Enhancing oil-in-water emulsion separation performance of polyvinyl alcohol hydrogel nanofibrous membrane by squeezing coalescence demulsification

Zhu, Xu; Zhu, Lei; Li, Hui; Zhang, Chunyu; Xue, Jinwei; Wang, Ran; Qiao, Xurong; Xue, Qingzhong

doi:10.1016/j.memsci.2021.119324

Cited by 64 publications

(8 citation statements)

References 42 publications

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“…Compared with different types of demulsifying materials, 3H-SSFF has the significant advantages of excellent separation efficiency and high processing flux, while the emulsified oil droplets can be effectively demulsified and recovered (Figure h). ,− The 3H-SSFF promotes the oil droplet coalescence through the extrusion of the fluid with the interaction between oil droplets and hydrophobic surface. Herein, the energy source of destabilization of the emulsions by our approach is the kinetic energy of the fluid that provided by the pump and the interaction energy between oil molecules and hydrophobic interface.…”

Section: Resultsmentioning

confidence: 99%

Sequential Demulsification through the Hydrophobic-Hydrophilic-Hydrophobic Filtration Layer toward High-Performing Oil Recovery

Li,

Zhang,

Liu

et al. 2023

Environ. Sci. Technol.

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Demulsification using membranes is a promising method to coalesce highly stable emulsified oil droplets for oil recovery. Nevertheless, a structure of the current filtration medium that is not efficient for oil droplet coalescence impedes rapid permeability, thereby inevitably restricting their practical applications. Herein, we report a hydrophobic-hydrophilic-hydrophobic (3H) demulsification medium that exhibits a benchmark permeability of ∼2.1 × 10 4 L m −2 h −1 with a demulsification efficiency of >98.0%. Remarkably, this 3H demulsification medium maintains over 90% demulsification efficiency in the oil-in-water (O/W) emulsions with a wide range of surfactant concentrations, which shows excellent applicability. Based on the combined results of quasi situ microscope images and molecular dynamics simulations, we show that the polydimethylsiloxane-modified hydrophobic layer facilitates the capture and coalescence of oil droplets, the hydrophilic inner layer assists in squeezing the coalescence of enlarged droplets, and the third hydrophobic layer accelerates the discharge of demulsified oil to sustain permeability. The sequential demulsification mechanism between this 3H filtration layer provides a general guide for designing a demulsifying membrane with high demulsification efficiency and high flux toward oil recovery.

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Section: Resultsmentioning

confidence: 99%

Sequential Demulsification through the Hydrophobic-Hydrophilic-Hydrophobic Filtration Layer toward High-Performing Oil Recovery

Li,

Zhang,

Liu

et al. 2023

Environ. Sci. Technol.

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“…In the process of separating oil-in-water emulsions, membrane fouling is inevitable, but the degree of membrane contamination can be reduced by modification. Membrane performance was characterized by total fouling rate (Rt), reversible fouling rate (Rr), and irreversible fouling rate (Rir) which were calculated by equations [21,62] : Rt (%) = J e ∕J W1 × 100 (7) Rr(%) = (J W2 − J e ) ∕J W1 × 100 (8) Rir(%) = (J W1 − J W2 )∕J W1 × 100 (9) where J e (L m -2 h -1 ) is emulsion flux of membrane.…”

Section: Methodsmentioning

confidence: 99%

“…A large amount of oily wastewater generated from oil spills, oil extraction and various industrial productions has caused serious damage to the ecosystem. [1][2][3][4][5][6][7][8] The types of wastewater separation include filtration oil-water separation and absorption oil-water separation. Absorptive oil-in-water separation adopts porous materials such as sponges to separate oil and water through absorption, but these materials have a certain amount of absorption, DOI: 10.1002/mame.202100814 which is difficult to recycle after reaching saturation, and is easily cause secondary pollution.…”

Section: Introductionmentioning

confidence: 99%

Superwetting Polyvinlydene Fluoride Membranes with Micro‐Nano Structure for Oil‐in‐Water Emulsion Separation

Zhao

et al. 2022

Macro Materials & Eng

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Membrane technology is seen as one of the useful strategies for the treatment of oily wastewater, but the membrane fouling in the process of membrane filtration seriously may affect some properties and time-consuming. Hydrophilic membrane surface can reduce membrane fouling. The appropriate design for membrane composition and surface structure can transform membrane surface with expected performance. In this work, hydrophilic polyvinylidene fluoride (PVDF) membranes with micro-nanostructure are fabricated by in situ synthesis and layer-by-layer assembly strategies. A zeolitic imidazolate framework-8 (ZIF-8) and tannic acid are used to construct microstructure and support hydrophilic groups. The water contact angle and water flux of initial PVDF membrane are 110.67°a nd 6585.7 L m −2 h −1 , respectively, while the optimally modified membrane possesses water contact of 14.5°and water flux of 13641.8 L m −2 h −1 . The modified membrane not only owns good underwater oil repellency and oil adhesion resistance but also processes good separation performance for surfactant stable oil-in-water emulsion. Furthermore, the modified membranes exhibit constant permeability and underwater oleophobicity in cycling experiments and harsh environments, indicating that the modified coating has stability against shedding of the modified materials. This method supports valuable references for MOF application in the field of oil-water separation.

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“…The destabilized oil droplets collide and combine into larger oil droplets and eventually form the oil slick floating on the water surface. The wettability and pore size of the nanofiber membrane are the main factors to determine the coalescence of the oil droplets [ 100 , 101 , 102 ]. The demulsification efficiency (

) can be employed to evaluate the ratio of residual emulsion in the permeate [ 103 ]:

where

is the total volume of the water phase layer and the oil/water emulsion layer in the permeate,

is the water content in the feed oi/water emulsion and

is the volume of the permeate.…”

Section: Parameters Of Nanofiber Membrane Affecting the Oil/water Sep...mentioning

confidence: 99%

An Overview of Recent Progress in Nanofiber Membranes for Oily Wastewater Treatment

Sarbatly

Chiam

2022

Nanomaterials

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Oil separation from water becomes a challenging issue in industries, especially when large volumes of stable oil/water emulsion are discharged. The present short review offers an overview of the recent developments in the nanofiber membranes used in oily wastewater treatment. This review notes that nanofiber membranes can efficiently separate the free-floating oil, dispersed oil and emulsified oil droplets. The highly interconnected pore structure nanofiber membrane and its modified wettability can enhance the permeation flux and reduce the fouling. The nanofiber membrane is an efficient separator for liquid–liquid with different densities, which can act as a rejector of either oil or water and a coalescer of oil droplets. The present paper focuses on nanofiber membranes’ production techniques, nanofiber membranes’ modification for flux and separation efficiency improvement, and the future direction of research, especially for practical developments.

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Enhancing oil-in-water emulsion separation performance of polyvinyl alcohol hydrogel nanofibrous membrane by squeezing coalescence demulsification

Cited by 64 publications

References 42 publications

Sequential Demulsification through the Hydrophobic-Hydrophilic-Hydrophobic Filtration Layer toward High-Performing Oil Recovery

Sequential Demulsification through the Hydrophobic-Hydrophilic-Hydrophobic Filtration Layer toward High-Performing Oil Recovery

Superwetting Polyvinlydene Fluoride Membranes with Micro‐Nano Structure for Oil‐in‐Water Emulsion Separation

An Overview of Recent Progress in Nanofiber Membranes for Oily Wastewater Treatment

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