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Local fluoride contamination and bacterial infections in potable water have dangerous effects on the human body and are today a global concern.In this study,we have synthesized a pH-responsive bifunctional biopolymer nanocomposite (HAZ) of humic acid with incorporating aluminum zirconium bimetallic oxide by deep freeze-drying method.Fast nucleation and interconnection of nanoparticles form a highly porous network because of sublimation of frozen HAZ.This duo nanocomposite has efficiently worked for fluoride removal and showed potent antibacterial activity against the Escherichia coli Gram-negative and Staphylococcus aureus Gram-positive bacteria.The X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the hydroxyl groups act as a pivot in the ion exchange process of adsorption,each element of bimetallic oxide primarily takes part in the adsorption mechanism.The maximum adsorption capacity of the adsorbent was 180.62 mg/g at pH seven.Thermodynamic parameters like Gibbs free energy change (△G0),entropy (△S0),and enthalpy (△H0) indicate that the process was endothermic,feasible,and taken place by a chemisorption mechanism.This is the first novel freeze-dried bifunctional biopolymer nanocomposite composed of humic acid natural polymer incorporated with Al-Zr metal oxide,and it exhibited three times higher adsorption efficacy with excellent antibacterial action at a concentration of 5 μg/mL of the nanocomposite.