Colloidal deposition on polymer-brush-coated NF membranes

Segev-Mark, Naama; Vu, Anh Tuan; Chen, Ningyuan; Qian, Xianghong; Wickramasinghe, S. Ranil; Ramon, Guy Z.

doi:10.1016/j.seppur.2019.02.045

Cited by 11 publications

(2 citation statements)

References 32 publications

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“…The experimental setup is shown schematically in Figure . A custom-made crossflow filtration cell, with a sapphire glass viewing port, allows in situ observation using a confocal laser scanning microscope (TCS SP8, Leica Microsystems). − Channel dimensions within the cell are 0.6 mm ( H ), 6 mm ( W ), and 36 mm ( L ) with a total membrane filtration area of 216 mm 2 . The flow cell was mounted on the microscope stage, and imaging was made with a 25× water immersion objective with a numerical aperture of 0.95, corresponding to a 262 144 pixel (384 400 μm 2 ) field of view.…”

Section: Methodsmentioning

confidence: 99%

Atomic Layer Deposition for Gradient Surface Modification and Controlled Hydrophilization of Ultrafiltration Polymer Membranes

Itzhak

Segev-Mark

Simon

et al. 2021

ACS Appl. Mater. Interfaces

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In recent years, atomic layer deposition (ALD) has emerged as a powerful technique for polymeric membrane surface modification. In this research, we study Al 2 O 3 growth via ALD on two polymeric phase-inverted membranes: polyacrylonitrile (PAN) and polyetherimide (PEI). We demonstrate that Al 2 O 3 can easily be grown on both membranes with as little as 10 ALD cycles. We investigate the formation of Al 2 O 3 layer gradient through the depth of the membranes using high-resolution transmission electron microscopy and elemental analysis, showing that at short exposure times, Al 2 O 3 accumulates at the top of the membrane, reducing pore size and creating a strong growth gradient, while at long exposure time, more homogeneous growth occurs. This detailed characterization creates the knowledge necessary for controlling the deposition gradient and achieving an efficient growth with minimum pore clogging. By tuning the Al 2 O 3 exposure time and cycles, we demonstrate control over the Al 2 O 3 depth gradient and membranes' pore size, hydrophilicity, and permeability. The oil antifouling performance of membranes is investigated using in situ confocal imaging during flow. This characterization technique reveals that Al 2 O 3 surface modification reduces oil droplet surface coverage.

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Section: Methodsmentioning

confidence: 99%

Atomic Layer Deposition for Gradient Surface Modification and Controlled Hydrophilization of Ultrafiltration Polymer Membranes

Itzhak

Segev-Mark

Simon

et al. 2021

ACS Appl. Mater. Interfaces

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“…In our earlier work, we investigated colloidal deposition on PNIPAM-coated NF membranes [23]. We used direct confocal microscopy imaging to investigate, in real time, deposition of colloidal particles as well as the effect of changing the conformation of the grafted PNIPAM.…”

Section: Introductionmentioning

confidence: 99%

Oil Deposition on Polymer Brush-Coated NF Membranes

Mark

Ramon

et al. 2019

Membranes

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Membrane-based processes are attractive for treating oily wastewaters. However, membrane fouling due to the deposition of oil droplets on the membrane surface compromises performance. Here, real-time observation of the deposition of oil droplets by direct confocal microscopy was conducted. Experiments were conducted in dead-end and crossflow modes. Base NF 270 nanofiltration membranes as well as membranes modified by grafting poly(N-isopropylacrylamide) chains from the membrane surface using atom transfer radical polymerization were investigated. By using feed streams containing low and high NaCl concentrations, the grafted polymer chains could be induced to switch conformation from a hydrated to a dehydrated state, as the lower critical solution temperature for the grafted polymer chains moved above and below the room temperature, respectively. For the modified membrane, it was shown that switching conformation of the grafted polymer chains led to the partial release of adsorbed oil. The results also indicate that, unlike particles such as polystyrene beads, adsorption of oil droplets can lead to coalescence of the adsorbed oil droplets on the membrane surface. The results provide further evidence of the importance of membrane properties, feed solution characteristics, and operating mode and conditions on membrane fouling.

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