A selective and efficient chemosensor for the rapid detection of arsenic ions in aqueous medium

The development of selective, efficient, and economical sensors for the rapid determination of arsenic in an aqueous medium is of paramount importance, due to its negative impact on human health. In this study, zinc nanoparticles (ZnNPs) were prepared based on chitosan-functionalized Congo red dye (CFCR) via chemical synthesis. The characterization of the as-prepared material showed an interaction between Zn salt and CFCR. The FT-IR spectra revealed the presence of absorbing functional groups and suggest the formation of a cyclometalated-azo-compound due to a possible interaction between Zn and the N=N azo bond of CFCR. Also, TGA studies affirm that the presence of Zn increases the compactness of the material, thereby reducing the amount of weight loss via high-temperature pyrolysis. A monoclinic semicrystalline phase of CFCR-ZnNPs was revealed by XRD, while an oval-shaped and irregular particle distribution with sizes similar to 100 nm was observed in the TEM. The aqueous solution of CFCR-ZnNPs displayed excellent selective chemosensory property toward As3+ with an immediate color change from pink to blue. The new chemosensor was able to detect arsenic to as low as 1 mu g/mL at lower pH which is below the permissible limit of 10 mu g/mL in drinking water. Thus, the newly prepared material could be used for the selective detection of the As3+ ions aqueous medium.