2D nanochannels and huge specific surface area offer unique ways for water remediation and adsorption: assessing the strengths of hexagonal boron nitride in separation technology

This review highlights the advantages of incorporating hexagonal Boron Nitride (BN) into the current membrane-based architectures for water remediation over other well-explored 2D nanomaterials such as graphene, graphene oxide, molybdenum sulphide, MXenes. BN has an interlayer spacing of 3.3A⁰ which is similar to that of graphene, but smaller than that of the other 2D nanomaterials. BN is bioinert, and stable under harsh chemical and thermal conditions. When combined with thin film composite and mixed matrix membrane architectures, BN can help achieve high permeance, dye rejection, and desalination. Laminar membranes assembled by BN nanosheets do not swell uncontrollably in aqueous environments unlike graphene oxide. BN nanomaterials have a large specific surface area which implies more adsorption sites, and are inherently hydrophobic in nature, which means the adsorbent in its powder form can be easily separated from contaminated water. BN adsorbents can be regenerated by treating with chemicals or heating to high temperatures to remove the adsorbate, without damaging the BN, due to its thermal and chemical inertness. BN nanomaterials have the potential to circumvent the current shortcomings of membranes and adsorbents, while greatly enhancing the performance of membranes and adsorbents for water remediation.

Graphical Abstract