A study published in Nature Communications last week, reveals an innovative method for cleaning up micron-sized oil droplets from water.
The team of Chinese scientists from the Chinese Academy of Sciences, and Tsinghua, Pekin and Beihang Universities, designed structured cone arrays made of copper, which act as cactus needles and can effectively clean up remains of oil spills.
The researchers were inspired by the way cactus needles extract water from the air and with the help of surface tension and the cone-shape of the spines, move the water droplets to the needle base. The technology is essentially an array made of copper and silicon polymer conical needles. These are only 0.5 millimeters long and are able to remove 99% of the oil mixed with water. When placed under water, the copper-silicon structures capture the droplets and transport them towards the base of the needles.
Cleaning up tiny oil droplets have always been challenging, despite the numerous advances that have been made in technologies for cleaning of oil spills. The micron-sized droplets are not affected by phase separation, a process which occurs in the oil-water mixture as part of conventional cleaning methods. The authors of the study are convinced that by mimicking the functions and shape of cactus needles, they were able to develop a technique, which overcomes this limitation.
The method was welcomed by various specialists in the field. Professor Joanna Aizenberg of Harvard University, was impressed by the way the researchers took a biological system and used it to create the bio-inspired design. Professor Stephen Michielsen from North Carolina State University commented that the invention could also be used to clean oil from air, when it is aerosolised in compressed air, and replace conventional filters.