Zinc peroxide is produced by adding zinc oxide or hydroxide to a solution of hydrogen peroxide. Zinc Peroxide is used as a curing agent in carboxylated NBR, as inhibitor in the accelerated vulcanisation of rubber and as a filler in siloxane elastomers. It also finds use in the cosmetic industry and for medical purposes.
Barium and strontium peroxides have been used among the conventional inorganic peroxides as an oxidant for use in explosives or in pyrotechnics. The disadvantage of the peroxides of barium and strontium heretofore employed as oxidants for explosives and pyrotechnics resides, on the one hand, in the basic reaction products obtained after the oxidation reaction and the adverse effect of such reaction products on the corrosion resistance of the metallic materials present. Furthermore, such peroxides are very susceptible to the effects of atmospheric moisture, forming hydrolysates having a lower proportion of available oxygen. Barium peroxide furthermore exhibits the great disadvantage that barium compounds injurious to health are formed during the combustion reaction.
In solving this problem, it has now been found that zinc peroxide represents a suitable oxidant for explosives and pyrotechnical compositions or mixtures. By means of the zinc-containing reaction products, the corrosion of metallic materials in a moist atmosphere can be drastically reduced, and the MAK [maximum working place concentration] values of zinc--as compared to those of the barium compounds--prove that danger to health is thus reduced by a factor of 10.
The amount of zinc peroxide used in the igniter and initiator charges depends on the type and quantity of the accompanying substances. Igniter charges having a proportion of 10-30% by weight of the initiator explosives, and 0-10% by weight of a reductant, require generally 50-60% by weight of zinc peroxide.
Zinc peroxide, however, is useful as an oxidant in explosive mixtures, not only in a blend with initiators in igniter and initiator charges, but also in a mixture with secondary explosives or in pyrotechnical mixtures. Examples for secondary explosives have been cited above, namely nitrocellulose and pentaerythritol tetranitrate (PETN). Additional examples are mixtures with octogen, as well as mixtures with secondary explosives exhibiting a large negative oxygen balance. When using zinc peroxide in pyrotechnical mixtures, such a mixture contains in some cases additional oxidants, as well as reductants. The proportion of zinc peroxide in these mixtures ranges suitably between 40 and 60% by weight, preferably between 45 and 55% by weight, based on the total weight. Besides metals and/or metallic compounds, the pyrotechnical mixtures can also contain organic reductants, e.g. polyoxymethylene, lactose, or polyethylene. In these cases, for example, with a weight ratio of zinc peroxide/reductant of 85/15, a vigorous reaction is obtained. When using organic reductants, it is possible for the zinc peroxide content in the pyrotechnical mixtures to be up to 90% by weight.
Carbamide peroxide is the most commonly used active ingredient in home bleaching systems. It breaks down into hydrogen peroxide and urea in aqueous solution. Although concentrations of 10% carbamide peroxide (equivalent to approximately 3% hydrogen peroxide) are most commonly used, bleaching systems containing up to 22% carbamide peroxide are available for home use.
Dental care; Home bleaching is a popular dental procedure used to whiten teeth. The first clinical study of nightguard vital tooth bleaching using a carbamide peroxide product was published in 1989.1. The carbamide peroxide is a mixture of hydrogen peroxide and carbamide whose amino groups neutralise the acidity of the hydrogen peroxide. This compound acts as an oxidative bleaching agent that liberates oxygen. It is able to oxidatively degrade numerous organic colouring agents present both in food products and in pharmaceutical products that produce dental colourings. In general, the organic colouring agents owe their dyeing capacity to the present of chromophor groups, that is to say, chemical groups rich in electrons, generally conjugated double bonds. Illustrative examples of organic colorants are, erythrosine, used as a developer for bacterial plaque, tartracine, used as a food additive, indigotine, used in the formulation of some drugs, and tetracycline, an antibiotic that produces dental colourings that range from yellow to brown. It is believed that oxidative degradation (oxidative bleaching) of this type of colorant occurs via a mechanism that implicates the decomposition of hydrogen peroxide and the formation of free radicals (HO--) that attack the double bonds present in the molecules of said colorants and, subsequently, produce the breakage of the double bonds and the oxidation of the carbons implicated to corresponding carbonyl groups. The carbonyl groups formed, although they also possess .pi. (Pi) electrons as in the C.dbd.C double bonds, absorb in the ultraviolet zone of the spectrum and so do not contribute to discoloration.
Hemorrhoid and anorectal disease treatmen; The urea hydrogen peroxide provides a cleansing, healing, and oxygenating action on hemorrhoid tissues and on anorectal tissues, such as fissures and fistulas. It decomposes to provide epidermal irrigation and desquamation (keratolysis), and produces bacteriostatic activity by way of damaging bacterial proteins. It also inhibits triglyceride (lipid and sebum) hydrolysis, thereby reducing levels of free fatty acids. This tends to decrease inflamation of surrounding tissues or lesions. The production of oxygen also demonstrates a mild astringent activity on injured tissue and, as noted above, hydrogen peroxide exerts a cleansing and debriding action through effervescent activity. The urea aids in solubilizing organic debris. Oxygen (O.sub.2) stimulates re-epithelization of insured or denudated skin or tissue. The degradation byproducts of urea hydrogen peroxide are harmless and nontoxic if absorbed through the rectal mucosa. The urea hydrogen peroxide can be used in an amount of by weight of between about 2%-40%, and more preferably between about 5%-10%, and most preferably between about 7% and 10%. Benzoyl peroxide may be used in the foregoing amounts in place of carbamide peroxide as the oxygenating agent.
Skin blemish treatment; Acne vulgaris is an inflammatory disease of the pilosebaceous glands characterized by an eruption of the skin, often pustular in nature but not supprative. Acne is a common affliction of the adolescent and affects a small but significant percentage of the adult population. Acne lesions are of four basic types: comedones (blackheads or whiteheads), papules, pustules, and cysts (or nodules). Various topical agents are utilized in the treatment of acne and these include sulfur, resorcinol, salicylic acid, benzoyl peroxide, vitamin A acid and topical antibiotics.There are a variety of methods for treating acne vulgaris including topically applying various scrubbing or abrasive compositions, topically applying deep cleaning or astringent compositions and also exposure to ultraviolet radiation. Nevertheless, acne vulgaris is seldom cured and only can be contained with difficulty. Carbamide peroxide is an agent used to soften earwax for removal. Carbamide peroxide applied topically to the skin is useful in the treatment of acne vulgaris. Also, surprisingly carbamide peroxide achieves such beneficial effects without much of the irritating and sensitizing effects of benzoyl peroxide. It has also been found that combinations of carbamide peroxide with certain chemical agents known to be effective in treating acne are more effective in treating acne than would be expected by treatment with the individual agents themselves. Such formulations include combinations of carbamide peroxide and one or more of nicotinamide or topical antibiotics such as erythromycin base, clindamycin phosphate and tetracycline hydrochloride.
