Abstract
There is a general drive to adopt highly porous and less tortuous supports for forward osmosis (FO) membranes to reduce internal concentration polarization (ICP), which regulates the osmotic water permeation. As an abundant waste material, eggshell membrane (ESM) has a highly porous and fibrous structure that meets the requirements for FO membrane substrates. In this study, a polyamide-based biocomposite FO membrane was fabricated by exploiting ESM as a membrane support. The polyamide layer was deposited by the interfacial polymerization technique and the composite membrane exhibited osmotically driven water flux. Further, biocomposite FO membranes were developed by surface coating with GO for stable formation of the polyamide layer. Finally, the osmotic water flux of the eggshell composite membrane with a low structural parameter (~138 µm) reached 46.19 L m−2 h−1 in FO mode using 2 M NaCl draw solution.
Highlights
Forward osmosis (FO), as a novel and emerging separation technique, has received attention for various applications from low-cost water purification [1] and renewable energy production [2] to protein enrichment [3]
Fabricated eggshell membrane (ESM)-GO composites were denoted by ESM-GO 0.1, 0.5, 1 following GO contents (1, 0.5, 1%) of solution used in spin coating
The pure water permeability of ESM was as high as 15,400 L m−2 h−1 bar−1, which is considerably higher than that of thin film composite (TFC) membrane supports fabricated by phase inversion [8]
Summary
Forward osmosis (FO), as a novel and emerging separation technique, has received attention for various applications from low-cost water purification [1] and renewable energy production [2] to protein enrichment [3]. Higher water transport can be achieved in the FO process by enhancing the water permeability of the selective layer and by structural enhancement of the support layer to reduce the ICP. ICP reduces the effective osmotic pressure applied to the selective layer, as the permeated water dilutes the draw solution (DS) in the support layer. The low structural parameter results weaker ICP and can be achieved by higher porosity, thinner thickness, and lower pore tortuosity. In previous studies on minimizing the ICP, structural parameter was reduced by optimizing the material composition [6,7] and incorporating nanoparticles [8,9,10,11] by the phase inversion method, and by employing a novel fabrication strategy using electrospinning [12,13,14]. SScchheemmaattiicc ooff ((aa)) ccoommppoossiittee mmeemmbbrraannee ffoorr FFOO aanndd ((bb)) ffaabbrriiccaattiioonn pprroocceessss
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