Chinese scientists design membranes to recover oil, water for waste treatment

HANGZHOU, Nov. 8 (Xinhua) — A Chinese scientific team has developed an innovative membrane system that can efficiently separate oil and water from complex fluids, a breakthrough with significant implications for environmental protection and resource recovery.
The new technology has the potential to effectively treat oily wastewater, which is a prevalent pollutant in both daily life and industry and poses serious threats to ecosystems and water sources.
Existing membrane technology struggles with the challenges of concurrently recovering oil and water from surfactant-stabilized mixtures where oil droplets are dispersed in water.
Now scientists from Zhejiang University have designed a novel membrane system called the Janus channel, which is named after the two-faced Roman god Janus, reflecting its dual-purpose design.
The study, published on Friday in the journal Science, describes the invention, which consists of a narrow, confined channel flanked by two contrasting membranes that are water-compatible and water-repellent, respectively.
As the emulsion flows through this channel, water molecules are passed through a water-compatible membrane under pressure, while oil droplets that collide into larger droplets can be captured and removed by the other membrane.
The system boasts remarkable separation efficiency, recovering around 97 percent of oil and roughly 75 percent of water with a purity above 99 percent, according to the study.
The membranes can be utilized for wastewater treatment in the petroleum and metallurgy sectors, as well as for separating emulsified products in the food and biomedical industries, Xu Zhikang, a corresponding author of the paper, told Xinhua.
The concept can also be extended to various challenging separation processes in major industries, including the “separation of water or glycerol from biofuels, valuable metals from mine tailings, and proteins and vitamins from dairy products,” according to a Perspective article in the journal.
The research team has secured a patent for the technology and is now looking to launch a start-up or partner with companies to further advance its development. ■