Thiourea dioxide is also called formamidine-sulfinic acid or aminoiminomethanesulfinic acid and is often abbreviated as TDO or TUD. Thiourea dioxide is a powdered stable compound, which dissolves in water and decomposes gradually to exhibit a reducing action. But, this reaction is slow, and particularly in an acidic to weakly alkaline region. Thiourea dioxide is stable and its reducing action is weak. Usually, thiourea dioxide dissolves in water and produces sulfoxylic acid through formamidine-sulfinic acid. This reaction is promoted by the application of heat or in the presence of an alkali, and a strong reducing action is thereby exhibited. TDO is useful as a reducing agent ; it reduces vat dyes, ketones to alcools and hydrocarbons and conjugated unsaturated acids to the corresponding saturated acids. It is an excellent antioxidant in the stabilization of percholorethylene. It is mainly used in dyeing and paper making industry stead of using sodium hydrosulphite, organic synthesis in synthetic fibre industry, additive of polymerzation, stabilizer for polythene sensitizer of photographical emulsion.
In the dyeing of fibrous products using oxidation-reduction dyeing type dyes such as vat dyes and sulfur dyes, it is sodium hydrosulfite (hereinafter referred to simply as "hydrosulfite") that has heretofore been mainly used as a reducing agent. However, hydrosulfite is poor in preservative stability and undergoes an oxidative decomposition to a large extent upon contact with air, for which reason it is an actual situation that hydrosulfite is used in large excess amount as compared with a theoretically required amount. Such decomposition of hydrosulfite is specially remarkable in a continuous pad dyeing, in which the decomposition proceeds to a remarkable extent during a short period of time from the padding of a reducing solution on the cloth until steaming. Moreover, when handling, hydrosulfite produces a bad smelling gas; therefore, also in point of public nuisance based on a bad smell there has been a demand for a reducing agent free from smell.
Thiourea dioxide, which is also called aminoiminomethanesulfinic acid or formamidinesulfinic acid, is sold on the market industrially and is available as a white powder superior in preservative stability and having neither oxidizing property nor reducing property, but displays reducing property when an aqueous solution thereof is made alkaline or heated. Its reducing power is very large, stability in an aqueous alkali solution is good and decomposition by an air oxidation is less remarkable, with little production of a bad smell. Thus, thiourea dioxide is an excellent reducing agent. For this reason, application of thiourea dioxide to various fiber fields including dyeing, printing, discharge printing and reduction clearing has been studied and announced in literatures. Oxidation-reduction dyeing using thiourea dioxide boasts of following advantages.
>> High brightness, good brightness stability;
>> Maximum pulp strength at minimum cost;
>> Minimum environmental pollution
Bleaching of pulp for papermaking is roughly divided into bleaching with a peroxide, bleaching with a chlorine-containing oxidizing agent, and bleaching with a reducing agent, and these have been employed depending on the kind of pulp and purpose of use in consideration of their bleaching characteristics and effects.
The bleaching with a peroxide represented by H.sub.2 O.sub.2 is employed mainly for bleaching of mechanical pulp and for deinking/bleaching of waste newspaper because of its bleaching effect on pulp containing lignin.
Since the bleaching with a chlorine-containing oxidizing agent is effective for chemical pulp containing a slight amount of lignin, bleaching with Cl.sub.2, NaClO or ClO.sub.2 is mainly carried out in multistage bleaching of kraft pulp, and bleaching with NaClO in bleaching of waste wood-free or mechanical paper. For example, in the bleaching of waste wood-free or mechanical paper, a 12% NaClO solution is added to pulp in an amount of about 8% based on the amount of pulp and mixed therewith, whereby the bleaching is carried out.
The bleaching with a reducing agent is excellent in decolonization of dye type coloring materials, but it has a limited-bleaching capability for peroxide type chemicals and chlorine-containing chemicals and entails a high cost. For these reasons and the like, it has been employed mainly for bleaching of mechanical pulp demanding a low brightness grade to be incorporated into newspaper, post-bleaching after H.sub.2 O.sub.2 bleaching of mechanical pulp demanding a high brightness grade and post-bleaching after H.sub.2 O.sub.2 deinking/bleaching of waste newspaper. In general, Na.sub.2 S.sub.2 O.sub.4 or TUDO of the dithionite family has been used as the reducing agent. Of these, Na.sub.2 S.sub.2 O.sub.4 has been mainly used from the viewpoint of bleaching capability, chemicals cost, etc. However, TUDO bleaching has recently come to be spotlighted as a substitute for NaClO bleaching in bleaching of waste wood-free or mechanical paper and as a substitute for Na.sub.2 S.sub.2 O.sub.4 bleaching in post-bleaching after H.sub.2 O.sub.2 deinking/bleaching of waste newspaper, from the viewpoint of the problem of waste water pollution by organic chlorine compounds represented by dioxins, demand for energy conservation, decoloring effect on dye type coloring materials, etc.
Thiourea dioxide is an ecological alternative product to sodium hydrosulfite (sodium dithionite) or to sodium formaldehydsulfoxylate dihydrate. In alkaline medium from 70°C it has higher red-ox potential than sodium hydrosulfite. That is the reason why thiourea dioxide is more effective on imperceptible dosing and why the waste water is not contaminated with salts (sodium sulphate or sodium sulphite).
Another advantage of Redutex is its storage. Redutex is not auto flammable. If the storage conditions are observed, content of thiourea dioxide in Redutex does not change with time.
By final reducing purification by dyeing with dispersed dye and by printing, by removing of defective dyeing, by purifying of dyeing machines, by reducing of sulphur dyes by dyeing on machines.
Compared with the peroxide bleach alone, bleach system activated with DECOBS in detergent formulations has significantly improved the washing performance in following aspects:
>> Effective low temperature bleaching;
>> Energy savings;
>> Protection of fibers and colours;
>> Disinfective action
>> Improvement of odour and general washing effect;
>> Reduction of the peroxide quantity
DECOBS could be applied in textile bleaching to react with hydrogen peroxide in the bleach bath to produce a stronger oxidant. In traditional peroxide bleaching process the reaction temperature should be high enough to enable the bleach action, which usually resulting in a big energy consumption and the incapability of bleaching heat sensitive fabrics. The use of DECOBS as bleach activator enables bleaching at lower process temperatures and under milder pH conditions. Such bleaching conditions are particularly suited to today’s sensitive synthetic fibers and complex fabric blends. Thus, DECOBS incorporated bleaching distinguish itself from traditional processes through following benefits:
>> Lower processing costs and increased productivity;
>> Improved product quality, e.g. fabric whiteness, fiber strength;
>> Broader bleach application on a wide range of materials.
Oxygen based bleaching is used for pulp bleaching because of its environmental benefits and oxidizing power, But pulp bleaching by hydrogen peroxide alone suffers from some performance disadvantages such as the reduction of whiteness, fiber length and loss of strength, as well as the poor delignification performance. For the sake of avoiding such disadvantages, DECOBS is suggested to react with hydrogen peroxide to form a pulp bleaching solution. The addition of DECOBS into pulp bleaching solution results in a satisfactory bleaching effect.
