Insights on the Adsorption Properties of Functionalized Polyketone for Diclofenac Sodium Removal

Aliphatic polyketones, known for their low cost, simple synthesis, and ease of functionalization, have gained attention as potential wastewater treatment materials. However, their application for pharmaceutical removal remains underexplored. To investigate their feasibility as drug adsorbents, the polyketone was modified with four functional groups: hydroxyl, amine, imidazole, and benzene rings, using a one-step Paal-Knorr reaction. This catalyst- and solvent-free reaction is simple, generating water as the sole byproduct. The modified polyketone adsorbents were evaluated for their ability to remove diclofenac sodium, a pharmaceutical compound frequently detected in water resources. Batch adsorption experiments revealed that polyketone modified with amine groups exhibited the highest adsorption capacity for diclofenac sodium. Further studies demonstrated that the amine-functionalized polyketone showed good selectivity for diclofenac sodium, even in the presence of other pharmaceutical contaminants. Hence, an amine-modified polyketone was selected for the adsorption behavior studies to explore the underlying mechanism. The results indicated that the removal of diclofenac sodium was governed by electrostatic interactions, hydrogen bonding, and π-π interactions, with relative importance varying as a function of solution pH. Adsorption isotherm analysis demonstrated that the Freundlich model provided a better fit to the experimental data, suggesting multilayer adsorption on the adsorbent surface. The Langmuir model indicated a maximum adsorption capacity of 61 mg/g for diclofenac sodium. In conclusion, this study highlights the potential of amine-modified polyketones as an efficient and selective adsorbent for removing diclofenac sodium from aqueous solutions. This material shows promise for applications in wastewater treatment, particularly in environments with mixed pharmaceutical pollutants.