Feasibility of in-situ quality assessment of zinc contamination in water

Metal pollution is a global problem, especially due to the dispersion of trace metals in freshwater surrounding abandoned mining areas. This paper reports the experimental procedure used for continuously detecting changes in the concentration of zinc in water using a combination of three methodologies based on electromagnetic (EM) waves: UV-Vis spectrophotometer; impedance analyser; and a novel microwave sensor method. With this last methodology, two planar sensors were used: interdigitated electrode (IDE) pattern on polytetrafluoroethylene (PFTE) substrate, and the same kind of sensor functionalised with bismuth III oxide coating. Reflected power as spectra signals were analysed in the 10 MHz-15 GHz frequency range. Results show signals were linearly dependent on the type of metal measured and on its concentration with R
²
= 0.9942, R
²
= 0.999 and R
²
= 0.9899 respectively for absorbance, capacitance and reflected power measured with a coated IDE sensor. In conclusion, this novel sensing system could be a cost-effective alternative for detecting metal pollution in-situ, and in real-time.