H202 and peracids will react with unsaturated compounds to produce epoxides. Epoxidation is an oxygen-transfer reaction, for which hydrogen peroxide and its derivatives are very well suited. This is reflected in the fact that a wide variety of peroxygen systems have been applied to a range of olefin types, and some of these applications are among the long established industrial uses of peroxygen products.

Epoxides are valuable and versatile commercial intermediates owing to the large range of reactions they undergo. The majority of transformations occur with active hydrogen compounds such as ammonia, amines, organic acids, alcohols and sulphur compounds.

'In-Situ' Percarboxylic Acids

The simplest and generally most economic way to carry out an epoxidation is to generate the peracid (performic acid or peracetic acid) in the reaction medium.

Epoxidation with 'in-situ' performic is an established commercial process. Major applications are the epoxidation of long chain olefins (usually of soya-bean oil). The resulting epoxides are relatively stable to ring opening. Vegetable oils, polybutadiene, natural and synthetic rubbers, and polyesters have been epoxidized by this procedure.

Cation exchange resins are also employed as catalysts for 'in-situ' peracetic acid (PAA) and reduce epoxide losses, particularly in the presence of hydrocarbons, or chlorinated solvents. This has been used to effect the epoxidation of soya-bean oil to a high grade epoxy soya-bean oil, and for polybutadiene epoxides.

Direct Methods

The only widely adopted direct method of epoxidizing olefins using H2O2 is under alkaline conditions. Alkaline H2O2 has the advantage of being cheap and convenient to operate. However, chemically its use is restricted to the epoxidation of olefins deactivated by electron withdrawing groups. Industrial processes must be designed with care as H2O2 rapidly decomposes at high pH and organic peroxides can be formed as by-products of the reaction.

Halogenation

Hydrogen peroxide will readily oxidise hydrogen halides and their acidified salts to liberate the corresponding halogen, with the exception of fluorine.

In-situ generation of halogens can be used for the preparation of a wide range of organic halides or for the recovery of bromine from hydrogen halide waste streams.

The system may be used for olefin halogenation, including epoxide preparation via halohydrins and aromatic halogenation including phenols and amines. Aromatic halogenation may require catalytic activation.

In the case of bromine, the system can be used for the oxidation of alcohols or aromatic side-chains.

 

Advantage of peroxygen systems

In-situ generation of halogens offers many advantages including:-

• Efficient utilisation of the halogens (HX is continuously reoxidised by H2O2)
• Effluent-free processes – water is the only downstream product
• Elimination of halogen transport and associated handling problems

For a more detailed discussion on this application of peroxygen technology please contact us.

 

Typical products 

INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hydroxylation of olefins

The hydroxylation of olefins is the addition of hydrogen peroxide across a double bond, to produce a diol. H202 is a powerful hydroxylation agent applied for olefins and aromatic nuclei.  Where the epoxide is formed as an intermediate, the diol product is usually trans- with respect to the olefin.

Long-chain aliphatic vic-diols and their derivatives have properties which make them useful as modifiers in protective coatings, plastics, lubricants, waxes, emulsifiers, and textile finishing agents.

Many conversions take place with high yield and high purity under relatively mild conditions. The conditions used for hydroxylation are generally more vigorous than for the intermediate epoxidation reaction.

Hydroxylation using hydrogen peroxide is applicable to all olefins including those with electron withdrawing groups attached.

Transformations can yield either the anti- or the syn- product. They can be carried out in either alkaline or acidic media.

Hydroxylation of the aromatic nucleus

Hydroxylation of the aromatic nucleus is also possible and is used on an industrial scale to produce hydroquinone and catechol.

Advantages of peroxygen systems

• Percarboxylic acids are highly reactive and easy to use. They may be used in-situ, preformed as an equilibrium product, as a distilled acid or aqueous solution, in an organic solvent or in solid form.
• Metal catalysed hydroxylations reduce the effluent loading of these systems compared to stoichiometric metal oxidant systems.
• Alkaline peroxide is relatively inexpensive, convenient to use and can be applied in the hydroxylation of a variety of electron deficient olefins.

