Stable surface-modified TpPa-SO3H/PVDF membrane for efficient dye separations showing excellent photocatalytic degradation performance

Abstract

Fully utilizing the unique characteristics of COFs in surface-modified membranes is an ongoing research focus. Current challenges include ensuring the stability of the COFs separation layer on the membrane surface and developing environmentally friendly production methods for COFs surface-modified membranes. In this study, a simple room-temperature synthesis method was employed to prepare an aqueous colloidal solution of TpPa-SO₃H. Subsequently, TpPa-SO₃H nanosheets were loaded onto a hydrophobic PVDF membrane using vacuum filtration, resulting in the TpPa-SO₃H/PVDF membrane. This green and efficient modification method yielded a defect-free TpPa-SO₃H layer on the membrane surface, exhibiting excellent hydrophilicity (water contact angle of 50.8°). For dye separation, the TpPa-SO₃H/PVDF membrane (F2) demonstrated high rejection rates (>98 %) for most dye molecules, along with good recyclability and filtration stability. Even after exposure to extreme acidic conditions, the separation performance of the modified membrane remains consistent, showcasing remarkable acid resistance. Furthermore, the prepared modified membranes exhibited effective photocatalytic degradation of various dyes (>90 %) as well as excellent stability and reusability. The modified membrane has shown significant self-cleaning effects in the three cycles of photocatalytic self-cleaning performance testing. This effectively demonstrates its potential in the domain of photocatalytic self-cleaning, exhibiting its capabilities and viability in the respective field.