The chelating resins Dowex A1 and its purified form, Chelex 100, contain the iminodiacetate functional group. The resins can exchange cations from solutions of high pH and anions from low pH solutions. Further, the iminodiacetate functional group provides chelating capability leading to special selectivity for multivalent ions such as Sb(V) and Hg(II). A systematic study of the sorption characteristics of Chelex 100 was initiated in our laboratory. Distribution coefficient values (Kd) were measured for Zn(II), Cd(II), Sn(IV), Sb(V) and Hg(II) as a function of HCl concentration and for Cu(II) and Pb(II) as a function of pH. The results obtained thus far indicate that Sb(V) and Hg(II) have high Kd values in acid chloride solutions. A radiochemical separation procedure was developed for the determination of Hg by neutron activation analysis using sorption onto Chelex 100.
The sorption of uranium-Arsenazo III complex was studied using Dowex-1x8 and carbonized apricot stone. The results show a
similarity between the two sorbents since the percentage uptake of a uranium complex in the ratio 1 : 1 reaches 100% and 92%
on the Dowex-1x8 and the carbonized apricot stone, respectively. Also the uptake of the complex on either sorbents increases
with increasing the hydrogen ion concentration to reach a maximum value at pH 2.5. The two sorbents are used to study the
sorption of uranium(VI) from seawater in the presence of 0.002% of Arsenazo III and 10-3M EDTA, where it is found that uranium is completely sorbed by the two sorbents.
Authors:G. Pacheco, G. Nava-Galve, P. Bosch, and S. Bulbulian
The ability of some antural Mexican clays to sorb radioactive Co from aqueous solution and then desorb it has been measured. The clay cations seem to be exchanged with cations present in the solution. It was observed that the amount of sorbed Co2+ depends nearly linearly on the Na++K+ content in the montmorillonites. It was found that the crystallinity was not altered after Co2+ sorption. Crystallinity of clays, before and after cobalt exchange, was determined by X-ray diffraction.
Authors:K. Ioannides, T. Mertzimekis, D. Karamanis, K. Stamoulis, and I. Kirikopoulos
The kinetics of radiocesium sorption and desorption by cation solutions and the corresponding radiocesium distribution profiles in sediment cores were investigated. The results have shown that a significant percentage of radiocesium is adsorbed in the sediments during the first 3 d. Radiocesium reaches rapidly (< than 5 d) at a depth which does not exceed 3.5 cm. The desorption of radiocesium was found to depend on cation concentrations. Empirical laws are derived both for cesium adsorption and desorption.
Authors:J. Goworek, A. Kierys, M. Iwan, and W. Stefaniak
Mesoporous materials MCM-41 with the hexagonal arrangement of pores
were obtained using dodecyltrimethylammonium bromide and octadecyltrimethylammonium
bromide as templating surfactants. Adsorption of toluene and propan-1-ol on
the as-synthesized MCM-41 silica samples was investigated using the TG-DTG,
DTA and DSC techniques. The sorption mechanism of used adsorptives is discussed
in terms of hydrophobicity of pore interior filled with template as well as
Information about the sorption of radionuclides on natural materials used for cementation of liquid radioactive wastes (RAW) is important for predictions of migration rates of radionuclides in the products of fixation. Cementation process for conditioning liquid RAW uses, besides cement, materials which improve quality of products. In Czechoslovakia technology among these materials are clinoptilolite tuffit, mordenite tuff, tobermorite and fly ash. Liquid RAW issued from nuclear power plants contains the principal radionuclides60Co,134Cs and137Cs, therefore, a sorption study of these radionuclides was carried out. pH of liquid RAW was 12.5–13.7 and salt content ca. 200 g·dm–3. Results of sorption are given by distribution coefficients. The best results for cesium in those pH region and salt content had mordenite tuff DCs=100 dm3·kg–1 and the worst results had fly ash DCs=4.1 dm3·kg–1. The best results for cobalt in those solutions had tobermorite DCo=38 dm3·kg–1 and the worst results had fly ash DCo=6.9 dm3·kg–1.
In this paper, the special sorption properties of mercury(II) on calcium-montmorillonite is shown. Mercuric hydroxide (Hg(OH)2) produced by the hydrolysis of mercuric ions is fairly soluble, solubility is 3.2 × 10−4 mol/dm3. As a result, indifferently of the usual behavior of other hydroxides, it remains in the aqueous solution. The sorption properties
are determined by the fact: there is no precipitation at higher pH values. Montmorillonite contains permanent as well as pH-dependent
charges, so the cation exchange on the permanent changes, in the interlayer space of montmorillonite and the sorption of neutral
mercuric hydroxide molecules can be studied simultaneously. So, two interfacial processes of the same substance, namely the
ion exchange of hexahydrate mercuric(II) ions and the sorption of neutral mercuric hydroxide molecules, can be studied in
the same system.
Authors:Songsheng Lu, Lei Chen, Yunhui Dong, and Yixue Chen
Iron oxide/multiwalled carbon nanotube magnetic composites (denoted as magnetic composites) were synthesized and characterized
in detail. The magnetic composites can be separated from aqueous solution easily by using magnetic separation method. The
application of magnetic composites in the removal of Eu(III) from large volumes of aqueous solutions was studied. The results
indicated that the sorption of Eu(III) on the magnetic composites was strongly dependent on pH values and weakly dependent
on ionic strength. The sorption of Eu(III) on the magnetic composites was mainly dominated by inner-sphere surface complexation.
The linear sorption isotherms of Eu(III) suggested that Eu(III) sorption on the magnetic composites was far from saturation.
The large sorption capacity and the easy magnetic separation method indicate that the magnetic composites may be a promising
suitable material in nuclear waste management in future.
The study was undertaken to evaluate the feasibility of oxidized multiwalled carbon nanotube (oxidized MWCNT) for the removal
of radiocobalt (60Co) from aqueous solutions. The oxygen functional groups of oxidized MWCNT were characterized by FT-IR and XPS. Batch experiments
were performed to study the sorption of cobalt as a function of contact time, solid contents, pH, ionic strength, foreign
ions, and temperature. Two kinetic models viz. pseudo-first-order and pseudo-second-order were used to determine kinetic sorption
parameters, and the kinetic sorption could be described more favorably by the pseudo-second-order model. The thermodynamic
parameters (∆G°, ∆S°, ∆H°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II)
on oxidized MWCNT was an endothermic and spontaneous processes. The results suggest that oxidized MWCNT can be used efficiently
in the treatment of industrial effluents containing radioactive and heavy metal ions.
Authors:A. Kitamura, T. Yamamoto, S. Nishikawa, and H. Moriyama
Sorption behavior of Am(III) onto granite was investigated. The distribution coefficient (Kd) of Am(III) onto granite was determined in the solution of which pH was ranged from 2.9 to 11.4 and ionic strength was set
at 10−2 and 10−1. TheKd values were found to increase with increasing pH and with decreasing ionic strength. The obtained data were successfully
analyzed by applying an electrical double layer model. The optimum parameter values of the double layer electrostatics and
adsorption reactions were obtained, and the selective adsorption behavior of Am(III) onto the granite was discussed.