Construction of self-cleaning nanofiltration membranes inspired by biomimetic catalysis utilizing cobalt phthalocyanine

Surface modification of membranes can inhibit the adsorption of contaminants on their surface. However, it is an unavoidable fact that minor contaminants will adsorb onto and accumulate within the membrane pores, ultimately leading to a deterioration in membrane performance. Researchers have attempted to incorporate nanoparticles with catalytic properties into membrane materials to enhance their self-cleaning ability. Nevertheless, the embedded nanocatalytic particles are susceptible to aggregation within the membrane, adversely affecting its separation performance. Biomimetic catalytic technologies, which emulate the structure and function of biological systems, offer a promising approach to tackle this challenge. In this work, a water-soluble biomimetic catalytic material was first synthesized through a chemical reaction between cobalt phthalocyanine and PEG(PEG@CoPc). Subsequently, more chemical reaction sites were introduced onto PEG@CoPc via host–guest interactions between PEG and α-cyclodextrin (α-CD). The PEG@CoPc(α-CD) serves as an aqueous monomer, which is cross-linked with 1,3,5-Benzenetricarbonyl chloride (TMC) to prepare polyester nanofiltration membrane. The optimized membrane showed a water flux of 32.35 L/m²·h·bar and a CR/NaCl selectivity of 270. The CoPc component can catalyze the decomposition of H₂O₂ to produce hydroxyl radicals (·OH). These radicals degrade the organic dyes in the NF membranes into CO₂, H₂O, and small amounts of acid, effectively eliminating membranes fouling.