Cation exchange capacity Properties

Soils and vadose zone information, including soil characteristics (type, holding capacity, temperature, biological activity, and engineering properties), soil chemical characteristics (solubility, ion specification, adsorption, leachability, cation exchange capacity, mineral partition coefficient, and chemical and sorptive properties), and vadose zone characteristics (permeability, variability, porosity, moisture content, chemical characteristics, and extent of contamination)... 

Some properties of the rock used in this study were measured The cation exchange capacity (cec) was determined by the barium sulfate method as described by Mortland and Mellor (33). Surface area was measured by using a Digisorb Meter (Micromeritics Instrument Corporation) through nitrogen adsorption. Estimation of mineral composition and indentification of the rock were performed by X-ray diffraction. 

This fact may explain the superiority of montmorillonite over vermiculite as an adsorbent for organocations (3, 4). Complicating this description, however, is the fact that a sample of any particular layer silicate can have layer charge properties which vary widely from one platelet to another (j>). By measuring the c-axis spacings, cation exchange capacity, water retention, and other properties of layer silicates, one obtains the "average" behavior of the mineral surfaces. 

The sorption behavior of 11 PAH compounds (a training set, Table 11) on various solid phases (e.g., three soils and two sediments) with different properties to relevant sorption (e.g., organic carbon content, clay content, pH, cation exchange capacity CEC Table 12), was determined by batch equilibrium studies [1]. Batch equilibrium tests were designed to determine rates of equilibrium sorption under conditions of high mixing and high surface areas of the solid particles (see Chap. 3). 

The dichroic properties of the Li modiEed montmorillonite were followed by orientation of thin films (0-45°) in the IR beam (FTIR Brucker IFS 88). The cationic exchange capacity (CEC) of the samples calcined at 400°C was evaluated. 

The determination of surface properties of particles is an important key to understanding interactions of trace elements and organic compounds between particulate and dissolved phases in estuarine and coastal systems. Specific surface area (SSA), cationic exchange capacity (CEC) and heat of immersion (AH) have been measured on native and treated suspended sediment and after oxidation with 15% H202- SSA and A H have also been measured on samples leached with NaOH and Na-dithionite in order to remove amorphous aluminosilicates. 

Based on their data for sorption onto a lake sediment, Kiewiet et al. (1996) derived an equation predicting sorption coefficients of CnEOms as a functions of alkyl chain length and the number of oxyethylene units. Di Toro et al. (1990) proposed a model for description of sorption of anionic surfactants which includes sorbent properties (organic carbon content, cation exchange capacity, and particle concentration) and the CMC as a function of the solution properties (ionic strength, temperature). The CMC is used as a relative hydrophobicity parameter. Since the model takes the contribution of electrostatic as well as hydrophobic forces explicitly into account, it is an example of an attempt to model surfactant behavior on the basis of the underlying mechanisms. 

Barium is not very mobile in most soil systems. The rate of transportation of barium in soil is dependent on the characteristics of the soil material. Soil properties that influence the transportation of barium to groundwater are cation exchange capacity and calcium carbonate (CaCO) content. In soil with a high cation exchange capacity (e.g., fine textured mineral soils or soils with high organic... 

Zeolites and inorganic ion-exchange catalysts have been treated in reactive milling to alter their properties. For example, the amorphization of Zeolite A has been described by Kosanovic et al. [93] these authors observed a loss of crystallinity, a decrease of cation-exchange capacity, and an increase of solubility of A and Y zeolites which was caused by breaking of Si-O-Si and Si-O-Al bonds in the zeolite. 

A wide range of research publications has identified various soil properties and their potential influence on substance behavior. Soil properties such as organic matter, iron, manganese, and aluminum (hydro)oxide concentrations, cation exchange capacity, and pH can all affect the bioavailability, form, and toxicity of substances. 

The term pHznc in Equation 3.24 represents the point of zero net charge (PZNC). It is the pH value at which the cation exchange capacity equals the anion exchange capacity (Fig. 3.28). Equation 3.24 shows that pHznc varies with ionic strength (n), whereas pH0 or PZC is an intrinsic property of the mineralogically heterogeneous soil (Uehara and Gillman, 1980). 

If the framework structure of a zeolite remains constant, the cation exchange capacity is inversely related to thd Si/Al ratio. Furthermore, fine tuning of the adsorptive and catalytic properties can be achieved by adjustment of the size and valency of the exchangeable cations. Dealumination of certain silica-rich zeolites can be achieved by acid treatment and the resulting hydrophobic zeolites then become suitable for the removal of organic molecules from aqueous solutions or from moist gases. 

Some basic properties, such as basal spacing (d001), internal and total specific surface area, and cation-exchange capacity (CEC) of some natural montmorillonite or bentonite with high montmorillonite samples are listed in Table 2.1. Similar characteristics of different cation-exchanged montmorillonites are given in Section 2.3. 

Bentonite rocks have many uses in the chemical and oil industries and also in agriculture and environmental protection. The usefulness of bentonite for each of these applications is based on its interfacial properties. These properties are determined by geological origin, chemical and mineral composition (especially montmorillonite content), and particle size distribution, and they include the specific surface area (internal and external), cation-exchange capacity (CEC), acid-base properties of the edge sites, viscosity, swelling, water permeability, adsorption of different substances, and migration rate of soluble substances in bentonite clay. 

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