In Situ Separation of Chemical Reaction Systems Based on a Special Wettable PTFE Membrane

Abstract

Oil-water separation is a worldwide subject because of the increasing demands in numerous applications, involving separation of immiscible products from chemical reaction systems in synthetic industry. Owing to the limitations of low efficiency, high energy consumption, and multiple operations in conventional methods, membranes with special wettability have been widely developed in recent years to effectively separate various oil-water systems. However, few works on treating chemical reaction systems have been reported because of the lack of stability of current membranes in harsh environments, especially during long-term work. Herein, a continuous in situ separation of chemical reaction systems based on a special wettable porous polytetrafluoroethylene membrane is successfully conducted. The membrane possesses (1) an intrinsic (with no modification) special wettability of highly hydrophobic/oleophilic in air and superoleophilic under water and 2) an excellent long-term durability in acidic, alkaline, saline, organic, or heating environments. The in situ separation process exhibits both large separation flux (>3500 L m −2 h −1 ) and high product purity (>99.00%) by continuously filtering synthetic products without interrupting chemical reactions, which is of great significance in industrial fields.

A review of femtosecond laser-structured superhydrophobic or underwater superoleophobic porous surfaces/materials for efficient oil/water separation

“…Xu et al prepared a superwetting PTFE membrane with regular micro-porous array by using a laser PBP ablation method. 209 The membrane exhibits highly hydrophobic/oleophilic in air and underwater superoleophilic. A continuous in situ separation of chemical reaction system was well conducted by using the functional membrane.…”

Efficient separation of immiscible oil/water mixtures using a perforated lotus leaf

“…5,9,10 To verify the oil/water separation capability for both light and heavy oils, the perforated lotus leaf with 2 mm spacing between the holes was fixed between two Teflon fixtures, which are popularly used in oil/water seperation. 43 Figure 3A shows the separation process of nhexane/water mixture (the superhydrophobic facet is upward, Movie S5). When the mixture of oil dyed by oil red and water dyed by Methyl blue (ρoil < ρwater) was poured into this device, the oil/water mixture firstly contacts with the superhydrophobic surface of lotus leaf.…”

Superhydrophobicity and Durability in Recyclable Polymers Coating

“…The use of PTFE in the production of superhydrophobic materials is relatively recent and many approaches have been tried and tested. In general, two are the main approaches: roughening a PTFE surface to achieve the superhydrophobicity, such as by plasma etching [42], templating [43], sand paper [44], sanding [45], laser technologies [46][47][48]; or by deposition on substrate of a thin film of PTFE by a pulsed laser deposition [49], RF plasma sputtering [50], RF-magnetron sputtering [51], supercritical CO 2 [52], electrospinning [53], and chemical vapor deposition (CVD) [54]. Today, spray coating is not widespread; however, this method has the advantage of being simple, with a high efficiency and obtaining a good hydrophobicity and, when used, a final heat treatment is often required [55,56].…”