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

• Published in: Mine water and the environment Vol. 37; no. 3; pp. 617 - 624
• Main Authors: Frau, Ilaria, Korostynska, Olga, Mason, Alex, Byrne, Patrick
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-09-2018; Springer Nature B.V
• Subjects: Analytical methods; Capacitance; Chemical contaminants; Circuit boards; Detection; Drainage; Earth and Environmental Science; Earth Sciences; Ecotoxicology; Electromagnetic radiation; Emergency preparedness; Emergency response; Environmental monitoring; Feasibility studies; Geology; Gold; Heavy metals; Hydrogeology; Industrial Pollution Prevention; Laboratories; Lead; Metal concentrations; Metals; Mine drainage; Mine waters; Mineral Resources; Mines; Mining; Monitoring; PCB; Pollutants; Pollution monitoring; Polychlorinated biphenyls; Polytetrafluoroethylene; Printed circuits; Protective coatings; Quality standards; Real time; Resonant frequencies; Sample size; Scientific imaging; Sensors; Solutions; Spectroscopy; Spectrum analysis; Substrates; Technical Article; Temporal resolution; Trace metals; Ultraviolet radiation; Water pollution; Water Quality/Water Pollution; United States > US; Toxic metal pollution; Pb; Acid mine drainage; Water quality monitoring; Microwave reflected power
• ISSN: 1025-9112; 1616-1068
• DOI: 10.1007/s10230-018-0511-7

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.