Uses of sulphuric acid

In common with most other compounds in this chapter, the major use of sulphuric acid has been in the preparation of fertiUzers, e.g. 

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In some instances the use of sulphuric acid leads to unsatisfactory results. Thus with formic acid carbon monoxide would be evolved. Esters of formic acid are most simply prepared from the alcohol and excess of formic acid, for example ... 

Esterification with cycloaliphatic alcohols is comparatively easy when the alcohol is saturated with hydrogen chloride and treated with excess of the acid, but a very impure ester results from the use of sulphuric acid as a catalyst, for example ... 

The barium sulphate may be precipitated either by the use of sulphuric acid, or from homogeneous solution by the use of sulphamic acid solution which produces sulphate ions on boiling ... 

After use the cells must be carefully washed with distilled water, or if an organic solvent which is not miscible with water was employed, they must be rinsed with a solvent which is miscible with both the solvent used and with water, and then well washed with distilled water. Finally, they are rinsed with ethanol followed by drying, which may be conveniently done in a vacuum desiccator. Cells which have become contaminated can usually be cleaned by soaking in a solution of a detergent, such as Teepol. For obstinate contamination recourse may be made to the use of sulphuric acid-sodium dichromate cleaning mixture (CAUTION ) (Section 3.8). After soaking overnight the cells are well washed with water and finally dried. 

Beckmann rearrangement of oxime is an acid catalysed reaction. The environmental problems associated with the use of sulphuric acid instigated interest to use number of solid acid catalysts [1], There are only scanty references about Lewis acid ion-exchanged MeAlPOs. Beyer et al. [2], Mihalyi et al. [3] and Mavrodinova et al. [4] already suggested the presence of Lewis acid metal ions as MO+ species in zeolites. The present study focussed the synthesis and characterisation of Fe3+, La3+ and Ce3+ ion-exchanged MAPO-36. The catalytic results of Beckmann rearrangement of cyclohexanone oxime over ion-exchanged catalysts are delineated in this article. 

In the early 1980s, Nobel (a reagent manufacturing company) developed selective apatite collectors (Lilaflot series) based on modified fatty acids, which were capable of removing apatite without any loss of ilmenite. The pH in the ilmenite circuit was controlled with the use of sulphuric acid. In 1980, the tall oil used in the pyrite circuit was replaced with Lilaflot 100 (modified fatty acid). 

There are two types of tantalum electrolytic capacitor wet and solid . Both varieties consist of a porous anode made by sintering tantalum powder at 1800 °C in vacuum. In the wet type the porous structure is impregnated with sulphuric acid, anodized to form a thin layer of Ta205 and encapsulated in a tantalum container that also serves as the cathode. The use of sulphuric acid gives a lower e.s.r. than that of the aluminium electrolytic and increases the temperature range within which the unit can be run. In the solid type the liquid... 

Later on, the furnace was adapted for the use of sulphuric acid instead of bisulphate. In this case the acid was led in through the hollow shaft of the stirring device into the arms, and flowing out of these it was distributed over the salt. 

The use of sulphuric acid in methanol provides a diamond layer-friendly electrolyte. As shown in Fig. 5.15, aqueous sodium hydroxide changes the morphology of the BDD anode surface (DeClements and Swain 1997) but the electrode can still... 

The second method is azeotropic condensation polymerization of lactic acid, which produces high-molecular weight PLA without using chain-extenders or esterification-promoting adjuvants. This type of polymerization needs high reaction rates and thus uses catalysts however, due to the use of catalysts, the PLA produced by this method is not suitable for some applications, such as medical, since any residual catalyst offers toxicity within the polymer, which is harmful for medical applications. In addition to toxicity, residual catalyst degrades PLA in further processing (39). On the other hand, the level of residual catalyst can be reduced with the use of sulphuric acid (55,56). 

There are three important results obtained by the use of sulphurous acid in steep water.. First, the foulness of the steep tanks is eliminated. Secondly, the sulphurous acid is found to soften the com more effi ... 

Phosphate and sulphate modifiers were incorporated by the addition of appropriate amounts of 0.01 M sulphuric or phosphoric acid to a pre-calcined aerogel followed by further calcination at 873 K. Samples are labeled as X-SiZr (y) where X refers to either sulphated (S) or phosphated (P) samples, and y refers to the mole ratio of sulphate/phosphate relative to zirconium in the preparation method. For comparison purposes, samples of zirconia and sulphated zirconia were also prepared. This was achieved via precipitation from zirconium isopropoxide (Aldrich 70 wt.%). The same H2O Zr propanol ratios were employed as used during the preparation of the mixed oxides. A sulphated zirconia, prepared by the use of sulphuric acid as hydrolysis catalyst was prepared for comparative purposes and had a nominal S Zr ratio of 0.30 1. A further sample was prepared where segregation of components was induced by thermal treatment by calcination at 1373 K for 6 h.of the non-treated SiZr (0)... 

Matting acid, sulphuric acid when used as a matting agent. Matting is the process by which metals and other substrates have their surface sheen removed to leave a dull, lustreless finish. It can also be used to describe the use of sulphuric acid as an etchant. 

In the same paper, the conversion of 6a-thiathiophthens into 1,2-dithiolylidene ketones is discussed. The use of sulphuric acid as a reagent for this purpose, with unsymmetrically substituted compounds, may lead to only one or both of the possible isomeric ketones. With 2-methyl-5-phenyl-6a-thiathiophthen, treatment with sulphuric acid gives the ketone (18), confirming an earlier report which had been questioned. 

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