A new method for the mitigation of piperazine transfer rate to prepared nanofiltration membranes by modified PVDF substrate through MOF-303@GO

• The MOF-303@GO composites with different MOF-303 loading amounts were prepared. • MOF-303@GO slowed down the diffusion rate of the piperazine monomer. • The interaction between MOF-303@GO and the piperazine monomer was calculated using DFT. • Thin and rough PA layers for the nanofiltration membrane were prepared. High-efficiency polyamide nanofiltration membranes were recognized as crucial for alleviating freshwater scarcity. However, the rapid reaction rate between piperazine (PIP) and trimesoyl chloride (TMC) resulted in low membrane flux and suboptimal separation efficiency, which limited the application and development of membrane technology. Herein, a novel MOF-303@GO nanomaterials were prepared by in-situ growth method, which were anchored in the framework of the substrate membrane through a phase separation method to regulate the speed of interfacial polymerization reaction to improve the performance of composite nanofiltration membranes. The MOF-303@GO was found to exhibit an adsorption effect on PIP monomers for the accumulation of the PIP molecules around the MOF-303@GO in the membrane pore, which effectively slowed transfer rate of PIP. This process resulted in a thin PA layer and rough surface, which alleviated the resistance to water molecule transport during the membrane separation process. The adsorption mechanism between MOF-303@GO and PIP was profoundly demonstrated by density-functional theory calculations. Besides, the fabricated membrane demonstrated a good water permeability of 14.53 L·m −2 ·h −1 ·bar −1 , along as well as a high Na 2 SO 4 rejection of 96.56 %. This research provided a novel material to regulate the diffusion state of PIP molecules and introduced a key strategy for uniformly blending to modify the substrate membrane, offering a potential solution to the issue of excessively rapid IP reaction rates.