Oxidation

Over the past few years the importance of hydrogen peroxide and its derivatives as oxidising agents has grown considerably. In contrast to many other oxidising agents, hydrogen peroxide is attractive from an environmental viewpoint as it forms only water when its oxidising power is spent. Similarly, peroxyacids form organic acids which can often be recovered or recycled.

The advantages of hydrogen peroxide and its derivatives include:-

Solubility – Hydrogen peroxide and its derivatives can be soluble in water, many organic solvents and the substrates themselves.

Availability – Various grades of hydrogen peroxide and peracetic acid are now produced worldwide.

Mildness – Useful for sensitive materials as oxidations generally proceed under relatively mild conditions. Reactions are often specific and generally only a small excess of hydrogen peroxide or derivative is required.

Stability – Hydrogen peroxide loses less than 1% active oxygen content by weight per year under standard storage conditions.

Oxidation by hydrogen peroxide can be achieved under neutral, acid or alkaline conditions, as well as in the presence of catalysts. In some applications however, the oxidising power of hydrogen peroxide is insufficient and a more active oxidant such as a peroxyacid is required. These systems are widely used. Other systems include the use of hydrogen peroxide with haloacids and sodium perborate with acetic acid to generate oxidants in-situ.

The following list gives examples of applications of H202 for oxidations : alcohols, ketones, aldehydes, aromatic side-chains, aromatic nuclei, organic compounds containing nitrogen (amines) or sulphur and hydrogen halides.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products 

INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The area of Chemical Purification is a diverse one with regard to both the chemicals treated and the reagents used. The reasons for purification may also be quite varied and naturally depend on the manufacturing process, grade, application etc. Improvements may consist in the removal of  colour, odour, minor chemical contaminants or any combination of these.

Although adsorptive materials such as activated carbon, clays, and zeolites, have been used for a number of years, their disposal or regeneration can be expensive.

Hydrogen peroxide is one of the most widely used oxidizing agents. It can be added either directly (under acidic, neutral, or alkaline conditions), in the presence of a solvent or catalyst, or in the presence of other purification agents.

In general the types of products purified in this way fall into one of eight broad cataogories as listed below:-

Product type
 
1 Petroleum Products
2 Surfactants
3 Natural Oils, Fats, Waxes
4 Natural Sugars and Related Products
5 Miscellaneous Organics
6 Synthetic Polymers
7 Inorganic Salts and Acids
8 Clays, Talcs & Minerals
 

Advantages of peroxygens

Peroxygen purification methods are fast, simple, and occur under mild conditions.
Hydrogen peroxide forms only water and oxygen when its oxidising power is spent.
Improvements can be seen in colour and odour.

Lactone formation

Ketones can be oxidised to esters by percarboxylic acids or in some cases by H202. Cyclic ketones form lactones of which the manufacture of ε - caprolactone from cyclohexanone is one example.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 
1 Petroleum Products
2 Surfactants
3 Natural Oils, Fats, Waxes
4 Natural Sugars and Related Products
5 Miscellaneous Organics
6 Synthetic Polymers
7 Inorganic Salts and Acids
8 Clays, Talcs & Minerals
 

 

Advantages of peroxygens

Peroxygen purification methods are fast, simple, and occur under mild conditions.
Hydrogen peroxide forms only water and oxygen when its oxidising power is spent.
Improvements can be seen in colour and odour.

Lactone formation

Ketones can be oxidised to esters by percarboxylic acids or in some cases by H202. Cyclic ketones form lactones of which the manufacture of ε - caprolactone from cyclohexanone is one example.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 

 
1 Petroleum Products
2 Surfactants
3 Natural Oils, Fats, Waxes
4 Natural Sugars and Related Products
5 Miscellaneous Organics
6 Synthetic Polymers
7 Inorganic Salts and Acids
8 Clays, Talcs & Minerals
 

 

Advantages of peroxygens

Peroxygen purification methods are fast, simple, and occur under mild conditions.
Hydrogen peroxide forms only water and oxygen when its oxidising power is spent.
Improvements can be seen in colour and odour.

