Nanomaterials for Advanced Membrane Filtration Technologies

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Environmental Nanoscience and Nanotechnology".

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 14679

Special Issue Editor


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Guest Editor
Center for Membrane Technology, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg Øst, Denmark
Interests: nanofiltration; ultrafiltration; membrane distillation; advanced oxidation processes; sol–gel synthesis; graphene oxide; photocatalytic membranes; water detoxification

Special Issue Information

Dear Colleagues,

 The most recent developments in the field of nanomaterials and nanotechnologies have been enabling the design of new generations of artificial membranes with novel functions and enhanced molecular separation properties for water detoxification and as separation devices in biorefineries. Indeed, nanoparticles with a defined size and porosity, nanofibers, nanotubes, and 2D graphene-based materials can be used as building blocks for the fabrication of innovative membrane systems, which can combine high selectivity with high permeation rates (e.g., of water molecules) or which can have new functions, such as the ability to generate reactive oxygen species. On the other hand, big challenges for these materials are their deposition as defect-free thin layers over porous substrates and their durability under cross-flow conditions. Moreover, if released in the environment, some of these nanomaterials might cause concern for their toxicity. Therefore, notwithstanding their promising properties, many of these nanomaterials still require basic research and technical development before application in commercial membranes.  

The present Special Issue will focus on the most recent advances in nanomaterials for molecular separation membranes. Investigators are here invited to submit original research articles, letters, and critical reviews, on novel membrane devices or novel nanomaterials which have interesting properties from the perspective of membrane design (e.g., pore structure, self-cleaning properties, fast water transport). Works with no filtration experiments will be also considered for publication in this Special Issue, but only if they include a clear explanation of the advances that the nanomaterial can bring when applied to a membrane filtration system.

Dr. Vittorio Boffa
Guest Editor

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Keywords

  • Water purification
  • Desalination
  • Gas separation
  • Pervaporation
  • Nanofiltration
  • Ultrafiltration
  • Membrane distillation
  • Anti-fouling coatings
  • Self-cleaning membranes
  • Advanced oxidation-integrated membranes

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Published Papers (5 papers)

