Mixed acid, spent

MIXED ACID, SPENT see ACID MIXTURES, SPENT, NITRATING ... 

More recently investigations of the solubility of nitroglycerine in mixed acids (spent acids) have been made by Oehman [108], Klassen and Humphrys [25] (Fig. 9). 

MIXED ACID, spent 1849 60 SODIUM SULFIDE, hydrated with not less than 30% water... 

During my Cleveland years, I also continued and extended my studies in nitration, which I started in the early 1950s in Hungary. Conventional nitration of aromatic compounds uses mixed acid (mixture of nitric acid and sulfuric acid). The water formed in the reaetion dilutes the acid, and spent aeid disposal is beeoming a serious environ-... 

To solve some of the environmental problems of mixed-acid nitration, we were able to replaee sulfuric acid with solid superacid catalysts. This allowed us to develop a novel, clean, azeotropic nitration of aromatics with nitric acid over solid perfluorinated sulfonic acid catalysts (Nafion-H). The water formed is continuously azeotroped off by an excess of aromatics, thus preventing dilution of acid. Because the disposal of spent acids of nitration represents a serious environmental problem, the use of solid aeid eatalysts is a significant improvement. 

SOLVENT, n.o.s. SPENT MIXED ACID see ACID MIXTURES, SPENT, NITRATING STAIN see PAINTS, ENAMELS, LACQUERS, STAINS, etc. STANNIC CHLORIDE see TIN TETRACHLORIDE 1993 ... 

Mixed acid is a mixt of the conventional 50/50 NG-MA and spent acid, such that it contains about 27% nitric acid and 10% water or about 1,7 parts of spent acid to 1 part of MA Glycerine flow into the injector is controlled by the acid flow (much like the suction in a... 

Sources of thermochemical data for such calculations are Vol 7, H38 Lff Heat Effects — Data for Common Explosives NBS Circular 500 (Ref 39a) Cox Pilcher (Ref 89) and the studies of Rhodes Nelson (Ref 24b) and McKinley Brown (Ref 28a) on mixed acids As an example of such a calculation we will compute the heat evolution and temp rise occurring during the mixed acid nitration of glycerol to NG. We will assume that a typical 50/50 nitric acid/sulfuric acid MA is used and that the MA/glycerol ratio is 5/1. Further assumptions are that all the glycerol is converted to NG, and that the heats of soln of NG in die. spent acid, and of spent acid in the NG, are negligibly small (cf discussion of these effects by the writer in Ref 51). The net reaction is then ... 

A method which appears to be essentially equivalent to the best ABL method was patented by Brennecke (Ref 10) who claims better utilization of the spent acid and solvent and better yield in a repetitive, step-wise procedure. Another modification patented by Rolewicz et al (Ref 12) utilizes mixed acid and methylene chloride extrn and appears to be little different from the above methods, except that the nitric acid is made oxide-free. A method of obtaining 98.4% pure Petrin from its mixts with PETN and PE dinitrate is claimed by Brennecke (Ref 16)... 

Industrial TNT production produces both atmospheric and water pollution. The spent acid from the three stages of mono-, di- and tri-nitration pose considerable disposal problems. On an industrial scale the mixed acid from previous di- and tri-nitrations is usually refortified with nitric acid and used for mono- and di-nitration respectively. Diluted sulfuric acid is often... 

Heat of nitration of glycerin. Suppose we wish to estimate the heat evolved in nitrating 1 mole of glycerin with mixed acid. To simplify this illustrative example we will assume initial mixture — 1 mole glycerin/3 moles 100% nitric acid/6 moles 100% sulfuric acid final mixture -1 mole nitroglycerin completely separated from the spent acid which is now diluted by 3 moles of water the entire heat of dilution is due to 3 moles water dissolving in 6 moles of 100% sulfuric acid. Thus... 

A colorimetric method based on the violet color produced by ferrous sulfate in sulfuric acid in the presence of N03 was announced by English in 1947 (Ref 9) and applied to the determination of NA and nltrosylsulfuric acid (NSA) in spent mixed acid. Since then a number of papers (Refs 13, 14, 15, 16 and 17) have extended the method to NOa, organic nitrates and RDX -HMX mixtures Analytical Methods The visual determination of the endpoint (appearance of a permanent brown color) in the dead-stop titrimetric method is reported accurate to 0.03ml (Ref 3) and was used recently by Frejacques and LeClercq (Ref 12) for analysis of Pentolites, Tetryls, NGu, NG prepns, and Nitroethane-EGDN expls. The endpoint has been criticized as difficult to see, and if problems arise, electrometric methods are available for detection (Refs 6,... 

Desseigne (Ref 15) prepd DNDMO in 97% yield by nitrating dimethyloxamide with mixed nitric-sulfuric acid contg the amt of nitric acid 20% in excess of requirement. Mixed acid was of such compn that resulting spent (residual) acid contained less than 12.5% water... 

DVS. It is described as Dehydrating Value of Sulfuric in Mixed Acids 1 in Refs 3, 4 5-This value is also known as Spent Acid Concentration", because the lower the DVS is, the weaker is the spent acid due to uiw presence of too much water. With such weak acid, further nitration might stop (or even reverse), even if there is still some nitric acid left. The importance of not having too much water in spent acid is discussed in the last paragraph on p D43-R of Ref 5 DVS is also known as Driving Value of Sulfuric Acid" because it really promotes the nitration reactions (Ref 4)... 

Before nitration starts, the nitrator is filled with spent add up to the level of the overflow (5). The water inlet to the cooling coils is opened, the stirrer is set in motion, and through pipes (5) and (7) fresh mixed acid is introduced to be carried off with the stream of liquid and blended with the spent acid. Mixing takes place without any notable thermal effect. Part of the liquid is recirculated via the pipe (8) and part is run through the overflow (5) to a separator. Glycerine enters through the... 

Mixed acid. The nitrating acid is a conventional mixed acid, and spent acid is added in such a quantity that the HN03 content is 26.5-27.5% HN03 and the water content 9.5-10.0%. This water content is below the limit which may cause incomplete nitration. The ratio spent add mixed acid is 1.6-1.75. 

The nitration was carried out by a batch method, each charge comprising 420 kg diglycol and 1218 kg mixed acid. As a safety precaution for storing the spent acid, an excess of 293 kg HN03 was added to the mixed add (theoretically 499 kg of HNOj are necessary for nitrating 420 kg of diglycol). 

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