Adsorption Parameters of Cd(II), Pb(II), and Hg(II) on Zirconium(IV) Phosphate Chemically Grafted onto Silica Gel Surface

✍ Scribed by Noemi Nagata; Lauro T. Kubota; Maria I.M.S. Bueno; Patricio G. Peralta-Zamora

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 126 KB
• Volume: 200
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1997.5344

✦ Synopsis

have given rise to great interest for analytical purposes (12), Adsorption properties of metallic ions not essential for human since several evaluations have demonstrated that most of metabolism, such as cadmium, lead, and mercury, on silica chemthese materials show strong adsorption capacities and mainly ically modified with zirconium( IV ) phosphate, SiZrP, were invesselective characteristics, important for speciation (13). Sevtigated using batch systems. The immobilization procedure was eral investigations have demonstrated that modified materiefficient and the functionalization degree was 2.82% for zircoals are able to adsorb nonessential metal ions such as cadnium ( 0.31 mol g 01 ) and 2.54% for PO 30 4 (0.27 mol g 01 ) . These mium, lead, and mercury, which are potential pollutants.

results indicate that phosphate reacted with zirconium in a 1:1

However, more emphasis has been given to silica modified ratio. The equilibrium is reached very quickly ( 15 min ) , indicatwith organic groups that are able to provide a great number ing that the adsortion sites are well exposed. The best adsorption parameters were evaluated using 50 mL of aqueous phase at pH of different materials ( ) to adsorb metal ions from aqueous 4.5, an adsorption time of 15 min, and 0.2000 g of adsorbent. (15) and nonaqueous solvents (18-20).

From adsorption isotherms obtained for the metals ions and dis-

For inorganic functionalized silica, few studies of metal tribution coefficients the affinity of SiZrP for the metal ions studion adsorption properties have been described in the literaied increases in the order Cd( II) õ Pb( II) õ Hg( II ). Twice as ture (21, 22). However, these materials can present advanmuch lead was adsorbed by the SiZrP surface ( Nf Å 10.0 mmol tages such as stability, adsorption of cations or anions deg 01 ) as cadmium ( Nf Å 5.0 mmol g 01 ) . For mercury, the capacity pending on the solution pH (23), and high selectivity (24), was greater ; nevertheless an adsorption plateau was not observed.

giving rise to separation or even speciation (25).