Preparation of modified silica for heavy metal removal

2-hydroxy-5-nonyl-acetophenoneoxime, di-2,4,4-trimethylpentyl phosphinic ac id, and a tertiary amine were bound on the silica surface after surface mod ification. The adsorption of the metal chelating agents appears to be due t o physical attraction such as van der Waals interactions and not covalent b onding. Stability tests show that the adsorbents are stable under acidic co nditions. Batch tests were conducted fur heavy metal ion adsorption and elu tion. Heavy metal ions which were adsorbed to the surface of the adsorbents could be recovered by elution with 0.1 M HCl.