Improved quality in e.g. colour reversion properties, fiber strength, brightness, shade;
Lower reaction temperature, lower energy cost, shorter operation term.
Potassium monopersulfate is used as an auxiliary oxidant (shocking agent) in swimming pools and spas for the purpose of reducing the organic content of the water. It is the active ingredient in most non-chlorine shock products designed for use in swimming pools, and it’s the active ingredient in essentially all non-chlorine shock products formulated for use in spas and hot tubs. Shock products containing potassium monopersulfate provides many benefits.
>> It will not produce chloramines or generate irritating chloramines odors
>> It can promotes maximum sanitizer efficiency by oxidizing and eliminating contaminant waste
>> It restores sparkle and clarity
>> It is gentle on pool surfaces—dissolves quickly and completely and will not bleach or fade vinyl liners or painted surfaces
>> It will not raise calcium hardness or increase cyanuric acid stabilizer levels
>> It is easy to use—simply broadcast uniformly over pool water surface, with filter running, to ensure complete mixing and circulation
Potassium monopersulfate fits easily into most water treatment programs for all types of pools and spas and provides sufficient oxidation to enhance sanitizer efficiencies and produce clear, sparkling water.
Potassium monopersulfate can be added to pool water day or night, and swimming can resume after a short waiting period to allow for adequate mixing and dispersion throughout the pool. No mixing is required—potassium monopersulfate is completely soluble in water and dissolves quickly. Broadcast monopersulfate shock slowly and uniformly over the surface of the water, adding about two-thirds of the total dose over the deep end. Shock with the filter running to ensure complete mixing and good circulation.
How to use potassium monopersulfate?
>> For residential swimming pools; For pools with moderate daily use, add potassium monopersulfate weekly at a dose of one pound per 10,000 gallons of pool water. More frequent and/or heavier doses may be required when bather loads are extremely heavy or following heavy rains or high winds.
>>For public swimming pools; A good starting point is to shock weekly with one to two pounds of potassium monopersulfate per 10,000 gallons of pool water. The dose required and the shock frequency will depend largely on the bather load.
>>For spas; Potassium monopersulfate should be added to spa water after every use, at a dose of about one to two ounces per 250 gallons, to immediately oxidize and eliminate organic contaminants introduced by bathers. Public spas which are used every day may need to oxidize with potassium monopersulfate daily.
Potassium monopersulfate offers a distinct advantage over less soluble, dry oxidants such as sodium perborate, particularly at relatively low temperatures. At the preferred proportions of one part sodium bromide to two parts sodium chloride by weight, optimum leaching values are obtained from the minus 250 mesh precious-metal-bearing ores at pH values from 3.2 to 3.6 and oxidation-reduction potential values from +750 to +850 millivolts. Bromine and chlorine are liberated, and the chlorine synergistically oxidizes the precious metal complexes enabling up to 98% of the precious metal to be extracted in the form of water soluble metal bromides.
Below is an example illustrating a process using potassium monopersulfate as oxidant.
First, add 500 gallons of water to a 1000 gallon capacity tank to which was also added 2000 pounds of precious-metal-bearing ore having a particle size reduced to minus 250 mesh. The ore had been assayed by atomic absorption, emission spectroscopy and fire assay and found to contain 5.8 ounces of gold, 13.2 ounces silver, 0.41 ounce platinum and 1.54 ounce rhodium per ton.
The resultant slurry was stirred and 40 pounds of sodium bromide (97% technical grade) and 80 pounds sodium chloride (technical grade) were slowly added and the resultant slurry was stirred for 30 minutes, after which 0.25 pound increments of potassium monopersulfate were added, while the oxidation/reduction potential was monitored. The addition of potassium persulfate was continued until the potential reached 800 millivolts and the pH between 3.2 and 3.6. After the addition of 1.5 pounds of potassium monopersulfate the oxidation/reduction potential increased to +900 millivolts, and hydrochloric acid was added to reduce the potential to +810 millivolts. The slurry was stirred for five hours, and monitored every 30 minutes to determine its oxidation/reduction potential and pH. Potassium persulfate and hydrochloric acid were added in slight amounts as necessary to maintain the potential at 800 plus or minus 50 millivolts, and the pH between 3.2 and 3.6.
After five hours, the slurry was filtered and the filtrate was pumped to a 750 gallon holding tank equipped with a stirrer.
The precious metals in the filtrate were recovered by adding one gallon of an aqueous solution of 6 weight percent sodium borohydride and 20 weight percent sodium hydroxide was added. The oxidation/reduction potential of the liquid was adjusted to and maintained at -600 millivolts, plus or minus 50 millivolts and the pH of the liquid was maintained at 8.3 to 8.7 by the addition of sodium borohydride and hydrochloric acid.
After two hours of stirring, the liquid was filtered to recover the precipitate of precious metals. The filtrate was reconstituted for reuse.
The filtered solids were dried and purified to determine that the recovery, per ton of ore, was: 5.64 ounces of gold, 12.6 ounces of silver, 0.38 ounces of platinum, and 1.48 ounces of rhodium.
Integrated circuits are made up of millions of active devices formed in or on a silicon substrate. The active devices, which are initially isolated from one another, are interconnected to form functional circuits and components. The devices are interconnected through the use of well-known multilevel interconnections. The electrical connections between different interconnection levels are made through the use of metallized vias. In one semiconductor manufacturing process, metallized vias or contacts are formed by a blanket metal deposition followed by a chemical mechanical polish (CMP) step. In a typical chemical mechanical polishing process, the substrate is placed in direct contact with a rotating polishing pad. A carrier applies pressure against the backside of the substrate. During the polishing process, the pad and table are rotated while a downward force is maintained against the substrate back. An abrasive and chemically reactive solution, commonly referred to as a "slurry" is applied to the pad during polishing. The slurry initiates the polishing process by chemically reacting with the film being polished.
Despite the desirability of using a film forming mechanism in a CMP process there remains problems with formulating CMP slurries that can control the thickness of the layer of film formed as well as problems ensuring that the film formed is abradable. These problems can result in a CMP slurry that exhibits unacceptably low polishing rates or poor polishing results. Thus, a need remains for a CMP slurry that is capable of forming a removable thin abradable layer on a substrate surface and more particularly on the surface of a copper alloy containing substrate. A desireable CMP slurry will exhibit good thin film polishing selectivities and simultaneously give polished substrates with minimal dishing and low defectivity. The chemical mechanical polishing slurry, ("CMP slurry"), is a useful product that comprises an oxidizer, an abrasive, a complexing agent, a film forming agent, and other optional ingredients.
