A novel dual-layer bicomponent electrospun nanofibrous membrane for desalination by direct contact membrane distillation

Abstract

In this study, a bicomponent nanofibrous composite membrane was fabricated by electrospinning and was tested for desalination by direct contact membrane distillation (DCMD). The nanofibrous membrane was composed of a dual-layered structure of poly(vinylidenefluoride-cohexafluoropropylene) (PH) nanofibers and polyacrylonitrile (PAN) microfibers. Morphological characterization showed slightly beaded cylindrical PH nanofibers with porosity of about 90%. The contact angles of PH and PAN nano/microfibers were 150 o and 100 o , respectively. The nanofibrous membranes were tested by DCMD and a high water flux of 45 and 30 Lm -2 h -1 was obtained for distilled water and 35 gL -1 NaCl solutions as feed, respectively using DL2 membrane (i.e., 25/75 PH/PAN thickness ratio). The present dual-layer membrane showed better flux performance compared to a commercial flat-sheet membrane. The results suggest the potential of the dual-layer nanofibrous membrane for DCMD applications.

Improving Nanofiber Membrane Characteristics and Membrane Distillation Performance of Heat-Pressed Membranes via Annealing Post-Treatment

“…Contact angle, which was generally used to indicate hydrophobicity of membrane surface, was measured by Theta Lite 100 (Attension) (Biolin Scientific, Paramus, NJ, USA) with sessile drop method [24,26]. Then 5~8 µL of water droplet was placed onto the membrane surface for analysis.…”

“…After the neat membrane was heat-pressed, the band at 840 cm −1 representing the β phase increased from 53% to 63.6%, while the band in terms of the α phase did not appear after the heat-press treatment. The increase in the transmittance of β phase bands indicated the increase in the crystallinity of the membrane as the amorphous phase of the PVDF was converted into the β phase due to the mechanical deformation, caused by the pressure applied on the membranes during heat-pressing [25,26]. Vineet et al found that annealing PVDF …”

Graphene/PVDF flat-sheet membrane for the treatment of RO brine from coal seam gas produced water by air gap membrane distillation

“…The driving force is the partial vapor pressure difference resulting from the thermal gradient between the hot feed and cool permeate streams [7,8]. Theoretically, it can reject 100% of the salts and non-volatile components at the feed.…”

“…The membrane porosity, defined as the volume of pores divided by the total volume of the membrane, was measured via a gravimetric method [7]. Membrane samples with equal sizes of 2 cm × 2 cm were immersed in ethanol (Scharlau).…”

Modification of Nanofiber Support Layer for Thin Film Composite Forward Osmosis Membranes via Layer-By-Layer Polyelectrolyte Deposition

“…Generally, high osmotic flux and low structural parameter values were achieved for nanofiber membranes, making it a suitable method for fabrication of FO membranes. Nanofiber-supported TFC membranes applied for water-based separation processes have been the subject of various studies in the past [20][21][22][23][24][25][26][27]. While nanofiber electrospinning is a practical and noncostly method in membrane fabrication, it is still somehow limited by the electrospinning condition optimization, selection of specific materials suited for particular applications, nanofiber post-treatment [25], nanofiber strength and stability [28], membrane swelling [29], and poor adhesion of the selective polyamide layer from the nanofiber support [20].…”