Adsorption of Co{sup 2+} and Zn{sup 2+} ions on hydrous Fe(III), Sn(IV), and Fe(III)/Sn(IV) oxides

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Journal of Colloid and Interface Science

DOI:https://doi.org/10.1006/jcis.1996.0594· OSTI ID:404604

Misak, N Z; Ghoneimy, H F; Morcos, T N ^[1]

---

1. Atomic Energy Authority, Cairo (Egypt)

Thermal analysis has shown that contrary to the case of Zn{sup 2+}, considerable amounts of water enter in HFO (hydrous ferric oxide), HSO (hydrous tannic oxide), and HMO (hydrous mixed oxide) when Co{sup 2+} is adsorbed. A large amount of Co{sup 2+} and Zn{sup 2+} in all the oxides cannot participate in isotopic exchange, seemingly because of being trapped inside the micropores, a fact hindering oxide capacity determination by isotopic dilution. The % adsorption-pH curves for tracer and 10{sup {minus}3} M transition metal chloride solutions show a general preference to Zn{sup 2+} over Co{sup 2+} by all the oxides, in agreement with thermal analysis data. Large shifts of these curves to the left occur with tracer experiments on many samples on adding 0.1 M NaCl, probably due to Cl{sup {minus}} adsorption accompanied by a change in the adsorption mechanism. Conclusions from log K{sub d}-pH plots may be erroneous, probably due to changes in the activity coefficients of surface species even at sufficiently low surface coverages. More adsorption of Co{sup 2+} and Zn{sup 2+} generally occurs on the oxide of lower pH{sub PZC} (higher acidity).

• OSTI ID: 404604
• Journal Information: Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 1 Vol. 184; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ADSORPTION
COBALT
HYDRATION
IRON OXIDES
PH VALUE
SORPTIVE PROPERTIES
THERMODYNAMIC PROPERTIES
TIN OXIDES
ZINC