Removal of Heavy Metals from Aqueous Solution by Apple Residues in Packed Columns

The column experiments were carried out ir,a glass column of 1.5 cm internal diameter and 30 cm length with apple residues (AR) and phosphated AR (P-AR) to investigate the removal characteristics of copper, lead and cadmium from aqueous solution. The effects of feed concentration, chemical tratment of AR, feed rate, co-ion, cations and ligand were studied. The cation exchange capacity of the original AR Nas very low. AR was modified with phosphorus (V) oxychloride to improve its physico-chemical properties and greatly enchanced the capacity of metal removal. The metal removal capacity by P-AR was three to four times higher than that by AR in the removal of copper and lead. AR as well as P-AR showed higher selectivity for lead ions than copper and cadmium ions. The presence of organic ligand in solution significantly decreased the capacity of copper removal due to metal-ligand complex formation. After exhaustion of the residues, the column was regenerated successfully by a simple elution procedure.