Lactone formation

Ketones can be oxidised to esters by percarboxylic acids or in some cases by H202. Cyclic ketones form lactones of which the manufacture of ε - caprolactone from cyclohexanone is one example.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 

 
1 Petroleum Products
2 Surfactants
3 Natural Oils, Fats, Waxes
4 Natural Sugars and Related Products
5 Miscellaneous Organics
6 Synthetic Polymers
7 Inorganic Salts and Acids
8 Clays, Talcs & Minerals
 

 

Advantages of peroxygens

Peroxygen purification methods are fast, simple, and occur under mild conditions.
Hydrogen peroxide forms only water and oxygen when its oxidising power is spent.
Improvements can be seen in colour and odour.

Lactone formation

Ketones can be oxidised to esters by percarboxylic acids or in some cases by H202. Cyclic ketones form lactones of which the manufacture of ε - caprolactone from cyclohexanone is one example.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 

 
1 Petroleum Products
2 Surfactants
3 Natural Oils, Fats, Waxes
4 Natural Sugars and Related Products
5 Miscellaneous Organics
6 Synthetic Polymers
7 Inorganic Salts and Acids
8 Clays, Talcs & Minerals
 

 

Advantages of peroxygens

Peroxygen purification methods are fast, simple, and occur under mild conditions.
Hydrogen peroxide forms only water and oxygen when its oxidising power is spent.
Improvements can be seen in colour and odour.

Lactone formation

Ketones can be oxidised to esters by percarboxylic acids or in some cases by H202. Cyclic ketones form lactones of which the manufacture of ε - caprolactone from cyclohexanone is one example.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 

 
1 Petroleum Products
2 Surfactants
3 Natural Oils, Fats, Waxes
4 Natural Sugars and Related Products
5 Miscellaneous Organics
6 Synthetic Polymers
7 Inorganic Salts and Acids
8 Clays, Talcs & Minerals
 

 

Advantages of peroxygens

Peroxygen purification methods are fast, simple, and occur under mild conditions.
Hydrogen peroxide forms only water and oxygen when its oxidising power is spent.
Improvements can be seen in colour and odour.

Lactone formation

Ketones can be oxidised to esters by percarboxylic acids or in some cases by H202. Cyclic ketones form lactones of which the manufacture of ε - caprolactone from cyclohexanone is one example.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 

 
1 Petroleum Products
2 Surfactants
3 Natural Oils, Fats, Waxes
4 Natural Sugars and Related Products
5 Miscellaneous Organics
6 Synthetic Polymers
7 Inorganic Salts and Acids
8 Clays, Talcs & Minerals
 

 

Advantages of peroxygens

Peroxygen purification methods are fast, simple, and occur under mild conditions.
Hydrogen peroxide forms only water and oxygen when its oxidising power is spent.
Improvements can be seen in colour and odour.

Lactone formation

Ketones can be oxidised to esters by percarboxylic acids or in some cases by H202. Cyclic ketones form lactones of which the manufacture of ε - caprolactone from cyclohexanone is one example.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60
INTEROX ST 70
INTEROX CG 35
INTEROX CG 50
INTEROX CG 60
INTEROX CG 70

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The unique properties of peroxygens make them particularly suited to provide protection for the environment in all areas of everyday life and throughout industry. From pollution prevention to abatement and cure, peroxygens can provide an effective solution to environmental problems.

Advantages of Peroxygens :

• Hydrogen peroxide is itself non-toxic and has breakdown products of only water and oxygen.
• When handled and stored correctly, hydrogen peroxide is an oxidant which is safe and easy to work with.
• Hydrogen peroxide is a liquid which is totally miscible with water therefore allowing ease of dosing and control.
• Hydrogen peroxide can be used to make Caro’s acid, on-site as required, using Solvay Interox technology. Caro’s acid provides a particularly powerful oxidation system.
• A solid form of hydrogen peroxide is also available from Solvay Interox It dissolves in water to yield an alkaline solution of hydrogen peroxide and sodium carbonate. 

