Bentonite effects

Kozai, N., T. Ohnuki, and S. Muraoka, 1995. Sorption behavior of neptunium on bentonite—effect of calcium ion on the sorption. Mat. Res. Soc. symp. proc. 353,... 

Yang, S., Li, X, Lu, Y, Chen, Y. Wang, X. (2009) Sorption of Ni(ll) on GMZ bentonite effects of pH, ionic strength, foreign ions, humic acid and temperature. Applied Radiation and Isotopes, 67,1600-1608. 

Various other soft materials without the layer—lattice stmcture are used as soHd lubricants (58), eg, basic white lead or lead carbonate [598-63-0] used in thread compounds, lime [1305-78-8] as a carrier in wire drawing, talc [14807-96-6] and bentonite [1302-78-9] as fillers for grease for cable pulling, and zinc oxide [1314-13-2] in high load capacity greases. Graphite fluoride is effective as a thin-film lubricant up to 400°C and is especially useful with a suitable binder such as polyimide varnish (59). Boric acid has been shown to have promise as a self-replenishing soHd composite (60). 

In low sohds muds, vinyl acetate—maleic anhydride copolymers were once used to extend or enhance the viscosity of bentonite suspensions (141). This function is largely performed by polyacrylamides. The vinyl acetate—maleic anhydride copolymers can also have a flocculating effect on drill sohds. Concentrations generally are quite low (0.14—0.57 kg/m (0.05—0.2 Ib/bbl)). 

The modification of bentonite with alkylsilanes improves the dispersing properties [991]. Incorporation of phosphonate-type compounds in bentonites for drilling mud permits the blockage of free calcium ions in the form of soluble and stable complexes and the preservation or restoration of the initial fluidity of the mud [1222]. The phosphonates also have dispersing and fluidizing effects on the mud. 

Sodium chloride can be used as an accelerator in formulations that are bentonite free. The maximal bottom-hole temperature is 70° C. In concentrations above 5%, the effectiveness is reduced. Saturated sodium chloride solutions act as retarders. 

Fig. 24. Effect of bentonite additive on the balling rate of iron ore pellets. [From Kapur et al. (K7).]...

In a similar investigation Sastry and Fuerstenau (S4) used up to 1.5% Wyoming bentonite in a teconite feed with 48.4, 50.3, and 52.3% volume moisture. The water retention capacity was calculated as 0.47 0.11, independent of the water and bentonite contents. An evaluation of bentonites from three sources by Nicol and Adamiak (N3) indicates that the Wyoming bentonite has the highest cation exchange capacity and also the maximum retardation effect on the balling rate. 

Manganese dioxide on bentonite clay has also been used for oxidation of phenols to quinones (30-100%) [97] and Mn02 on silica effects the dehydrogenation of pyrrolidines (58-96%) [98]. 

Chemat and his collaborators [92] reported the UV- and MW-induced rearrangement of 2-benzoyloxyacetophenone, in the presence of bentonite, into l-(o-hydroxy-phenyl)-3-phenylpropane-l,3-dione in methanol at atmospheric pressure (Sch. 14.2). The reaction, performed in the reactor shown in Fig. 14.7, was subject to a significant activation effect under simultaneous UV and MW irradiation this corresponded at least to the sum of the individual effects (Fig. 14.11). The rearrangement, however, was not studied in further detail. Such competitive processes can be described by the diagram in Fig. 14.9, because the product obtained from both types of activation was the same. 

Mayer and coworkers128 discovered that kojic acid is a moderately effective activator for nicotine insecticides. When tested against the melon worm (Diaphania hyalinata L.) and the southern armyworm (Prodenia eridania Cram.), kojic acid (alone) was not toxic but the toxicity of a 5% nicotine sulfate-pyrophyllite dust was increased 35 %, and that of a 5 % nicotine bentonite-bentonite spray by some 50%, by the addition of 5% of kojic... 

The application of ion exchangers to dextrose process liquors involved considerable experimental work because of a number of factors which do not enter into their application to water purification. The accumulation of fats and proteins on the resin surfaces must be guarded against by proper clarification of the liquors to be treated. Such accumulation may result from precipitation as the neutralization progresses, and may soon destroy the effective acid-removing capacity of the anion exchange resin. This difficulty can effectively be eliminated by prior precipitation of thfe refinery residue from the acid liquor by bentonite, a colloidal clay of opposite electrical charge to the colloids,21 followed by filtration. 

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