TAED
TAED is an ecologically safe, readily biodegradable, and mineralizable chemical used as a bleach activator in bleach boosters, dishwashing detergents, cleaners acting as disinfectants, industrial detergents, and cleaning and bleaching agents for textile bleaching.
TAED
Use of the substance/preparation.
Industry sector: Detergents Intermediates
Type of use: Perborate activator
Composition/information on ingredients
Chemical characterization
Tetra acetyl ethylene diamine
CAS number: 10543-57-4
Chemical name: N,N,N, N-tetraacetylethylenediamine
Empirical formula C 10 H 16 N2 O4
Molecular mass: 228 g/mol
CAS no. 10543 – 57 – 4
EINECS no. 234 – 123 – 8
UIPC nomenclature N,N-1,2-ethanediylbis (N-acetyl-)acetamide
Other names N,N-ethylenebis-diacetamide
N,N,N,N-tetraacetyl-1,2-diaminoethane
USES OF TAED
Heavy duty detergents
Concentrates
Compact powders
Bleach boosters
Soaking agents
Dishwashing detergents
HDL anhydrous
Denture cleaners
Disinfectant cleaners
Hard surface cleaners
Textile bleaching
Paper bleaching
Consumers expect the best possible results from a modern detergent.
Top of consumer requirements is the complete elimination of difficult stains simultaneously with the gentle treatment of fibres and colours.
Washing and bleaching should be carried out in a single operation; the consumer can only be expected to do additional work, such as soaking, in the case of heavily soiled washing.
TAED satisfies these requirements in the best possible manner.
TAED is a bleach activator chemical in laundry detergents.
TAED delivers highly reactive peracetic acid in the washing liquor even at temperatures of 20°C, as well as free hydrogen peroxide depending on the excess of persalt.
The combination of both oxidizing agents guarantees the best possible bleaching result on a large number of stubborn stains and at the same time a hygienically clean wash.
The overall washing result is influenced positively, colours and fibres are protected and the overall quality of the laundry is enhanced.
Washing at boiling point is not necessary, since a comparable result is already obtained at 40 and 60°C saving energy and costs.
TAED is especially environmentally friendly.
TAED is produced industrially in a continuous process free of by-products with optimum use of raw materials.
TAED is safe to handle, toxicologically harmless and combined with sodium percarbonate
TAED is a bleaching system which safeguards the environment.
TAED is stable in storage and compatible with other detergent ingredients such as layered silicates, enzymes, and optical brighteners.
TAED satisfies all the requirements for use in conventional and compact detergents.
TAED at a glance: multi-active, economical, and environmentally friendly
TAED is a chemical with many functions
TAED releases highly reactive peracetic acid in the washing liquor, even at room temperature.
The peracetic acid reacts with a large number of stains as a result of its oxidation potential.
At the same time, it acts as a disinfectant and kills bacteria and germs under mild conditions.
In addition, unpleasant odors (tobacco, cooking smells) are decomposed by oxidation, and the efficiency of fragrances is thus enhanced.
As a mild oxidizing agent, peracetic acid is compatible with most dyes, and no damage to the fabric is observed even with frequent use.
Deodorization
Bleaching Hygiene
Preservation of colours and fibers color
TAED – Efficient and economical
The positive effect of TAED on the bleaching result is visible even at 20°C.
TAED reaches its optimum spectrum of activity in the temperature range of 30 to 60°C.
Significantly better stain removal is possible at these temperatures than detergent without TAED.
At temperatures above 70°C, excess hydrogen peroxide supports the effect of the peracetic acid.
The effective utilization of the activator system is visible if pure peracetic acid is used for bleaching instead of the TAED.
In this case a comparable result is obtained.
TAED – Compact and environmentally friendly
The use of TAED makes it possible to produce effective bleaching systems in terms of weight and volume for incorporation in compact powders.
It is possible to reduce the persalt concentration by about 50% without any loss in efficiency.
The system proves to be especially environmentally friendly combined with sodium percarbonate, which supplies alkali and at the same time enables additional savings in chemicals to be made
TAED
The stains and the bleaching agent
Laundry necessarily comes into contact with natural and synthetic dyes in daily use.
These may vary in origin: drinks (coffee, tea, fruit juices or red wine), fruit or vegetables (spinach, carrots or marmalade), sauces (ketchup, soya or gravy) or spices (saffron and curry).
Natural dyes are often mixtures of substances, whose chemical structures have only been partly explained.
