Effect of mineral acids

Aromatic polysulfone is chemically stable. It is resistant to the effect of mineral acids, alkalis and salt solutions. It is even more stable to carbohydrate oils at higher temperatures and small loadings [149]. 

Fig. 7. Corroding effect of mineral acids on boronized and unboronized Ck45 steel.

Fluorinated Acids. This class of compounds is characterized by the strength of the fluorocarbon acids, eg, CF COOH, approaching that of mineral acids. This property results from the strong inductive effect of fluorine and is markedly less when the fluorocarbon group is moved away from the carbonyl group. Generally, their reactions are similar to organic acids and they find apphcations, particularly trifluoroacetic acid [76-05-1] and its anhydride [407-25-0] as promotors in the preparation of esters and ketones and in nitration reactions. 

At 0.9 °C the rate of bromination of biphenyl relative to benzene was approximately 1,270, compared to 26.9 in the presence of mineral acid, and this latter value is fairly close to that obtained with 50 % aqueous dioxan. The possibility that the positive brominating species might be protonated bromine acetate, AcOHBr+, was considered a likely one since the reaction rate is faster in aqueous acetic acid than in water, but this latter effect might be an environmental one since bromination by acidified hypobromous acid is slower in 50 % aqueous dioxan than in... 

Two studies have used single cells to study the effect of phenolic acids on mineral absorption. In sterile cell cultures of Paul s Scarlet rose, 100 pM ferulic acid inhibited Rb+ absorption in about 10 min when the cells were 4-5 days old (37). Uptake from 0.2 mM RbCl was inhibited about 25% and absorption from 5.0 mM RbCl was inhibited 45%. Absorption by 10-day-old cells was affected little. Salicylic acid at 10 pM inhibited PO - absorption by Scenedesmus, a unicellular green alga (38). These studies show that allelochemicals inhibit mineral absorption in cellular systems as well as tissue systems (Table I). 

Singer A, Huang PM (1990) Effect of humic acid on the crystallization of aluminum hydroxides. Clays Clay Miner 38 47-52... 

For example, the industrial preparation of mineral acids, such as sulfuric, hydrochloric and nitric, inevitably leads to them containing small concentrations of metals as impurities. If the acid is to be used purely as an acid in a simple reaction, the presence of small amounts of metals is probably unimportant. If, however, the acid is to be used to digest a sample for the determination of trace metals by atomic absorption spectrometry, then clearly the presence of metallic impurities in the acid may have a significant effect on the results. For this latter application, high-purity acids that are essentially metal-free are required. 

Application of ion exchange refining to the process for the manufacture of dextrose may be understood from the following description of such a process. Triple-washed starch is diluted with ion-free water to the desired concentration and is acidified with a definite quantity of mineral acid such as hydrochloric or sulfuric. It is desirable that the acidified starch slurry be held for at least thirty minutes in order to permit an effective equilibrium acidity to be reached. The starch slurry may contain a quantity of soft water salts which consume acid, and since this consumption is variable, the acidity is checked and adjusted to the desired level following the holding period. The conversion is then carried out at elevated temperature and under pressure for a period sufficient to yield maximum dextrose. The conversion may be carried out batchwise in an autoclave, or continuously. 

When the source of initiation is altered from ionising radiation to UV, analogous additive effects to those previously discussed have been found. For reasonable rates of reaction, sensitisers such as benzoin ethyl ether (B) are required in these UV processes. Thus inclusion of mineral acid or lithium perchlorate in the monomer solution leads to enhancement in the photografting of styrene in methanol to polyethylene or cellulose (Table V). Lithium nitrate is almost as effective as lithium perchlorate as salt additive in these reactions (Table VI), hence the salt additive effect is independent of the anion in this instance. When TMPTA is included with mineral acid in the monomer solution, synergistic effects with the photografting of styrene in methanol to polyethylene are observed (Table VII) consistent with the analogous ionising radiation system. 

