Removal of copper and lead using polyvinyl alcohol-capped bismuth-zinc oxide (PVA/Bi-ZnO) nanocomposite as an adsorbent

Heavy metal contamination of water resources, particularly by copper (Cu2+) and lead (Pb2+), poses severe risks to human health and aquatic ecosystems globally. Existing adsorbent materials often lack the combination of high adsorption capacity, structural stability, and cost-effective synthesis required for practical wastewater remediation. This study reports the facile synthesis of a polyvinyl alcohol-capped bismuth-zinc oxide (PVA/Bi-ZnO) nanocomposite via co-precipitation and evaluates its performance as a high-efficiency adsorbent for simultaneous Cu2+ and Pb2+ removal from aqueous media. The nanocomposite was characterized by FT-IR, SEM, EDX, and XRD. Adsorption was optimized at pH 6.0 (Cu2+) and pH 7.0 (Pb2+), with equilibrium attained within 60 and 40 min, respectively. Isotherm data conformed exclusively to the Langmuir model, yielding maximum capacities of 40.03 mg g-1 (Cu2+) and 65.43 mg g-1 (Pb2+). Pseudo-second-order kinetics confirmed chemisorption as the rate-controlling mechanism. Thermodynamic parameters (ΔG < 0, ΔH < 0, ΔS < 0) confirmed spontaneous, exothermic adsorption. This is the first study to investigate the synergistic PVA/Bi2 O3 -ZnO binary oxide system for simultaneous Cu2+ and Pb2+ remediation, with demonstrated efficacy in real Hyderabad city sewerage wastewater and 87–95% regeneration efficiency using 0.1 M HCl