Publication

Abstract : The process of identifying the presence of heavy metals in water is crucial in industries causing heavy metal pollution so that apt treatment processes can be followed. Visual detection serves as an effective qualitative detection method, in which a particular metal can be selectively identified by colour changes. For the first time, a highly selective visual detection procedure of Pb(II) in water is reported using a floral extract. The flowers of Ixora coccinea have been chosen for our study because of its easy availability and non-toxicity. Nine different metals such as Ni(II), Cu(II), Fe(II), Fe(III), Hg(II), Zn(II), Cd(II), Pb(II) and Cr(VI) were investigated using ethanolic extract of the flower under basic condition. Among the nine different metals, the floral extract responded positively only for Pb(II). The extract was coated on top of common ear buds and observed for colour change just by dipping it in metal ion solutions. Coating on the ear buds enhanced the ease through which we could recognize the presence of Pb(II) just by 'dip and look' procedure. The interference from co-existing cations and anions with the detection method was investigated. The detection limit using the suggested method was found to be 0.4ppm. The UV and GC-MS results prove that the selective colouration is due to the complex formation of flavonols in the extract with Pb(II). The proposed method also answered positively while tested for an industrial effluent containing 4ppm Pb(II) ion. Thus, a novel receptor based on a natural extract has been developed and verified for sensing Pb(II) ions using easy-to-use tool like ear buds, which can be viable by small-scale industries from developing countries. © 2019 Elsevier Ltd.