Determining the Optimum Exposure and Recovery Periods for Efficient Operation of a QCM Based Elemental Mercury Vapor Sensor

Abstract

In recent years, mass based transducers such as quartz crystal microbalance (QCM) have gained huge interest as potential sensors for online detection of elemental mercury (Hg 0 ) vapor from anthropogenic sources due to their high portability and robust nature enabling them to withstand harsh industrial environments. In this study, we determined the optimal Hg 0 exposure and recovery times of a QCM based sensor for ensuring its efficient operation while monitoring low concentrations of Hg 0 vapor (<400 ppb v ). The developed sensor was based on an AT-cut quartz substrate and utilized two gold (Au) films on either side of the substrate which functions as the electrodes and selective layer simultaneously. Given the temporal response mechanisms associated with mass based mercury sensors, the experiments involved the variation of Hg 0 vapor exposure periods while keeping the recovery time constant following each exposure and vice versa. The results indicated that an optimum exposure and recovery periods of 30 and 90 minutes, respectively, can be utilized to acquire the highest response magnitudes and recovery rate towards a certain concentration of Hg 0 vapor whilst keeping the time it takes to report an accurate reading by the sensor to a minimum level as required in real-world applications.

A smart nanofibrous material for adsorbing and detecting elemental mercury in air

“…Additional time is caused by the adsorption of Hg 0 traces from the surrounding environment (measuring chamber) up to the achievement of a sufficient number of Hg 0 atoms adsorbed on the surface sensor to be electrically revealed. However, this sensor looks extremely encouraging if compared to other sensors currently involved in detecting mercury in air (Drelich et al, 2008;Kabir et al, 2015;Sabri et al, 2009;Mohibul Kabir et al, 2015;Raffa et al, 2006;James et al, 2012James et al, , 2013Chemnasiri and Hernandez, 2012;Sabri et al, 2011;Keebaugh et al, 2007;Crosby, 2013;McNicholas et al, 2011).…”

Application of the Quartz Crystal Microbalance Method for Measuring Mercury in the Air of Working Environments Involved to Artisanal and Small-scale Gold Mining (ASGM)

“…Researchers have reported the viability of QCM for measuring Hg in industrial environments, where concentrations are higher than 100 μg m -3 . [7][8] When airborne Hg reacts with the surface of the Au electrode of a QCM, the electric resonance oscillation frequency of the electrode changes in proportion to the mass change caused by the Hg adsorption. This device is called a QCM-Hg.…”

Using Quartz Crystal Microbalance for Field Measurement of Liquid Viscosities

“…During the last few decades, quartz crystal microbalances (QCMs) are increasingly being studied as a sensitive, rapid, high-performance, and inexpensive microsensors capable of performing in liquid environments [5][6][7][8][9][10][11][12]. A QCM is a shear mode device consisting of a thin quartz disk sandwiched between two circular, metallic electrodes of the same diameters.…”