Ultra-High Bromine Removal from Waste Water and Downstream High-Value Utilization Using Melanin-Like Polymers

Bromine (Br₂) plays vital roles in various chemical reactions in laboratories and industries, however, the excessive use of Br₂ inevitably causes their leakage, which increases the risk of environmental pollution. Although efficient Br₂ capture is highly desirable, current removal materials still face grand challenges from unsatisfactory removal efficiency as well as limited function. Polydopamine (PDA), as the most representative analog of melanin-like polymers, has shown great potential in different fields during the past few decades. Herein, a triple-level chemical engineering process is innovatively proposed to achieve the high-value application of PDA. The active hydrogens of aromatic groups within PDA nanoparticles (NPs) enable the active substitution reactions with Br₂, while abundant polar groups enhances the physical adsorption of Br₂, thus realizing an extremely high Br₂ removal capacity of 9511 mg g^-1, which far exceeds the average level of Br₂ removal materials reported. More interestingly, the resulting brominated-PDA (PDA-Br) NPs can be downstream upcycled to realize harvesting of precious metal silver/gold, and the resulting Ag⁺-loaded PDA-Br NPs (PDA@AgBr NPs) further exhibits superior anti-bacterial ability. Overall, this work not only innovatively expands the emerging application scope of melanin-like polymers, but also paves a new pathway toward the design of robust materials for high-value utilization.