Syzgium cumini extract- a natural naked eye colorimetric sensor for selective and sensitive detection of Fe2+ in aqueous medium

Detection of metal ions using colorimetric technique offers a key to the development of a selective methodology to the qualitative analysis of the metal ions. In the current investigation, the utilization of abundantly available natural resource has been done wherein a simple fruit extract from Syzgium cumini in water offered a natural sensor to detect as well as eliminate Fe2+ ions, a pollutant from potable water. In the Indian subcontinent, the tropical fruit Syzgium cumini, also known as jamun in the local language, is widely grown. Anthocyanin is the main component of Syzgium cumini extract (SCE). Anthocyanin has been shown to form stable coordination complexes with heavy metal ions such as Al3+, Sn3+, and others. As a result, divalent transition metal ions such as Cu, Mn, Co, Fe, and Ni, which are possible metal contaminants in the environment, were chosen for this investigation. Only Fe2+ ions generated a Prussian blue coloured complex with SCE and the complex could be removed with a simple centrifugation process. The sensitivity of SCE towards Fe2+ ions was found to be in the region of 1 ppm, indicating that this green approach is extremely sensitive and selective.