According to a report from the University of Adelaide in Australia, chemical engineering researchers have developed a new ultra-sensitive, low-cost and portable system for detecting mercury in environmental water. The findings were recently published in the journal ACS Applied Materials and Interfaces.
The new technology is based on an optical sensing system that can detect low levels of mercury. The researchers commented on the importance of detecting mercury, noting that the naturally occurring element has accumulated in water supplies at an accelerated rate due to global industrialization. Depending on the level of exposure, mercury can cause harm the brain, heart, kidneys, lungs, and immune system, and exposure is particularly harmful to babies in the womb and young children, even at lower levels, compared to adults.
"Recently, these concerns have seen the introduction of a global convention aimed at controlling, monitoring and reducing mercury pollution at a world scale.
"There are current systems capable of monitoring mercury at trace levels, but they are huge machines that can't be easily moved, are very expensive and complicated to use and require comprehensive training. Samples also require chemical treatment before analysis.
In the report, the researchers noted that their system "is very cost-competitive, only as big as a mobile phone, and easy to use. With very basic training, someone could take it to a river or lake and do a mercury reading on the spot."
International and joint-university effort
The project was a collaboration between the Losic Nano Research group in the School of Chemical Engineering and University Rovira i Virgili in Spain, and most of the experimental work has been carried out by PhD candidate Tushar Kumeria. The team has engineered a nanoporous material called nanoporous anodic alumina to make a special structure called a rugate filter.
The surface of the filter has been modified to make it selective to mercury ions. As water flows through the pores of the filter, the mercury ions become attached to the surface. An optical system - reflection spectroscopy - measures the amount of mercury present.
A range of tests have shown the sensor can detect mercury at levels of 200 parts per billion in a complex mixture of other metal ions and environmental samples. Continued work will seek to enhance the optical signals for even higher sensitivity.
Commenting on the team's work, Dr Abel Santos, Australian Research Council Postdoctoral Fellow with the University's School of Chemical Engineering."The promising sensing performance of this system along with its cost-competitiveness and portability make it an excellent potential alternative to current analytical techniques. This technique could provide the basis for future point-of-analysis systems for monitoring water quality on site and may help implement better monitoring processes around the world."