The effect of mineral and organic soil constituents on the mineralisation of LAS, AE, stearyl trimethylammonium chloride (STAC) and sodium stearate (main soap component) in soils was studied by Knaebel and co-workers [38]. The four 14C-labelled compounds were aseptically adsorbed to montmorillonite, kaolinite, illite, sand and humic acids and subsequently mixed with soil yielding surfactant concentrations of about 50 jig kg-1. The CO2 formation in the serum bottle respirometers was monitored over a period of 2 months indicating that the mineralisation extent was highest for LAS (49-75%). Somewhat lower amounts of produced CO2 were reported for AE and the stearate ranging from 34-58% and 29-47%, respectively. The mineralisation extent of the cationic surfactant did not exceed 21% (kaolinite) and achieved only 7% in the montmorillonite-modified soil. Associating the mineral type with the mineralisation kinetics showed that sand... 

The inclusion of mineral acid in the grafting solution has recently been shown to increase the radiation copolymerisation yield, particularly when styrene is grafted to trunk polymers like wool (3) and cellulose (4) i.e. polymers which readily swell in polar solvents such as methanol. This acid effect is important since for many copolymerisation reactions, relatively low radiation doses are required to yield finite graft. The process is particularly valuable for monomers and/or polymers that are either radiation sensitive or require high doses of radiation to achieve the required graft. 

Greenfield ef. ai.l l) observed a reduction of signal intensity that correlates with sample intake effects from the modified solution viscosity and/or surface tension of mineral acids. This, coupled with peristaltic pumping of solutions into the nebulizer, considerably reduces physical interferences. Increased salt concentration also has an effect on solution physical properties. In the experience of these authors, the high levels of salt in the matrix also increases the noise from the nebulizer system. This degradation of nebulizer performance, which is not necessarily accompanied by a proportional reduction in sensitivity, is the cause of the observed deterioration of detection limits in real samples as opposed to ideal solutions. 

Attin, T., Meyer, K., Hellwig, E., BuchaUa, W., and Lennon, A. M. (2003). Effect of mineral supplements to citric acid on enamel erosion. Arch. Oral Biol. 48, 753-759. 

The effect of various acids on the stability of NC was examined by CKrauz A. Majrich, ChemObzor 7,209 1(5(1932) CA 27,28 12(19 3 3). They found that mineral acids lower the stability of NC as also do some org acids such as aliphatic carbozylic acids and some of their derivatives. Aliphatic... 

Potassium permanganate oxidises arsenious acid rapidly and quantitatively in the presence of a trace of potassium iodide, which acts catalytically.7 The reaction takes place in the presence of mineral acid and the use of an indicator or of sodium bicarbonate is unnecessary. The titration may be carried out at any temperature up to 95° C. A slight correction is necessary for the oxidation of the iodide other iodides are less effective than the potassium salt. This method is comparable in accuracy with the iodometric method. 

Creatinine has been prepared generally from urine1 or muscle,2 though its formation from creatine by the action of mineral acids has also been studied.3 The conversion of creatine into creatinine has also been effected by heating in an autoclave 4 and by treatment with zinc chloride.5 The above technique has been developed 6 since creatine has become available in relatively large quantities as a by-product.7... 

The immediate changes in UV spectra57 exhibited by the substrates on addition of mineral acids are consistent with a rapid protonation equilibrium, S+H+ < SH+, to form the conjugated acid. In order to interpret the rate data, one must first correct the observed values of k,j, for the amount of protonated substrate. Spectrophotometric methods are widely applicable for determination of the ionization ratio, I = CSH+ /Cs, of moderately basic substrates74. For A-f-butylbenzaldoxime and 2-/-butyl-3-phenyloxaziridinc, however, the rate of the hydrolysis reaction (t /2 = 1 min) at the maximum in the profile at 24.2 °C made it impossible to measure the zero-time absorption of the substrates. However, allowing for medium effects in the absorption spectra, the substrates appeared to be essentially fully protonated in solutions of CH+ > 2 M in all three acids. 

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