Chemistry of inorganic compounds – Sulfur or compound thereof – Oxygen containing
Patent
1993-06-08
1995-07-04
Langel, Wayne
Chemistry of inorganic compounds
Sulfur or compound thereof
Oxygen containing
C01B 1798
Patent
active
054298121
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the manufacture of peroxidic compositions and more particularly to a process for the manufacture of peroxomonosulphuric acid-containing solutions.
Peroxmonosulphuric acid, which is alternatively called Caro's acid, after the person which first made it, can be made by reaction between concentrated hydrogen peroxide and concentrated sulphuric acid or even oleum. The reaction can be represented as: does not proceed completely, but attains an equilibrium for the two reactants and two products. These trials were conducted using an excess of sulphuric acid above the theoretical ratio of 1:1, and often in the region of about 2:1 to 5:1 in order to favour the conversion of hydrogen peroxide rather than sulphuric acid to Caro's acid. Provided that appropriate care was taken to avoid significant decomposition of the peroxidic compounds such as by agitating and cooling the reaction mixture sufficiently, the trials demonstrated that equilibration occurred very quickly when the reactants were brought into contact, and the position of the equilibrium depended consistently upon the overall concentrations of the two reagents and the mole ratio of H.sub.2 O.sub.2 and H.sub.2 SO.sub.4 employed, ie it depended upon how much H.sub.2 O.sub.2, H.sub.2 O and H.sub.2 SO.sub.4 was added. The choice of the order of introduction of the reactants to each other did not affect the position of the equilibrium.
One of the attractive uses for Caro's acid solutions comprises oxidative detoxification of effluent solutions, of which one example comprises inorganic cyanides or nitriles. During such detoxification processes, it is often desirable to maintain at least a minimum alkaline pH, to avoid the evolution of a noxious gas. The use of Caro's acid solutions accordingly requires the addition of a neutralising alkali in an amount that is proportionate to the total amount of acid added. The use of Caro's acid solutions made using an excess of sulphuric acid not only increases the cost of neutralisation, but can increase the extent of formation of insoluble sulphate precipitates if an alkaline earth metal neutraliser such as lime is used.
Accordingly, and in order to reduce the amount of sulphuric acid that requires neutralisation in use, investigations have been made into the production of Caro's acid solutions from mixtures containing a substoichiometric amount of sulphuric acid, ie an excess amount of hydrogen peroxide.
However, it has been found that when a substoichiometric amount of sulphuric acid is reacted with aqueous hydrogen peroxide, the proportion of Caro's acid that is produced can be much less than the expected equilibrium amount, ie less than the amount expected by extrapolation from trials conducted using excess sulphuric acid, depending upon the way in which the reaction is carried out. On the other hand, it has also been found that if process is carried out in a different way, the proportion of Caro's acid formed can approach or approximate to the expected amount.
It is an object of the present invention to identify process conditions in which the problem of impaired production of Caro's acid is ameliorated or avoided.
According to the present invention there is provided a process for the production of Caro's acid-containing solution by reaction between a concentrated hydrogen peroxide solution and a concentrated sulphuric acid solution characterised in that the total amount of sulphuric acid employed is substoichiometric relative to the hydrogen peroxide, and further characterised by the steps of first forming a body of fluid that is sulphuric acid-rich, and secondly introducing into said body of fluid the hydrogen peroxide solution with agitation, thereby causing the mixture progressively to become sulphuric acid-lean.
By the term sulphuric acid-rich herein is meant that the body of fluid contains greater than one mole of sulphuric acid per mole of hydrogen peroxide and correspondingly the term sulphuric acid-lean means that there is less than one mole of sulphuric acid per mole of hydroge
REFERENCES:
patent: 2926998 (1960-03-01), D'Addieco et al.
patent: 3900337 (1975-08-01), Beck et al.
patent: 3939072 (1976-02-01), Laforte
patent: 5141731 (1992-08-01), Meier et al.
McDonogh Colin F.
Sanders Neil J.
Langel Wayne
Solvay Interox Limited
LandOfFree
Manufacture of peroxidic compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Manufacture of peroxidic compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Manufacture of peroxidic compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-758624