Anthocyanin from red beetroots for sensing and removing nickel ions from water

Abstract

Anthocyanin is a natural colorant that is suspected to have chelation ability with metal ions. In this study, anthocyanin was extracted from red beetroots (Beta vulgaris), purified by chelating with basic lead acetate, reconverted, and used for qualitative analysis with the addition of various heavy metal ions (Cd2+, Ni2+, Fe3+, Cr3+) that are considered as environmental pollutants. The aim was to investigate whether anthocyanin could be used as a sensing and chelating material for harmful heavy metal ions from water. UV-visible spectra were recorded within the same wavelength range (200 nm-900 nm) while adding micro drops of highly concentrated known aqueous solutions of these metal ions (0.1 M) to the anthocyanin solutions prepared by dissolving 0.100 g of precipitated anthocyanin in 3 mL of 5% HCl in methanol. Unlike the other heavy metal ions studied, only Ni2+ showed some spectral changes with an isosbestic point at λmax ~ 430 nm, in 5% HCl in methanol at pH 4.5, indicating Ni2+ to anthocyanin interaction, probably through coordinating anthocyanin to Ni2+ center. The spectral data also showed the appearance of a new band around 400 nm, upon adding Ni2+. Hence, this study could be developed for using anthocyanin extracted from red beetroot for detecting Ni2+ present in water.