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Research

14 pages, 4658 KiB  
Article
Tuning Porosity of Reduced Graphene Oxide Membrane Materials by Alkali Activation
by Yang Shen, Luca Maurizi, Giuliana Magnacca, Vittorio Boffa and Yuanzheng Yue
Nanomaterials 2020, 10(11), 2093; https://doi.org/10.3390/nano10112093 - 22 Oct 2020
Cited by 17 | Viewed by 2925
Abstract
The alkali-activation method allows for obtaining highly porous carbon materials. In this study, we explored the effect of activation temperature and potassium hydroxide concentration on the pore structure of reduced graphene oxide (rGO), as potential membrane material. Above 700 °C, potassium species react [...] Read more.
The alkali-activation method allows for obtaining highly porous carbon materials. In this study, we explored the effect of activation temperature and potassium hydroxide concentration on the pore structure of reduced graphene oxide (rGO), as potential membrane material. Above 700 °C, potassium species react with the carbon plane of rGO to form nanopores. This activation process is deeply studied through DSC measurements and isothermal gravimetric analysis. The porosity of the formed materials consists of both micro- and mesopores, with most of the pores having a size smaller than 10 nm. The specific surface area and pore volume increase with increasing the potassium hydroxide/graphene oxide weight ratio (KOH/GO) up to 7 (897 m2∙g−1 and 0.97 cm3∙g−1, respectively). However, for a synthesis mixture with KOH/GO of 10, the specific surface area of the produced material drops to 255 m2∙g−1. The film-forming ability of the porous reduced graphene oxide (PRGO) was tested by drop-casting on porous silicon carbide substrates. In this case, continuous PRGO films were obtained only from dispersions with 5 g∙L−1 GO loading and KOH/GO ≤3. Such films can still have high specific surface area and pore volume (up to 528 m2∙g−1 and 0.53 cm3∙g−1) and main pore volume <10 nm. Hence, they can potentially be applied as membrane devices, but their scalability and their adhesion on the substrate under realistic filtration conditions still remain challenges. Full article
(This article belongs to the Special Issue Nanomaterials for Advanced Membrane Filtration Technologies)
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12 pages, 3660 KiB  
Article
Desalination of Groundwater from a Well in Puglia Region (Italy) by Al2O3-Doped Silica and Polymeric Nanofiltration Membranes
by Xianzheng Ma, Cejna Anna Quist-Jensen, Aamer Ali and Vittorio Boffa
Nanomaterials 2020, 10(9), 1738; https://doi.org/10.3390/nano10091738 - 1 Sep 2020
Cited by 8 | Viewed by 2111
Abstract
Some of the groundwater aquifers in the Puglia Region, Italy, suffer from high salinity and potential micropollutant contamination due to seawater infiltration and chemical discharge. The objective of this study is twofold: to evaluate the performance of the recently reported alumina-doped silica nanofiltration [...] Read more.
Some of the groundwater aquifers in the Puglia Region, Italy, suffer from high salinity and potential micropollutant contamination due to seawater infiltration and chemical discharge. The objective of this study is twofold: to evaluate the performance of the recently reported alumina-doped silica nanofiltration membranes for water potabilization, and to provide a possible solution to improve the groundwater quality in the Puglia Region while maintaining a low energy-footprint. Two lab-made alumina-doped silica membranes with different pore structures, namely S/O = 0.5 and S/O = 2, were tested with real groundwater samples and their performances were compared with those of a commercial polymeric membrane (Dow NF90). Moreover, groundwater samples were sparked with acetamiprid, imidacloprid, and thiacloprid to test the membrane performance in the presence of potential contamination by pesticides. At a trans-membrane pressure of 5 bar, NF90 could reduce the groundwater conductivity from 4.6 to around 1.3 mS·cm−1 and reject 56–85% of the model pesticides, with a permeate flux of 14.2 L·m−2·h−1. The two inorganic membranes S/O = 2 and S/O = 0.5 reduced the permeate conductivity to 3.8 and 2.4 mS·cm−1, respectively. The specific energy consumption for all three membranes was below 0.2 kWh·m−3 which indicates that the potabilization of this groundwater by nanofiltration is commercially feasible. Full article
(This article belongs to the Special Issue Nanomaterials for Advanced Membrane Filtration Technologies)
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12 pages, 1701 KiB  
Article
Effect of Temperature and Branched Crosslinkers on Supported Graphene Oxide Pervaporation Membranes for Ethanol Dehydration
by Azeem Bo Strunck, Anil Suri and Vittorio Boffa
Nanomaterials 2020, 10(8), 1571; https://doi.org/10.3390/nano10081571 - 10 Aug 2020
Cited by 5 | Viewed by 2418
Abstract
We describe the performance of graphene oxide (GO) membranes stabilized by crosslinkers and supported on polyethersulfone films in the dehydration of ethanol in a continuous cross-flow pervaporation set-up. We used two crosslinker species with branched structures (humic acid-like substances derived from urban waste [...] Read more.