Whilst some stains, as long as they have not undergone ageing, can be removed by washing them out quickly, chemical destruction of the chromophore is necessary for stubborn soiling.
Various bleaching agents are used for the washing process worldwide, depending on the region.
In countries with typical cold wash conditions (10–30°C), such as in North America or the Far East, chlorine bleaching (sodium hypochlorite) is still used.
In 5% solution it is a highly reactive oxidizing agent and disinfectant.
However, overdosing of the reactive chemical may easily cause damage to the fibers and dyes in textile fabrics.
Furthermore, the formation of halogen-containing substances during storage, use and, in the effluent has resulted in the search for alternative, more environmentally compatible systems.
Sodium perborate has been used in Europe as a bleaching agent since the beginning of the 20th century.
Its crystalline structure guarantees stability in storage and enables it to be incorporated directly in detergents.
Unfortunately, the hydrogen peroxide formed on being introduced into water only develops its oxidizing properties at temperatures higher than 80°C, preferably in the pH range of 11 to 12.
The effect which can be achieved with persalts alone is only slight at 30–60°C.
However, this low-temperature range becomes accessible as a result of adding a suitable activator such as TAED.
TAED is tetraacetylethylenediamine which was first described in 1911.
The activity of TAED as a bleaching agent activator was recognized at the end of the fifties and it has been a component of modern heavy duty detergents in Europe since the beginning of the eighties.
TAED is not protected by patent and can be used in all countries of the world because it is a registered chemical.
The Tetraacetylethylenediamine molecule is electrically neutral, but has a polar character as a result of the two imide structures.
In the presence of acceptors it acts as a potential acylating agent with the transfer of two acetyl groups.
The solubility of TAED in water is only limited, but increases considerably as the temperature rises.
With an intrinsic pH value of 4.5–5.0 it is weakly acidic and is largely stable in water in this pH range.
In solution it hydrolyses both in an acid and also in an alkaline medium with the formation of two molecules of acetic acid.
TAED is less soluble in commercial organic solvents.
Exceptions are halogenated hydrocarbons such as methylene chloride and chloroform.
By virtue of the process TAED is obtained in the form of colourless crystals.
The melting point of TAED gives it excellent mechanical and chemical stability, which is further increased for use in alkaline detergents preferably by an additional granulation or coating.
TAED powder and granules are stable almost indefinitely in sealed containers from which heat and moisture are excluded.
A faint odour of acetic acid of the TAED powder is typical of the product, especially after standing for a long time in sealed containers.
It is essential to observe the safety regulations for dustlike products during the technical processing of TAED powder.
Active oxygen bleaching is a complex chemical reaction and takes place in at least two partial stages.
In the first stage, perhydrolysis, TAED reacts with hydrogen peroxide (from perborate or percarbonate).
Two molecules of peracetic acid and the easily biodegradable and toxicologically harmless diacetylethylenediamine (DAED) are generated.
This reaction takes place in a few minutes in the pH range between 10 and 11 almost independently of the temperature and even at room temperature.
The mechanism, in which the peracetic acid subsequently reacts with the chromophoric systems of the soiling, has not yet been finally clarified.
The formation of active oxygen, i.e. the transfer of a peroxide oxygen atom of the peracid and therefore the bleaching result, are influenced both by the substrate and also by the pH value.
On the one hand singlet oxygen is possible as a bleaching agent, as is the peracid or its anion on the other.
The bleaching reaction itself is a first order reaction in regard to the oxidizing agent and highly dependent on the temperature in the range of 20 to 50°C.
Another crucial factor for a good bleaching result is the approach rate of the peracid to the soiled fibre surface.
0.67 g peracetic acid (or 0.14 g active oxygen) is released per gram TAED.
According to the stoichiometry the TAED : perborate tetrahydrate weight ratio should be 1 : 1.35, when using monohydrate 1 : 0.9.
However, in practice a small excess of persalt is necessary to balance its activity losses during storage and decomposition as a result of the interaction with the enzyme catalase and to ensure the optimum use of both components across all washing temperatures.
The peracetic acid formed is itself insensitive to catalase.
5% by wt. TAED are therefore recommended to activate 8–10% by wt. PB*1 or 12–15% by wt.
When using the less stable percarbonate its proportion in the formulation should be 10–15% by wt. TAED quantities <50 mg/l washing liquor do not produce any appreciable bleaching action, an increase up to 500 mg/l is associated with a constant increase in the degree of whiteness.
