Removal of Copper and Lead Ions from Water Using Dopamine-Modified Waste Marine Plastic

Plastic waste poses a serious threat to marine ecosystems due to its ability to adsorb environmental contaminants and facilitate their long-range transport. This study investigates the potential of repurposing marine plastic debris as an adsorbent for dissolved heavy metals in wastewater. Raw and dopamine-functionalised polypropylene ropes were tested for the removal of Cu²⁺ and Pb²⁺ ions from aqueous solutions. Dopamine functionalisation significantly improved adsorption performance, with capacities increasing from 122 to 233 µg/g to 317 and 536 µg/g for Cu²⁺ and Pb²⁺, respectively. Characterisation results demonstrated that the modification introduced amine and catechol groups, enhancing electrostatic interactions and metal chelation. Column experiments showed that combining plastic adsorbents with activated carbon extended the operational lifespan of the packed bed by approximately 82%. This work provides new insight into the environmental reuse of real-world marine plastic waste and demonstrates that such materials can be effectively integrated with conventional adsorbents for sustainable wastewater treatment.