Kaolin evaluation

A major advantage of the simple model described in this paper lies in its potential applicability to the direct evaluation of experimental data. Unfortunately, it is clear from the form of the typical isotherms, especially those for high polymers (large n) that, even with a simple model, this presents considerable difficulty. The problems can be seen clearly by consideration of some typical polymer adsorption data. Experimental isotherms for the adsorption of commercial polymer flocculants on a kaolin clay are shown in Figure 4. These data were obtained, in the usual way, by determination of residual polymer concentrations after equilibration with the solid. In general, such methods are limited at both extremes of the concentration scale. Serious errors arise at low concentration due to loss in precision of the analytical technique and at high concentration because the amount adsorbed is determined by the difference between two large numbers. 

An evaluation of numerous clays, including kaolins and bentonites of comparable particle size and distribution, revealed a wide variation in the properties of LDEE-clay composites prepared under identical conditions with similar loadings. This may be attributed to the interference with the radical reactions involved in the coupling sequence. This is confirmed, in part, by the finding that the most effective clays were those which were reported to have been treated with sodium polyphosphate to improve their dispersibility in water during papermaking processes. Solomon reported (1) that treatment of the clays which inhibited radical reactions with sodium polyphosphate reduced the inhibition. 

Silica-magnesia matrices have not yet been properly evaluated as an RCC catalyst matrix. However, such a matrix in conjunction with stabilized zeolite might provide an attractive matrix with a Kaolin-enhanced dual pore structure. Silica-magnesia matrices are notorious for their poor regeneration characteristics. When prepared by the dual pore Kaolin-enhanced method, they might be easier to regenerate and, thereby, open up a new family of residuum catalysts. Such catalysts have not yet been explored. 

The absorptive properties of commonly used powders such as titanium dioxide (TiC>2), zinc oxide (ZnO), kaolin, cornstarch, and methylcellulose were shown to differ considerably when evaluated under standardized conditions (Figure 22.2). The highest water absorption was shown with ZnO and kaolin, followed by cornstarch and Ti02. Methylcellulose formed a gel with water that prevented the entire soaking of the powder, and thus water absorption remained low. 

Kaolin has a use in plastisol formulations giving good rheological control. Calcium carbonate is also used in this area. An alternative to calcium carbonate, phyllite, has been evaluated. This material, which contains quartz, muscovite and kaolinite, was characterised on the basis of paste viscosity, gelation and fusion behaviour, and mechanical properties (70). 

Dehydration of Air. Asaeda et al. [19S4] evaluated gamma-alumina membranes on kaolin supports with a reported pore diameter of about 1 nm for air dehydration under a temperature of 31 to 7VC and a low TMP of 0.04 to 0.39 bar. A separation factor of 7 to 460 was obtained. The corresponding permeance is about 9.9x10 cm (STP)/s-cm -cmHg. 

Many other materials, including synthetic aluminas, aluminum carbonates, aluminum silicates, magnesium silicates, various forms of attapulgite and sepiolite (81-83), alumina-pillared acid-activated montmorillonite (84), synthetic mica mont-morillonite, HY-zeolite, zirconium phosphate (85), mica, kaolin, and synthetic hectorite (86), have been evaluated for their ability to purify virgin fats and oils, but none were as good as acid-activated bentonite. 

The activated partial thromboplastin time (APTT), also known as the kaolin-cephalin clotting time (KCCT), primarily evaluates the intrinsic system. In-vitro coagulation of plasma is initiated by the addition of negatively charged particles such as kaolin with phospholipid, and calcium and exogenous thromboplastin. 

In contrast, low-methoxy (LM) pectins gel in the presence of divalent cations, especially calcium, by the egg box mechanism proposed for alginates. Moreover, calcium pectinate gels prepared at neutral pH are heat stable, whereas acidic pH gels are thermo-reversible. Gel strength depends on the extent of esterification (levels from 30% to 50% are optimal), the distribution of ester groups on the chain, and the average molecular weight. LM pectins have been used traditionally in antidiarrheal formulations with kaolin. HM pectins were evaluated in controlled release matrix formulations. Pectin microspheres were reported to improve ophthalmic bioavailability of piroxicam in rabbits compared with commercial piroxicam eye drops. ... 

Albert KS, DeSante KA, Welch RD, DiSanto AR. Pharmacokinetic evaluation of a drug interaction between kaolin-pectin and clindamycin. J Pharm Sci 1978 67 1579-1582. 