Source of Oxygen

As a potential source of oxygen, hydrogen peroxide is used in biological treatment particularly at times of overload, for the treatment of bulking sludges, and for the prevention of denitrification in settling tanks.  The addition of hydrogen peroxide provides oxygen which can prevent the system from going anaerobic and producing H2S. H2O2 is one of the few chemicals which can destroy H2S by converting it to SO4 = or S.

Water Treatment

 

Hydrogen peroxide provides an effective means of purifying and detoxifying industrial and municipal effluents containing toxic pollutants such as cyanides, sulphides and reduced sulphur species, mercaptans, formaldehyde and many others. Such pollutants may be present in the effluents of refinery, chemical, wood preservation, steel and metal pickling operations and in certain municipal waste streams. SOLVAY has developed processes in which the oxidation by means of hydrogen peroxide is catalysed in the most appropriate way for the pollutant to be eliminated (see also the section on Organice destruction/COD/BOD).

In certain circumstances a body of water, either a river or ’lake’ can become depleted in oxygen. Normally when water is saturated with oxygen from air it has a level of ~8 mg/l. If organic material i.e. sewerage is present in the water, bacteria can rapidly consume the available oxygen, lowering the level of dissolved oxygen (DO) to a level at which aquatic life may begin to experience problem. If a localised area of the water system does become anaerobic the bacteria which flourish in these conditions can release sulphides which are not only toxic but also smell.

A number of water companies around the world maintain stocks of H2O2 for emergency or seasonal treatment, simply mixing in H2O2 when the DO levels drop to ensure aquatic life or eliminate any odour problems.

As a liquid H2O2 readily mixes into water, unlike oxygen gas which requires complex absorption equipment. The addition of hydrogen peroxide is usually carried out by adding the H2O2 to a recirculating stream of water to ensure that it is diluted to some extent before it is mixed into the water.

H2O2 decomposes to release oxygen and water.  The decomposition is accelerated by contact with bacteria in the water and so effectively all oxygen is absorbed.

As the levels of oxygen in saturated water are so low very little H2O2 is required. To raise the level of dissolved oxygen in 1 m3 of water by 1 mg/l requires only 6.07 g of 35% H2O2.

For a more detailed discussion on this application of peroxygen technology please contact us.

 

 

 

 

 

 

 

 

Cyanide

Cyanide, one of the most toxic and fast-acting poisons known, and can pose serious threats to people and wildlife. However cyanide is widely used in industry and the discharge of cyanide wastes from mining operations and electroplating processes is increasingly attracting public and regulatory attention.See Section on Mining - Gold

Thiocyanates

In the mining industry, when alkaline cyanide comes into contact with sulphide minerals, i.e. as in the gold mining industry, the cyanide can be converted to thiocyanate. See section on Mining - Gold

Nitrite

In many cases, particularly in the case of effluent from hardening shops, electroplating plants etc. nitrite and cyanide co-exist in effluents. Nitrite is an undesirable component of a waste water as, being an easily oxidisable chemical, it adds to the Biological Oxygen Demand (BOD) of the waste water, causing oxygen depletion downstream of the discharge. In most circumstances nitrite discharge above 20mg/l level is prohibited.

Peroxygen Treatments 

Peroxygens are widely used throughout industry for the safe and effective treatment of cyanide, thiocyanate and nitrite in process and waste waters.  In addition to H2O2 other peroxygens such as Caro's acid and sodium percarbonate may also be employed.

Dechlorination

Chlorine and its derivatives are commonly used in industry, as disinfectants, or to carry out a chemical oxidation, they are very effective. These products cannot be released into the environment as they are exceedingly toxic to life and in certain circumstances chlorinate organic compounds to create even more toxic chemicals.

In order to discharge chlorine containing waste into the environment or for subsequent processing it may be necessary to ‘destroy’ the chlorine. One of the common methods of doing this is to use sulphur dioxide either as a gas or in a more readily soluble form as a bisulphite. Sulphur dioxide as a gas is not easy to handle and requires precautions and special material of construction.

