Hexagonal boron nitride incorporated polymer nanocomposites for water remediation

Abstract

The isolation of graphene in 2004 sparked a revolution in the study and applications of 2D nanomaterials in various disparate fields. Separation technology is no exception. 2D nanomaterials possess numerous desirable properties such as large specific surface area, high aspect ratio, nanometre level thickness and more, which make them suitable for separation processes such as membrane separation and sorbent-based oil-water separation. This thesis focuses on one such nanomaterial - hexagonal boron nitride (hBN, a 2D nanomaterial analogous to graphene), and the applications of hexagonal boron nitride nanosheets in polymer nanocomposites for water remediation. The first part of the thesis will focus on developing polymer nanocomposite water filtration membranes to achieve dye rejection and fouling resistance. Our process involved integrating functionalized hexagonal boron nitride nanosheets into a polyvinylidene fluoride and polydopamine interpenetrating network membrane through the non-solvent-induced phase separation route. The resulting membranes demonstrate high pure water flux, effective dye rejection over multiple cycles of operation when tested with anionic and cationic dyes, and high resistance to fouling on testing with bovine serum albumin as the model foulant. The second part of the thesis will focus on developing polymer nanocomposite foams incorporated with hBN nanosheets for oil-water separation. Separation of oil from oil-contaminated water is pertinent for cleaning up oil spills, leaks, and untreated wastewater effluents from various industries as the oil can damage marine ecosystems and have far-reaching, long-lasting repercussions. Selective oil sorption from oil-contaminated water can be achieved using polymer foams as sorbents. Herein, we prepared flexible polyurethane (PU) and polydimethylsiloxane (PDMS) foams, which were infused with hBN nanosheets through a facile template leaching process to study the oil sorption performance of the foams across various model oils. The selective removal of oil from oil-water stratified mixtures using these foams was tested under static and agitated conditions. These foams could retain their sorption capacity over multiple study cycles while maintaining their structural integrity. In conclusion, this thesis demonstrates the potential of hexagonal boron nitride nanomaterials and their polymer nanocomposites in enhancing the current polymer-based membrane and foam architectures for water remediation applications.