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عنوان فارسی مقاله:
جداسازی انتخابی آب و روغن با غشای مش توسط مویینگی
عنوان انگلیسی مقاله:
Selective separation of oil and water with mesh membranes by capillarity
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Need for oil/water separation The separation of oil and water from oil/water mixtures is an ancient challenge that is becoming more important [1–3]. Discharged oil can cause severe environmental and ecological damage directly and because the oil is flammable and can decompose to form other harmful chemicals, further polluting the natural environment and threatening aqueous habitats and affecting human health [2]. Furthermore, chemicals used in clean-up operations can cause environmental harm. Apart from these environmental and ecological issues, a wide range of industrial processes require the separation of oils or fats from aqueous solutions and the scarcity of water in many arid regions adds to the demand for efficient oil/water separation technologies [4]. Another important consideration in choosing the technology used to effectseparation is the possible reuse of the recovered oil. Although traditional methods such as skimmers, centrifuges, coalesces, settling tanks, depth filters, magnetic separations, flotation technologies, and ignition of oil can remove oil from oily wastewater, these techniques are mainly useful for oil water mixtures and unstable emulsified oils, as their working mechanisms are sensitive to the oil droplet size and/or the density difference between water and oil [5–7]. Moreover, because they require long processing times or gas or chemical input, these conventional separation systems usually are expensive and require a large amount of space and energy [5,6]. More stringent environmental controls and the pressure of economic development have led to a strong desire to produce more efficient, cost-effective processes for oil and water separation [8]. Utilizing engineered wetting of solid surfaces to design an oil/water separation process based on capillary processes has been recognized as an effective approach [9–11]. For practical applications it is necessary to preferentially maintain one phase at the surface in addition to preventing fouling of the surfaces, therefore materials with extreme surface wettability of two types are employed. These are solids with surfaces that are superhydrophobic and superoleophilic or surfaces with the inverse wettability that are superoleophobic and superhydrophilic. Such surfaces when exposed to mixtures of oil and water preferentially attract one of the phases in order to reduce the overall interfacial energy of the system. 1.2. Weak assembly From a molecular viewpoint the interfacial energy arises due to the loss of cohesion energy when a molecule is moved from the bulk to the interface. For liquid oil, we can approximate the cohesive energy of a molecule to the translational kinetic energy. Assuming half the cohesive interactions are lost for a molecule at the interface, the molecular energy shortfall at the interface is ~3 KBT/4 for an air interface. As such, wetting is an example of weak assembly, where the lowering in interaction energy for an oil molecule moving from the liquid–liquid interface to the liquid–solid interface is ~KBT, whereas the lowering in interaction energy for a water molecule moving to a hydrophilic surface is NKBT, due to both dispersion and polar interactions and is therefore an example of strong assembly. It is the difference in these energies that is used to effect oil/water separation using mesh membranes. The self-structuring of fluids at the interface can be devised to affect macroscopic separation of the fluids, provided the external forces are insufficient to overcome the capillary force on one phase, but not the other. For separating oil–water mixtures under gravity, a membrane that is superhydrophilic and superoleophobic (when submerged) will allow water to pass but provide a capillary barrier to the passage of oil, provided the hydrostatic head is insufficient to overcome the effect of the Laplace pressure that arises from the weak assembly of the oil molecules. A membrane of the other type (superhydrophobic and superoleophilic) will allow oil to pass and prevent the passage of water. 1.3. Theory of superhydrophobicity and superhydrophilicity The wettability of a surface is usually quantified by the contact angle of a droplet of liquid on the surface. The droplet can either be in air or in another immiscible fluid. For smooth, homogenous, ideal surfaces the contact angle of a droplet on a surface immersed in another liquid is described by the balance of the interfacial energies in Young's equation;
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کلمات کلیدی:
Facile Fabrication of a Polyethylene Mesh for Oil/Water Separation in ... pubs.acs.org/doi/full/10.1021/acsami.6b07432 by T Zhao - 2016 - Cited by 6 - Related articles Aug 26, 2016 - Herein, a highly efficient oil/water separation mesh with durable chemical ...... with Mesh Membranes by Capillarity Adv. Colloid Interface Sci. Bioinspired Underwater Superoleophobic Membrane Based on a ... pubs.acs.org/doi/abs/10.1021/acsami.5b06326 by YQ Liu - 2015 - Cited by 23 - Related articles Aug 24, 2015 - Bioinspired Underwater Superoleophobic Membrane Based on a Graphene Oxide Coated Wire Mesh for Efficient Oil/Water Separation. Selective separation of oil and water with special wettability mesh ... pubs.rsc.org/en/content/articlehtml/2017/ra/c7ra00237h by D Liu - 2017 Feb 24, 2017 - Otherwise, oleophobic/superhydrophilic mesh membranes can be .... and the three dimensional capillary effect: water completely fills all of the ... Full-Text PDF - MDPI.com www.mdpi.com/2313-7673/1/1/4/pdf by R Ramachandran - 2016 - Related articles Aug 4, 2016 - biomimetic surfaces, such as superhydrophobicity, membrane penetration ...... The rough surface of the mesh for oil-water separation having pores of ... The capillary pressure Pcap across the interface of the liquid L is given ... Filtration Membrane https://courses.washington.edu/conj/bess/filtration/filtration.htm Glomerular filtration is a process of bulk flow: water and low molecular ... from the lumen of the capillary, across the filtration membrane, and into Bowman's space. ... Proteins from adjacent foot processes interact to form a mesh-like barrier that ... Water Treatment Unit Processes: Physical and Chemical https://books.google.com/books?isbn=0824706951 David W. Hendricks - 2006 - Technology & Engineering Hollow-Fiber and Capillary Capillary and hollow-fiber membranes are ... on the tube; (c) feed water mesh spacer showing fibers; (d) path taken by water, i.e., ...
