Effect of the Mixed Oleophilic Fibrous Coalescer Geometry and the Operating Conditions on Oily Wastewater Separation

Lu, Hao; Yang, Qiang; Xu, Xiahong; Wang, Hualin

doi:10.1002/ceat.201400773

Cited by 30 publications

(7 citation statements)

References 36 publications

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“…Attention should be paid to the rapid development of superoleophobic/superoleophilic, superhydrophilic/superhydrophobic surfaces [19][20][21][22][23] and membranes [24][25][26][27] as well as energy-efficient modular separation devices, which are used for separation of oil-water emulsions and gas-liquid mixtures. Additionally, the appliance of inertial gas-dynamic separation of gas-dispersion flows in the curvilinear convergent-divergent channels [28] to improve the reliability of compressor equipment is presented in [29].…”

Section: Literature Reviewmentioning

confidence: 99%

Identification of the Interfacial Surface in Separation of Two-Phase Multicomponent Systems

et al. 2020

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The area of the contact surface of phases is one of the main hydrodynamic indicators determining the separation and heat and mass transfer equipment calculations. Methods of evaluating this indicator in the separation of multicomponent two-phase systems were considered. It was established that the existing methods for determining the interfacial surface are empirical ones, therefore limited in their applications. Consequently, the use of the corresponding approaches is appropriate for certain technological equipment only. Due to the abovementioned reasons, the universal analytical formula for determining the interfacial surface was developed. The approach is based on both the deterministic and probabilistic mathematical models. The methodology was approved on the example of separation of two-phase systems considering the different fractional distribution of dispersed particles. It was proved that the area of the contact surface with an accuracy to a dimensionless ratio depends on the volume concentration of the dispersed phase and the volume of flow. The separate cases of evaluating the contact area ratio were considered for different laws of the fractional distribution of dispersed particles. As a result, the dependence on the identification of the abovementioned dimensionless ratio was proposed, as well as its limiting values were determined. Finally, a need for the introduction of the correction factor was substantiated and practically proved on the example of mass-transfer equipment.

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Section: Literature Reviewmentioning

confidence: 99%

Identification of the Interfacial Surface in Separation of Two-Phase Multicomponent Systems

et al. 2020

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“…Separation of the surfactant‐free oil/water emulsions becomes more difficult due to the formation of an unstable oil‐water suspension with large particle size. The surfactant‐stabilized oil/water emulsions are the most difficult to separate among the three types of oily wastewaters, particularly attributing to the small particle size of the surfactant‐stabilized emulsions (generally less than 20 µm), [ 22–25 ] thus making the effective separation of surfactant‐stabilized oil/water emulsions challengeable. [ 26–27 ] Despite various kinds of traditional separation methods have been employed to separate oily wastewater, including electrochemical, sedimentation, biological, centrifugation, flocculation, and adsorption, [ 28–37 ] shortcomings such as undesirable separation efficiency, prone to secondary pollution and high energy consumption [ 38–40 ] limited their further application.…”

Section: Introductionmentioning

confidence: 99%

Design, Development, and Outlook of Superwettability Membranes in Oil/Water Emulsions Separation

Cai

Fang

2021

Adv Materials Inter

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Oil leakage and discharge of industrial organic solvents are the main reasons for the oily wastewater. The separation of oil/water emulsions has been a global challenge due to the small particle size of the emulsions and their stabilities. An effective method is needed to resolve these issues. Superwettability membrane method has demonstrated a high separation efficiency, fast separation speed, low energy consumption, good scalability, easy operation, and recyclability. In essence, the special wettability of material is mainly determined by two factors: the chemical compositions of material surface and the surface morphology. Herein, in this review, the development of special wettability separation membranes is discussed including different preparation methods, and material preparation, such as superhydrophobic/super lipophilic, superhydrophilic/underwater superoleophobic, superlipophilic/superhydrophobic under oil, smart membranes with switchable wettability, and special wettability membranes with self‐healing or self‐cleaning property. The representative works of each part are introduced, focusing on preparation methods, innovations and separation performance of membranes. Finally, challenges and future directions in this field are also described.

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“…First, the emulsified droplets are captured by the fibers when permeating through the coalescing medium; second, continuous coalescence between emulsified droplets will transform the tiny droplets into the larger droplets; lastly, the enlarged droplets are easily released from the fibers when the hydrodynamic force overcomes the adhesive force between droplets and fibers, further separated by gravity and buoyancy. However, the detailed mechanism behind the coalescence separation is not thoroughly understood although many researchers have experimentally studied the effects of operating parameters and chemical–physical properties of fibers such as flow speed, wettability, pore size, fiber size, and filter porosity. − Therefore, it is still a challenge to further improve the separation performance of a fiber-based coalescer.…”

Section: Introductionmentioning

confidence: 99%

Simulation Study on the Dynamic Behaviors of Water-in-Oil Emulsified Droplets on Coalescing Fibers

Chen

Ding

et al. 2020

Langmuir

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Although increasing superwetting membranes have been developed for separating oil−water emulsions based on the "size-sieving" mechanism, their pores are easily blocked and fouled by the intercepted emulsified droplets, which would result in a severe membrane fouling issue and a sharp decline in flux. Instead of droplet interception, a fiber-based coalescer separates oil/water emulsions by inducing the emulsified droplets to coalesce and transform into layered oil/water mixtures, exhibiting an ability to work continuously for a long time with high throughput, which makes it a promising technology for emulsion treatment. However, the underlying mechanism of the separation process is not well understood, which makes it difficult to further improve the separation performance. Hence, in this work, the dynamic behaviors of water-in-oil emulsified droplets on the surface of the coalescing fiber were numerically investigated based on the phase-field model. The attachment, transport, and detachment behaviors of droplets on fibers were directly observed, and the effects of fiber wettability, orientation, arrangement, and fluid speed were studied in detail. First, it was observed that the droplets will move downstream along the fiber surface under the effect of fluid shear, and the large droplets tend to coalesce with their downstream small droplets on the same fiber surface because they move faster compared to the small droplets. Second, it was found that the emulsified droplet will spontaneously transport to the intersection of two angled fibers under the drive of asymmetric Laplace pressure, which demonstrated that the emulsified droplets tend to gather at the intersection of fibers when permeating through a coalescing medium. Third, it was found that the detachment behaviors of droplets from the fiber surface are strongly affected by their size, fiber wettability, and fluid velocity. In addition, the results of our simulation show that the backside of two closely attached fibers can further inhibit the detachment of droplets. We truly believe that our research results are of significance to optimize the parameters of a fiber-based coalescer for separating oil− water emulsions and to develop novel oil/water separators.

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Effect of the Mixed Oleophilic Fibrous Coalescer Geometry and the Operating Conditions on Oily Wastewater Separation

Cited by 30 publications

References 36 publications

Identification of the Interfacial Surface in Separation of Two-Phase Multicomponent Systems

Identification of the Interfacial Surface in Separation of Two-Phase Multicomponent Systems

Design, Development, and Outlook of Superwettability Membranes in Oil/Water Emulsions Separation

Simulation Study on the Dynamic Behaviors of Water-in-Oil Emulsified Droplets on Coalescing Fibers

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