The optimum bleaching result is achieved, if the pH value at the beginning of the washing process is initially between 10 and 11, to guarantee optimum perhydrolysis, and is subsequently reduced to values between 9 and 10 to obtain the best possible bleaching effect
TAED –
Hygiene and deodorization
Bacteria and other microbial germs do not only occur as pathogens, but are also responsible for the formation of sweat and the production of unpleasant odours.
In the past the microbes adhering to the laundry were destroyed completely by the heat during the boiling wash.
In modern detergents the bleaching system fulfils this function at much lower temperatures.
The destruction of bacteria, germs and unwanted odours results in a “hygienically clean” 40°C wash corresponding to the standard of the boiling wash.
The antimicrobial action of peracetic acid and of hydrogen peroxide has long been known.
Whilst peracetic acid displays effective bactericidal, virucidal and fungicidal properties, hydrogen peroxide has a particularly antiseptic and bacteriostatic action.
Its sporicidal properties are also to be emphasized.
Both supplement each other ideally.
Both perborates and percarbonate are suitable as a source for hydrogen peroxide.
In the absence of a bleaching system a large number of germs survive in the washing liquor or on the laundry at washing temperatures below 60°C.
95% of the microorganisms are destroyed by the persalt, but destruction rates of >99.99% are achieved only by the addition of TAED.
Even at washing temperatures below 40°C, where the activity of hydrogen peroxide – in particular with short washing cycles – is not very good, the efficiency can be improved by using TAED and the spectrum of activity can be broadened considerably.
Systems containing TAED are therefore also used in disinfectants and cleaning agents with antimicrobial action (denture cleaners).
In addition to the germicidal action, odours adhering to the laundry such as kitchen and tobacco odours or sweat are destroyed by the bleaching system.
Here too, the effectiveness can be clearly enhanced by TAED.
This is particularly important in perfumefree detergent formulations
Chlorine bleaching is not very suitable for bleaching dirty coloured laundry and delicate fabrics on account of its aggressiveness.
Although hydrogen peroxide is far milder, its effectiveness
on stubborn stains is not sufficient in the coloured
wash.
Detergents and bleaching agents containing TAED on the other hand guarantee the optimum bleaching result at the same time as the best
possible care of the textiles.
There is no fear of the dyes fading, i.e. the chromophore system of the dye molecules being destroyed by oxidation, using typical concentrations of the TAED.
Most dyes proved inert towards peracetic acid.
The cause of the bleeding is the detachment of dye particles from the fabric, which may result in colour changes or the fading of coloured textiles.
Frequently the surfactant or builder combination is responsible for this, not the bleaching system.
Furthermore detached dye particles may be deposited on other textiles during the washing process and discolour the fabric.
Modern detergents often
contain inhibitors, mostly on a polymeric base, to suppress this dye transfer.
The function of these additives can be taken over by the TAED system to a certain degree, by the peracetic acid which has been formed bleaching the detached dyes in the washing liquor and making them invisible.
Another damage caused by washing, although seldom observed, is spotting.
This involves partial fading of a dye in the form of dots, caused by an excessive concentration of bleaching agent locally.
This may be the case for example with improper soaking, if a high concentration of bleaching agent is deposited on the fabric, without the washing liquor being agitated sufficiently.
Undesired spotting can be prevented effectively by using suitable TAED granules.
In rare cases damage to the fibres in the form of tears or holes can be seen after frequent washing.
The reason for this is generally catalytic decomposition of the hydrogen peroxide, caused by traces of metal ions, which get into the washing liquor through the water or the soil on the laundry.
The hydroxyl radicals released split the cellulose fibres forming oxycellulose, which results in a decrease in the average degree of polymerization of the cotton and a loss of tensile strength.
Additions of sequestering agents or silicates to the detergent formulation are suitable for preventing catalytic damage.
A reaction of the TAED with the cotton fibre is only observed to a lesser degree in the boiling wash and does not cause any significant damage to the fibres even with frequent washing
Preservation of the colour
Most classes of dyes behave inertly towards detergents containing TAED.
Neither any lightening or change in shade is observed.
There are no interactions with the persalt with the 40 and 60°C wash, the addition of TAED causes no negative effects either.
However, the consumer should check the colour fastness of coloured textiles prior to washing, particularly when using bleach boosters.
Dye transfer inhibition
TAED is an expedient addition to dye transfer inhibitors.
