Surface modification of sporopollenin with calixarene derivative: Characterization and application for metal removal

In this study, p-tert-butylcalix[4]-aza-crown (CAC) immobilized sporopollenin (Sp) was used as a sorbent for the removal of Cu(II), Pb(II) and Zn(II) from aqueous media. Sporopollenin was firstly functionalized with 3-chloropropyltrimethoxysilane (CPTS) in order to obtain chloro-sporopollenin (Sp-Cl). The Sp- Cl was reacted subsequently with CAC yielding CACbonded sporopollenin (Sp-Cl-CAC). The new sorbent was characterized by infrared spectroscopy (FTIR), thermal analysis (TG/DTG) and scanning electron microscopy (SEM). The sorption properties of modified sorbent (Sp-Cl-CAC) are also investigated. The optimum pH values for the separation of metal ions from aqueous solution onto Sp-Cl-CAC were 5.0 for Pb(II) and Cu(II) and 5.5 for Zn(II). The maximum sorption capacities for Cu(II), Pb(II) and Zn(II) were 0.07 (4.44 mg g -1), 0.07 (4.58 mg g -1) and 0.14 (29.00 mg g -1) mmol g -1, respectively. Sorption thermodynamic parameters of such as free energy (δG°), enthalpy (δH°), and entropy (δS°) were evaluated. © Springer Science+Business Media B.V. 2011.