A preferred oxidizer is urea hydrogen peroxide. Because urea hydrogen peroxide is 34.5 wt % hydrogen peroxide and 65.5 wt % urea, a greater amount by weight of urea hydrogen peroxide must be included in CMP slurries of this invention to achieve the desired oxidizer loading set forth above. For example, a range of 1.0 to 12.0 weight percent oxidizer corresponds to a urea hydrogen peroxide weight three times as great or from 3.0 to 36.0 weight percent. A CMP slurry comprising urea hydrogen peroxide can be formulated by a number of methods including combing urea peroxide with water, and by combing urea and hydrogen peroxide in an aqueous solution in a mole ratio range of from about 0.75:1 to about 2:1 to give a urea hydrogen peroxide oxidizer. The CMP slurry incorporated with urea hydrigen is effective in controlling polishing selectivities of titanium, copper, and titanium nitride. The polishing slurry of may be used during the various stages of semiconductor integrated circuit manufacture to provide effective polishing at desired polishing rates while minimizing surface imperfections and defects.
Magnesium peroxide is a fine, odorless and tasteless, white powder. When the pH shifts toward neutral, magnesium peroxide slowly releases oxygen via intermediate formation of hydrogen peroxide. Magnesium peroxide is primarily used as the main oxygen source for in-situ bioremediation. It also finds use in oxygenating the lower parts of artificial or natural lakes, as well as wastewater and effluent, in coating seeds to improve germination and seedling survival rates, in oxygenating the roots of plants, and as the bleach agent in personal formulations.
Oxygen-release compounds increase the oxygen content of contaminated areas, enhancing biological activity and thus promoting natural attenuation. The specific compound used will depend on soil chemistry, concentration of target organics, type of target organics and cleanup levels. Parameters of interest are release rate of oxygen at different effective partial pressures and ratio of oxygen released to amount of oxygen applied. Researchers studied the solid oxidants below with respect to dissolution rate and ease of movement through other media:
• Na2CO3•1.5H2O2 encapsulated sodium percarbonate
• free sodium percarbonate crystals
• CaO2, calcium peroxide
• MgO2, magnesium peroxide
Oxygen movement in the subsurface is influenced by:
• soil heterogeneity
• moisture content, which can hinder O2 movement
• pore size—a function of sediment age and history
• tortuosity, caused by small pore sizes, which increases O2 path distance
Soil morphology directly influences O2 diffusion through the soil and soil redox potential, and the biological degradation that will occur at interfacial areas. In the interstitial pores, microbes are protected from toxic compounds. “Interstitial pore space attachment also makes predation more difficult.
Solid oxidants can exhibit slow dissolution and fall into a reaction-limited domain. Conversely, these compounds can release oxygen from their surfaces rapidly, exhibiting transport limitations. Researchers predicted that the encapsulated Na2CO3 •1.5H2O2’s release of O2 was by diffusion-limited transport while the other studied oxidants were controlled by chemical reaction kinetics of dissolution. The kinetics of dissolution have both chemical and thermodynamic limitations. Reactions are as follows:
2H2O + MgO2<=> Mg(OH)2(s) + H2O2
2H2O + CaO2(s) + <=> Ca(OH)2(s) + H2O2
4Na2CO3•1.5H2O2 <=>8Na+ + 4CO3- + 6H2O2
H2O2 + H2O2<=> O2 + 2H2O
Some of the reaction products produced—Mg(OH)2 and Ca(OH)2 —have solubility values lower than the ions added. Such precipitates may coat reactant particles and block pores in both the soil and reactant particles, limiting transport of reacting ions and particles.
Sodium percarbonate would release O2 by diffusion-limited transport whereas chemical kinetic reactions would control dissolution rate of other oxidants. Release rates of MgO2 and CaO2 could be limited because of self-encapsulation.
Experiments and results
The unencapsulated Na2CO3• 1.5H2O2 had the most rapid release rate, followed by CaCO2, and encapsulated Na2CO3•1.5H2O2. MgO2 had the slowest O2 release by several orders of magnitude.
However, the large size of both forms of Na2CO3•1.5H2O2 slows transport of bulk particles. CaO2 and MgO2 both have fractions small enough to permit migration where soil particles, and thus pore spaces, are larger than the particles of soil oxidant. In some cases, lack of movement of oxidant particles may be desirable in establishing stationary oxidative zones.
Adding oxidants to water also changes the water’s pH, usually in the range of 10 to 12. Shifts to high pH conditions generally have a negative effect on indigenous bacteria, but soils can have a buffering capacity to counteract or neutralize the pH shifts.
Other conclusions Release rates that are too rapid for biological uptake rates will prevent the utilization of all O2. Oxygen release rates below optimum may result in reduced aerobic metabolism or failure to maintain aerobic respiration. Of the oxidants tested, MgO2 has the widest application based on
• O2 release rate, which was the longest
• pH shift, which was lowest
• O2 release per mass, which was highest
Oxygen release compound, commonly known as magnesium peroxide (MgO2), raises the dissolved oxygen concentration of aquifers, thereby creating conditions which may stimulate indigenous, petrophilic microbes to aerobically degrade petroleum contamination to carbon dioxide and water.
Oxygen generation: Magnesium peroxide, when hydrated, releases oxygen per the following reaction:
MgO2+ H2O --> 1/2 O2+ Mg(OH)2
>> Application methods: Magnesium peroxide can be introduced to an aquifer by either the retrievable filter sock method or by direct-push injection as a slurry. In situations where there is an open excavation as a result of either an underground storage tank removal, or remediation via excavation, magnesium peroxide as a dry powder can be mixed with low level contaminated soil before backfilling. Typically, the amount of compound applied to the soil is at least about 100 grams per metric ton of soil and preferably from about one to ten kilograms of compound per metric ton of soil.
>> Uses: Some noteworthy uses of magnesium peroxide in the remediation of petroleum are: (1) at sites where adequate nutrients for bioremediation already exist in an aquifer, and dissolved oxygen is all that is needed to accelerate the rate of contaminant biodegradation; (2) as an oxygen barrier for groundwater contamination plume control; (3) as a polishing step to meet target rehabilitation contaminant levels when active site remediation, such as pump-and-treat or other physical methods, is no longer cost-effective; and (4) as the oxygen supplier, in combination with other injected bioremediation products that directly introduce either nutrients and/or microbes into aquifers.
Calcium peroxide is a yellowish solid peroxide which slowly decomposes to release oxygen at a "controlled" rate. It decomposes in moist air, is practically insoluble in water, and dissolves in acids, forming hydrogen peroxide. A 1:100 aqueous slurry has a pH of about 12.
Calcium peroxide is an ecologically pure substance, which can be used in different fields of industry and agriculture.
In environmental protection it is used:
>>for treating waste water and remediation of groundwater
>>for decontaminating soil
In agriculture it is used:
>>as fertilizing rich with oxygen;
>>for stimulating seed growth and their germinating power;
>>for presowing treatment of rice seed, which allows to do planting not by seedlings, but by dry seeds, coated with calcium peroxide. Such a technique sufficiently decreases work expenditure and increases crop capacity.
In aquaculture it is used:
>> to provide sufficient dissolved oxygen;
>> to adjust pH value;
>> to reduce the subaqueous content of ammonium and nitrogen;
>> to eliminate carbon dioxide and sulfureted hydrogen;
>> to prevent anaerobe from proliferation and killing nosogenetic bacteria, defecating aqueous body;
In poultry-raising it is used:
>> to decontamination of fodder;
>> to increase productivity, hens safety and improving their eggs.
