An advance in the treatment of water, inspired by a marine creature

The research, a collaboration of Menaleem Elimelech's Yale and Huazhang Zhao Laboratories of Peking University, used a material known as a nanocoagulant to rid water of its contaminants. By eliminating a wide range of contaminants in a single step, the discovery promises to dramatically improve the secular use of coagulants for water treatment. The results are published today in Nature Nanotechnology.

When added to water, conventional coagulants such as aluminum sulphate and other metal salts remove larger particles of water by causing them to become waterlogged. regroup in bigger formations and to be deposited. Since these coagulants do not remove the smallest dissolved particles in the water, additional treatment methods are needed. The use of several technologies for water treatment is however expensive, consumes a lot of energy and may require a large amount of land. Creating an effective and easy-to-use technology to remove all contaminants from the water is essential to address the worldwide water scarcity.

The research team synthesized a new highly stable nanocoagulant, different from conventional coagulants in terms of structure, performance and behavior. In addition to removing suspended particles, this nanocoagulant also removes small dissolved contaminants.

"The behavior of the nanocoagulant is controlled by its structure," said Ryan DuChanois, Ph.D. student in Elimelech's lab. "Under certain conditions, the nanocoagulant retains a structure allowing it to be stored over time."

Actinia is a spherical body of sea anemone with tentacles that retract at rest and spread while catching prey. With this model of marine predator, researchers synthesized the coagulant using organic and inorganic components to replicate the structure of Actinia.

Similar to Actinia, the nanocoagulant has a core-shell structure that rotates in water. The hull destabilizes and meshes large particles in suspension, while the exposed nucleus captures the smaller, dissolved ones. It removes a broad spectrum of contaminants, from traces of micropollutants to larger particles – many of which escape conventional methods and pose significant public health problems.

"The ability to remove nitrates was quite surprising, as traditional water coagulants have negligible nitrate removal," said Elimelech, professor of chemical and environmental engineering Roberto C. Goizueta. It is also essential for water treatment, as nitrate contamination is associated with the "baby blue" syndrome, a life-threatening disease that affects young children in some parts of the world.

As it is a one-step process, said Professor Huazhang Zhao of Peking University, the work is promising to replace current water treatment methods and significantly reduce the costs of running the treatment. some water. "It also opens the door to making" smart "materials that can transform the configuration and work according to its environment," he said.

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More information:
Jinwei Liu et al., Actinia multi-functional Nanocoagulant for the one-step removal of water contaminants, Nature Nanotechnology (2018). DOI: 10.1038 / s41565-018-0307-8