Protonated carbon nitride incorporated polyamide thin film nanocomposite for reverse osmosis desalination

Abstract

Protonated carbon nitride (pCN) prepared from acid treatment of carbon nitride (CN) was incorporated in the polysulfone (PSf) substrate and polyamide (PA) layer to produce thin film nanocomposite (TFN) membrane. The hydrophilicity of CN is expected to improve the surface hydrophilicity of the membrane and acid treatment of nanoparticle is aimed to further enhance the surface structure and prevent the agglomeration of nanomaterial from taking place. pCN loading used in the PSf substrate was 0.5% while in the PA layer was varied as 0.05%, 0.1% and 0.15%. All the membrane prepared were characterized in terms of morphology, structural properties, and surface chemistry. Reverse osmosis dead-end filtration system was used to determine the water permeability and the salt rejection. It was observed that, all the membrane prepared could maintain the salt rejection with improvement of water permeability. However, the salt rejection was sacrificed when higher loading of 0.15% pCN was tested, although the water permeability of the membrane has reached approximately 0.5 LMHbar. This work demonstrates that the use of pCN in RO membrane can improve the water permeability without sacrificing the salt rejection.