Adsorption of Cesium, Strontium, and Cobalt Ions on Magnetite and a Magnetite-Silica Composite
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- 作者：Armin D. Ebner ; James A. Ritter ; and James D. Navratil
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2001
- 出版时间：April 4, 2001
- 年：2001
- 卷：40
- 期：7
- 页码：1615 - 1623
- 全文大小：151K
- 年卷期：v.40,no.7(April 4, 2001)
- ISSN：1520-5045
文摘
Constant pH adsorption isotherms for nonradioactive Cs+, Sr2+, and Co2+ on pure magnetiteand a 80% (w/w) magnetite-silica composite were measured at 25 
C over a wide range of metalion concentrations. The adsorption studies were carried out at four different pH's: 6, 7, 8, and9 for Cs+ and Sr2+ and 5, 6, 7, and 8 for Co2+. All of the constant pH isotherms exhibited typeI behavior with a saturation capacity that was pH-dependent and increased with increasingpH. The corresponding distribution coefficients increased with increasing pH but decreased withincreasing metal ion concentration; they were also 10-1000 times lower than those reported inthe literature for more selective but more expensive adsorbents. These two magnetite-basedadsorbents also exhibited moderate regeneration conditions, with nearly 90-100% regenerationachieved in most cases at pH values between 1 and 3. A Langmuir model with pH-dependentparameters was also fitted successfully to all of the constant pH adsorption isotherms. Thisexperimental data and the corresponding pH-dependent Langmuir correlation should findconsiderable use in the design and development of inexpensive fixed-bed adsorption processesfor the removal of the radioactive isotopes of Cs+, Sr2+, and Co2+ from aqueous solutions thatare produced in nuclear facilities. Magnetite, when encased in silica and placed in a packedcolumn, can also be used as the charging element in high gradient magnetic separation, therebyremoving not only metal ions via surface complexation (adsorption) but also nanoparticles of aparamagnetic nature.
C over a wide range of metalion concentrations. The adsorption studies were carried out at four different pH's: 6, 7, 8, and9 for Cs+ and Sr2+ and 5, 6, 7, and 8 for Co2+. All of the constant pH isotherms exhibited typeI behavior with a saturation capacity that was pH-dependent and increased with increasingpH. The corresponding distribution coefficients increased with increasing pH but decreased withincreasing metal ion concentration; they were also 10-1000 times lower than those reported inthe literature for more selective but more expensive adsorbents. These two magnetite-basedadsorbents also exhibited moderate regeneration conditions, with nearly 90-100% regenerationachieved in most cases at pH values between 1 and 3. A Langmuir model with pH-dependentparameters was also fitted successfully to all of the constant pH adsorption isotherms. Thisexperimental data and the corresponding pH-dependent Langmuir correlation should findconsiderable use in the design and development of inexpensive fixed-bed adsorption processesfor the removal of the radioactive isotopes of Cs+, Sr2+, and Co2+ from aqueous solutions thatare produced in nuclear facilities. Magnetite, when encased in silica and placed in a packedcolumn, can also be used as the charging element in high gradient magnetic separation, therebyremoving not only metal ions via surface complexation (adsorption) but also nanoparticles of aparamagnetic nature.