb2?, for which three adsorption mechanisms were identified by XPS. At low initial concentrations of Pb2? (C0 \ 100 ppm), the adsorption-mechanism is governed by electrostatic interactions between carboxylate groups and Pb2?; meanwhile, at (C0 = 1000 ppm) mono and bi-dentate complexes dominate the adsorption-mechanism. Finally, when 110 \ C0 \ 1000 ppm, both mechanisms co-exist. The maximum adsorption capacity was 43.55 mg/g, according to the Langmuir model, while CNF/CNS showed the characteristic diffraction peaks of cellulose type II. Our results highlight the high potential of these novel CNF/CNS biosorbents in the treatment of wastewater contaminated with toxic metals and afford new insights on adsorption mechanisms.