Peracetic acid attacks the detached dye molecules sensitive to oxidation in the washing liquor and thus prevents any discolouration of neighbouring textiles.
This is particularly the case with the 60°C wash.
Protection of the fibre
TAED shows only slight reactivity towards the cellulose fibres of the cotton.
Even with frequent washing only minimal damage to the fibres is observed, i.e. a decrease in the average degree of polymerization [DP value], which does not represent any significant reduction in the serviceability of the textiles.
Genuine damage to the fibres on the other hand is caused by traces of metal ions.
There are numerous applications for TAED.
TAED can be used both for the activation of perborates (monohydrate or tetrahydrate) and also percarbonates (stabilized or unstabilized).
TAED is compatible with all the commercial ingredients of modern detergents and cleaning agents.
Particularly sensitive components such as enzymes, optical brighteners and perfume oils are available in TAED-compatible variants.
As a solid TAED is particularly suitable for use in products in powder form.
It is generally used in granulated form to improve its handling, suppress the interaction with other ingredients and increase stability in storage.
Various types of granules optimized for the relevant field of application can be obtained commercially.
The main fields of application for the TAED system are conventional, concentrated, and compact heavy-duty detergents, bleach boosters and dishwashing detergents.
TAED displays optimum effectiveness in the temperature range of 30–60°C.
Use in liquid products is still in development, since ,in this case greater demands are made on the storage stability of the TAED system.
Sufficient stability can be obtained in anhydrous liquid systems.
The sterilizing action of TAED is valued above all in denture cleaners and cleaning agents for hard surfaces.
TAED powder in the form of anhydrous suspensions makes simple dosage possible for industrial laundries.
Additional potential areas of application are textile and paper bleaching, where initial positive results were obtained for the substitution of chlorine bleach by the TAED system.
TAED –
A bleaching activatorwith numerous application possibilities
Possible uses:
Heavy duty detergents
Concentrates
Compact powders
Bleach boosters
Soaking agents
Dishwashing detergents
HDL anhydrous
Denture cleaners
Disinfectant cleaners
Hard surface cleaners
Textile bleaching
Paper bleaching
TAED is normally used in granule form in detergent formulations.
They ensure excellent stability in storage, prevent interaction with sensitive detergent components and guarantee optimum utilization during the washing process.
TAED granules are easy to process, low in dust and free flowing.
In order to ensure the greatest possible flexibility on processing, the TAED granules normally are not given any further additives besides granulating auxiliary agents and coating materials.
When incorporated properly into suitable formulations they also ensure an excellent stability even after a longer storage period.
TAED should be adapted to the relevant formula.
In addition to the concentration of the bleaching system the pH value of the resultant washing liquor is of crucial importance in order to obtain the best possible effect.
It can be controlled by the use of pH regulators.
The use of multi-active TAED makes it possible to produce more effective bleaching systems in terms of volume with a reduced percentage of persalt and excellent low temperature
bleaching efficiency without any losses in the
boiling wash.
A further reduction in volume of the detergent can be achieved by the incorporation of layered silicates, which are effective as builders, alkali sources, heavy metal ion binders and surfactant carriers.
TAED is also highly effective in these formulations.
Significant increase in performance as a result of using TAED
By adding 0.1 g/l TAED and 1.0 g/l perborate the same bleaching effect can be obtained as with 2.5 times of the non-activated persalt.
Activated formulations therefore enable significant savings in persalt to be made (saving in volume) with the same or better bleaching efficiency.
The discharge of chemicals into the environment can therefore be reduced considerably.
More cost-efficient bleaching systems can be produced with TAED by means of suitable formulations.
Significant reduction in volume with activated bleach systems
The use of TAED makes it possible to reduce the volume of the bleaching system by about 50%.
The successive replacement of excess perborate by TAED is the first stage, without any reduction in performance.
The use of the more volume-effective perborate monohydrate instead of tetrahydrate leads to an additional reduction in volume.
The combination of environmentally friendly percarbonate with TAED is economically and ecologically the most expedient solution of a bleaching system for compacts
Optimized bleaching systems
The concentrations and weight ratios stated are guidelines and have to be optimized if necessary.
In unbuffered formulations containing TAED the lowering of the pH value takes place largely automatically as a result of the acetic acid formed.
In buffered systems the use of acid additives with retarded dissolving behaviour is advisable.
TAED in concentrated and compact powders
TAED is eminently suitable for use in concentrated and compact powders.