If a treated solution containing free sulphur dioxide becomes acidic the gas can be evolved, creating an unhealthy environment for the workers. As sulphur dioxide itself is toxic, any treated effluent cannot be discharged into the environment if it retains sulphur dioxide in solution.

An alternative is to use hydrogen peroxide, it is a liquid and so mixes in readily into solutions, it does not freeze until very low temperatures are reached, and it can be discharged into the environment rapidly decomposing to give water and oxygen.

 

 

 

 

 

Gas scrubbing, involves the removal of hazardous or toxic gases from a gas stream. The pollutant is removed from the gas phase and usually absorbed in a liquid, often water based. The types of compound treated would include Oxides of Nitrogen (NOx), Sulphur dioxide (SOx), Mercaptans, Formaldehyde and Sulphides and reduced sulphur species.  Gas absorbed can be reacted in the liquid phase directly or be collected and subsequently reacted or disposed of. A method of absorbing the gas is in a scrubber, where the gas is contacted intimately with a large surface area of the liquid, this can be achieved in a number of ways. In a packed column scrubber the gas is passed up a column with a liquid that is being run down the scrubber over packing, the liquid is recycled through the column. Packing provides a large surface area for contact of the gas with the liquid. Packings can be simple and inexpensive or intricate and costly and made from a variety of materials.

Examples of successful treatments are -NOx removal from Stainless Steel Pickling operations, deodourisation of gaseous effluents from animal carcass rendering, and sulphur dioxide oxidation.
 
Odour Control

Odours, consisting often of mixtures of components, are produced in a variety of industries such as sewage treatment, animal carcass rendering, food processing and animal feed manufacture. These mixtures may contain both acidic components (hydrogen sulphide, mercaptans, phenols, aldehydes, fatty acids) and basic compounds (ammonia, amines), and may be effectively treated by washing with both acidic and alkaline solutions of hydrogen peroxide. This method of treatment avoids imparting odours to the cleaned gas, which is possible with some other oxidants.

Hydrogen peroxide is not always the complete answer to all such problems, since considerations of scale, capital and running costs may render it less attractive economically or practically than other processes. Where applicable the use of hydrogen peroxide does afford significant benefits, particularly in producing clean processes with effluents that are reusable or that may be disposed of without damage to the environment.

Its use should be investigated as a matter of course whenever the need arises for gaseous effluent treatment, since even though it may not improve the absorption process itself, and in a number of cases it does, clean oxidation or reduction of the liquid effluent may be beneficial.

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60

Organic destruction/COD/BOD reduction

As environmental laws become stricter, despite waste minimisation and cleaner processes, there is an increasing need to break down potential pollutants, before they have the chance to ‘escape’ into the environment, or in some instances treat them to prevent their spread into the environment. Peroxygens can be used in a number of known processes to treat these types of materials, either by a simple oxidation or by a more complex route involving an Advanced Oxidation Process (AOP) in which the hydrogen peroxide is used as a source of radicals. Radical based processes are reported as being one million times faster than a simple oxidation with hydrogen peroxide.

The technology is applied to aqueous solutions, however they may be aqueous solutions derived from scrubbing noxious gas streams, directly from pollutants present in the aqueous phase or from an aqueous phase generated by washing a contaminated solid.

Examples of AOP's include Fenton’s, Photo Fenton’s and other Fenton’s systems, UV peroxide, Ozone peroxide, UV / Ozone / Peroxide and Wet Oxidation (High temperature and Pressure)

Advanced oxidation processes rely on forming hydroxyl radicals. They are formed in nature by the action of energy contained in the UV of sunlight on water or water vapour in the atmosphere. The radicals formed react with organic materials gradually breaking them down using a stepwise process.

AOP’s rely on the strength of the hydroxyl radical to attack organic molecules, generating them in a more controllable manner.  Hydroxyl radicals are almost the most powerful of all the available oxidants only slightly less powerful than fluorine in terms of oxidation potential.

