Wood-based catalytic filter decorated with ZIF-67 for highly efficient and continuous organic pollutant removal

High-performance catalytic filters with both high removal efficiency and high water flux are essentially demanded for organic wastewater purification but still remain a great challenge. Herein, taking full advantage of the well-aligned liquid transport channels of natural wood and the excellent catalytic activity of metal–organic frameworks (MOFs), we developed a high-efficiency wood-based catalytic filter (ZIF-67@wood) for continuous and highly efficient catalytic degradation of methylene blue (MB) in water. The wood scaffold was pretreated with a sodium hydroxide (NaOH) solution to create nucleation sites for in situ growth of ZIF-67 nanocrystals within the wood channels, which function as catalytic sites to activate peroxymonosulfate (PMS) to generate reactive radicals (·OH and SO4•−) for MB degradation. As the MB solution flows through the catalytic filter, the abundant well-distributed vessel channels of natural wood serve as the primary pathways for rapid fluid transport and enhance the contact between organic contaminants and ZIF-67 nanocrystals. The obtained ZIF-67@wood catalytic filter demonstrated a high MB removal efficiency (∼90 %) with a water flux rate of 5119 L m−2h−1 under gravity-driven conditions, outperforming most previously reported MOF-based composites. Moreover, multiple ZIF-67@wood catalytic filters can be readily integrated and assembled as a flow-through catalytic reactor for continuous MB degradation. Such cost-effective, highly efficient, and scalable wood-based catalytic filters hold great promise for practical wastewater treatment.