Tripolyphosphate-functionalized cellulose: A green solution for cadmium contamination.

This study introduces a highly efficient tripolyphosphate -tethered cellulose sorbent for cadmium (Cd⁺) removal from aqueous solutions. Characterization through FTIR and SEM revealed the material's structural properties. The sorbent achieved 99% Cd⁺ removal even at a minimal dosage of 0.05 g. Optimal sorption occurred within the pH range of 4-6, influenced by the sorbent's weak acidic functional groups. Rapid kinetics, reaching equilibrium within a minute, and a high sorption capacity (up to 18.03 mg/g at 50 °C) were observed. Langmuir isotherm modeling confirmed monolayer sorption, and thermodynamic studies indicated a spontaneous, endothermic process with increased randomness at the solid-liquid interface. Selectivity studies demonstrated strong Cd⁺ removal performance in the presence of competing ions, with minimal interference from monovalent ions but notable effects from divalent ions. The sorbent exhibited consistent reusability over multiple cycles. XPS analysis conclusively established an ion exchange mechanism between Cd⁺ and negatively charged PO groups as the primary removal pathway. This research highlights the potential of TPP-tethered cellulose as a promising sorbent for effective Cd⁺ remediation.