Temperature bentonite

Non-soap greases using finely divided solids as thickeners are useful as lubricants at elevated temperatures. Materials used include organO Clays such as dimethyldioctyl-decyl-ammonium bentonite (Bentone greases) or selected dyestuffs which produce brightly coloured greases. 

Sodium Dispersions. Sodium is easily dispersed in inert hydrocarbons (qv), eg, white oil or kerosene, by agitation, or using a homogenizing device. Addition of oleic acid and other long-chain fatty acids, higher alcohols and esters, and some finely divided soHds, eg, carbon or bentonite, accelerate dispersion and produce finer (1—20 -lm) particles. Above 98°C the sodium is present as Hquid spheres. On cooling to lower temperatures, soHd spheres of sodium remain dispersed in the hydrocarbon and present an extended surface for reaction. Dispersions may contain as much as 50 wt % sodium. Sodium in this form is easily handled and reacts rapidly. For some purposes the presence of the inert hydrocarbon is a disadvantage. 

Dispersed Noninhibited Systems. Drilling fluid systems typically used to drill the upper hole sections are described as dispersed noninhibited systems. They would typically be formulated with freshwater and can often derive many of their properties from dispersed drilled solids or bentonite. They would not normally be weighted to above 12 Ib/gal and the temperature limitation would be in the range of 176-194°F. The flow properties are controlled by a deflocculant, or thinner, and the fluid loss is controlled by the addition of bentonite and low viscosity CMC derivatives. 

Other factors must also be considered. Similarly the replacement of 1 % milling clay by /4% of the more colloidal bentonite is beneficial. Large additions of quartz at the mill improve heat resistance and, provided the firing temperature is increased to dissolve a sufficient quantity of this silica in the glass, the acid resistance is also enhanced. 

The use of polyisoprene or butadiene-styrene latex with bentonite or chalk filler and polyoxypropylene as an additive has been used in a plugging solution for oil and gas wells [1042]. The solution can be pumped but coagulates within the formation at temperatures of 100° C within 2 hours. This causes a reduction in permeability. The formulation is particularly useful in deep oil deposits. 

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. 

The reaction of neomycin with many compounds has been described in Section 3, hence numerous reports of neomycin incompatibility may be expected. Dale and Rundman have extensively reviewed the compatibility of neomycin with substances that may be encountered by the formulation pharmacist. Kudalker et al 03 have described the incompatibility of the antibiotic with rancid oils, and the incompatibility with bentonite, a montomorill-onite clay, has been reported by Danti and Guth306. The incompatibility with lactose, causing a discoloration of the mixture has been studied by Hammouda and Salakawy- 0 . The amount of browning produced was shown to be dependant on the initial pH of the solution. The rate of discoloration of the lactose/neomycin powder was directly related to the temperature of storage and the relative humidity of the atmosphere. Discoloration was overcome by addition of sodium bisulphite. 

Very many acidic solids and liquids, immiscible with hydrocarbons, will catalyse the oligomerisation of isobutene at ambient temperatures. Among the more common are syncatalysts prepared from boron fluoride and a protonic substance BH (B = OH, CHsO, C2H50, t-C4H90, CH3C02, etc.) mineral acids natural and synthetic alumino-silicates, (e.g., Fuller s earth, bentonite, attapulgite) and metal oxides containing small quantities of water. 

Compare the agglomeration rate of an aqueous suspension containing 104 virus particles per cubic centimeter (d = 0.01 pm) with that of a suspension containing, in addition to the virus particles, 10 mg liter1 bentonite (number cone. = 7.35 106 cm3 d = 1 pm). The mixuture is stirred, G = 10 sec1, and the temperature is 25° C. Complete destabilization, a = 1, may be assumed. (This example is from O Melia, 1978.)... 

