Novel dual-heterojunction photocatalytic membrane reactor based on Ag2S/NH2-MIL-88B(Fe)/poly(aryl ether nitrile) composite with enhanced photocatalytic performance for wastewater purification

Abstract

The separation and reuse of powdered photocatalysts have become a significant obstacle to applying photocatalytic technology in engineering. Here, we propose a method that is fully applicable to the conventional solvent-nonsolvent induced phase separation (NIPS) technique by mixing porous nano photocatalyst NH2-MIL-88B(Fe) into polyaryl ether nitrile(PEN) with carboxyl groups in situ construction of nano-functionalized photocatalytic matrix membrane (NH2-MIL-88B(Fe)/PEN). Then, silver sulfide(Ag2S) was grown on the surface of the NH2-MIL-88B(Fe)/PEN film as a separation layer by thermal reaction self-assembly to obtain a photocatalytic composite film Ag2S/NH2-MIL-88B(Fe)/PEN. The formation of the double heterojunction can effectively inhibit the recombination of photogenerated electrons and holes, and the heterojunction is established at the interface after the composite material is constructed, thereby reducing the resistance and accelerating the photoinduced carrier transfer. The experimental results show that under optimal conditions, the well-stabilized Ag2S/NH2-MIL-88B(Fe)/PEN ternary composite membrane can remove 99.97 % of SDZ, and the mineralization rate is 85.41 %. After 8 cycles of Ag2S/NH2-MIL-88B(Fe)/PEN photocatalytic membrane, the removal rate of SDZ is still as high as 91.76 %, indicating that the catalytic membrane has good reusability and stability. The photocatalytic film system can also achieve good strength, toughness, and high-temperature resistance. Furthermore, possible photo-degradation pathways were investigated based on LC-MS/MS analysis to better understand the photo-degradation process. This study provides a new idea for developing a new generation of multifunctional photocatalytic membranes.