Background: In recent decades, agricultural residues have been widely applied in the development of novel materials in order to obtain high-value products and reduce disposal issues. Objectives: In this work, corn cob residual biomass was used to prepare a biosorbent chemically modified with alumina nanoparticles. Methods/Analysis: The alumina nanoparticles were synthesized by sol-gel methodology and loaded into biomass matrix using an organic solvent. The corn cob biomass was characterized by ultimate analysis, FT-IR technique, Boehm titration and point of zero charges method, which provide information related charge of biomass surface, diversification of functional groups and elemental composition. SEM and EDX analyses were also performed in order to study morphology and composition of the prepared biosorbent. Batch adsorption experiments were carried out to evaluate the effect of pH and particle size on adsorption efficiency and determine suitable conditions for further experimentation. Findings: The physicochemical characterization of corn cob biomass revealed the presence of carboxyl, hydroxyl and amine functional groups in FT-IR spectrum. After loading alumina nanoparticles, this spectrum exhibited characteristic peaks of aluminum bonds suggesting a successful synthesis. In addition, it was observed that pH played an important role in removal yield results, hence, pH=6 were selected as suitable value for performing further experiments. The removal yield for cadmium and nickel ions using chemically modified biomass were 91 and 86%, respectively, results higher than those obtained using biomass. Novelty/Improvement: The modification with Al2O3 nanoparticles enhances adsorption process and could be applied to other sources of biomass. Keywords: Agricultural Residues, Alumina Nanoparticle, Biosorbent, Removal Yield