Abstract
Developing low-cost, durable, and high-performance materials for the separation of water/oil mixtures (free oil/water mixtures and emulsions) is critical to wastewater treatment and resource recovery. However, this currently remains a challenge. In this work, we report a biopolymer microfiber assembly, fabricated from the recovery of tissue waste, as a low-cost and high-performance filter for oily wastewater treatment. The microfiber filters demonstrate superhydrophilicity (water contact angle of 28.8°) and underwater superoleophobicity (oil contact angle of 154.2°), and thus can achieve separation efficiencies of >96% for both free oil/water mixtures and surfactant-stabilized emulsions even in highly acidic (pH 2.2)/alkaline (pH 11.8) conditions. Additionally, the prepared microfiber filters possess a much higher resistance to oil fouling than conventional membranes when filtering emulsions, which is because the large-sized 3D interconnected channels of the filters can delay the formation of a low-porosity oil gel layer on their surface. The filters are expected to practically apply for the oily wastewater treatment and reduce the amount of tissue waste entering the environment.
Highlights
Wastewater, generated from diverse sources ranging from oil leakage, crude oil mining, metal processing to domestic sewage, may cause serious environmental problems [1] and the waste of resources, if not properly treated
In this work, considering their superhydrophilic/underwater superoleophobic property, we report that these biomass wastes can be converted into nearly no-cost microfiber filters with a very facile method for the efficient oily wastewater treatment
The flux of the microfiber filters can be recovered after fouling, just by soaking them in dimethyl sulfoxide for two hours and subsequently compressing them
Summary
Wastewater, generated from diverse sources ranging from oil leakage, crude oil mining, metal processing to domestic sewage, may cause serious environmental problems [1] and the waste of resources, if not properly treated. To obtain superhydrophilic/underwater superoleophobic or superhydrophobic/superoleophilic materials, their surfaces are usually specially designed with micro/nanostructures, inspired by the natural creatures (such as lotus leaf and water strider) [6,7,8,9], or grafted with hydrophilic/hydrophobic chemical groups [10], or coated with hydrophilic/hydrophobic nanomaterials (such as graphene, metal oxide/hydroxide and zeolite) [11,12,13,14,15,16]. These artificial superwetting materials are relatively expensive. This is because their pore size (tens of micrometers) is usually much larger than oil droplets [17]
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