Superhydrophobic meshes that can repel hot water and strong corrosive liquids used for efficient gravity-driven oil/water separation

Abstract

Oil-polluted water has become a worldwide problem due to increasing industrial oily wastewater as well as frequent oil-spill pollution. Compared with underwater superoleophobic (water-removing) filtration membranes, superhydrophobic/superoleophilic (oil-removing) materials have advantages as they can be used for the filtration of heavy oil or the absorption of floating oil from water/oil mixtures. However, most of the superhydrophobic materials used for oil/water separation lose their superhydrophobicity when exposed to hot (e.g. >50 °C) water and strong corrosive liquids. Herein, we demonstrate superhydrophobic overlapped candle soot (CS) and silica coated meshes that can repel hot water (about 92 °C) and strong corrosive liquids, and were used for the gravity driven separation of oil-water mixtures in hot water and strong acidic, alkaline, and salty environments. To the best of our knowledge, we are unaware of any previously reported studies on the use of superhydrophobic materials for the separation of oil from hot water and corrosive aqueous media. In addition, the as-prepared robust superhydrophobic CS and silica coated meshes can separate a series of oils and organic solvents like kerosene, toluene, petroleum ether, heptane and chloroform from water with a separation efficiency larger than 99.0%. Moreover, the as-prepared coated mesh still maintained a separation efficiency above 98.5% and stable recyclability after 55 cycles of separation. The robust superhydrophobic meshes developed in this work can therefore be practically used as a highly efficient filtration membrane for the separation of oil from harsh water conditions, benefiting the environment and human health.

Durable and Recyclable Superhydrophobic Fabric and Mesh for Oil–Water Separation

“…[14][15][16]25,26] Hence, a variety of nanomaterials are used to generate hierarchical surface roughness necessary for superhydrophobic properties; some of these include nanodiamonds, silica, iron oxide, titania, alumina, carbon soot, and carbon nanotubes. [17,2,[18][19][20][21][22][23] To specifically exploit superhydrophobic surfaces for oil-water separation, these nanomaterials are usually deposited on porous substrates such as fabric, foam, mesh, and filter papers to fabricate the absorbent with selective wetting toward oil. [2,5] Although the available superhydrophobic materials completely repel water and absorb oil from the mixture, their industrial applications are limited due to their insufficient durability and limited recyclability.…”

A facile one-step preparation method of recyclable superhydrophobic polypropylene membrane for oil–water separation

“…In order to get high flux for practical application in oil-water separation these superhydrophobic materials coated metallic mesh and textile sheets were also developed, such as the carbon nanotubes grown on stainless steel mesh by thermal chemical vapor deposition with a diffusion barrier of Al 2 O 3 film 10 , 1-hexadecanethiol grafted copper mesh through solution-immersion in nitric acid solution and sequential modification with 1hexadecanethiol 11 , teflon coated stainless steel mesh by spray-anddry method 12 , waste-potato-residue/candle-soot/silica/attapulgite coated meshes by one-step spray-coating method [13][14][15] , polyacrylamide hydrogel coated stainless steel mesh from a photoinitiated polymerization process with acrylamide, N , N'methylene bisacrylamide, 2,2'-diethoxyacetophenone, and polyacrylamide 16 , a block [poly(2-vinylpyridine)-bpolydimethylsiloxane] copolymer grafted non-woven textiles and polyurethane sponges by a block copolymer-grafting strategy 17 , surface coating of polyester textile via chemical vapour deposition of trichloromethylsilane 18 and electrospinning, dip-coating and spincoating of heptadecafluorodecyl polyhedral oligomeric silsequioxane + cross-linked poly(ethylene glycol) diacrylate, or poly (methylmethacrylate) onto stainless steel wire meshes. 19,20 However, all these above fabrication procedures are either costly or complicated.…”

Recent Advances in the Fabrication of Superhydrophobic Surfaces

“…Inspired by this method, synthetization of microcapsules in realizing expectant smart and selfhealing coatings followed by appropriate technologies to coat the substrate will be achieved. 17,39 and so on. In the following section, we firstly and mainly introduce the electrodeposition method for superhydrophobicity and other electroless deposition, using state-of-the-art researches as the representatives to introduce the advanced development.…”

“…38,149 At present, research about special wettability materials for oil/water separation has attracted much interest of scientific workers and has been reported in many publications. 23,32,38,39,51,80,113,145,150154 As a typical example, Jiang et al prepared the superhydrophobic and superoleophilic Teflon-coated mesh for oil/water separation for the first time in 2004. 153 Since then novel functional surfaces with extreme wettability have been widely investigated.…”