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All-in-one mercury removal

25 March 2010

Finding and removing mercury from environmental waters could soon be accomplished with an 'all-in-one' magnetic microsphere developed by Chinese scientists. 

The mercury(II) ion is the most stable form of inorganic mercury and is known to have detrimental effects on humans and the environment. It is released into the environment by activities including fossil fuel combustion, waste batteries and chemical manufacturing. Most of the current methods for the detection and removal of mercury require large and expensive instruments which are not suitable for environmental analysis and, in most cases, the two processes have to be performed separately. 

Shengyang Tao, from the Dalian University of Technology, and colleagues have created a nanocomposite microsphere that can detect, adsorb and remove mercury from water. The ability to combine all these functionalities in a single material is unique, says Tao. 

Tao manufactured the microspheres using a simple procedure and inexpensive materials. A magnetic Fe3O4 core was encased in a non-porous inner silica shell and then a mesoporous silica outer shell, combined with a Rhodamine B-derivative (a fluorescent dye) was added. The Rhodamine B acts as a probe to find the mercury, which is then adsorbed by the silica shell. Applying a magnetic field attracts the microspheres, pulling them and the mercury out of the water. 

Xing Dong, from the US magnetic material research company Steward Advanced Materials, is impressed with the results, 'the beauty of their work is that the novel materials have high selectivity and the mercury-laden materials can be removed rather easily as a whole by external magnetic field.' 

Tao says the particles could be used to detect also have potential applications in the medical field. 'We are trying to integrate more than three functions in a microsphere to use in the nano-medical area,' he adds. 

Rebecca Brodie