Microporous carbon from fullerene impregnated porous aromatic frameworks for improving the desalination performance of thin film composite forward osmosis membranes

Abstract

Porous additives and polymer modifications are becoming increasingly common routes to address some of the current challenges faced by membrane technologies. Here, using carbonization and pre-impregnation of fullerene to enhance the performance of a porous aromatic framework, we have developed a novel hydrophobic porous membrane additive (C₆₀@PAF₉₀₀) for enhancing the performance of forward osmosis (FO) water purification membranes. We examined the influence of C₆₀@PAF₉₀₀ loading on the polyamide (PA) layer in the fabrication of novel thin film nanocomposite (TFN) FO membranes and subsequently investigated the desalination performance of the resulting TFN FO membranes. The results showed that the addition of nanoporous C₆₀@PAF₉₀₀ greatly enhanced the water flux and water permeability of TFN FO membranes. Using 2 mol L⁻¹ NaCl as the draw solution and 10 mmol L⁻¹ NaCl as the feed solution, adding 0.01 w/v% C₆₀@PAF₉₀₀ into the FO membrane increased the water flux from 7.4 LMH to 12.4 LMH in the ALFS mode (active layer facing the feed solution) and from 12.6 LMH to 21.3 LMH in the ALDS mode (active layer facing the draw solution). To understand these results, the effect of C₆₀@PAF₉₀₀ on the surface morphology and chemistry of TFN FO was also investigated. Compared to the pristine FO membranes, the TFN FO membranes possessed a less dense crosslinked network due to the influence of C₆₀@PAF₉₀₀ on the interfacial polymerization process, and the interfacial repulsion between C₆₀@PAF₉₀₀ and polyamide. Together, this study provides an insight into the performance and potential effects of C₆₀@PAF₉₀₀ on advanced TFN FO membranes.