In cattle-breeding it is used:
>> for prophylaxis of casein-stone formation in the abomasum and diarrhoea with newborn calves;
>> as an antimicrobic effect;
>> for stimulating protective organism strength;
>> for normalizing activity of the alimentary canal;
>> for activizing digestion work;
>> for great increasing live-stock safety.
In precious metal production it is used:
>> for leaching precious metals in the formation of cyano complexes (particularly complexes with gold and/or silver) from ores, ore concentrates, and other particle-shaped, solid materials.
In bakery industry it is used:
>> to improve bread crumb and its porosity;
>> to keep moisture in dough during its baking;
>> to initiate yeast growth.
In dental care it is used:
>> for tooth bleaching
Calcium is the main constituent of plant cell walls, and is most abundant in actively dividing root and shoot cells. It is particularly advantageous to supplement calcium levels in germination/rooting, pre and early flowering. By having sturdy cell walls, plants are less susceptible to insect and disease, while providing greater dry weights.
Oxygen is essential at the roots for water and nutrient absorption during photosynthesis. During this stage plants are metabolizing macro and micronutrients, as well as enzymes, hormones, organic acids, etc. for storage in plant tissue to fuel growth. Plant friendly microbes require a constant supply of oxygen in order survive and flourish. Without a good supply of oxygen, anaerobic microbes may begin to set up shop, thus leading to a host of problems including nutrient deficiencies, and root disease.
Recent studies suggest that individual plant cells under attack from viruses require tremendous amounts of oxygen to oxidize themselves(sort of a cell “suicide”) in order to prevent neighbouring cells from becoming infected with the virus. As all living things, plant viruses require food, which tends to be plant D.N.A. and R.N.A. so once the cell has destroyed itself, the isolated virus must starve and die, leaving behind healthy and uninfected plant cells.
Calcium peroxide is composed of oxygen being held in a tight bond with calcium, both of which are indispensable when growing high-performance crops. One of the greatest benefits of calcium peroxide, is that it provides a continuous constant supply of both calcium and oxygen, which as you know now, are very important in plant production. In comparison with hydrogen peroxide, you are getting 2 oxygen molecules and one calcium molecule for each unit of compound (CaO2) supplied. The breakdown is as follows: CaO2-----1,Ca + 2,O. As mentioned previously H2O2 decomposes into 1,H2O and 1, O. So you are able to get twice the oxygen with the benefits of calcium in a worry free slow release formulation. Calcium peroxide will break down more rapidly with increased temperatures and decreased pH, making it an ideal product for indoor growers with peat-based potting mixes. An additional benefit is the increased calcium levels in the peat substrate increasing buffering capacity, thus reducing the effects of nutrient toxicity, which we all know can lead to a host of problems.
Calcium peroxide is also known to be useful in land farming. In clayey soils it can provide a source of oxygen and improve hydraulic conductivity , permitting more efficient movement of nutrients and oxygen through the soil. The calcium peroxide treated soils shows increased total microbial populations and species diversity. Increasing species diversity suggests the ability to degrade a wilder range of chemical contaminants.
Below are some applications for crop growing.
Potato- by disseminating 8 kgs of calcium peroxide on 10 are land, the production may be increased by 43%.
Melon- in a green house fertilize the individual plant with 60 grams of calcium peroxide, the fruit bearing number can be increased by 30%, and sweetness can be enhanced by 7%.
Strawberry- fertilize the individual plant with 2 grams of calcium peroxide, the fruit bearing number can be increased by 30%, the individual fruit weight can be increased by 30%, and sweetness can be enhanced by 30%.
Cotton- fertilize the individual plant with 5 grams of calcium peroxide, the fruit bearing number can be increased by 30%, the individual fruit weight can be increased by 30%, and sweetness can be enhanced by 12%.
Calcium peroxide may be mixed with other fertilizers to form so called Oxygen Fertilizer. Such fertilizers include urea, calcium perphosphate, potassium sulfate and compound fertilizer, etc. In a bioremediation application in which additional nutrient supplementation is desired, a wide variety of different formulations of fertilizers may be made utilizing the principles of this invention. The nominal percentages of the various macronutrients, micronutrients, and surfactant could be varied to provide fertilizers having formulations tailored to the specific environments in which they are used. The ingredients of several formulations and typical weight ranges are as follows
Ingredient Weight Percent
calcium peroxide 5-60
potassium dihydrogen phosphate
dipotassium hydrogen phosphate
potassium nitrate 0-40
ammonium nitrate 0-50
trace metals 0.0-5.0
Typical specific formulations are as follows:
19.96% calcium peroxide
15.30% potassium dihydrogen phosphate
17.96% dipotassium hydrogen phosphate
0.1% trace metals
18.34% KH.sub.2 PO.sub.4
18.34% K.sub.2 HPO.sub.4
0.11% trace metals
19.96% calcium peroxide
38.26% diammonium phosphate
21.62% potassium nitrate
0.1% trace metals
11.74% calcium peroxide
42.19% diammonium phosphate
23.84% potassium nitrate
0.1% trace metals
When dissolved in water, calcium peroxide breaks down into calcium hydroxide, oxygen and water. This characteristic gives calcium peroxide a function as the conditioner of water quality which provides a comfortable environment for aquatic life breeding like fishes, shrimps and crabs. The benefits for application of calcium peroxide in aquaculture embody in following aspects.
-providing sufficient dissolved oxygen; This is typically useful for increase the unit production by enhance the breeding density at a limited area, and solve the problem of oxygen-lacking in some seasons especially winter. Unlike other oxygen release chemicals that release oxygen rapidly, calcium peroxide provides a stable and continued source of oxygen thus it is considered an economical oxygen source for extensive aquacultural applications.
-adjusting pH value; Calcium peroxide is approved to be efficient in improving the subaqueous pH value and prevent water from acidification.
-reducing the subaqueous content of ammonium and nitrogen; Ammonium and nitrogen are major factor that prevents fishes from developing, by disseminating calcium peroxide into water, the ammonium and subaqueous content can be remarkably reduced.
-eliminating carbon dioxide and sulfureted hydrogen; in a pond covered with a ice cap, carbon dioxide usually exists in a big quantity and hinders the oxygen absorption of fishes, calcium peroxide also show a great effect on elimination carbon dioxide. Calcium peroxide can remove sulfureted hydrogen during its oxygen release process, this improve the water quality at the lower part.
-preventing anaerobe from proliferation and killing nosogenetic bacteria, defecating aqueous body; Calcium peroxide is an oxidizer than acts as a disinfectant which may efficiently kill ananerobe and nosogenetic bacteria. Calcium peroxide may facilitate depositing floccules and clearing turbid water thus improves the photosynthesis of natant foliage to increase dissolved oxygen.
