Adsorptive properties, vermiculites

Based on these rate laws, various equations have been developed to describe kinetics of soil chemical processes. As a function of the adsorbent and adsorbate properties, the equations describe mainly first-order, second-order, or zero-order reactions. For example. Sparks and Jardine (1984) studied the kinetics of potassium adsorption on kaolinite, montmorillonite (a smectite mineral), and vermiculite (Fig. 5.3), finding that a single-order reaction describes the data for kaolinite and smectite, while two first-order reactions describe adsorption on vermiculite. 

Stefan Dultz., Jong Hyok An., Beate Riebe. Organic cation exchanged montmorillonite and vermiculite as adsorbents for Cr(VI) Effect of layer charge on adsorption properties. Applied Clay Science. 2012, 67,125-133. 

Properties Platelet-type crystalline structure. High porosity, high void volume to surface area ratio, low density, large range of particle size. Insoluble in water and organic solvents soluble in hot concentrated sulfuric acid. Water vapor adsorption capacity of expanded vermiculite less than 1%, liquid adsorption dependent on conditions and particle size, ranges 200-500%. Noncombustible. 

It has been verified that the degree of hydration of the vermiculite clay matrix can exert remarkable effects on the magnetic properties of its intercalation compounds. Furthermore, vermiculite has been recently used for studies involving the adsorption of oil-contaminated water samples [1]. 

The adsorption of crude oil was performed in dehydrated (expanded) and hydrophobized vermicuHte samples, denoted here as EV (expanded vermicuHte) and HV (hydrophobized vermiculite), respectively. Vermiculite samples with five different grain sizes were used 100-150, 150-200, 200-250, 250-325, and 325-400 mesh. The crude oil had the following properties density, 34.2 °API (at 15.6°C) and viscosity, 8.4 cP (at 37.8°C) ... 

The structure and the sorption properties of partially hydrophobized silicates (do-decylammonium and dodecyldiammonium vermiculites) were investigated in aqueous solutions of n-butanol. The alcohol is preferentially adsorbed on the surface. The interlayer composition is calculated from adsorption and X-ray diffraction data. In the air-dried state the organic cations lie flat on the interlamellar surface. In aqueous n-butanol solutions, the basal spacing of dodecylammonium vermiculite gradually increases with the extent of n-butanol adsorption because the chains increasingly point away from the surface. The basal spacing of dodecyldiammonium vermicuiite is virtually independent of the interlayer composition, because the expansion of the interlayer space is sterically restricted and a... 

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