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

Abstract

The authors report durable and recyclable nanocomposite superhydrophobic coatings on two different substrates of fabric and mesh as prepared by titania nanoparticles and polydimethysiloxane (PDMS). The felted wool fabric and the steel mesh are initially coated with a thin layer of PDMS, which is followed by the deposition of nanocomposite coating of titania nanoparticles embedded in PDMS. The dual surface modification of two kinds of substrates generates highly hydrophobic surface character, which is retained after durability performance as measured in ultrasonication, sand, and emery paper abrasion tests. Oil-water separation experiments are performed using water mixtures with four oils, that is, n-hexane, toluene, kerosene, and diesel to ensure the industrial applications of prepared composite materials.Moreover, nanocomposite coatings are tested for several cycles of oil-water separation in harsh conditions such as hot water, sodium chloride, and hydrochloric acid. The adopted approach improves the separation performance by inducing durability of the prepared nanocomposite coatings along with introducing recyclable character.

Recent Advances in Robust Superwettable Membranes for Oil–Water Separation

“…Similar results were obtained when ultrasonication treatment for 18 h was carried out in an attempt to cause significant damage to superhydrophobic PDMS@silica‐film‐coated polyester textiles (Figure g) . By contrast, the WCAs for a superhydrophobic fabric and mesh prepared from TiO 2 nanoparticles and PDMS were reduced to less than 150° after 3 h ultrasonication, which indicates the loss of super‐water‐repellent property . By means of a electrospinning technique and sintering treatment, a polytetrafluoroethylene@polyvinyl alcohol (PTFE@PVA) nanofibrous membrane with good mechanical stability was fabricated, and the membrane resisted the effects of sonication for 80 min .…”

“…Similar to the adhesive‐mediated durable membranes, the use of covalent‐bonding‐based superwettable coatings involving various immobilized hydrogels/aggregates/complexes/particles and building blocks on porous 2D or 3D macroscopic substrates is regarded as a popular strategy for reducing damage arising from abrasion. Recently, several membranes have been developed with improved mechanical (abrasion‐resisting) robustness for the separation of oil–water mixtures . Based on a one‐step alkaline‐induced phase‐inversion process, a robust polyionized sodium polyacrylate‐grafted poly(vinylidene fluoride) (PAAS‐ g ‐PVDF) hydrogel‐coated nonwoven fabric was prepared by Gao et al and used for the separation of immiscible oil–water mixtures.…”

“…After moving forward 965 cm, the WCAs of the resultant surface ranged from 153° to 166°, and the SAs varied between 4° and 7°, indicating superior wearability, despite the 251.2 µm thickness loss (Figure c) . Micro/nanoparticles are the most popular building blocks for superwettable surfaces, and assembled membranes with enhanced mechanical‐abrasion‐resistant properties and performance have been extensively developed …”

“…Apart from the previously mentioned linear abrasion treatment, where the superwettable surface of membrane was positioned face‐down on sandpaper, sand‐flow‐based multidirectional attack abrasion test has also been employed to examine mechanical stability, as illustrated in Figure a . Based on the related literature, water‐jet‐based abrasion tests are rarely conducted for the characterization of permeable superwettable membranes compared to that of impermeable solid surfaces.…”

“…Therefore, in addition to the required antiabrasion ability, other mechanical properties of the coating and bulk membrane materials, such as tensile strength, flexibility, elongation, and toughness, are of very importance for stable oil–water separation. These can be examined by the previously mentioned stress–strain, stretching/deformation, bending, tape peeling, scratching, ultrasonication, and laundering tests …”