Dosage of calcium peroxide for oxygen-lacking pond
In contaminated aquifers, however, microbially mediated aerobic degradation is limited by the amount of oxygen in the groundwater. Aerobic processes rapidly use up the dissolved molecular oxygen (DO) in contaminated areas and can depress the DO to less than 0.5 mg/L. Under conditions of oxygen depletion several anaerobic biodegradation processes, including denitrification, iron reduction, sulfate reduction and methanogenesis , can use other electron acceptors.
The addition of oxygen releasing compounds to soils or groundwater can be an effective treatment technology capable of reducing the levels of contaminants in groundwater. Calcium peroxide as an oxygen releasing compound increases the oxygen content of contaminated areas, enhancing biological activity and thus promoting natural attenuation.
Injection of calcium peroxide slurry through diffusion tubing into soils or groundwater creates a zone “of sustained high DO (dissolved oxygen) in groundwater around the injection well and changes the dominant groundwater conditions from anaerobic to aerobic. The oxygen-enhanced zone is able to biodegrade benzene and ethylbenene, which had been relatively resistant to natural attenuation in the plume under the initial anaerobic conditions. Thus, calcium peroxide can be used advantageously for the oxygenation of the hypolimnion.
|Injection Applications||Inject as a 25%-65% slurry|
|Typical Application Rate||
0.1%-1.0% by weight on soil (approx. 2-6 pounds/cubic yard of soil)
about 500 milligrams per Liter (mg/L)
|PH of a 1% slurry at 25 ℃||Approx. 11-12|
|Soil Moisture Required for Activation||5%-10%|
|Theoretical weight ratio of oxygen to hydrocarbon for aerobic degradation||3:1|
Most fruits, vegetables and cereals produce gaseous ethylene and carbon dioxide during storage. It is said that such gaseous ethylene and carbon dioxide promote the ripening of the above foods and, thus, hasten the deterioration or perishing thereof. Calcium peroxide performs the functions of not only retaining the freshness of the foods but also deodorizing the foods. If desired, conventional germicides and/or insecticides may be used together therewith.
It is presumed that calcium peroxide removes ethylene and carbon dioxide, which are produced from the food. That is, calcium peroxide produces oxygen and is converted into slacked line due to moisture present, and the oxygen reacts with ethylene and the calcium hydroxide catches carbon dioxide.
The convertion of calcium peroxide into calcium hydroxide and oxygen occurs by very slow degrees. The amount of oxygen is such that the amount of oxygen produced from 1g of calcium peroxide is capable of reacting with 2.5 ml of gaseous ethylene having a pressure of 0.1 atm. Further, the afore-said foods produce ethylene and carbon dioxide at very low rates, e.g. it is said that 1kg of banana produces approximately 1 mg of ethylene and approximately 1.7 mg of carbon dioxide. Therefore, the freshness of the afore-said foods can be retained for a long period of time, usually for approximately two months or more.
The amount of calcium peroxide used varies depending upon the particular food and the period for which the food is stored or transported. In general its amount may be within the range from 1 to 50 g, preferably 10 to 30 g, per Kg of the food.
The calcium peroxide powders or granules in the afore-said forms are placed in storehouses and shipholds used for storage or transportation of the foods. They also may be placed in bags and other types of containers used for storage or transportation of the food. Further, they also may be placed in a refrigerator.
It is preferable that these powders or granules are not in contact with the food, although calcium peroxide does not exert a special, undesirable influence on the food. Usually, these powders or granules are placed in a small bag or other vessel prior to use. They may also be used in the form of a thin layer, which is placed inside a small bag or which is sandwiched between two pieces of paper.
In the process for the melting of mineral compositions in preparation for their transformation into fibers e.g. glass, calcium peroxide is added to the batch of vitrifiable mineral components in the melting furnace to provide a low temperature oxidizing environment. The calcium peroxide may be added to the batch materials prior to their introduction into the furnace, or may be added directly to the furnace along with the mineral components. However, it is generally preferred that the calcium peroxide be premixed with the mineral components prior to their introduction into the furnace to ensure that the calcium peroxide is substantially homogeneously distributed throughout the composition. The calcium peroxide is preferably added to the composition in an amount up to about 5 percent by weight of the total composition.
As the temperature of the batch reaches about 575-600.degree. F. (301.7-315.6.degree. C.), the calcium peroxide begins to decompose into oxygen and calcium oxide. Decomposition of the calcium peroxide generally peaks at about 700.degree. F. (371.1.degree. C.). Accordingly, when the glass batch reaches such temperatures, oxygen is released from the calcium peroxide and creates an environment favorable for the oxidation of any organic impurities contained in the glass batch. Importantly, since the glass batch is still well below its melting point, the gaseous by-products of such oxidation, as well as any excess oxygen released from the calcium peroxide decomposition, are able to pass through the granular batch material and escape without forming an insulating layer that impedes melting of the batch. Further, by removing the organic impurities prior to melting of the mineral composition, the presence of carbon in the molten composition is reduced, which tends to reduce SO.sub.2 off gassing and to decrease the propensity for foam formation in the molten mineral composition.
As the temperature of the glass batch increases further within the furnace, the remaining calcium oxide dissolves into the molten glass. As a result, no residues are generated which undesirably affect the quality of the glass, nor are potentially environmentally unfriendly by-products generated by the decomposition of the calcium peroxide oxidizing agent.
>>Calcium peroxide facilitates to remove the oceanic or lacustrine red tides. By adding 100mg~500mg of calcium peroxide per Liter of water, the occurrence of red tide can be eliminated in 24 hours.
>> By coating rice seeding with calcium peroxide, herbicide and plaster of paris, usually 4 kgs calcium peroxide for 24 kgs of rice seeds, yield can be increased by 10% and the cost can be reduced by 50%.
>> The harmful CO (carbon oxide) from the lighted cigarette may be greatly reduced when calcium peroxide (amount 0.5%~10%) is added during the manufacturing process. At the smoking rate of 50ml/s, the CO discharging amount of the calcium peroxide blended is remarkably reduced to 2700mg/kg, as compared with the amount of 5000mg/kg discharged by normal cigarette.
>> Calcium peroxide is administered to the pigs via the oral route in a proportion of 0.02 to 1.3 % by weight of the total food ration. The percentage of lean meat and the quality of the carcasses are thus substantially improved.
>> Calcium peroxide may be used in the detoxification of waste water containing cyanides and/or cyano complexes, heavy metals and sulfides with a substantial effect.
Sodium perborate usually exists in two forms, tetrahydrated and monohydrated. Sodium perborate tetrahydrate is obtained by addition of hydrogen peroxide to a sodium metaborate solution at a temperature close to 20.degree. C. Sodium perborate monohydrate is produced by dehydrating sodium perborate tetrahydrate in a fluid bed with heated air. Sodium perborate releases nascent oxygen at elevated temperatures, and so acts as a hydrogen peroxide bleach. The monohydrated form is essentially showing three advantages in comparison with the tetrahydrated form: a higher content of available oxygen, a higher heat stability and a higher dissolution rate into water.