Soil Remediation

Remediation of contaminated sites and groundwater requires technologies which can destroy persistent and problem causing pollutants in an environmentally and economically acceptable way.

 

With their unique combination of properties, peroxygen based technologies can very often answer this need – providing environmentally acceptable, economic and highly effective solutions to pollution problems.

Peroxygens, particularly hydrogen peroxide, are capable of oxidatively destroying many of the most commonly occurring pollutants in solid, aqueous or gaseous wastes to give innocuous or easily biodegradable products.

A number of treatment technologies are applied in contaminated site remediation :-

• Pump and Treat
• Direct oxidation, in-situ or ex-situ
• Biological treatment, in-situ or ex-situ

For a more detailed discussion on this application of peroxygen technology please contact us

Typical products
 
INTEROX ST 35
INTEROX ST 50
INTEROX ST 60

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The treatment of sulphides can be investigated in more detail within the section on Gas Scrubbing.  However it should be noted that many other sulphur species may also be treated by peroxygens including the following :-

• Sulphides

• Elemental Sulphur

• Polysulphides

• Sulphite

• Thiosuphite

• Dithionite

• Polythinates

• Mercaptans

• Dialkyl disulphides

• Dialkyl sulphides

For a more detailed discussion on this application of peroxygen technology please contact us.

The bactericidal and algicidal proper­ties of hydrogen peroxide coupled with the advantage that no harmful residues are formed when it decomposes, have led to its use in disinfection applications :

• disinfection of cartons and plastic bottles in aseptic filling machines
• cleaning of equipment and lines in the food processing, beverage and dairy industries
• treatment of industrial water circuits and air-conditioning systems
• horticultural and agricultural uses
• animal husbandry and fish farm uses
• pharmaceutical clean room sterilisation
• skin & wound antiseptic
• medical equipment disinfection
• treatment of swimming pools and whirlpools

Typical products

INTEROX AG Bath
INTEROX AG Dual
INTEROX AG Spray
INTEROX FCC 35
INTEROX ST 35

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

There are 2 main types of chemical pulps, Sulphite and Kraft, with the latter being by far the most predominant.

Sulphite pulps are easily bleached to full brightness with hydrogen peroxide and oxygen in one or two stages.

Kraft pulps are more difficult to bleach to full brightness requiring 3-5 bleaching stages depending on the type of wood, softwood or hardwood. An enormous number of bleaching processes are possible but they can be divided in one of 3 categories – Conventional Chlorine (largely disappeared from today’s bleach plant), ECF (Elemental Chlorine Free) and TCF (Total Chlorine Free) with ECF being the preferred bleaching technology employed. Hydrogen Peroxide can be used in all the above categories.

• In Conventional Chlorine and ECF bleaching processes, modest quantities of hydrogen peroxide can be applied to reinforce one or more of the alkaline extraction stages either alone or in combination with oxygen. Principal benefits arising from the use of hydrogen peroxide are: 
  
  • debottlenecking for increased pulp mill production capacity in mills that are chlorine dioxide limited
  • improved bleach plant runability – superior brightness stability
  • reduced environmental impact
  • possible bleach cost savings

 

• TCF and ‘mild ECF’ - Environmental legislation and market pressure have forced the pulp and paper industry to explore alternatives to conventional chlorine based bleaching systems. Developed during the last decade, TCF and especially ‘mild ECF’ bleaching sequences rely heavily on the use of oxygen based oxidising agents for both delignifying and bleaching purposes. Although hydrogen peroxide can be used for delignifying and bleaching, the use of stronger oxidants such as Caro’s acid and Peracetic acid are more appropriate for delignification. Running dedicated pressurised stages at temperatures close to 110o C can boost the performance of hydrogen peroxide

 

With the application versatility of peroxygen based bleaching chemicals, an existing bleaching line can be incrementally modified to satisfy evolving environmental constraints, whilst at the same time minimising initial investment, delaying major investment as well as selecting investments which can serve final as well as intermediate goals.

