Enhancement of vapor flux and salt rejection efficiency induced by low cost-high purity MWCNTs in upscaled PVDF and PVDF-HFP hollow fiber modules for membrane distillation

A low-cost poly(ethyleneimine)–cobalt (PEI–Co) complex solution with high O2 absorption capacity (as high as 1.5 L O2 (STP)/L solution) was developed and used in a bio-mimetic system to produce high-purity O2 from air.

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

Membranes ◽

10.3390/membranes11020120 ◽

2021 ◽

Vol 11 (2) ◽

pp. 120 ◽

Cited By ~ 1

Author(s):

Ashok K. Sharma ◽

Adam Juelfs ◽

Connor Colling ◽

Saket Sharma ◽

Stephen P. Conover ◽

...

Keyword(s):

Hollow Fiber ◽

Direct Contact ◽

Plasma Polymerization ◽

Polyvinylidene Fluoride ◽

Hydrophobic Surface ◽

Diffusion Path ◽

High Water ◽

Membrane Distillation ◽

Vapor Flux ◽

Direct Contact Membrane Distillation

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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Seawater Desalination by Modified Membrane Distillation: Effect of Hydrophilic Surface Modifying Macromolecules Addition into PVDF Hollow Fiber Membrane

Membranes ◽

10.3390/membranes11120924 ◽

2021 ◽

Vol 11 (12) ◽

pp. 924

Author(s):

Mochammad Purwanto ◽

Nindita Cahya Kusuma ◽

Ma’rup Ali Sudrajat ◽

Juhana Jaafar ◽

Atikah Mohd Nasir ◽

...

Keyword(s):

Hollow Fiber ◽

Polyvinylidene Fluoride ◽

Hollow Fiber Membrane ◽

Membrane Distillation ◽

Hydrophilic Surface ◽

Hollow Fiber Membranes ◽

Permeate Flux ◽

Seawater Desalination ◽

Salt Rejection ◽

Fiber Membranes

Hollow fiber membranes of polyvinylidene fluoride (PVDF) were prepared by incorporating varying concentrations of hydrophilic surface-modifying macromolecules (LSMM) and a constant amount of polyethylene glycol (PEG) additives. The membranes were fabricated by the dry-wet spinning technique. The prepared hollow fiber membranes were dip-coated by hydrophobic surface-modifying macromolecules (BSMM) as the final step fabrication. The additives combination is aimed to produce hollow fiber membranes with high flux permeation and high salt rejection in the matter of seawater desalination application. This study prepares hollow fiber membranes from the formulation of 18 wt. % of PVDF mixed with 5 wt. % of PEG and 3, 4, and 5 wt. % of LSMM. The membranes are then dip-coated with 1 wt. % of BSMM. The effect of LSMM loading on hydrophobicity, morphology, average pore size, surface porosity, and membrane performance is investigated. Coating modification on LSMM membranes showed an increase in contact angle up to 57% of pure, unmodified PVDF/PEG membranes, which made the fabricated membranes at least passable when hydrophobicity was considered as one main characteristic. Furthermore, The PVDF/PEG/4LSMM-BSMM membrane exhibits 161 °C of melting point as characterized by the DSC. This value indicates an improvement of thermal behavior shows so as the fabricated membranes are desirable for membrane distillation operation conditions range. Based on the results, it can be concluded that PVDF/PEG membranes with the use of LSMM and BSMM combination could enhance the permeate flux up to 81.32 kg·m−2·h−1 at the maximum, with stable salt rejection around 99.9%, and these are found to be potential for seawater desalination application.

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Concentration of 1,3-dimethyl-2-imidazolidinone in Aqueous Solutions by Sweeping Gas Membrane Distillation: From Bench to Industrial Scale

Membranes ◽

10.3390/membranes9120158 ◽

2019 ◽

Vol 9 (12) ◽

pp. 158 ◽

Cited By ~ 2

Author(s):

Ricardo Abejón ◽

Hafedh Saidani ◽

André Deratani ◽

Christophe Richard ◽

José Sánchez-Marcano

Keyword(s):

