Development of A Novel Corrugated Polyvinylidene difluoride Membrane via Improved Imprinting Technique for Membrane Distillation

Abstract

Membrane distillation (MD) is an attractive technology for desalination, mainly because its performance that is almost independent of feed solute concentration as opposed to the reverse osmosis process. However, its widespread application is still limited by the low water flux, low wetting resistance and high scaling vulnerability. This study focuses on addressing those limitations by developing a novel corrugated polyvinylidene difluoride (PVDF) membrane via an improved imprinting technique for MD. Corrugations on the membrane surface are designed to offer an effective surface area and at the same time act as a turbulence promoter to induce hydrodynamic by reducing temperature polarization. Results show that imprinting of spacer could help to induce surface corrugation. Pore defect could be minimized by employing a dual layer membrane. In short term run experiment, the corrugated membrane shows a flux of 23.1 Lm−2h−1 and a salt rejection of >99%, higher than the referenced flat membrane (flux of 18.0 Lm−2h−1 and similar rejection). The flux advantage can be ascribed by the larger effective surface area of the membrane coupled with larger pore size. The flux advantage could be maintained in the long-term operation of 50 h at a value of 8.6 Lm−2h−1. However, the flux performance slightly deteriorates over time mainly due to wetting and scaling. An attempt to overcome this limitation should be a focus of the future study, especially by exploring the role of cross-flow velocity in combination with the corrugated surface in inducing local mixing and enhancing system performance.

Improving Performance of Electrospun Nylon 6,6 Nanofiber Membrane for Produced Water Filtration via Solvent Vapor Treatment

“…Electrospun nanofiber mats have huge surface area to volume ratio, high porosity, great water permeability and flexibility [17,18]. These attributes enable electrospun nanofibers to demonstrate their functionality and is widely applied in air filtration [19,20], water treatment [21,22], desalination [23,24], and adsorption [25,26].…”

Review on Blueprint of Designing Anti-Wetting Polymeric Membrane Surfaces for Enhanced Membrane Distillation Performance

“…In the Cassie-Baxter state, air trapped in the grooves between surface features forms a composite (air/solid) hydrophobic surface, leading to a larger contact angle compared to the contact angle θ with a flat surface. In contrast, in the Wenzel state, the liquid on the surface enters the grooves, leading to higher surface wettability, due to the increase in contact area [7,39,40]. Therefore, it can be concluded from the Wenzel equation that surface roughness amplifies the wettability of the original surface.…”

“…In addition to that, RO does not need any other chemicals as it separates dissolved substances from the feed stream. Apart from these prominent advantages, RO has several limitations as compared to MD process, which are as follows [5][6][7]: (1) Membrane fouling propensity is higher in RO process; whereas, lower membrane fouling occurs due to the reduced chemical interaction between membrane and process solution. (2) RO needs high operating pressure compared to MD process.…”

Patterned Membrane in an Energy-Efficient Tilted Panel Filtration System for Fouling Control in Activated Sludge Filtration

“…It shows that introducing an imprinting step to form surface corrugation leads to an increase in contact angle (99 • ± 2.39 • to 106 • ± 3.70 • ), pore size (0.5 ± 0.02 to 0.78 ± 0.10 µm; as shown in Figure 2), porosity (41% ± 6.0% to 65% ± 8.1%), thickness (228 ± 3.21 to 269 ± 5.32 µm), and CWP (550 ± 3.02 to 642 ± 0.32 L/m 2 h bar). The underlying mechanisms for formation of such structure have been detailed elsewhere [30]. This study focuses only on the mutual effect of surface corrugation and a tilted panel in enhancing hydraulic performance [29].…”

“…The pattern on top of the membrane surface introduces periodic resistance to the axial flow, which promotes mixing in the boundary layer created at the membrane surface due to the formation of fluid eddies, which increase the turbulence, friction, and pressure drop [27,28]. This would be expected to reduce the membrane fouling and improve the hydraulic performance [29,30]. Previous studies focused on exploiting a single approach (i.e., tilting the panel, forming surface corrugation, etc.)…”