Ofoefule SI, Okonta M. Adsorption studies of ciprofloxacin evaluation of magnesium trisilicate, kaolin and starch as alternatives for the management of ciprofloxacin poisoning. Boll Chim Farm 1999 138 239-242. 

Table I. Comparison of Molecular Sieve and Kaolin Catalyst Cracking Evaluations (39)...

The effect of crystallinity of the sample is rather difficult to evaluate because of the definition of the term degree of crystallinity Carthew (91) defined the latter, in the case of kaolin samples, as the perfection of crystal orientation and not the size of the crystal. Using five different samples of kaolin, he found that the area of the endothermic dehydration peak decreased with a decrease in sample crystallinity. The peaks appeared to be sharper as the degree of crystallinity of the sample increased. This effect of crystallinity was said to be similar to that of change in particle size, and could probably be explained in a similar manner. 

Six surfactants/cosolvents were selected for the evaluation program on the basis of (a) solution chemistry, (b) proven ability to desorb/solubilize PAHs from soil particle surfaces in previous studies, (c) human health and environmental protection, and (d) compatibility with in situ electrochemical remediation technique. The chosen surfactants/cosolvents were (a) 3% Igepal CA-720, (b) 5% Igepal CA-720, (c) 5% Triton X-100, (d) 3% Tween 80, (e) 40% ethanol, and (f) a mixture of 40% ethanol and 5% Igepal CA-720. Two clayey soils, kaolin and glacial till, were selected for the study. Kaolin consists mainly of kaoUnite clay mineral, while glacial till consists of a combination of different soil minerals including quartz, feldspar, carbonates, iUite, chlorite, vermiculite, and trace amounts of smectite. 

The effect of ammonia as a complexing agent to enhance the efficiency of electrochemical remediation was evaluated by Vereda-Alonso et al. (2007). Laboratory-scale experiments on copper-spiked kaolin were carried out to explore if metal precipitation could be prohibited at neutral and alkaline pH. Ammonia was added at the anode compartment and migrated into the soil as ammonium by electromigration. Tvo set of experiments were performed (a) using ammonia solution as anolyte and sodium nitrate as catholyte, and (b) combining the ammonia enhancement with the addition of acetic add into the cathode (weak-acid enhancement). The results indicate that metal recovery with only ammonia was less than 40%, while the combination of ammonia and add enhancements achieved a copper recovery of more than 90%. 

Reddy and Maturi (2005) examined the feasibility of using electrokinetic remediation for the removal of mixed contaminants (i.e. mixtures of heavy metals and PAHs) from kaolin (low permeability soU). Likewise, different types of flushing solution were evaluated by a laboratory experimental program, including a cosolvent (n-butylamine), surfactants (3% Tween 80 and 5% Igepal CA-720), and a cyclodextrin (10% hydroxypropyl-j8-cyclodextrin or HPCD). It was reported that... 

Ariffin, A., Ariff, Z. M, Jikan, S. S. (2011). Evaluation on extrudate swell and melt fracture of polypropylene/kaolin composites at high shear stress. J. Reinf. Plus. Compos., 30, 609-619... 

Varghese et al. [81-84] evaluated pure montmorillonite, kaolin, and synthetic fluorohectorite by mixing an aqueous dispersion of clay, an aqueous dispersion of natural latex. 

All of the systems described are now available with an incorporated differential thermal analyzer. DTA has been described in Section 16.2, so a few examples of the advantages of combining these systems will be presented. The incorporation of a DTA with one of the optical analyzers described requires the use of two thermocouples to measure the temperature difference between the sample and a reference standard (calcined kaolin or alumina). As noted, the optical noncontact instruments described are particularly useful in the glass and ceramics industries, so examples of evaluating raw materials from these industries will be described (from Paganelli and Venturelli). 

Table 13.8 Evaluation of kaolin in cross-linked polyethylene typically used in medium voltage cable [15],...

An additional evaluation [18] of the extension of rutile Ti02 by different fillers was conduded by assessing blister resistance in two types of liquid, thermosetting polyester resins (namely ortho- and ortho-neopentyl glycol (NPG). The performance of the filler/pigment portion of the cured polyester gel coat was compared after exposure to water at 65 °C for 1150 h (Table 13.12). Untreated kaolin provided better blister resistance than untreated talc or calcium carbonate. Vinylsilane surface-treated kaolin gave the best blister resistance, reducing the size and extent of blisters... 

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