Monitoring the Removal of Lead and Cadmium Ions From Environmental Samples Using a Hybrid Composite of Zinc Tungstate and Treated Papyrus

ABSTRACT

This study presents a novel hybrid adsorbent, ZWSPPAC, synthesized by integrating zinc (Zn) tungstate (ZnWO ₄ ) with activated carbon derived from chemically treated papyrus biomass. The composite was evaluated for the removal of Pb ⁺² and Cd ²⁺ ions from both synthetic solutions and real environmental samples. Its physicochemical properties were characterized using FT‐IR, TGA‐DTA, x‐ray diffraction (XRD), SEM‐EDX, BET, and pHzpc analyses. Batch adsorption experiments were conducted to investigate the effects of key parameters, including pH (1–6), contact time (10–120 min), initial metal concentration (150 mg L ⁻¹ ), and adsorbent dosage (10 mg). The maximum experimental adsorption capacities reached 91 mg/g for Pb ²⁺ and 124 mg/g for Cd ²⁺ under the evaluated batch conditions, while the theoretical monolayer adsorption capacities calculated from the Langmuir isotherm model reached 122.6 mg/g for Pb ²⁺ and 131.92 mg/g for Cd ²⁺ . Equilibrium data were best described by the Langmuir isotherm model, while adsorption kinetics followed a pseudo‐second‐order model, indicating chemisorption as the dominant mechanism. Thermodynamic analysis confirmed the exothermic nature of the process. Application to real environmental samples demonstrated removal efficiencies of 79% for Pb ²⁺ and 89% for Cd ²⁺ . These findings highlight ZWSPPAC as a cost‐effective, eco‐friendly, and efficient adsorbent for the remediation and monitoring of heavy metal‐contaminated environments.