A novel coalescing material for high efficiency oil-water separation

Abstract

Among numerous oil-water separation materials, coalescence materials have received widespread attention. In this work, we prepared a lotus leaf-shaped Janus coalescing material by physically mixing polyethylene (PE) and polypropylene (PP) first, pressing it into sheets, then single-face hydrophilic modifying by chemical oxidation method, followed by pressing into a lotus leaf shape. Finally, holes were physically punched at the upper and lower sides of the coalescing material to let the oil drops pass through freely, greatly reducing the time for oil droplets to float. The shape of lotus leaves could provide more opportunities for oil droplets to collide and coalesce. The coalescing materials had asymmetric wettability, with specific surfaces that were oleophilic on the one hand and hydrophilic on the other. The oil droplets adhered to the oleophilic side of the coalescing material, coalesced and grew, then floated up and passed through the coalescing sheet layer by layer until they reached the oil collecting port to realize oil-water separation. The structural parameters of the coalescing material were progressively optimized. The obtained coalescing material exhibited a high oil-water separation efficiency of 99.40 ± 0.5% with good stability during a 48 h continuous oil-water separation, which provided a reference for the development of efficient coalescing materials.