Sodium perborate has been in detergent and personal care formulations for many years. Its oxidative power improves the cleaning, bleaching, stain removal and deodorizing performance of powder detergent formulations, all fabric dry bleachs, denture cleaners, automatic dishwasher detergents and various institutional and industrial laundry products. It’s main disadvantage is that the bleaching action only takes place at elevated temperatures. To release it’s bleaching action at lower temperatures, an activator must be added.
Both sodium perborate and sodium percarbonate are oxygen release bleaching chemicals that are widely applied in various bleach compositions. It is known that sodium perborate as the bleaching agent has a high bleaching effect at high temperatures but the effect is lowered at low temperatures. On the other hand, sodium percarbonate has an effective bleaching action even at low temperatures and is very valuable from the viewpoint of saving of energy. Sodium percarbonate is an attractive perhydrate for use in detergent compositions because it dissolves readily in water, is weight efficient and, after giving up its available oxygen, provides a useful source of carbonate ions for detergency purposes.
Sodium perborate has a better stability and has been a mature bleaching ingredients for long time. But it is increasingly replaced by sodium percarbonate duo to its disadvantages in energy saving and environment protection. Sodium percarbonate exhibits an excellent bleaching effect even at a low temperature and is environmentally friendly, but it is less stable in detergent formulations. However, many processes have been found to improve its stability.
Sodium percarbonate (or sodium carbonate peroxyhydrate) is an addition compound of sodium carbonate and hydrogen peroxide. When dissolved into water, its releases H2O2 and soda ash (sodium carbonate).
2Na2CO3 . 3H2O2 ---> 2Na2CO3 + 3H2O2
The pH of the resulting solution is typically alkaline, which activates the H2O2 for bleaching. The dry powder contains about 30% w/w H2O2.
Sodium percrabonate has a wide range of applications in various solid detergent products and all fabric bleaches. We may also find its usages in oxygen release compositions, personal care formulations, disinfectants, food bleaches, pulp and paper bleaches and textile bleaches, etc.
Compared with chlorine bleaching chemicals that have contaminations on the environment, sodium percarbonate is an environmentally friendly chemical which decomposes into oxygen, water and natural soda ash when in contact with hydrous media.
Sodium percarbonate is increasingly being the substitute for sodium perborate in detergent formulations due to its lower dissolving temperature in water, as well as the characteristic of no contamination on soil, as sodium perborate is made of borax which is found to have negative impact on the soil quality.
Detergent or bleach compositions formulated with sodium percarbonate have an strong stain removal capability. It is very effective as a laundry presoak for heavily stained articles. It is color safe. It brightens colors and prevent fabric form become yellowed or darkened.
Sodium percarbonate is effective as a disinfectant on both bacteria and virus. It’s an excellent ingredient in personal care and home care formulations for hygiene.
For its environmental advantages, sodium percarbonate is a good oxygen release chemical for agricultural and aquicultural applications.
Shangyuchem has been producing sodium percarbonate for more than a decade. Due to its abundant R & D investment and tech innovation, Shangyuchem is able to provide its customers with different specs of quality coated and uncoated sodium percarbonate. Shangyuchem currently has a production capability of 100,000mt annually which can meet customers’ increasing demands on a sustainable base. You’ll feel satisfied with the cooperation with Shangyuchem not only for the reason of good product quality, timely and safe delivery, but also the excellent after market service and tech support.
Sodium percarbonate is used as an active oxygen component in detergents, bleaches and cleaning agents. Due to the unsatisfactory storage stability of the uncoated sodium percarbonate in warm/moist surroundings and in the presence of certain detergent and cleaning agent components, sodium percarbonate must be stabilized against the loss of active oxygen. An essential principle of stabilization involves encasing the sodium percarbonate particles in a coating of components having a stabilizing action. Here comes the definetion: the coated sodium percarbonate is the sodium percarbonate crystals coated with single or multiple layers of various substances in order to increase active oxygen stability and optimize storage and ensiling properties.
Coated sodium percarbonate is the more commonly commercialized peroxide compared with the uncoated sodium percarbonate. But the uncoated product is still the preferred ingredient for simply mixing with enough quantity of soda ash and some surfactants to form the popular oxygen bleaches.
Detergent compositions containing sodium percarbonate are known in the art. Sodium percarbonate is an attractive perhydrate for use in detergent compositions because it dissolves readily in water, is weight efficient and, after giving up its available oxygen, provides a useful source of carbonate ions for detergency purposes.
However, the inclusion of percarbonate salts in detergent compositions has been restricted by the relative instability of the bleach both as is and in use. Sodium percarbonate loses its available oxygen at a significant rate in the presence of ions of heavy metals such as iron, copper and manganese and also in the presence of moisture, these effects being accelerated at temperatures in excess of about 30.degree. C. To solve this problem, several solutions have been found.
1, Sodium percarbonate is coated with a hydrophobic substance or the like.
2, Magnesium silicate is incorporated in a detergent composition containing sodium percarbonate.
3, A chelating agent which forms an easily water-soluble metal chelated compound such as nitrilotriacetate (NTA) or ethylene diamine tetraacetate (EDTA) is incorporated in a detergent composition.
4, Zeolite A is replaced by maximum aluminium zeolite P (zeolite MAP) since zeolite MAP itself is of greater liquid carrying capacity than zeolite A.
5,The elimination of impurities, such as heavy metals which catalyze the decomposition reaction during detergent processing, alleviates the instability of aqueous SCP solutions.
6, Provide sufficient sodium carbonate in the composition to be able to combine with all of the available water in the composition to form sodium carbonate monohydrate. the term "available water" includes water chemically available as hydrogen peroxide, water of crystallization of sodium carbonate hydrates and free water which may temporarily exist in the composition.
Since its introduction in early 1989, there has been significant interest among the dental profession and the general public for home-use tooth bleaching products and methods. Typical dental bleaching compositions include from 5-20% by weight of carbamide peroxide (CO(NH.sub.2).sub.2.H.sub.2 O.sub.2), which is a complex of urea and hydrogen peroxide. However, sodium perborate has been found to be an another dental bleaching agent.
An advantage of perborate-based bleaching agents rather than aqueous hydrogen peroxide or carbamide peroxide is that perborates are allowed for dental bleaching procedures in some countries that do not permit the use of aqueous hydrogen peroxide and carbamide peroxide for dental bleaching. Perhaps perborate compounds are more gentle on surrounding gums and tissues compared to either aqueous hydrogen peroxide or carbamide peroxide. Nevertheless, perborates were found to be unstable when blended with carboxypolymethylene, which is the tackifying agent of choice in the vast majority of home bleaching kits presently on the market. For this reason, a tackifying agent that is stable in the presence of perborate bleaching agents has been developed, which comprises a mixture of a suitable polyol and a finely divided gel-forming particulate such as fumed silica, otherwise known as silica fume.
