Nanoscaled gold and silver: Simultaneous removal and transformation to functional materials.

Based on an "acid-assisted cool welding" technology which was realized by virtue of the freezing process in the presence of acid, nanoscaled gold (Au) and silver (Ag) from wastewater could be removed very facilely and efficiently. The technology was independence of the freezing temperature, size as well as shape of those nanoscaled units. Besides, some functional materials like porous nanostructures with highly and stably catalytic activity could be also obtained during the removal. Our research not only provided a new method to remove nanoscaled Ag or Au from wastewater, but also built up a unique route to transform those nano-units into functional materials simultaneously.