Incorporating arginine-FeIII complex into polyamide membranes for enhanced water permeance and antifouling performance

Nanofiltration membranes featuring excellent separation and antifouling performances are highly desired for applications such as water purification. In this study, inspired by the phenomenon of coordination-driven self-assembly and the structures of aquaporins in nature, an arginine (Arg)-FeIII complex was designed and incorporated into the polyamide layer during interfacial polymerization, endowing the resultant nanofiltration membranes with enhanced water permeance and prominent antifouling performance. Owing to the active amine groups, the Arg-FeIII complex could react with trimesoyl chloride (TMC) and thus act as the aqueous additive in company with piperazine (PIP), which improved the compatibility between the organic phase and aqueous phase. The interfacial channels between the Arg-FeIII complex and the polyamide matrix as well as the hydrogen bonds interaction between water and the Arg-FeIII complex facilitated the rapid water transfer. When the content of the Arg-FeIII complex reached 0.3 g/L, the water permeance was elevated significantly, twice than that of the pristine polyamide membrane. Meanwhile, the rejections for Na2SO4 and dyes were close to those of the pristine polyamide membrane. Furthermore, the resultant membranes displayed exceptional antifouling performance. Introducing the metal-organic complex into the interfacial polymerization process proves an effective and promising attempt to fabricate membranes with high performance for water resource reclamation.