Novel thin film nanocomposite membranes decorated with few-layered boron nitride nanosheets for simultaneously enhanced water flux and organic fouling resistance

Operational longevity of conventional thin film composite (TFC) nanofiltration (NF) membranes is significantly challenged by natural organic matter (NOM) fouling. Besides, surface modification of TFC membranes with nanomaterials results in their partial to complete confinement within the thin film, hampering the exploitation of nanomaterials full potential in improving NF performance. Incompatibility of nanomaterials with the polymeric matrix, and the resultant defect formation in the thin film can also lead to detachment of nanomaterial from the membrane surface. Herein, a modified interfacial polymerization (IP) reaction is developed to fabricate fouling-resistant thin film nanocomposite (TFN) NF membranes decorated with few-layered amine functionalized-boron nitride BN(NH2) nanosheets. The reactive edges of nanosheets are the geneses of fantastic properties; amine functionalities and electron deficient B atoms available at the edge regions render the nanosheets highly hydrophilic and negatively charged, respectively, favouring fouling mitigation. Compared with control counterparts, membranes decorated with BN(NH2) nanosheets revealed 59% enhancement in flux and 50% improvement in total fouling resistance, while maintaining NOM separation above 92%. BN(NH2)-decorated membranes showed long-term operational stability and enhanced recoverability, and nanosheet detachment tests eliminated the possibility of BN(NH2) leaching out during filtration.