University of Texas at Austin. — In: Lake, C.B., R.K. Rowe 2005: A comparative assessment of volatile organic compound (VOC) sorption to various types of potential GCL bentonites. — Geotextiles and Geomembrans, 23, pp. 323 – 347
Authors:C. Barba, M. Martí, A. Roddick-Lanzilotta, A. Manich, J. Carilla, J. L. Parra, and L. Coderch
that water sorption of wool is well documented [ 8 ], there are few data on water sorption of human nails.
The amount of water in a sample may be expressed in terms of either regain or moisture content. Regain is the mass of adsorbed water over
As part of the laboratory support program for the field migration experiment at the Grimsel Test Site (GTS) in the Swiss Alps, the sorption behaviour of cesium on Grimsel mylonite was studied. Batch sorption experiments were carried out in N2 atmosphere (<3 ppm O2). The adsorption isotherms were reversible and non-linear for cesium concentrations of between 3.2·10–8 and 5.0·10–4M. Two different sites appear to be involved in sorption depending on whether Cs loading was high (10–6–10–3 meq/g) or low (10–7–10–6 meq/g). At low Cs loadings adsorption was considered to occur mainly at the crystal edges of mica particles. Selectivity coefficients for exchange between cesium and potassium were calculated for different Cs loadings. It was suggestd that by varying the potassium concentration of the solution and by making some assumptions, a Kd value for cesium at the migration site could be estimated. Data were fitted to both Freundlich and Dubinin-Radushkevich isotherms. The empirical Freundlich parameters enabled a site distribution function to be calculated and a mean energy of sorption of about 12 kJ/mol was found using Dubinin-Radushkevich isotherms approach.
Batch sorption experiments with237Np using kaolinite and molasse clays were carried out under oxic conditions. The sorption kinetics and the effects of particle size of clay samples, concentration of neptunium in the solutions and the pH below and above the point of zero charge of the clays on the sorption coefficients were studied. The sorption coefficients of neptunium, on kaolinite were between 23 and 1100 ml/g at pH 1.5 and 7.6, respectively, whereas, sorption on the molasse clay was not affected significantly by pH (Rd
Sorption of Co on bentonite has been studied by using a batch technique. Distribution coefficients (Kd) were determined for the bentonite-cobalt solution system as a function of contact time, pH, sorbent and sorbate concentration and temperature. Sorption data have been interpreted in terms of Freundlich, Langmuir and Dubinin-Radushkevich equations. Thermodynamic parameters for the sorption system have been determined at three different temperatures. The positive value of the heat of sorption,
H0=22.08 kJ/mol at 298 K shows that the sorption of cobalt on bentonite is endothermic, where as the negative value of the free energy of sorption,
G0=–10.75 kJ/mol at 298 K shows the spontaneity of the process.
G0 becomes more negative with an increase in temperature which shows that the sorption process is more favourable at higher temperatures. The mean free energyE
7.7 kJ/mol for sorption of cobalt on bentonite shows that ion-exchange is the predominant mode of sorption in the concentration range of the metal studied i.e. 0.01 to 0.3 mol/dm3. The presence of some complementary cations depress the sorption of cobalt on bentonite in the order of K+>Ca2+>Mg2+>Na+. Some organic complexing agents and natural ligands also affect the sorption of cobalt. The desorption studies with ground water at low cobalt loadings on bentonite show that about 97% metal is irreversibly sorbed.
Batch sorption experiments using nickel have been carried out on marl, a sedimentary, carbonaceous rock. All experiments were performed with a synthetic water of pH 7.3 and in an atmosphere of N2/1% CO2. Over the equilibrium nickel concentration range of 10–11–10–5M, sorption was linear and reversible with Rd of 819 ml g–1. Owing to the linear sorption behavior, Rd was independent of rock/water ratio (r/w=1/5–1/100). The data suggested that at [Ni] lower than 10–7M an isotope exchange mechanism operated, whereas at higher [Ni], sorption involved ion exchange. Sorption experiments on some of the components of marl indicated that nickel adsorbs mainly on the clay minerals and on the trace of iron hydroxide present; sorption on calcite and quartz was low.
Authors:L’. Fortunová, M. Reháková, S. Nagyová, S. Dolinská, S. C. Mojumdar, and E. Jóna
The study of the sorption of pyridine derivates by copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) is a continuation of our previous study of copper forms of zeosorbents
Chelating resins are used for preconcentrating metal ions in trace analysis. As part of a systematic study of sorption characteristics
of the chelating resin Chelex 100, the sorption of Zn(II) and Cd(II) in different aqueous media was investigated. The distribution
coefficient (DC) values for both Zn(II) and Cd(II) were extremely low (<4) in 0.5 to 6M HNO3 and H2SO4 solutions. In HCl solution, theDC values for both Zn(II) and Cd(II) were higher, reaching a peak of nearly 40 in 3M HCl solutions. TheDC values for both Zn(II) and Cd(II) increased with increasing pH in chloride, nitrate, and sulfate solutions (0.1M); the value
was nearly 104 for both Zn(II) and Cd(II) between pH 5 and 7 and pH 6 and 8, respectively.
Authors:A. A. Helal, Aly A. Helal, N. Z. Salim, and S. M. Khalifa
A humin sample, isolated from organic soil (peat) was used to investigate its interaction with different kinds of radioelements
in batch systems. The sorption of the radionuclides 110mAg, 60Co and 65Zn by peat humin was studied under different conditions. The results indicated that humin has high ability to sorb the investigated
nuclides with the sequence Co2+> Zn2+> Ag+, and can retained up to 1.04 mmol/g of Ag+, 1.63 mmol/g of Zn2+and 1.73 mmol/g of Co2+. The sorption process was time dependent and the percentage of uptake increased with pH to reach a maximum at pH~7.5, which
corresponds to the pKavalue of the humin.