Adsorption of Pb(II) and Cu(II) by succinic anhydride-modified apple pomace

To address the environmental issues arising from the substantial accumulation of apple pomace (AP), a succinic anhydride-modified AP, denoted as SAMAP, was synthesized through succinylation for the treatment of heavy metal ions. The structural characteristics and the thermal stability of SAMAP were characterized by FTIR, CP/ MAS 13C NMR and thermogravimetry. The batch adsorption with a dosage of 35 g L-1 at pH 5.0 and ambient temperature indicated that adsorption rates of Cu(II), Zn(II), and Pb(II) by AP were 53.85%, 60.44%, and 82.24%, respectively, while those by SAMAP were 90.54%, 50.73%, and 89.83%, respectively. P-value analysis further confirms the significant difference in metal ion adsorption between AP and SAMAP. The maximum adsorption capacity of SAMAP for Pb(II) is 121.43 mg g-1. Column adsorption further verified the durability and applicability of SAMAP for treating Cu(II) and Pb(II). The adsorption mechanism of SAMAP for Cu(II), and Pb(II) primarily involves electrostatic interactions and the coordination via carboxylic groups on SAMAP, as supported by enhanced binding energies of C1s and O1s and a weakening vibration of C-O in carboxylic groups shown in XPS and FTIR spectra after adsorption. This study provides a promising potential for using AP to remove Cu(II) and Pb(II) in effluents.