Porous hydrophobic-hydrophilic composite membranes for direct contact membrane distillation

Puranik, Aishwarya A.; Rodrigues, Lydia N.; Chau, John; Li, Lin; Sirkar, Kamalesh K.

doi:10.1016/j.memsci.2019.117225

Cited by 29 publications

(20 citation statements)

References 32 publications

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“…However, the leak rates are extremely low. By manipulating plasma conditions, the LEP value can be substantially increased as was observed earlier with flat membranes [34]. In Table 5, we provide an idea about the rate of salt leakage as measured by change in conductivity of the distillate at the LEP for PP based hollow fiber membranes.…”

Section: Resultsmentioning

confidence: 74%

“…The incoming distillate side cold water temperature varied from 22.8 °C to 29.4 °C (73 °F to 85 °F) depending upon the heat exchanger, room temperature and, more importantly, the inlet brine temperature and the membrane distillation rate. The DCMD experimental setup for flat membranes has been described in references [11,12,23,34]. A chlorinated polyvinyl chlroide (CPVC) based rectangular cell described in [23] with a membrane area of 0.0011 m 2 was used for the flat membranes.…”

Section: Methods and Proceduresmentioning

confidence: 99%

“…These flat membranes were used as substrates for plasma coating. A highly porous ultrathin hydrophobic coating of polyfluorosiloxane polymer was deposited on these membranes by vacuum-based plasma polymerization [34]. Puranik et al [34] have provided details of the plasma exposure variation between different samples of flat PVDF substrate membranes.…”

Section: Materials and Chemicalsmentioning

confidence: 99%

“…A highly porous ultrathin hydrophobic coating of polyfluorosiloxane polymer was deposited on these membranes by vacuum-based plasma polymerization [34]. Puranik et al [34] have provided details of the plasma exposure variation between different samples of flat PVDF substrate membranes. The fluorosiloxane polymers on flat films were deposited in a tubular batch reactor under reaction conditions similar to those used for the HFMs, except that the reaction times were slightly longer.…”

Section: Materials and Chemicalsmentioning

confidence: 99%

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Porous Hydrophobic–Hydrophilic Composite Hollow Fiber and Flat Membranes Prepared by Plasma Polymerization for Direct Contact Membrane Distillation

et al. 2021

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High water vapor flux at low brine temperatures without surface fouling is needed in membrane distillation-based desalination. Brine crossflow over surface-modified hydrophobic hollow fiber membranes (HFMs) yielded fouling-free operation with supersaturated solutions of scaling salts and their precipitates. Surface modification involved an ultrathin porous polyfluorosiloxane or polysiloxane coating deposited on the outside of porous polypropylene (PP) HFMs by plasma polymerization. The outside of hydrophilic MicroPES HFMs of polyethersulfone was also coated by an ultrathin coating of porous plasma-polymerized polyfluorosiloxane or polysiloxane rendering the surface hydrophobic. Direct contact membrane distillation-based desalination performances of these HFMs were determined and compared with porous PP-based HFMs. Salt concentrations of 1, 10, and 20 wt% were used. Leak rates were determined at low pressures. Surface and cross-sections of two kinds of coated HFMs were investigated by scanning electron microscopy. The HFMs based on water-wetted MicroPES substrate offered a very thin gas gap in the hydrophobic surface coating yielding a high flux of 26.4–27.6 kg/m2-h with 1 wt% feed brine at 70 °C. The fluxes of HFMs on porous PP substrates having a long vapor diffusion path were significantly lower. Coated HFM performances have been compared with flat hydrophilic membranes of polyvinylidene fluoride having a similar plasma-polymerized hydrophobic polyfluorosiloxane coating.

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Section: Resultsmentioning

confidence: 74%

Section: Methods and Proceduresmentioning

confidence: 99%

Section: Materials and Chemicalsmentioning

confidence: 99%

Section: Materials and Chemicalsmentioning

confidence: 99%

See 2 more Smart Citations

Porous Hydrophobic–Hydrophilic Composite Hollow Fiber and Flat Membranes Prepared by Plasma Polymerization for Direct Contact Membrane Distillation

et al. 2021

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“…A large number of studies have focused on making super-hydrophobic surfaces in order to increase wetting and scaling resistance [25]. While others have looked into applying hydrophilic characteristics to hydrophobic porous membranes or vice versa [26][27][28], which has the effect of drawing water molecules in the membrane pores. Although this tends to increase the degree of temperature polarization, which, in turn, theoretically, would have a negative effect on flux.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Flux Performance in PTFE Membranes for Direct Contact Membrane Distillation

et al. 2020

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This work focused on enhancing the flux on hydrophobic polymeric membranes aimed for direct contact membrane distillation desalination (DCMD) process without compromising salt rejection efficiency. Successful coating of commercial porous poly-tetrafluoroethylene membranes with poly(vinyl alcohol) (PVA) was achieved by solution dipping followed by a cross-linking step. The modified membranes were evaluated for their performance in DCMD, in terms of water flux and salt rejection. A series of different PVA concentration dipping solutions were used, and the results indicated that there was an optimum concentration after which the membranes became hydrophilic and unsuitable for use in membrane distillation. Best performing membranes were achieved under the specific experimental conditions, water flux 12.2 L·m-2·h-1 [LMH] with a salt rejection of 99.9%. Compared to the pristine membrane, the flux was enhanced by a factor of 2.7. The results seemed to indicate that introducing hydrophilic characteristics in a certain amount to a hydrophobic membrane could significantly enhance the membrane distillation (MD) performance without compromising salt rejection.

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Membrane Surface Modification by Electrospinning, Coating, and Plasma for Membrane Distillation Applications: A State‐of‐the‐Art Review

et al. 2021

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Membrane distillation (MD) is a thermally driven separation process where a hydrophobic and microporous membrane separates nonvolatile compounds. Because of its advantages, this process appears as an efficient way to recover water from industrial effluents. However, the commercial membranes used in the MD process still have operational troubles with complex industrial wastewater and against harsh operational conditions. Fouling, wetting, and low time of operation compromise the membrane function and make the total consolidation of MD technology difficult beyond the traditional application (desalination). Membrane modification can be key to mitigating these operational problems, allowing MD's expansion to complex separations. In this context, herein the main technologies to modify the membranes for MD applications of the last five years are comprehensively summarized. Three kinds of postfabrication modifications are focused on: electrospinning, coating, and plasma, including polymeric and ceramic membranes. A critical analysis of each technique is developed, discussing their potentialities and the properties achieved through them. This review enables the understanding of the operational problems of MD technology and leads to finding feasible alternatives to their mitigation. It also clarifies the evolution in membrane modification, discusses the development directions, and points out the future challenges of modifications.

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Porous hydrophobic-hydrophilic composite membranes for direct contact membrane distillation

Cited by 29 publications

References 32 publications

Porous Hydrophobic–Hydrophilic Composite Hollow Fiber and Flat Membranes Prepared by Plasma Polymerization for Direct Contact Membrane Distillation

Porous Hydrophobic–Hydrophilic Composite Hollow Fiber and Flat Membranes Prepared by Plasma Polymerization for Direct Contact Membrane Distillation

Enhancement of Flux Performance in PTFE Membranes for Direct Contact Membrane Distillation

Membrane Surface Modification by Electrospinning, Coating, and Plasma for Membrane Distillation Applications: A State‐of‐the‐Art Review

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