Evaluating the potential of superhydrophobic nanoporous alumina membranes for direct contact membrane distillation

Subramanian, N. Sankara; Qamar, Adnan; Alsaadi, Ahmad Salem; Gallo, Adair; Ridwan, Muhammad Ghifari; Lee, Jung-Gil; Pillai, Sreekiran; Arunachalam, Sankara; Anjum, Dalaver H.; Sharipov, Felix; Ghaffour, Noreddine

doi:10.1016/j.jcis.2018.08.054

Cited by 57 publications

(28 citation statements)

References 70 publications

(67 reference statements)

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“…The thermal conductivity of the membrane surface must be as low as possible [51] Fouling resistance The polymeric membrane can be coated with fouling resistant materials to ensure high permeate flux [52] Thermal stability The MD polymeric membrane must show high thermal stability up to 80 • C. [53] Chemical resistance The MD membranes must exhibit good chemical resistance because they may come in contact with acids and bases [54] 4.…”

Section: Layersmentioning

confidence: 99%

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

2019

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Recently, membrane distillation (MD) has emerged as a versatile technology for treating saline water and industrial wastewater. However, the long-term use of MD wets the polymeric membrane and prevents the membrane from working as a semi-permeable barrier. Currently, the concept of antiwetting interfaces has been utilized for reducing the wetting issue of MD. This review paper discusses the fundamentals and roles of surface energy and hierarchical structures on both the hydrophobic characteristics and wetting tolerance of MD membranes. Designing stable antiwetting interfaces with their basic working principle is illustrated with high scientific discussions. The capability of antiwetting surfaces in terms of their self-cleaning properties has also been demonstrated. This comprehensive review paper can be utilized as the fundamental basis for developing antiwetting surfaces to minimize fouling, as well as the wetting issue in the MD process.

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Section: Layersmentioning

confidence: 99%

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

2019

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“…Also, it has been demonstrated that intrinsically wetting materials with reentrant cavities can entrap air upon immersion in wetting liquids, and thus, achieve the function of omniphobic surfaces. Based on this body of work 27,28,29,30 and previous experience with DCMD 31 , we decided to create membranes that have pores with reentrant inlets and outlets. It was envisioned that such a membrane could entrap air upon immersion in wetting liquids due to its microtexture, giving rise to the idea of GEMs.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the experimental set-up with silica-GEMs suffered from what is known as temperature polarization, wherein the hot side loses heat to the cold side, lowering the flux31 .…”

mentioning

confidence: 99%

Proof-of-Concept for Gas-Entrapping Membranes Derived from Water-Loving SiO<sub>2</sub>/Si/SiO<sub>2</sub> Wafers for Green Desalination

Das

Arunachalam

Ahmad

et al. 2020

JoVE

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Desalination through direct contact membrane distillation (DCMD) exploits water-repellent membranes to robustly separate counterflowing streams of hot and salty seawater from cold and pure water, thus allowing only pure water vapor to pass through. To achieve this feat, commercial DCMD membranes are derived from or coated with water-repellent perfluorocarbons such as polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF). However, the use of perfluorocarbons is limiting due to their high cost, non-biodegradability, and vulnerability to harsh operational conditions. Unveiled here is a new class of membranes referred to as gas-entrapping membranes (GEMs) that can robustly entrap air upon immersion in water. GEMs achieve this function by their microstructure rather than their chemical make-up. This work demonstrates a proof-ofconcept for GEMs using intrinsically wetting SiO 2 /Si/SiO 2 wafers as the model system; the contact angle of water on SiO 2 is θ o ≈ 40°. Silica-GEMs had 300 μm-long cylindrical pores whose diameters at the (2 μm-long) inlet and outlet regions were significantly smaller; this geometrically discontinuous structure, with 90° turns at the inlets and outlets, is known as the "reentrant microtexture". The microfabrication protocol for silica-GEMs entails designing, photolithography, chrome sputtering, and isotropic and anisotropic etching. Despite the water loving nature of silica, water does not intrude silica-GEMs on submersion. In fact, they robustly entrap air underwater and keep it intact even after six weeks (>10 6 seconds).On the other hand, silica membranes with simple cylindrical pores spontaneously imbibe water (< 1 s). These findings highlight the potential of the GEMs architecture for separation processes. While the choice of SiO 2 /Si/SiO 2 wafers for GEMs is limited to demonstrating the proof-of-concept, it is expected that the protocols and concepts presented here will advance the rational design of scalable GEMs using inexpensive common materials for desalination and beyond.

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“…It is a thermally-driven separation process, in which only vapors transfer through a microporous hydrophobic membrane [3,[5][6][7]. MD membranes are made of hydrophobic polymeric materials such as polyvinylidene fluoride (PVDF), polypropylene, and polytetrafluorethylene (PTFE) [4,[8][9][10][11][12]. MD can treat high salinity feed solutions that RO cannot, including RO brine and wastewaters from shale gas industry [6,7,13,14].…”

Section: Introductionmentioning

confidence: 99%

“…Membrane wetting is generally observed during the long-term operation of the MD process [24]. Factors affecting membrane wetting include transmembrane pressure, capillary condensation, scale deposition (inorganic fouling), organic fouling, surfactants, and membrane degradation [8,19,23,25]. The membrane wetting reduces the quality of product water and changes the flux through the membrane [21,26].…”

Section: Introductionmentioning

confidence: 99%

Fouling-induced wetting of membranes in membrane distillation (MD) systems

Kim¹,

Cho²,

Choi³

et al. 2019

Desalination and Water Treatment

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One of the challenges of membrane distillation (MD) technology is the wetting of the membranes. However, relatively little information is available on membrane wetting induced by fouling in MD process. Accordingly, this study examines the MD membrane wetting caused by fouling under various conditions. Various feed solutions containing NaCl, CaSO 4 , humic acid, alginate, and SDS were compared using polyvinylidene fluoride and polytetrafluoroethylene membranes in a series of MD experiments. Scanning electron microscope (SEM), liquid entry pressure and dynamic contact angle were used to interpret the results from the MD wetting experiments. Results showed that wetting was induced by severe fouling in the cases of 200,000 mg L-1 NaCl solution and 200,000 mg L-1 NaCl and 2,000 mg L-1 CaSO 4 solution. The organic matters (50 mg L-1 humic acid and 50 mg L-1 alginate) did not cause neither fouling nor wetting by themselves. On the other hand, the addition of 50 mg L-1 SDS accelerated wetting. Based on these experimental results, the wetting potentials for various combinations of foulants are presented.

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Evaluating the potential of superhydrophobic nanoporous alumina membranes for direct contact membrane distillation

Cited by 57 publications

References 70 publications

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

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

Proof-of-Concept for Gas-Entrapping Membranes Derived from Water-Loving SiO<sub>2</sub>/Si/SiO<sub>2</sub> Wafers for Green Desalination

Fouling-induced wetting of membranes in membrane distillation (MD) systems

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