Sorption of Zn(II) on marine sediments by a sequential extraction-radiotracer technique

The sorption behavior of Zn(II) on the mineral fractions of a marine sediment collected from Sagami Bay (Japan) was investigated using a sequential extraction-radiotracer technique. The extractions used were: (i) 1 M CH3COONH4; (ii) 4 × 10−2 M NH2OHt·HCl/25% CH3COOH; (iii) 30% H2O2(pH 2); and (iv) 7 M HNO3. The residues remaining after the chemical treatment were collected, and used for the sorption experiments with 65Zn(II) as a tracer. The sorption isotherms of 65Zn(II) on all the fractions except for one with a strong acid treatment fitted a Langmuir type equation. The capacities of the individual mineral fractions for 65Zn(II) sorption were estimated from the isotherms. Treatment with 7 M HNO3 removed almost all the sorptive sites for Zn(II) ions.