Stabilization, of hydrogen peroxide

Maximum stability of hydrogen peroxide would be attained, if no impurities at all would have entered during manufacture or storage. As, however, all produots contain impurities, depending on the production method used, certain substances must be added to improve the stability of the peroxide. 

In view of the great number of substances which act as catalysts accelerating the decomposition of the hydrogen peroxide, it is not surprising that a very large number of stabilizers is known. 

The efficiency of these negative eatalysts or inhibitors depends first of all on the amount of impurities contained in the hydrogen peroxide. If impurities are few the solution can be stabilized for a long time. If considerable amounts of impurities are present the addition of stabilizers has no effect. It is, therefore, preferable to redistil the product. 

Apart from this, the efficiency of the stabilizers depends on the pH of the solution. Commercial grades of hydrogen peroxide which must be stored for a long time are adjusted to achieve a slightly acid reaction (pH = 2—6), at which 

Substances which are employed to stabilize hydrogen peroxide for a long period of storage are divided according to their nature into inorganic acids, inorganic salts and organic compounds. Industrially it is usual to add several different stabilizers at the same time as the total efficiency of the mixture by far exceeds the sum of the efficiency of all the individual stabilizers. 

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The specific gravity of an 80% solution of hydrogen peroxide is 1.34. The solution is fairly stable at room temperature and decomposes only at an elevated temperature (the stability of hydrogen peroxide will be descussed later). To increase the stability of this solution, stabilizing substances such as phosphoric acid and its salts or 8-hydroxyquinoline were added. 

Fig. 24.2. Operational stability of hydrogen peroxide sensors (PB-modified sensors). Applied potential —50mV vs. int. ref. Continuous monitoring of current in continuous flow mode (10 pi min-1). Arrows indicate where solution of hydrogen peroxide was renewed, (a) Two sensors tested with 10-4 and 2 x 10-4moll-1 of hydrogen peroxide, (b) Six months old sensor tested with a solution of 2 x 10-4moll-1 of hydrogen peroxide. Reprinted from Ref. [59] with permission from Elsevier.

Some thermodynamic data relevant to the stability of hydrogen peroxide are summarised below (all energies in kJ mol-1 at 25 °C) ... 

Research conducted at Washington State University, as well as in situ applications by commercial entities, has indicated that stabilization of hydrogen peroxide is necessary for effective subsurface injection [39]. Without stabilization, added peroxide decomposes rapidly through interaction with iron oxyhydroxides, manganese oxyhydroxides, dissolved metals, and enzymes (e.g., peroxidase and catalase). Some of these peroxide decay pathways involve nonhydroxyl radical-forming mechanisms, and therefore are especially detrimental to Fenton oxidation systems. 

The final product is drained off from the retort, cooled and stored in aluminium tanks in which, if necessary, it is stabilized with phosphoric acid, pyrophosphate and 8-hydroxyquinoline. The stability of hydrogen peroxide with a high percentage is very high. After being stored a year in aluminium tanks it loses hardly more than 0.5 to 1 per cent of active oxygen. In view of this, it is also suitable for shipment to tropical countries. 

Ensures stability of hydrogen peroxide and controlled bleaching resulting in an excellent white, minimum loss of yarn strength, no pinholing and economical use of hydrogen peroxide. 

The low level of chemical activity observed in some of these catalyst-free peroxide-carbohydrate systems may be due to the high stability of hydrogen peroxide in the absence of inorganic ions. ... 

Nelsen and Groennings [57] developed a method for the determination of trace amounts of organic compounds in hydrogen peroxide, which is a necessary step for checking the quality and stability of hydrogen peroxide. Their method consists in thermal decomposition of hydrogen peroxide, accompanied by oxidation of organic compounds to carbon dioxide. 

Containable temperature and pressures Fair. For hydrogen peroxide, conditions that minimize opportunities for decomposition must be used. The stability of hydrogen peroxide-containing reaction liquors depends on the concentration of the hydrogen peroxide, the temperature, and the materials present Experimental studies will be necessary to determine the highest concentrations of hydrogen peroxide that can be safely employed. 

As the potential of this technology is tremendous, companies are putting their effort in investigating the reaction kinetics and stability of hydrogen peroxide formation in a microreactor. Some such studies are performed at BASF Catalyst [57] and give a promising input for optimizing the reaction for more efficient... 

Chemical Reactivity - Reactivity with Water. Forms solution of hydrogen peroxide. The reaction is nonhazardous Reactivity with Common Materials There are no significant reactions under ordinary conditions and temperatures. At 50 °C (122 of) the chemical reacts with dust and rubbish Stability During Transport Stable below 60 °C (140 of) Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Solutions of hydrogen peroxide are of high purity, readily transportable in bulk quantities and exhibit long-term storage stability over a wide range of conditions. When stored in compatible vessels under ambient conditions and free from contamination, solutions of 35 %, 50 %, or 70 % H2O2 concentration will lose less than 1 % of their available oxygen content within a year. 

Certain metal salts effectively reduce the photoactivity of titanium dioxide pigments. Combination of these salts with an appropriate antioxidant and/or ultraviolet stabilizer provided highly efficient stabilization of polypropylene. The deactivation/ stabilization performance of the metal salts is adequately explained on the basis of their decomposition of hydrogen peroxide at the pigment surface and by annihilation of positive holes in the pigment crystal lattice. 

However, an important problem arises during the peroxidative removal of phenols from aqueous solutions PX is inactivated by free radicals, as well as by oligomeric and polymeric products formed in the reaction, which attach themselves to the enzyme (Nazari and others 2007). This suicide peroxide inactivation has been shown to reduce the sensitivity and efficiency of PX. Several techniques have been introduced to reduce the extent of suicide inactivation and to improve the lifetime of the active enzyme, such as immobilization. Moreover, Nazari and others (2007) reported a mechanism to prevent and control the suicide peroxide inactivation of horseradish PX by means of the activation and stabilization effects of Ni2+ ion, which was found to be useful in processes such as phenol removal and peroxidative conversion of reducing substrates, in which a high concentration of hydrogen peroxide may lead to irreversible enzyme inactivation. 

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