Technology is continually changing in the use of peroxygen based chemicals for the bleaching of Kraft chemical pulps. Contact us for the latest update of this evolving technology.

Mechanical pulp bleaching

The use of hydrogen peroxide, in combination with caustic soda, is a well established method for bleaching mechanical pulps. Bleaching with hydrogen peroxide achieves high, stable brightness and helps to improve strength as well as optical properties, whilst maintaining high yield.

Hydrogen peroxide is well suited to the bleaching of mechanical pulps because of its environmental friendly properties with the decomposition products being oxygen and water. There are essentially 3 types of bleaching technology for mechanical pulps:-

• Tower bleaching – this is by far the preferred bleaching process where bleaching normally takes place in a tower at high stock consistency. Where high brightness targets (>80o ISO) are systematically required, a 2 stage bleach plant with bleach filtrate recycle where the first stage operates at medium and the second stage at high stock consistency is normally employed.In some situations, a 2 stage bleaching system with hydrogen peroxide bleaching in the first stage followed by a reductive bleach stage can be employed.
• Steep bleaching – this is a lower capital cost option than conventional high stock consistency tower bleaching where bleaching takes place in a pulp pile at high stock consistency (similar to a chip pile). This system operates at lower temperatures and for longer bleach times than for conventional tower bleaching but is marginally more efficient.
• Refiner bleaching – where no bleach equipment is available, bleaching may be conducted during the refining stage by adding alkaline peroxide to the feed to either the primary or secondary refiner. Depending on the level of chemical added, it might also be possible to reduce the amount of refining energy required to produce particular pulp freeness.

There is a more recent technology, which combines pulping and bleaching in the one process, Alkaline Peroxide Mechanical Pulping.

• Alkaline Peroxide Mechanical pulping: this process involves the impregnation of the chips with an alkaline peroxide bleach liquor in one or more steps prior to atmospheric refining, hence combining pulping and bleaching in a single operation. This process is of particular interest for the production of high brightness hardwood kraft pulp substitutes. The potential for reduction in refining energy is another specific feature of this technology because moderate to large quantity of bleach chemicals is added to the process.

The most appropriate technology to choose depends on brightness and quality targets, energy constraints, capital and operating costs. Solvay Interox would be happy to help with the selection of the most appropriate technology for your particular situation.

Recycled pulp bleaching

Three types of processes are used to recycle waste paper:

• Flotation Deinking which makes ink particles hydrophobic by means of a collector in a flotation cell. The air bubbles generated at the bottom of the cell carry the ink particles to the surface where they are confined in foam which is removed.
• Ink Dispersion, where ink is not removed from the waste but microdispersed over the entire fibre mass.
• Washing Deinking which eliminates hydrophilic ink particles by successive dilution and thickening operations (2 to 5 cycles).

 

In deinking lines, peroxide is usually added to the pulper in order to compensate for yellowing of mechanical pulp due to the addition of caustic soda to aid in the deinking process.

Irrespective of the type of deinking process employed, peroxide may also be added to the disperser, screw deflaker or in a dedicated tower to increase the final brightness of the pulp.

For certain types of waste paper, the presence of wet strength resins can be a hindrance in the recycling process. The addition of Peracetic Acid permits the destruction of the wet strength resin prior to the deinking process.

Catalase is an enzyme produced by aerobic bacteria as a defence mechanism against hydrogen peroxide and as such can be a problem in most deinking circuits. The addition of larger quantities of peroxide to the pulper for a short period of time or shock dosing of the deinking circuit with Peracetic Acid may be used to solve the catalase problem

 

Metal Surface Treatment

Upon request Solvay can provide its customers with detailed technical information on any of the following areas:

Metal Surface treatment	Non Ferrous Metal Finishing
	NOx scrubbing (Stainless Steel industry)
	NOx supression (Stainless Steel industry)

Metals Extraction

Upon request Solvay can provide its customers with detailed technical information on any of the following areas:

