Waste sulphuric acid

An example where reactant concentration is solely governed by corrosion considerations is in the production of concentrated nitric acid by dehydration of weak nitric acid with concentrated sulphuric acid. The ratio of HN0j H2S04 acid feeds is determined by the need to keep the waste sulphuric acid at > 70 Vo at which concentrations it can be transported in cast-iron pipes and stored after cooling in carbon-steel tanks. 

Methacrylamide sulphate is then hydrolysed to methacrylic acid. The upper organic layer is distilled to yield high purity methacrylic acid. The lower waste acid layer is steam stripped to recover any dissolved methacrylic acid and the waste sulphuric acid is then disposed of or recovered. Two moles of sulphuric acid react with one mole of acetone cyanohydrin before elimination in the process. The major characteristic of the ACN process, therefore is the very large waste-acid stream. 

Destmctive combustion of gypsum and other waste Sulphuric acid containing inorganic or organic salts. 

Reconcentration of sulphuric acid A very large amount of tantalum heater surface has been installed in plants for the reconcentration of diluted sulphuric acid arising from metal pickling, oil refinery operations and from petrochemical processes producing alcohols and ketones. Since reconcentration provides a means of overcoming a waste of disposal problem, the use of such plants is expanding ... 

Journal of Applied Polymer Science 52, No.9, 31st May 1994, p. 1353-5 HYDROLYSIS OF WASTE PETP BY SULPHURIC ACID AT ISO C FOR A CHEMICAL RECYCLING... 

Waste PETP powder was hydrolysed to terephthalic acid and ethylene glycol in relatively dilute sulphuric acid and... 

Many standard reactions that are widely applied in the production of fine chemicals employ. strong mineral or Lewis acids, such as sulphuric acid and aluminium chloride, often in stoichiometric quantities. This generates waste streams containing large amounts of spent acid, which cannot easily be recovered and recycled. Replacement of these soluble mineral and Lewis acids by recyclable. solid acids, such as zeolites, acid clays, and related materials, would represent a major breakthrough, especially if they functioned in truly catalytic quantities. Consequently, the application of solid acids in fine chemicals synthesis is currently the focus of much attention (Downing et al., 1997). 

Citric acid (Ruthven, 1997). In the separation of citric acid from fermentation liquors the Sorbex process can be used. In the conventional process neutralization is carried out with lime followed by acidification with sulphuric acid to produce calcium sulphate as waste. The Sorbex technology avoids lime and sulphuric acid wastage and calcium sulphate disposal. 

Fish silage is usually produced from fish offals (heads, intestines, skin, etc.) or waste fish. The enzymes present in fish viscera decompose these tissues and the liquid protein hydrolyzate is the final product [9-11]. To avoid bacteria growth a pH about 2 is required and a relevant amount of organic or inorganic acid is added, usually it is sulphuric acid. The idea was to supply a certain amount of post-coagulation sludge for silage production [12]. 

Jurka and Carter [50] have described an automated determination of down to O.lpg L 1 mercury in river sediment samples. This method is based on the automated procedure of El-Awady [51] for the determination of total mercury in waters and waste waters in which potassium persulphate and sulphuric acid were used to digest samples for analysis by the cold vapour technique. These workers proved that the use of potassium permanganate as an additional oxidizing agent was unnecessary. 

Figure 9.1 compares the synthesis of acetophenone by classic oxidation of 1-phenylethanol with stoichiometric amounts of chromium oxide and sulphuric acid, with an atom efficiency of 42%, with the heterogeneous catalytic oxidation with O2, with an atom efficiency of 87%, and with water as the only by-product. This is especially important if we consider the environmental unfriendliness of chromium salts the potential environmental impact of reactions can be expressed by the environmental quotient (EQ), where E is the E-factor (kg waste/kg product) and Q is the environmental unfriendliness quotient of the waste. If Q is... 

In 1976 he was appointed to Associate Professor for Technical Chemistry at the University Hannover. His research group experimentally investigated the interrelation of adsorption, transfer processes and chemical reaction in bubble columns by means of various model reactions a) the formation of tertiary-butanol from isobutene in the presence of sulphuric acid as a catalyst b) the absorption and interphase mass transfer of CO2 in the presence and absence of the enzyme carboanhydrase c) chlorination of toluene d) Fischer-Tropsch synthesis. Based on these data, the processes were mathematically modelled Fluid dynamic properties in Fischer-Tropsch Slurry Reactors were evaluated and mass transfer limitation of the process was proved. In addition, the solubiHties of oxygen and CO2 in various aqueous solutions and those of chlorine in benzene and toluene were determined. Within the framework of development of a process for reconditioning of nuclear fuel wastes the kinetics of the denitration of efQuents with formic acid was investigated. 

Aciylamide is required in very large quantities as the pre-polymer of the polyacrylamide that is very widely used in polymer and flocculant apphcations. The chemical manufacture of acrylamide has been estabhshed for a long time. The original process involved treatment of acrylonitrile with sulphuric acid at 90°C. More recently processes have been introduced that require the use of copper catalysts and high temperatures (80-140°C), but result in the formation of large quantities of toxic waste, including HCN. The expensive copper catalyst used is difficult to regenerate. In addition the chemical process produces aciylamide that requires considerable purification, for instance because the... 

A factory in which soda ash is made is called an alkali works. A works using the Leblanc process is divided into several departments (1) The acid works where sulphuric acid is made (2) Salt-cake works (3) Black-ash works and lixiviation (4) White-ash (soda ash) works or caustic soda works (5) Bleaching powder works where the hydrogen chloride from the salt-cake works is converted into chlorine, and the latter converted into bleaching powder and (6) Sulphur extraction from tank-waste. The following is a diagrammatic representation of the Leblanc process ... 

Waste lead styphnate was destroyed by adding an excess of sodium carbonate most of the lead was then precipitated as a carbonate and a solution of sodium styphnate was formed. This solution was then treated with iron filings and acidified with sulphuric acid, reduction of the nitro groups took place, and the substance ceased to be dangerous. 

It is usual upon the large scalo to employ a smaller proportion of sulphuric add than when tho distillation Is performed in glass vessels, as it is quite possible to effect a complete decomposition of the nitrate by heating it with one-half its weight of sulphuric acid. Under these circumstances, however, a higher temperature is needed to expel the last portions of acid, and a considerable quantity of the nitric acid is thereby decomposed and wasted. The residue in the retort, when the smaller... 

The primary object of these improvements is to render again available in the manufacture the sulphur contained in alkaline waste, which in the ordinary method is totally lost. As those relate more especially to the economical production of sulphuric acid, they will be further noticed in connection with the article to be specially devoted to that substance. 

The sulphides of the alkali metals and of the alkaline earth metals are readily decomposed by weak acids, even by carbonic acid.3 Ily the use of these sulphides and dilute sulphuric acid it is possible to obtain hydrogen sulphide in a high degree of purity. The hydrosulphides of the alkaline earth metals arc convenient sources of hydrogen sulphide, yielding the gas on treatment with carbon dioxide or even by merely heating.4 The carbon dioxide method is applied on a technical scale in the extraction of sulphur from alkali waste (see p. 50). 

---