Separation of Oil from a Water/Oil Mixed Drop Using Two Nonparallel Plates

Abstract

In this work, we have developed a simple approach to separate oil from a microliter-scaled water/oil mixture by squeezing the mixture using two nonparallel plates. Three pairs of plates with Teflon, SU-8, and SiO2 coatings, respectively, are used in the tests, and all of these plates are capable of separating the water/oil mixed drops. 95.5% silicone oil and 97.0% light mineral oil have been collected from their corresponding mixtures with water through the pair of Teflon plates. Furthermore, on the basis of pressure difference inside a liquid drop, theoretical models have been developed to interpret the corresponding mechanisms of the separation process, as well as the observed phenomena. To judge whether two immiscible liquids could be separated using the developed approach, a sufficient condition has also been derived, which includes three theoretical relations. The sufficient condition is subsequently validated by experiments. This condition also provides criteria for choosing a good plate coating. Such a coating should ensure (i) the oil wets the plate surface with a relatively large contact angle, and has small contact angle hysteresis, and (ii) the advancing contact angle that the water/oil interface forms on the plate surface is larger than 90°.

Statics and dynamics of liquid barrels in wedge geometries

“…The statics and dynamics of liquid droplets in wedge geometries is an active research topic across disciplines, spanning biological physics (Prakash et al 2008), granular media (Bocquet et al 2002;Kohonen et al 2004;Grof et al 2008) and microfluidics (Dangla et al 2013;Renvoisé et al 2009;Luo & Heng 2014). More fundamentally, understanding the motion of droplets in wedges can shed light on complex phenomena, such as interfacial instabilities (Al-Housseiny et al 2012;Keiser et al 2016) and the impact of surface roughness on contact-line dynamics (Moulinet et al 2002).…”

Conditions for Barrel and Clam-Shell Liquid Drops to Move on Bio-inspired Conical Wires

“…Consequently, their mixtures are examined in this work. The corresponding contact angles are measured using an approach similar to that of refs 23 and 24 (Table 2 ). The second group of experiments simulates the situation of a fog test, which has small water drops emerge at the beginning of the test.…”

Corrosion resistance for superwetting immiscible oil/water separation porous materials

“…4 In 2017, Faze Chen etc reported a facile organic solvent free method was described to prepare a porous PVDF-MWCNT foam to separate immiscible oils/ organic solvents and aqueous solutions. 5 Therefore, many superwettability materials such as coating meshes, [6][7][8] sponges, [9][10][11] membranes, [12][13][14][15] foams, 16,17 textiles, 18,19 aerogels, 20,21 particles, 22,23 and others [24][25][26] are applied for oils/water separation. [27][28][29][30] Superwetting porous copper foam with superhydrophobicity and superoleophilicity are of greatest concern since these materials are affordable and well-prepared 3 dimensional (3D) network composite structures and large surface area compared with their counterparts in the form of membrane, sponges, textiles, ber and particle.…”