We describe the performance of graphene oxide (GO) membranes stabilized by crosslinkers and supported on polyethersulfone films in the dehydration of ethanol in a continuous cross-flow pervaporation set-up. We used two crosslinker species with branched structures (humic acid-like substances derived from urban waste and a synthetic hyperbranched polyol). The supported crosslinked GO films were prepared by rod coating on a polyethersulfone ultrafiltration membrane. Pervaporation experiments were carried out at temperatures of 40, 50, 60 and 70 °C. When the feed comprised pure water and ethanol, a much higher flux of water than ethanol was observed at all temperatures through GO films stabilized by the two crosslinkers (humic acid, GO-HAL, and the synthetic hyperbranched polyol, GO-HBPO), indicating the separation ability of these crosslinked membranes. For feed mixtures of water and ethanol, the GO-HAL and GO-HBPO membranes showed good separation performances by producing permeates with a significantly higher water content than the feed at all temperatures. Full article
(This article belongs to the Special Issue Nanomaterials for Advanced Membrane Filtration Technologies)
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15 pages, 4231 KiB  
Article
Selective Recovery of Europium and Yttrium Ions with Cyanex 272-Polyacrylonitrile Nanofibers
by Diego Morillo Martín, Leslie Diaz Jalaff, Maria A. García and Mirko Faccini
Nanomaterials 2019, 9(12), 1648; https://doi.org/10.3390/nano9121648 - 20 Nov 2019
Cited by 13 | Viewed by 3758
Abstract
Rare earth elements (REEs), which include lanthanides as yttrium and europium became crucial in the last decade in many sectors like automotive, energy, and defense. They contribute to the increment efficiency and performance of different products. In this paper nanofiber membranes have been [...] Read more.
Rare earth elements (REEs), which include lanthanides as yttrium and europium became crucial in the last decade in many sectors like automotive, energy, and defense. They contribute to the increment efficiency and performance of different products. In this paper nanofiber membranes have been successfully applied for the selective recovery of Eu(III) and Y(III) from aqueous solutions. Polyacrylonitrile (PAN) electrospun nanofibers were impregnated with a commercial organic extractant, Cyanex 272, in order to increase their affinity to rare earth metals ions. The coated nanofibers were characterized by SEM, ATR-FTIR, and TGA. Firstly, the adsorption of Eu(III) and Y(III) were evaluated in batch mode. Experimental data showed that the adsorption of Y(III) and Eu(III) corresponds to pseudo-second order model, with Langmuir sorption model being the best fit for both target ions. The results demonstrated that the adsorption capacity was high, showing a maximum capacity of 200 and 400 mg/g for Y(III) and Eu(III), respectively. Additionally, the presence of interfering ions does not show significative effects in the adsorption process. Finally, experiments in continuous mode indicated that the adsorption of the target elements is close to 100%, showing that PAN-272 is a promising material for the recovery of earth metal ions. Full article
(This article belongs to the Special Issue Nanomaterials for Advanced Membrane Filtration Technologies)
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12 pages, 2768 KiB  
Article
Surfactant-Assisted Fabrication of Alumina-Doped Amorphous Silica Nanofiltration Membranes with Enhanced Water Purification Performances
by Xianzheng Ma, Katarzyna Janowska, Vittorio Boffa, Debora Fabbri, Giuliana Magnacca, Paola Calza and Yuanzheng Yue
Nanomaterials 2019, 9(10), 1368; https://doi.org/10.3390/nano9101368 - 24 Sep 2019
Cited by 8 | Viewed by 2976
Abstract
Surfactant-templated 5 mol% Al2O3-doped silica membranes nanofiltration membranes were synthesized via the sol-gel method, and afterward, were optimized, and tested with respect to the permeability and rejection rate. The disordered silica network was stabilized by doping 5 mol% alumina. [...] Read more.
Surfactant-templated 5 mol% Al2O3-doped silica membranes nanofiltration membranes were synthesized via the sol-gel method, and afterward, were optimized, and tested with respect to the permeability and rejection rate. The disordered silica network was stabilized by doping 5 mol% alumina. Tetraethyl orthosilicate and aluminum isopropoxide were used as the silica and alumina precursors, respectively. Cetyltrimethylammonium bromide (CTAB) was used not only as a pore-forming agent, but also to control the reaction rate of the aluminum isopropoxide, thus obtaining highly homogeneous materials. The results about filtration of model solutions showed that the optimized membranes are featured by both a relatively high water permeability (1.1–2.3 L·m−2·h−1 ·bar−1) and a high rejection for salts (74% for NaCl, and >95% for MgSO4 and Na2SO4) and organic pollutants (e.g., about 98% for caffeine). High rejection of divalent ions and organic molecules was also observed when a real wastewater effluent was filtered. The influence of the synthesis conditions on the membrane performance is discussed. Full article
(This article belongs to the Special Issue Nanomaterials for Advanced Membrane Filtration Technologies)
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