Below is a sample dental bleaching composition that combines the following ingredients (in weight percent):
Anhydrous Propylene Glycol 54.3%
Fumed Silica 20%
Sodium Perborate Monohydrate 25%
Sodium Saccharine 0.7%
Zinc peroxide compound is used in the blowing composition in preparing a foamed product of high-melting synthetic resin such as polyamides, polyolefins, polyesters, polycarbonates, ABS resins, polysulfones, etc. It is a preferred accelerator in the vulcanisation of polysulphide rubber in order to produce oil and aging resistant rubberwares like sealants, tubes, rollings, etc. It may be applied in accelerated vulcanisation of nitril-carboxyl rubber to produce an attrition resistant rubber. The zinc peroxide compound is used as a curing agent in carboxylated NBR, it has the advantage of improved scorch resistance and storage stability of the uncured rubber compounds.
Zinc peroxide may function as an oxidant and oxygen donor in compositions or mixtures containing explosive materials. Such compositions are, for example, explosives or pyrotechnical compositions. In ceramic composition for dielectrics, zinc peroxide serves to facilitate burnout or removal of the organic binder during firing of the ceramic composition and minimizes the content of residual carbon in the fired ceramic composition.
Zinc peroxide can be formulated into well drilling and servicing fluid compositions which deposit an easily removable filter cake.
In pharmaceutical applications zinc peroxide is used as additive for aseptic products against skin disease.
It can also be used as oxidizing and bleaching agent for other fields.
It is well known to prepare foamed products from synthetic resins by decomposing a blowing agent incorporated in the resin. Various blowing agents useful for this application are also known which include, for example, those of the azo, nitroso and hydrazine types. These blowing agents must fulfill the requirements of being decomposable at a specified temperature but capable of remaining chemically as stable as possible at lower temperatures, being decomposable at the highest possible velocity, and leaving substantially no residue when decomposed so as not to produce any color, noxious odor or toxicity.
Such blowing agents are divided into two groups: those useful for low-melting synthetic resins, and those suited to high-melting synthetic resins. While a wide variety of blowing agents of these two categories have heretofore been developed, the latter group includes the blowing agents of the axodicarboxylic acid type. The axodicarboxylic acid-type blowing agents nevertheless have such a low stability against water that they are decomposable even in the presence of the water contained in air, whereas they undergo decomposition very slowly even at the decomposition temperature and leave a residue which produces a color and toxicity.
Azodicarbonamide is widely used as a blowing agent for preparing foamed products of various polymers. Azodicarbonamide is not hazardous, is decomposable to give off a large quantity of gas with a nontoxic odorless residue producing no pollutant when decomposed, and is therefore very advantageous over other organic blowing agents. However, since azodicarbonamide decomposes at a high temperature of about 200.degree. C., the compound, when used for foaming polymers comprising polyvinyl chloride, polyethylene or the like as a base material, entails the drawback that the polymer becomes thermally degraded or scorched owing to decomposition temperature of azodicarbonamide which is out of coincidence with the softening point of the base material. For this reason, it has been attempted to add a decomposition accelerator to azodicarbonamide to thereby render the amide decomposable at a lower temperature and at the highest possible velocity. Examples of useful decomposition accelerators are zinc oxide, metal salts of fatty acids and urea compounds. To be sure, these decomposition accelerators render azodicarbonamide decomposable at lower temperatures but are unable to freely adjust the decomposition temperature or velocity to any desired value. This leads to the drawback that azodicarbonamide is partially decomposed during kneading or extrusion prior to the foaming treatment, possibly making it difficult to obtain a foamed product of uniform cells or eventually resulting in a reduced blowing degree. Additionally the conjoint use of the decomposition accelerator will impede brisk decomposition of azodicarbonamide, or cause clogging, or corrosion of the die used for extrusion foaming step.
Zinc peroxides are found useful as such accelerators and leave only a greatly reduced amount of residue when decomposed. Unlike usual peroxides, zinc peroxide have a high chemical stability. Zinc peroxide can be used or preserved in a manner usual with blowing agents without any adverse effect on its thermal stability. The zinc peroxides useful as blowing agents in this invention decompose usually at a temperature of about 200 to about 260, preferably about 220.degree. to about 240.degree. C. although the decomposition temperature somewhat varies with the kind of the peroxide.
The conjoint use of azodicarbonamide, zinc peroxide and decomposition inhibitor permits the azodicarbonamide to decompose briskly and fully and produce a gas effectively without impairing the foaming properties of the amide despite the use of the inhibitor. The inhibitor can inhibit the initial-stage decomposition of the amide sufficiently. These features, namely brisk decomposition, full decomposition and inhibition of the initial-stage decomposition, provide a foamed product with minute cells in compact arrangement, result in a shortened foaming time and achieve a foaming degree at least twice as high as is conventionally attainable. The increased foaming degree leads to a reduction in the quantity of azodicarbonamide needed and therefore to a cost reduction.
Urea hydrogen peroxide is a combination of urea and hydrogen peroxide which releases hydrogen peroxide locally on application. Urea hydrogen peroxide is a well-known commercial product useful as an antiseptic and disinfectant in treatment of wounds, for bleaching hair, and as a readily biodegradable and environmentally safe bleaching agent, detergent and cleaning agent.
The most commonly used dental bleaching agent is carbamide peroxide , also called urea hydrogen peroxide, hydrogen peroxide carbamide, and perhydrol-urea. Carbamide peroxide has been used by dental clinicians for several decades as an oral antiseptic. Tooth bleaching was an observed side effect of extended contact time.
Urea hydrogen peroxide can be applied in the production of alcohol in which a starch- or sugar-based aqueous fermentation medium is prepared and to this fermentation medium is added urea hydrogen peroxide in an amount sufficient to substantially reduce the level of bacterial contaminants in the fermentation medium. The urea hydrogen peroxide is left in contact with the fermentation medium for a time of at least one hour and sufficient to substantially reduce the level of bacterial contaminants. Thereafter the fermentation medium is inoculated with yeast wherein the yeast produces catalase enzyme which degrades liberated hydrogen peroxide to water and oxygen. This oxygen is needed by the yeast for membrane sterol and unsaturated fatty acid synthesis. Both urea and oxygen are supplied in near optimum amounts for growth subsequent to the suppression of bacterial contaminants by urea hydrogen peroxide. The fermentation continues to produce alcohol, in particular fuel or industrial alcohol, at the highest possible yields.
Many household and personal care products are formulated with an active oxygen-releasing material to effect removal of stain and soil. Oxygen-releasing materials have an important limitation; their activity is extremely temperature-dependent. Temperatures in excess of 60 DEG C are normally required to achieve any bleach effectiveness in an aqueous wash system. Especially for cleaning fabrics, high-temperature operation is both economically and practically disadvantageous. Thus, bleaching activators have been applied in an object to activate bleaching reaction at low temperatures. These activators, also known as bleach precursors, often appear in the form of carboxylic acid esters or amides. In an aqueous liquor, anions of hydrogen peroxide react with the ester or amide to generate a corresponding peroxyacid which oxidizes the stained substrate. Commercial application of this technology is found in certain fabric bleaching detergent powders that mainly incorporating tetraacetylethylenediamine (TAED).