Gold processing	Pretreatment of ore (via either hydrogen peroxide or Caro's acid)     Enhanced Leaching (via hydrogen peroxide or calcium peroxide) Cyanide detoxification (via either hydrogen peroxide or Caro's acid) Metal processing
Uranium processing	Leaching Oxide precipitation

 
Metals Processing

Upon request Solvay can provide its customers with detailed technical information on any of the following areas:

Metal processing

Arsenic  Black Acid Cerium Chromium Cobalt Copper Iron Manganese Nickel Rare Earths Selenium and Tellurium Tungsten Vanadium Zinc Zirconium

Useful link : http://www.solvayh2o2-mining.com/

For a more detailed discussion on this application of peroxygen technology please contact us.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bleaching of Natural Products

Hydrogen peroxide is used for the bleaching of a wide and varied range of naturally occurring products including wood, cork, oils and fats, wax, coconut and palm fibres, birds nests, bones, furs, straw, wicker, feathers, nuts, sponges, lanolin and gelatine.

Foam Manufacture

Hydrogen peroxide is able to liberate large volumes of oxygen gas under controlled conditions with only water as a residue. Processes for the production of foam rubber (natural and synthetic), plastics and concrete have been developed.

Polymer Manufacture

Hydrogen peroxide is widely used as a source of free radicals in emulsion processes for the polymerisation of vinyl chloride, vinyl acetate, methyl methacrylate and many other monomers.

Starch Modification

Modification of starch to reduce its viscosity in solution can be achieved by oxidation with hydrogen peroxide. This provides the paper industry with a convenient route to the desired starch without producing any undesirable byproducts.

 

Hydrogen peroxide is undoubtedly the most versatile bleaching agent available to the textile industry. It offers many advantages namely :
• ease of application,
• potential for reducing process times,
• minimisation of effluent problems,
• preservation of the quality of pure and blended textile fibres,
• a high and extremely stable degree of whiteness.

Animal fibres

Wool and silk are bleached easily with hydrogen peroxide. After scouring, wool may be bleached by immersion or ad and dry techniques, using alkaline or acid solutions.

Prior to bleaching, silk is usually degummed. Hydrogen peroxide addition assists this process and it is universally used as the bleaching agent for natural silk, usually in an alkaline solution.

Artificial fibres or regenerated cellulose

Rayon and spun rayon produced from regenerated cellulose do not contain as many impurities as natural cellulosic fibres and therefore bleaching with hydrogen peroxide can be carried out under milder conditions.

Dye Oxidation

The use of hydrogen peroxide directly, or in the form of its derivatives sodium perborate and sodium carbonate peroxyhydrate, facilitates the oxidation of vat and some sulphur dyes after their application to textiles.

Synthetic fibres 

When used alone, synthetic fibres do not normally require bleaching. However, blends of synthetic fibres with natural or regenerated fibres, e.g. cotton -polyester are frequently bleached. The most popular bleaching agent is hydrogen peroxide and it is used in both batch and continuous processes.

 

 

 

 

 

ADDRESS	Solvay Chimica Italia S.p.A.
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Product Safety and Environment issues are among our highest priorities. We are committed to conducting our business so as to promote and continuously improve the responsible and sustainable management of our products throughout their entire life cycle. It is being achieved by a combination of responsible development and safety support to our partners. Everyone involved with our products shares the responsibility for the successful implementation of our policy.

The effectiveness of Product Stewardship implementation is ensured by the appropriate allocation of resources and responsibilities and by the development of effective programs to :

• Develop a comprehensive understanding and documentation of our products risks and take appropriate steps to manage them by prevention, control and reduction measures.

• Provide appropriate information to downstream partners (customers, distributors, agents and hauliers).

• Ensure safe transport and foster proper use, handling and recycling of our products.

• Educate and train employees on product hazards and proper use. Actively seek feedback on customer use and misuse of product and use it to revise information and advice.

• Maintain a system of monitoring and reviewing the Product Stewardship program and its implementation.

Product Stewardship is the responsibility of all our partners involved in the product life cycle. It will be successful only if everyone plays his part.