Assessment of nano-functionalized cellulosic paper for selective estimation of Cr (VI) using diffuse reflectance spectroscopy

ABSTRACT Contamination by hexavalent chromium [Cr (VI)] poses a threat to groundwater quality and its detection at point source is essential to provide early mitigating solutions. In this work, we report the fabrication of paper-based sensing system embedded with a novel nano-chromogenic complex having spherical gold nanoparticles modified with 1,5-diphenylcarbazide dye. This Au-DPC Functionalized paper strip develops pink color in <2 sec upon interaction with Cr (VI). With the developed optical fiber device a limit of detection of 0.02 ppm was achieved within a linear range of 0.01–0.4 ppm. RGB color analysis and data driven predictive modelling (KNN-model) demonstrated highest balanced accuracy score of 0.833 and cross validation accuracy of 0.714. Further, the portable optical fiber-based device offers advantages such as real-time monitoring, remote sensing capabilities, and the ability to integrate with existing optical systems for enhanced detection and analysis.