image: The Micro-nano structure organic hydrogel surface can separate oil-water mixture on demand. The surface maintains an ultra-high separating efficiency and flux of about 99.85% and 17750 L·m−2·h−1, and even after continuous cycles without cleaning, it could keep 99.1% and 16000 L·m−2·h−1 due to the excellent anti-fouling ability.
Credit: By Yun-yun Song, Jiang-shen Lu, Yang Zhang, Zhao-peng Yu*, Yan Liu and Zhong-qiang Zhang*.
Oil spills and oily industrial wastewater are a nightmare for factories, the environment, and public health. Separating oil from water might sound simple, but in reality it's one of the toughest jobs in wastewater treatment—especially when the mixture contains oils of different densities, tiny droplets, or sticky contaminants. Traditional membrane filters often clog, slow down, and lose efficiency over time.
In International Journal of Extreme Manufacturing, a research team has developed an organic hydrogel surface can instantly recognize whether it is in contact with oil or water—and switch its behavior to let the right liquid pass through while blocking the other.
When exposed to water, the surface becomes superhydrophilic (water-loving) and underwater superoleophobic (oil-repelling), allowing clean water to flow through while stopping oil. While in oil, it flips to superoleophilic (oil-loving) and underoil superhydrophobic (water-repelling), letting oil pass while holding back water.
This "smart" surface, created by combining laser-etched micro–nano structures with a special dual-component organic hydrogel coating, achieves a record-breaking separation speed of 17,750 liters per square meter per hour. That's three to five times faster than most current membranes, with over 99% efficiency even after repeated use without cleaning. Its antifouling ability means it can keep working for long cycles without losing performance.
Their innovation tackles three problems that have long frustrated engineers: membrane clogging and fouling during operation, weak responsiveness in existing "smart" materials, and poor performance with complex oil mixtures containing both light and heavy oils.
The potential impact is huge—from factories treating oily wastewater on-site to emergency clean-up after oil spills. The team is already working on versions that can withstand extreme pH conditions, handle difficult emulsions, and be produced on a large scale for industrial use.
"This is not just another filter; it's an intelligent surface that works on demand," the researchers say. "It could change the way industries think about wastewater treatment."
International Journal of Extreme Manufacturing (IJEM, IF: 21.3) is dedicated to publishing the best advanced manufacturing research with extreme dimensions to address both the fundamental scientific challenges and significant engineering needs.
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Journal
International Journal of Extreme Manufacturing
Article Title
Micro-nano manufacturing of a pre-identified organic hydrogel surface for selective oil/water separation with ultra-high flux
Article Publication Date
22-Jul-2025