Mercury Detection in Real Industrial Flue Gas Using a Nanostructured Quartz Crystal Microbalance

We present for the first time a nanostructured gold-based microsensor that can successfully detect elemental mercury (Hg-0) vapor through a nonspectroscopic means, directly from a real industry effluent gas sample obtained from an alumina refinery. The developed sensor did not require any preconditioning of the sampled industrial gas in order to remove humidity content as is the case for laborious solid sorbent methods (i.e., Appendix K and Method 30B) certified by the United States Environmental Protection Agency (US-EPA). The sensor was developed by electrodepositing gold (Au) nanostructures (nanospikes) directly on the electrodes of the humble quartz crystal microbalance (QCM) transducer. Significantly, despite attempting to introduce a memory effect into the sensor in order to replicate real world scenarios during testing, the developed sensor still reported the Hg-0 vapor concentrations in the industrial gas to within +/- 8% of the certified solid sorbent analysis conducted at the time of obtaining the sample from the refinery stream. The developed microsensor technology introduced here can potentially be the first certified solid-state He vapor monitoring system that can be utilized as part of Hg-0 control and removal processes in industry due to its exceptionally low susceptibility to cross-sensitivity, high accuracy, and ability to operate with untreated "real-world" sample gas.