Authors:Dong Wenming, Wang Xiangke, Shen Yi, Zhao Xudong, and Tao Zuyi
The factors affecting the sorption of radiocobalt by bentonite and kaolinite were studied with the aim to assess important factors which should be included in modelling radiocobalt migration in soils and waters. The distribution coefficients of radiocobalt sorption on bentonite and kaolinite from aqueous solutions were determined by using the batch method, and it was found that they were insensitive to the loading, the initial pH, the ionic strength, the humic substance and the sorption direction. Thus, the sorption characteristics of radiocobalt on bentonite and kaolinite facilitated the mathematical modelling of radiocobalt migration. In addition, the sorption kinetics and the sorption mechanism of radiocobalt on bentonite and kaolinite were also examined.
Authors:M. Olguin, M. Solache-Rios, D. Acosta, P. Bosch, and S. Bulbulian
The capacity of bentonite and purified bentonite to remove UO
ions from aqueous solutions has been investigated. The UO
uptake in these clays was determined for 0.2 and 0.002M uranyl nitrate solutions. It was found that under these conditions (0.2M) the maximum UO
uptake was 1.010±0.070 meq UO
/g of bentonite and 0.787±0.020 meq UO
/g of purified bentonite. In purified bentonite UO
sorption is irreversible up to 50 hours as no desorption was observed. Such is not the case in the natural bentonite. X-ray diffraction, thermal analyses, and transmission electron microscopy were used to characterize the solids. The uranium content was determined by neutron activation analysis.
-doped and non-doped organic aerogels and sorption properties of consequent (pyrolysed) carbonaceous materials.
Five samples of aerogels based on condensation of resorcinol (p
Authors:Chun-Nan Hsu, Dai-Chin Liu, and Hwai-Ping Cheng
The kinetic and equilibrium sorption behaviors of Cs+ on mordenite, a zeolite which can sorb cesium well, were investigated by using the batch method. Cesium-137 and the stable CsNO3 were used as tracer and carrier to study the influences on Cs+ sorption behaviors by changing Cs+ initial concentration, pH value, particle size of mordenite and experimental temperature. The equilibrium was reached in 3 days and the saturated amount of cesium sorbed is about 0.19 kg Cs/kg NM. The sorption data at 25°C and 90°C were fitted to Freundlich sorption model and nonlinear isotherms were found. However, linear isotherm was applicable with a Cs+ initial concentration less than 10–3M. The decrease of Cs+ sorption at elevated temperature suggested the sorption reaction was exothermic. The use of centrifugation to separate the liquid from solid phases in traditional batch techniques was not suitable to the kinetic experiment of Cs sorbed by mordenite for lower concentrations.
Authors:N. Kamei-Ishikawa, K. Tagami, and S. Uchida
This study investigated selenium sorption kinetics on humic acid (HA) as a function of initial Se concentration (10–300 μg·1−1) and solid/liquid ratio (0.01–0.1). From the result, it was clear that the Se sorption kinetics on HA could be expressed
by a pseudo-second order equation. This was possible because the sorption mechanism on HA is a multiple sorption process including
specific and non specific mechanisms. Additionally, the 3-D empirical equation for the amount of sorbed Se could be determined
as a function of the initial Se concentration and solid/liquid ratio.
The distribution coefficients for iodine have been determined in the system “hydrated manganese dioxide—nitric acid” (KD∼104). Some factors affecting the kinetics and yield of sorption are discussed, and the possibilities of practical application
indicated. A mechanism is outlined to explain the sorption of iodine on hydrated manganese dioxide.
Authors:P. S. Remya Devi, S. Kumar, R. Verma, and M. Sudersanan
Sorption of inorganic mercury (Hg2+) and methyl mercury, on chemically synthesized polyaniline, in 0.1-10N HCl solutions has been studied. Hg2+ is strongly sorbed at low acidities and the extent of sorption decreases with increase in acidity. The sorption of methyl
mercury is very low in the HCl concentration range studied. Sorption of Hg2+ on polyaniline in 0.1-10N LiCl and H2SO4 solutions has also been studied. The analysis of the data indicates that the sorption of Hg2+ depends on the degree of protonation of polyaniline and the nature of mercury(II) chloride complexes in solution. X-ray photoelectron
spectroscopy analysis (XPS) of polyaniline sorbed with mercury show that mercury is bound as Hg2+. Sorbed mercury is quantitatively eluted from polyaniline with 0.5N HNO3. Polyaniline can be used for separation and pre-concentration of inorganic mercury from aqueous samples.
Authors:M. Olguín, I. García-Sosa, and M. Solache-Ríos
The apparent diffusion coefficient of Sr2+ in natural Mexican erionite from Sonora at different pH and concentrations were determined. Neutron activation was applied to measure the sorption of strontium. The apparent diffusion coefficient values showed that the mobility of Sr2+ through the cavities of the erionite depended on the concentration of strontium and the pH of the solution. As a consequence the sorption of this ion by the erionite was affected by these parameters and the maximum sorption of Sr2+ was at pH higher than 3 and 0.0094 mol·l–1 strontium nitrate solution.
The sorption-desorption of uranium (VI) on Grimsel granite of Switzerland was studied under oxidizing conditions with an initial uranium concentration range of between 9.7·10–7 and 4.5·10–4M, using a batch technique. The sorption coefficients varied between 8.0 and 0.4 ml/g and sorption was not fully reversible. The data could be fitted to a Freundlich isotherm. By fitting the data with the Dubinin-Radushkevich equation, a mean energy of sorption of 10.7 kJ/mol was calculated, which corresponds to the energy of ion exchange reactions. The kinetic data could be interpreted by assuming diffusion into the crushed granite particles. The calculated pore diffusion coefficient was between 2.0·10–11–7.7·10–11 m2/s.