Tuning the underwater oleophobicity of graphene oxide coatings via UV irradiation

Li, Hang; Huang, Yi; Mao, Yating; Xu, Weiwei; Ploehn, Harry J.; Yu, Miao

doi:10.1039/c4cc03940h

Cited by 38 publications

(23 citation statements)

References 24 publications

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“…By using a sacrificial layer, stable GO hollow fibre membranes were successfully determined and these membranes can be post-treated in dry state to improve their performance. UV radiation has been used to modify the property of GO flakes, in which it can mildly reduce the functional groups on GO 21 22 . In our study, we post-treated the stabilised GO hollow fibre membranes with UV radiation and we found that it also led to similar changes to dry GO membranes in the air.…”

Section: Resultsmentioning

confidence: 99%

UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

Chong

Wang

et al. 2015

Sci Rep

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Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m−2 h−1 bar−1 for water, and 0.14 to 7.5 L m−2 h−1 bar−1 for acetone, with an unchanged low molecular weight cut off (~250 Da).

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Section: Resultsmentioning

confidence: 99%

UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

Chong

Wang

et al. 2015

Sci Rep

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“…They observed full recovery of the pure water permeability with the 10 nm thickness GO coating on the PA membrane surface, indicating absence of surface fouling and minimization of internal fouling in the membrane. Thereafter, Li et al treated GO dispersion with UV irradiation to modify its surface properties, and prepared 10 nm GO coated PA membranes with tunable underwater oleophobicity. They found a higher percentage of hydrophilic oxygen‐containing functional groups on the GO flakes after UV treatment, which led to its underwater superoleophobic property.…”

Section: Go Functional Coatings On Membranesmentioning

confidence: 99%

Graphene Oxide: A Novel 2‐Dimensional Material in Membrane Separation for Water Purification

Fathizadeh

Zhou

et al. 2017

Adv Materials Inter

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171

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a significant advantage, greatly facilitates GO deposition from solution using water as a low cost and environment-friendly solvent. [3] Recently, GO has attracted great attention as a novel 2-D membrane material in water purification application because of its excellent mechanical property, atomically thin thickness, excellent dispersion in water, and ease to form compact membrane structure or to be added into polymer matrix. [3,4] Concept demonstration/preliminary studies on using graphene-based membranes for water purification were focused on simulations for single layer graphene/ GO/reduced GO (rGO) with structural defects. Cohen-Tanugi et al., [5] using molecular dynamics (MD) simulation, found that hydrogenated and hydroxylated defects with appropriate sizes on graphene could have 2-3 orders of magnitude higher water permeability than commercial reverse osmosis (RO) membranes but similarly high salt rejection, suggesting great potential of single-layered graphene membranes for desalination. Lin et al. [6] showed by MD simulations that thermally reducing GO with different initial epoxy to hydroxyl ratios and different oxygen concentrations may generate selective defects on rGO for high water permeability and high salt rejection desalination. Figure 2a shows representative structures of rGO after reduction at 2,500 K, when GO flakes with different starting oxygen concentrations and epoxy concentrations or epoxy/hydroxyl ratios are used. With the increase of oxygen concentration and epoxy concentration, rGO becomes more defective and has bigger nanopores because of more carbon removal from the GO matrix. This suggests pores on rGO may be controlled by controlling starting GO composition and reduction conditions. Further, they studied desalination performance of defects on rGO after reduction at different temperatures and using GO with different oxygen concentrations and epoxy concentrations (Figure 2b). Too low oxygen concentration (17%) leads to complete water blocking irrespective of reduction temperature and initial epoxy concentration or epoxy/hydroxyl ratio. At higher initial oxygen concentration (25% and 33%), high water flux and 99% salt rejection can be obtained depending on reduction temperature epoxy/hydroxyl ratio. These promising simulation results, therefore, suggest appropriately reducing GO with desired starting composition As a newly emerging 2-dimensional (2-D) material with sub-nanometer thickness, graphene oxide (GO) has been widely studied either as a pure/skeleton membrane material or as an additive in and a functional coating on matrix membranes for water purification because of its unique physico-chemicomechanical properties. Manipulating or incorporating this novel 2-D material effectively into a membrane structure has been shown to significantly improve membrane performance, including increased water permeability, alleviated fouling, improved antibacterial properties, etc., which will eventually lead to lower energy consumption, longer lifetime, and lower maintenance cost. As the pure/...

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“…215,216 Advanced oil/water separation could be performed by a combination of a hierarchical surface roughness and surface chemistry. 215,216 Advanced oil/water separation could be performed by a combination of a hierarchical surface roughness and surface chemistry.…”

Section: Separation Of Liquids By Membranesmentioning

confidence: 99%

Ultrasonically treated liquid interfaces for progress in cleaning and separation processes

Radziuk

Möhwald

2016

Phys. Chem. Chem. Phys.

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Ultrasound and acoustic cavitation enable ergonomic and eco-friendly treatment of complex liquids with outstanding performance in cleaning, separation and recycling of resources. A key element of ultrasonic-based technology is the high speed of mixing by streams, flows and jets (or shock waves), which is accompanied by sonochemical reactions. Mass transfer across the phase boundary with a great variety of catalytic processes is substantially enhanced through acoustic emulsification. Encapsulation, separation and recovery of liquids are fast with high production yield if applied by ultrasound. Here we discuss the state of knowledge of these processes by ultrasound and acoustic cavitation from a perspective of a physico-chemical model in order to predict and control the outcome. We focus on the physical interpretation and quantification of ultrasonic parameters and properties of liquids to understand the chemistry of liquid/liquid interfaces in acoustic fields. The roles of thermodynamic enthalpy and entropy (incl. Laplace and osmotic pressure) in the context of sonochemical reactions (separation, catalysis, degradation, cross-linking, ion exchange and phase transfer) are outlined. The synergy of ultrasound and electric fields or continuous flow chemistry for cleaning and separation via emulsification is highlighted by specific strategies involving polymers and ultrasonic membranes.

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Tuning the underwater oleophobicity of graphene oxide coatings via UV irradiation

Abstract: UV-irradiation has been utilized as an effective and facile approach to tune the underwater oleophobicity of GO coatings/membranes by gradually modifying GO flake composition and surface morphology.

Cited by 38 publications

References 24 publications

UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

Graphene Oxide: A Novel 2‐Dimensional Material in Membrane Separation for Water Purification

Ultrasonically treated liquid interfaces for progress in cleaning and separation processes

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