Selective Entrapment of Pb2+ from Fresh Thunbergia laurifolia Leaves Extract and Thunbergia laurifolia Tea Extract

Abstract

The leaves of Thunbergia laurifolia and its tea were extracted by water. The abilities to chelate heavy metal ions of the extracts were studied by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and atomic absorption spectroscopy (AAS). The results showed that the extracts exhibited high selectivity for Pb 2+ chelation via a favourable-selective precipitation to Pb 2+ in aqueous solutions compared to other metal ions, such as Zn 2+ , Cu 2+ and Fe 3+ . The Pb 2+ removal capability of the extracts were 51-52%. The selective Pb 2+ -trapping process of the extracts of Thunbergia laurifolia could be attributed to predominant presence of the phytochemical compounds, tannin and saponin, in the Thunbergia laurifolia leave and tea. Moreover, Thunbergia laurifolia tea also exhibited antioxidant property as demonstrating by the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical method.