Synthesis and characterization of Cu²⁺ imprinted polymer-tannin extract from mango leaf (Mangifera indica L.) for selective separation of Cu²⁺

Tannins are secondary metabolites in Mango (Mangifera indica L.). This compound has a cluster of polyphenols as functional ligands for chelating Cu(II). Cu(II)-imprinted polymer-tannin (Cu-IP-tannin) was successfully synthesized by polymerization of phenol and formaldehyde with the complex of Cu(II)-tannins in acidic medium. Non-imprinted polymer (NIP) was similarly prepared without the presence of Cu(II) ions. The polymers were characterized by Scanning electron microscopy energy dispersive x-ray spectroscopy (SEM-EDS) and Fourier transform infra-red (FTIR). Cu(II) ions were completely removed by leaching the dried and powder of imprinted polymer with HNO₃ 0.5 M. The optimum pH of maximum adsorption of Cu(II)-IP-tannin was 7.0 for 120 minutes of contact time. The adsorption of Cu(II)-IP-tannin followed the Freundlich isotherm model with a maximum adsorption capacity of 99.08 mg/g. The relative values of the selectivity factor (α_r) of Cu(II)/Ni(II), Cu(II)/Pb(II) and Cu(II)/Fe(II) on a single metal ion selectivity test were 23.89, 55.71 and 26.25, respectively.