Turmeric Powder as a Natural Heavy Metal Chelating Agent: Surface Characterisation

The present study was conducted to investigate surface properties of turmeric in order to evaluateits detoxification potential and ability to sequester toxic metals ions. Scanning Electron Microscopy (SEM),Energy Dispersion Spectroscopy (EDS), Infra-Red (IR) spectroscopy and potentiometric titrations wereemployed for characterisation of the surface of turmeric powder. Spectroscopic studies revealed that thesurface of turmeric powder was porous mainly composed of polymeric -OH , -NH , -CH2 , -COO and-OH groups of polysaccharides. From potentiometric titrations and modelling of batch titration data, it wasfound that surface of the turmeric contains at least four binding sites with pKa values 3.56 (pK1), 4.83(pK2), 7.68 (pK3) and 10.4 (pK4). Turmeric powder contains highest concentration of amino and hydroxylgroups for the pK4 values i.e., 0.55 mmol/ g. The total binding sites concentration for turmeric powderwas 1.2 mmol/ g.