Adsorption on kaolinite

Adsorption on Kaolinite. For kaolinite, the polymer adsorption density is strongly dependent on the solid/liquid ratio, S/L, of the clay suspension. As S/L increases, adsorption decreases. This S/L dependence cannot be due totally to autocoagulation of the clay particles since this dependence is observed even in the absence of Ca2+ at pH 7 and at low ionic strength where auto-coagulation as measured by the Bingham yield stress is relatively weak (21). Furthermore, complete dispersion of the particles in solvent by ultra-sonication before addition of... 

Adsorption on Kaolinite. As for polyacrylamides, adsorption of XCPS on kaolinite is conducted as a function of S/L and the results extrapolated to S/L=0. However, the S/L dependence of XCPS adsorption on kaolinite is considerably less than that for HPAM. This is due to the flat conformation of the adsorbed molecules of semirigid xanthan (25) compared to the more extended conformation of flexible HPAM (27). The absence of loops and tails in the adsorbed XCPS layer thus diminishes the probability of flocculation of particles by polymer bridging. The slight dependence in adsorption on S/L may therefore be attributed to coagulation of particles induced by Ca. ... 

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. 

Providing a flat surface can be achieved, tapping mode AFM topological and phase imaging can be used to investigate HPAM adsorption and mineral surfaces. Information on the film height, the strength of interaction between polymer-mineral surface and an indication of the adsorption process may be obtained. HPAM adsorption on kaolinite was observed to form a flat uniform layer... 

Jardine, P. M., Parker, J. C., and Zelazny, L. W. (1985b). Kinetics and mechanisms of aluminum adsorption on kaolinite using a two-site nonequilibrium transport model. Soil Sci. Soc. Am. J. 49, 867-873. 

Manning B. A. and Goldberg S. (1996) Modeling arsenate competitive adsorption on kaolinite, montmorillonite and illite. Clays Clay Min. 44, 609-623. 

This is the case for water adsorbed on the silica (ground quartz). The corresponding experimental heats of immersion curve were reported by Partyka et al. [76,77] and are redrawn here by us in Fig. 7(A). Also in this figure the heat of immersion of kaolinite in water is shown for comparison, redrawn from the work of Fripiat et al. [95]. Figure 7(B) shows the comparison of the isosteric heats of adsorption Qst calculated from these immersion curves according to Eq. (35). Note that also in the case of water adsorption on kaolinite, Qst does not reach the value of the heat of liquefaction, equal to 40.7 kj mol . ... 

Hizal, J. and Apak, R., Modeling of copper(II) and lead(II) adsorption on kaolinite-based clay minerals individually and in the presence of humic acid, J. Colloid Interf. Sci., 295, 1.2006. 

Garrido, L.B., Volzone, C., and Tones Sanchez, R.M., OH-Al polymers and HMP adsorption on kaolinite Experimental conditions and viscosity of deflocculated suspensions. Colloids Surf. A, 121, 163, 1997. 

Sakurai and Huang (1995) also found that OX strongly reduced Cu and Cd adsorption on kaolinite and montmorillonite. Recently, Wu et al. (2003) found that Pb adsorbed onto montmorillonite, goethite, and humic acid decreased with increasing concentrations of EDTA and citric acid. 

It is also recognized (4) that in the case of ionic adsorbents, adsorption is determined in part by the surface charge of the adsorbent. In general, and OH" are potential - determining in mineral oxide-water systems therefore the surface charge, and the adsorption of sulfonate anions, would depend on the pH of the system (5) Somasundaran and Hanna (5) have found in fact that sulfonate adsorption on kaolinite decreases with increasing pH since the fraction of positive sites on the surface is expected to decrease. 

Keenan, A. G., R. W. Mooney, and L. A. Wood. 1951. The relation between exchangeable ions and water adsorption on kaolinite. Journal of Physical Chemistry 55, no. 9 1462-1474. doi 10.1021/jl50492a006. 

---