Rational designed molecularly imprinted triazine-based porous aromatic frameworks for enhanced palladium capture via three synergistic mechanisms.

[Display omitted] • MI-TBPAFs acted as a palladium capture platform through three synergistic mechanisms. • The MI-TBPAFs with numerous tailored binding sites exhibited extraordinary selective affinity with palladium. • Pd2+ was reduced into Pd0 by MI-TBPAFs via photocatalytic and chemical reduction effects. • MI-TBPAF-3 showed ultra-high adsorption capacity for palladium (435.4 mg/g) under simulated sunlight radiation. Herein, molecular imprinting technology (MIT) was introduced into construction of molecularly imprinted triazine-based porous aromatic frameworks (MI-TBPAFs) via Heck-coupling reaction for palladium extracting from wastewater. According to the decorating Pd-vinylpyridine complex (Pd@Vpy), MI-TBPAFs were given considerable tailor-made binding sites with strong affinities for palladium, which captured palladium from various metal ions precisely. The adsorption experiments showed that the extraction capacity of MI-TBPAF-3 was improved by 59.0% (435.4 mg/g) under simulated sunlight radiation. Mechanism analysis proved that Pd2+ was reduced into Pd0 by MI-TBPAF-3 via photocatalytic and chemical reduction effects originating from triazine base and pyridine nitrogen atoms in the extended π-conjugated framework respectively, thereby greatly increasing adsorption capacity by the sorption-reduction strategy. Organically combining the advantages of MIT, photocatalytic reduction and chemical reduction, three synergistic mechanisms, not only provides a new strategy for highly efficient palladium extraction, but also inspires new insights for precious metal recovery. [ABSTRACT FROM AUTHOR]