Comparison of Electromagnetic Wave Sensors with Optical and Low-frequency Spectroscopy Methods for Real-time Monitoring of Lead Concentrations in Mine Water

Abstract

The feasibility of using novel electromagnetic wave sensors for real-time monitoring of metal pollution in water was assessed. Five solutions with different concentrations of lead (0, 1, 10, 50, 100 mg/L) were measured using several sensing methods: UV-Vis spectroscopy, low frequency capacitance and resistance measurements, and two sensing systems based on microwave technology. With this last approach, two sensing devices were used: a resonant cavity and a planar sensor with gold interdigitated electrode design printed on a PTFE substrate with a protective PCB lacquer coating. Results confirmed the ability of these systems to quantify the lead concentration as changes in spectrum signal at specific frequencies of the electromagnetic spectrum. Spectra were unique, with clearly observed shifts in the resonant frequencies of the sensors when placed in direct contact with different lead solutions, demonstrating the possibility of continuous monitoring with great sensitivity, selectivity, and high spatial and temporal resolution. Consequently, determination of trace and toxic metals using microwave spectroscopy is a promising alternative to traditional grab-sampling and laboratory based analyses. On-line and continuous monitoring of real-time metal concentrations offers the potential for a more effective emergency response and the platform for better scientific understanding and remediation of contaminated mine drainage.

Real-Time Water Quality Monitoring with Chemical Sensors

“…During the last few years, several planar microwave sensors with different conformations have been developed and tested for differentiate compositions of water for both qualitative and quantitative concentration measurements [ 49 , 50 , 51 , 52 , 53 ]. Between planar sensing structures, Korostynska et al [ 49 ] confirmed the action of a novel planar sensor with a sensing element consisted of interdigitated electrodes (IDE, also defined as interdigital by other researchers) metal patterns (silver, gold and/or copper) for water analysis observing changes in the microwave part of the EM spectrum analysing 20 µL of deionized water (DIW), KCl, NaCl and MnCl at various concentrations ( Figure 9 a,b).…”

“…Between planar sensing structures, Korostynska et al [ 49 ] confirmed the action of a novel planar sensor with a sensing element consisted of interdigitated electrodes (IDE, also defined as interdigital by other researchers) metal patterns (silver, gold and/or copper) for water analysis observing changes in the microwave part of the EM spectrum analysing 20 µL of deionized water (DIW), KCl, NaCl and MnCl at various concentrations ( Figure 9 a,b). Then, Mason et al [ 50 ], Moejes et al [ 51 ] and Frau et al [ 52 ] demonstrated the ability to detect respectively Lincomycin and Tylosin antibiotics, Tetraselmis suecica and lead ions (Pb 2+ ) using gold (Au) eight-pair IDE sensors.…”

Worthwhile Relevance of Infrared Spectroscopy in Characterization of Samples and Concept of Infrared Spectroscopy-Based Synchrotron Radiation

“…spectroscopy could be used physically to separate electromagnetic waves of various frequencies [13,14]. erefore, it generates a spectrum which shows the constituents' frequencies [15,16].…”

Functionalised microwave sensors for real-time monitoring of copper and zinc concentration in mining-impacted water

“…Current research has demonstrated the possibility to determine the presence and concentration of specific components and pollutants in water, e.g. lead ions (Pb 2+ ) (Frau et al 2018a), sugars (Harnsoongnoen et al 2018), nitrates (Cashman et al 2017), phosphate (Nag et al 2019), antibiotics (Mason et al 2018), silver materials (Ateeq et al 2017), water in fuel (Andria et al 2019), marine algae (Moejes et al 2018), liquid mixtures, as acetone and water (Wei et al 2018), ethanol and water Wiltshire and Zarifi 2018).…”