Aqueous Solutions ◽

Hollow Fiber ◽

Water Flux ◽

Membrane Distillation ◽

Hollow Fiber Membranes ◽

Membrane Area ◽

Vapor Flux ◽

Aqueous Solvent ◽

Fiber Membranes ◽

Sweeping Gas

Sweeping gas membrane distillation (SGMD) is a useful option for dehydration of aqueous solvent solutions. This study investigated the technical viability and competitiveness of the use of SGMD to concentrate aqueous solutions of 1,3-dimethyl-2-imidazolidinone (DMI), a dipolar aprotic solvent. The concentration from 30% to 50% of aqueous DMI solutions was attained in a bench installation with Liqui-Cel SuperPhobic® hollow-fiber membranes. The selected membranes resulted in low vapor flux (below 0.15 kg/h·m2) but were also effective for minimization of DMI losses through the membranes, since these losses were maintained below 1% of the evaporated water flux. This fact implied that more than 99.2% of the DMI fed to the system was recovered in the produced concentrated solution. The influence of temperature and flowrate of the feed and sweep gas streams was analyzed to develop simple empirical models that represented the vapor permeation and DMI losses through the hollow-fiber membranes. The proposed models were successfully applied to the scaling-up of the process with a preliminary multi-objective optimization of the process based on the simultaneous minimization of the total membrane area, the heat requirement and the air consumption. Maximal feed temperature and air flowrate (and the corresponding high operation costs) were optimal conditions, but the excessive membrane area required implied an uncompetitive alternative for direct industrial application.

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Electrospun Nanostructured Membrane Engineering Using Reverse Osmosis Recycled Modules: Membrane Distillation Application

Nanomaterials ◽

10.3390/nano11061601 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1601

Author(s):

Jorge Contreras-Martínez ◽

Carmen García-Payo ◽

Mohamed Khayet

Keyword(s):

Reverse Osmosis ◽

Polyvinylidene Fluoride ◽

Membrane Distillation ◽

Permeate Flux ◽

Electrospinning Technique ◽

Salt Rejection ◽

Rejection Factor ◽

Nanofibrous Membranes ◽

Membrane Engineering ◽

Desalination Plants

As a consequence of the increase in reverse osmosis (RO) desalination plants, the number of discarded RO modules for 2020 was estimated to be 14.8 million annually. Currently, these discarded modules are disposed of in nearby landfills generating high volumes of waste. In order to extend their useful life, in this research study, we propose recycling and reusing the internal components of the discarded RO modules, membranes and spacers, in membrane engineering for membrane distillation (MD) technology. After passive cleaning with a sodium hypochlorite aqueous solution, these recycled components were reused as support for polyvinylidene fluoride nanofibrous membranes prepared by electrospinning technique. The prepared membranes were characterized by different techniques and, finally, tested in desalination of high saline solutions (brines) by direct contact membrane distillation (DCMD). The effect of the electrospinning time, which is the same as the thickness of the nanofibrous layer, was studied in order to optimize the permeate flux together with the salt rejection factor and to obtain robust membranes with stable DCMD desalination performance. When the recycled RO membrane or the permeate spacer were used as supports with 60 min electrospinning time, good permeate fluxes were achieved, 43.2 and 18.1 kg m−2 h−1, respectively; with very high salt rejection factors, greater than 99.99%. These results are reasonably competitive compared to other supported and unsupported MD nanofibrous membranes. In contrast, when using the feed spacer as support, inhomogeneous structures were observed on the electrospun nanofibrous layer due to the special characteristics of this spacer resulting in low salt rejection factors and mechanical properties of the electrospun nanofibrous membrane.

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Development of mass and heat transfer coupled model of hollow fiber membrane for salt recovery from brine via osmotic membrane distillation

Environmental Sciences Europe ◽

10.1186/s12302-021-00520-z ◽

2021 ◽

Vol 33 (1) ◽

Author(s):

Sher Ahmad ◽

Gabriela Vollet Marson ◽

Waheed Ur Rehman ◽

Mohammad Younas ◽

Sarah Farrukh ◽

...

Keyword(s):

Mass Transfer ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Heat And Mass Transfer ◽

Hollow Fiber ◽

Hollow Fiber Membrane ◽

Membrane Distillation ◽

Fiber Membrane ◽

Salt Recovery ◽

Osmotic Solution

Abstract Background In this research work, a coupled heat and mass transfer model was developed for salt recovery from concentrated brine water through an osmotic membrane distillation (OMD) process in a hollow fiber membrane contactor (HFMC).The model was built based on the resistance-in-series concept for water transport across the hydrophobic membrane. The model was adopted to incorporate the effects of polarization layers such as temperature and concentration polarization, as well as viscosity changes during concentration. Results The modeling equations were numerically simulated in MATLAB® and were successfully validated with experimental data from literature with a deviation within the range of 1–5%. The model was then applied to study the effects of key process parameters like feed concentrations, osmotic solution concentration, feed, and osmotic solution flow rates and feed temperature on the overall heat and mass transfer coefficient as well as on water transport flux to improve the process efficiency. The mass balance modeling was applied to calculate the membrane area based on the simulated mass transfer coefficient. Finally, a scale-up for the MD process for salt recovery on an industrial scale was proposed. Conclusions This study highlights the effect of key parameters for salt recovery from wastewater using the membrane distillation process. Further, the applicability of the OMD process for salt recovery on large scale was investigated. Sensitivity analysis was performed to identify the key parameters. From the results of this study, it is concluded that the OMD process can be promising in salt recovery from wastewater.

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