Speciation Analysis of Cr(VI) and Cr(III) in Water with Surface-Enhanced Raman Spectroscopy

Olga Dvoynenko; Shih-Lin Lo; Yi-Ju Chen; Guan Wei Chen; Hsin-Mei Tsai; Yuh-Lin Wang; Juen-Kai Wang

doi:10.1021/acsomega.0c05020

Speciation Analysis of Cr(VI) and Cr(III) in Water with Surface-Enhanced Raman Spectroscopy

ACS Omega. 2021 Jan 8;6(3):2052-2059. doi: 10.1021/acsomega.0c05020. eCollection 2021 Jan 26.

Authors

Olga Dvoynenko¹, Shih-Lin Lo², Yi-Ju Chen², Guan Wei Chen¹, Hsin-Mei Tsai¹, Yuh-Lin Wang^{1

3}, Juen-Kai Wang^{1

4}

Affiliations

¹ Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
² Environmental Analytical Laboratory, Environmental Protection Administration, Taoyuan City 32024, Taiwan.
³ Department of Physics, National Taiwan University, Taipei 10699, Taiwan.
⁴ Center for Condensed Matter Sciences, National Taiwan University, Taipei 10699, Taiwan.

Abstract

Identifying and quantifying chromium in water are important for the protection of precious water resources from chromium pollution. Standard methods however are unable to easily distinguish toxic hexavalent chromium, Cr(VI), from innocuous trivalent chromium, Cr(III), are time-consuming, or require large sample quantity. We show in this report that Cr(VI) and Cr(III) in water can be differentiated based on their distinct spectral features of surface-enhanced Raman scattering (SERS). Their SERS signals exhibit different pH dependences: the SERS features of Cr(VI) and Cr(III) are most prominent at pH values of 10 and 5.5, respectively. The obtained limit of detection of Cr(VI) in water is below 0.1 mg/L. Both concentration curves of their SERS signals show Langmuir sorption isotherm behavior. A procedure was developed to quantify Cr(VI) concentration based on the direct retrieval or addition method with an error of 10%. Finally, the SERS detection of Cr(VI) is shown to be insensitive to co-present Cr(III). The developed SERS procedure offers potential to monitor toxic chromium in fields.