Comparative chemical sensor for detection of chromium (VI) in aqueous solution

A process for purifying aqueous solutions containing heavy and toxic metals such as chromium (Cr) has been investigated. One of the extremely harmful pollutants in rivers and seawater is the heavy metal ions due to their direct impacts on human, animals and plants are hexavalent Cr (VI). Consequently, highly sensitive sensor to detect Cr is essential. Surface plasmon resonance (SPR) technique has attracted huge research interest in detecting heavy metals specifically. In this study, three types of prism-based SPR sensor, gold (Au)/silver (Ag), Au/polyaniline (PANI) and Au/titanium dioxide (TiO₂) nanostructured films, are investigated as potential sensing material to detect the presence of Cr (VI) ions in water. The base Au layer with thickness of 48.3 nm is deposited on a glass slide for all sensors. For Au/Ag, Au/PANI nanofibers and Au/TiO₂ sensor films, the Cr (VI) concentration is varied from 1 ppm to 15 ppm with sensitivity of 0.270 °ppm⁻¹, 0.082 °ppm⁻¹ and 0.039 °ppm⁻¹, respectively. Based on these results, the Au/PANI nanofibers are the most sensitive to Cr (VI) among the tested sensing materials.