For instance, 2-methylpropene reacted with acetic acid at 18°C in the presence of Al-bentonite to form the ester product (75). Ion-exchanged bentonites are also efficient catalysts for formation of ketals from aldehydes or ketones. Cyclohexanone reacted with methanol in the presence of Al-bentonite at room temperature to give 33% yield of dimethyl ketal after 30 min of reaction time. On addition of the same clay to the mixture of cyclohexanone and trimethyl orthoformate at room-temperature, the exothermic reaction caused the liquid to boil and resulted in an almost quantitative yield of the dimethyl ketal in 5 min. When Na- instead of Al-bentonite is used, the same reaction did not take place (75). Solomon and Hawthorne (37) suggest that elimination reactions may have been involved in the geochemical transformation of lipid and other organic sediments into petroleum deposits. 

Surface acidity and catalytic activity develop only after heat treatment of a coprecipitated mixture of amorphous silicon and aluminum oxides. Similar catalysts can be prepared by acid treatment of clay minerals, e.g., bentonite. The acidity is much stronger with silica-alumina than with either of the pure oxides. Maximum catalytic activity is usually observed after activation at 500-600°. At higher temperatures, the catalytic activity decreases again but can be restored by rehydration, as was shown by Holm et al. (347). The maximum of activity was repeatedly reported for compositions containing 20-40% of alumina. 

Fig. 12. Electron spin resonance spectra recorded at X-band for powdered clay samples at ambient laboratory temperature (a) montmorillonite, (b) kaolin, (c) Bentonite (Aldrich Chemical), (d) Bentonite (SSP/NF), (e) Magnabrite, (f) Polargel, (g) Volclay, and (h) Fuller s Earth (68).

IR spectra for the pillared bentonites in the OH-stretching region show an intense and broad OH-band centered near 3640 cm this band is shifted to near 3600 cm for the ACH-nontronite sample under study, Fig. 1. After pyridine sorption, only minor changes were observed in these spectra, indicating little reaction of the hydroxyl groups present with pyridine. As the degassing temperature is increased from 200 C to 500 C, OH bands decrease in intensity due to dehydroxylation reactions of the clay lattice. Fig. 1. Dehydroxylation is more facile in the iron-containing ACH-nontronite sample. Fig. IF. 

Fig. 1. Hydroxyl absorption bands for several smectites pillared with aluminum chlorhydroxide (ACH) soluctions A) Wyoming ACH-bentonite B) Texas ACH-bentonite C) Fe-bentonite D) ACH- Fe bentonite) E) (ACH, Fe)-bentonite and F) ACH-nontronite. Samples a) have been dried at 200 C and then loaded with pyridine and degassed at b) 200 C, c) 300 C, d) 400 C and e) 500 C in vacuo for 2 hours at each temperature.

Temperature Effects. The effect of a temperature increase from 25°C to 65°C is usually a small increase of the distribution coefficient (less than a factor of three). For the sorption of Cs on bentonite, which would correspond to an ion exchange process, the effect of increased temperature is the opposite. 

A portion of the wet sol-intercalated clay was mixed with a surfactant of quaternary ammonium salts [CH3(CH2)n-i N(CH3)3Br] by stirring for 2 hours. 15.75 mmol of surfactant was added to each gram of the starting bentonite clay. The resultant mixture of clay and surfactant was transferred into an autoclave and kept in an oven at 100°C for 3 days. The wet cake was washed with water to Cl ions free and the solid was recovered by filtration. The solid was dried in room temperature and calcined at 773 K. for 4 h. The calcined products were labeled as sol-PILB-Cn, where n denotes the number of carbon atoms in the alkyl chain of the surfactants used. Four samples were prepared sol-PILB-C12, -C14, -C16 and -C18. 

Geothermal cements are also employed to fix the steel wellbore casing in place and tie it to the surrounding rock (8). These are prepared as slurries of Portland cement (qv) in water and pumped into place. Additional components such as silica flour, perlite, and bentonite clay are often added to modify the flow properties and stability of the cement, and a retarder is usually added to the mixture to assure that the cement does not set up prematurely. Cements must bond well to both steel and rock, be noncorrosive, and water impermeable after setting. In hydrothermal applications, temperature stability is critical. Temperature cycling of wellbores as a result of an intermittent production schedule can cause rupture of the cement, leading to movement and, ultimately, failure of the wellbore casing. 

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