Wetting criteria for the applicability of membrane distillation

Franken, A.C.M.; Nolten, J.A.M.; Mulder, M.H.V.; Bargeman, D.; Smolders, C.A.

doi:10.1016/s0376-7388(00)80288-4

Cited by 383 publications

(190 citation statements)

References 10 publications

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“…The partial wetting phenomenon can be explained by the distribution of liquid entry pressures due to heterogeneous pore size distributions. 17 As the surface tension was reduced due to increasing SDS concentration, some larger pores became flooded by the SDS solution because their liquid entry pressures were reduced to levels lower than the hydraulic pressure in the feed channel. We note that our experimental observation is only qualitatively meaningful, as wetting of the PTFE membrane in real-world applications should depend not Photographs of the wetting behavior for both membranes are also given underneath the bar chart.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Omniphobic Membrane for Robust Membrane Distillation

Lin

Nejati

Boo

et al. 2014

Environ. Sci. Technol. Lett.

309

184

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In this work, we fabricate an omniphobic microporous membrane for membrane distillation (MD) by modifying a hydrophilic glass fiber membrane with silica nanoparticles followed by surface fluorination and polymer coating. The modified glass fiber membrane exhibits an antiwetting property not only against water but also against low surface tension organic solvents that easily wet a hydrophobic polytetrafluoroethylene (PTFE) membrane that is commonly used in MD applications. By comparing the performance of the PTFE and omniphobic membranes in direct contact MD experiments in the presence of a surfactant (sodium dodecyl sulfate, SDS), we show that SDS wets the hydrophobic PTFE membrane but not the omniphobic membrane. Our results suggest that omniphobic membranes are critical for MD applications with feed waters containing surface active species, such as oil and gas produced water, to prevent membrane pore wetting. ■ INTRODUCTIONMembrane distillation (MD) is a thermal separation process using a microporous hydrophobic membrane. 1−3 MD can operate at relatively low temperatures and is thus able to tap into the vast amount of low-grade waste heat. 4−6 MD is also advantageous over pressure-driven membrane processes, such as reverse osmosis (RO) or nanofiltration, as its low operating pressure reduces the capital cost due to the absence of expensive components, such as high pressure pumps and vessels, as well as pressure exchangers. Recently, MD has been proposed as a low-temperature thermal separation component for hybrid membrane processes coupled with forward osmosis for simultaneous wastewater reuse and mineral recovery 7,8 and with pressure retarded osmosis for harvesting low-grade waste heat. 9 Although MD, as any thermal separation process, is inherently less energy efficient than RO, 10,11 there exist scenarios in which MD may be preferred. For example, if an abundant amount of waste heat or solar thermal energy is readily available, MD can be employed to utilize such low-grade heat to considerably reduce the energy cost and carbon footprint for desalination compared to RO powered by conventional energy sources. 12−14 MD can also be used to desalinate high salinity brines, such as shale gas wastewater, as the osmotic pressure of such brines is far beyond the allowable pressure in RO operations. 15 In addition, MD can be employed for small-scale desalination in remote regions for which RO is not an option due to its dependence on grid power and costly high-pressure components that are not readily adaptable for small-scale systems.In MD desalination, a hydrophobic membrane is employed to create a vapor gap that separates a salty feed solution and the desalted permeate solution. 16 It is critically important that the membrane pores are not wetted by the feed solution as liquid flooding of the pores destroys the vapor gap and undermines the function of the membrane as a selective barrier for salt passage. 1,17,18 Preventing pore wetting is particularly challenging in desalinating shale gas wastewater or ot...

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Section: ■ Results and Discussionmentioning

confidence: 99%

Omniphobic Membrane for Robust Membrane Distillation

Lin

Nejati

Boo

et al. 2014

Environ. Sci. Technol. Lett.

309

184

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“…They are generally the most common technique for scale control because of low costs, and usually require dosing of less than 10 ppm [133]. However, antiscalants molecules, typically organic, often reduce the surface tension of the water, which can promote membrane wetting [134].…”

Section: Use Of Antiscalantsmentioning

confidence: 99%

Scaling and fouling in membrane distillation for desalination applications: A review

et al. 2015

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“…• In the presence of high organic content or surfactant in the feed, which can lower the surface tension of feed solution and/or reduce the hydrophobicity of the membrane via adsorption and lead to membrane wetting [77].…”

Section: Membrane Fouling and Wettingmentioning

confidence: 99%

Advances in Membrane Distillation for Water Desalination and Purification Applications

Camacho

Dumée

Zhang

et al. 2013

Water

642

342

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Membrane distillation is a process that utilizes differences in vapor pressure to permeate water through a macro-porous membrane and reject other non-volatile constituents present in the influent water. This review considers the fundamental heat and mass transfer processes in membrane distillation, recent advances in membrane technology, module configurations, and the applications and economics of membrane distillation, and identifies areas that may lead to technological improvements in membrane distillation as well as the application characteristics required for commercial deployment. Keywordsa function of temperature, vapor pressure, and of the gas molecular mass K 0 membrane characteristic defined by Equation (9) Kn Knudsen number K(T) a function of temperature and molecular weight of the gas l mean free path of the molecules l m distance between parallel spacer fibres (m) LEP Limit Entry Pressure (kPa) M molecular mass (g/mol) M w molecular weights of water (g/mol) M a molecular weights of air (g/mol) n number of CNTs per unit cross section in bucky-paper P pressure in the air gap (kPa) half time to reach the maximum intensity-laser flash technique (s) t proportion of conductive heat (balance due to evaporative heat) loss through the membrane T mean temperature in the pores (K)

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Wetting criteria for the applicability of membrane distillation

Cited by 383 publications

References 10 publications

Omniphobic Membrane for Robust Membrane Distillation

Omniphobic Membrane for Robust Membrane Distillation

Scaling and fouling in membrane distillation for desalination applications: A review

Advances in Membrane Distillation for Water Desalination and Purification Applications

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