Functional Hyper-Crosslinked Polypyrene for Reductive Decolorization of Industrial Dyes and Effective Mercury Removal...

A rigid and valuable hyper-crosslinked polymer (HCP) has been synthesized from the polycyclic aromatic hydrocarbon pyrene: hyper-crosslinked polypyrene (HCPPy). HCPPy was prepared through a simple one-step Friedel-Crafts alkylation reaction that involves ZnBr₂ -catalyzed crosslinking in the presence of an external crosslinker, bromomethyl methyl ether (BME). Interestingly, the unreacted bromomethyl groups (-CH₂ Br) on the surface of HCPPy could be quantified, which later aided in modification as per our requirement. We aimed at modifying with disulfide-containing cystamine dihydrochloride (Cys-HCPPy). Cys-HCPPy exhibited an extended π-conjugated system with uniform (∼1 μm diameter) morphology and high porosity (specific surface area: 445 m²  g^-1 ). As a fundamental application, the Cys-HCPPy composite was used as a sorbent to remove Hg²⁺ ions from aqueous media. Thus, at pH 6, the adsorption capacity for mercury ions reached 1124.82 mg g^-1 after 24 h. Furthermore, the immobilization of Ag nanoparticles on the surface of Cys-HCPPy (Ag@Cys-HCPPy) enhanced the catalytic properties, which allowed for the reductive decolorization of industrial dyes such as methylene blue, methyl orange, and Congo Red in the presence of NaBH₄ as a reducing agent.