TAED is generally added to the washing powder towards the end of the production process, to rule out excessive mechanical stress during the mixing process.
Optimum stability in storage is ensured in this way.
Together with other multifunctional ingredients, such as percarbonate and layered silicates, TAED makes it possible to produce highly compact powders.
Builder compatibility
TAED is compatible with all commercial builder systems and also display an excellent degree of conservation after several weeks storage.
However, the builder system has a significant influence on the stability of the persalt.
In particular (uncoated) sodium percarbonate rapidly loses activity in formulations containing zeolite.
Very good storage stability is guaranteed on the other hand in formulations free of zeolite based on SKS-6.
TAED in formulations containing SKS-6 / percarbonate
The change from formulations containing zeolite / perborate to more environmentally friendly detergents based on SKS-6 and percarbonate necessarily involves an increase in the pH value of the washing liquor.
As a result there is a shift in the performance spectrum of the TAED.
Whereas slight losses in performance have to be accepted with regard to hydrophilic soiling, the bleaching performance is improved with regard to more hydrophobic types of stains.
TAED in bleach boosters
Bleach boosters are increasingly gaining importance as detergency boosters and a component of building block systems.
They are used either to pretreat the wash (soaking) or as an additive to the normal detergent, if the heavy soiling of the wash so demands.
Combined with light duty or liquid detergents – used specifically and only if necessary– they can totally replace detergents containing bleach and make a significant contribution towards safeguarding the environment.
The main components of all bleach boosters are persalts – generally percarbonate (20–80%) – and TAED (3–15%).
In addition enzymes, surfactants and sequestering agents may be incorporated to enhance the efficiency towards stubborn stains such as grass, fruit or blood stains.
The appropriate choice of filler is crucial for the optimum performance of the bleach boosters.
This should take over the function of a pH regulator, buffer or stabilizer or as inert material improve the formulation’s thermostability.
The full bleaching power of bleach boosters containing TAED is realized in particular with the 40 and 60°C wash as well as in the soaking process at 20–40°C.
Crucial for the efficiency is the pH value of the washing liquor, which is a result of both the basic detergent and the bleach booster.
Formulations containing TAED based on 25% persalt are in most cases clearly superior in performance compared to bleach boosters consisting of pure persalt.
A significant additional effect is to be seen in the germicidal action.
Under certain circumstances the bleach boosters can affect the performance of the enzymes of the basic detergent negatively on account of the high content of bleaching agent. Optimum enzyme and bleaching performance is observed by the delayed addition of the bleach boosters (10–15 min. after the start of the wash).
Bleach boosters containing TAED are characterized by good storage stability.
However,it must be noted when choosing the formulation that mixtures of fire accelerating percarbonate with organic materials such as TAED or surfactants may have a tendency towards exothermic decomposition under unfavourable processing or storage conditions.
The processing instructions for persalts and TAED are to be observed to ensure safe handling.
In addition thermochemical investigation of the final formulation is advisable.
Special types of TAED granules for use in bleach boosters can be obtained commercially.
Optimized bleaching as a result of optimized additives
The efficiency of the TAED system can be optimized by the appropriate choice of additives.
Whereas the addition of sodium carbonate tends to have a negative effect on the bleaching action, acid substances – in the correct dosage – can increase the bleaching performance.
The use of citrate is advantageous, because it assists the bleaching reaction positively.
Activated and non-activated bleach booster formulations
In the case of bleach boosters without TAED (non-activated) the addition of an alkaline filler is recommended to assist the bleaching performance of the hydrogen peroxide.
In systems containing TAED the pH value should ideally be between 9 and 10, whereby the activity of the peracetic acid formed can be additionally improved.
Additives, like ox-gall soap or sequestering agents, have the effect of increasing the efficiency with regard to certain types of dirt.
Better bleaching results due to the activated bleach
The performance of different bleach boosters was tested at 40°C combined with different basic detergents, which cover a wide spectrum of the heavy duty, light duty and liquid detergents available on the market.
Advantages are clearly revealed for formulations containing TAED, the performance of which is up to 20% above that of pure percarbonate.
Bleach boosters in the soaking process
Bleach boosters containing TAED are clearly superior to non-activated formulations in the soaking process at room temperature.
Reaction periods of more than 12 hours result in only marginally additional bleach effect.
Influences on the bleaching result
Optimization of a bleach booster is generally more difficult than that of a heavy duty detergent.
The final bleaching result is not only influenced by the bleach booster, but also by the basic detergent used.
The fine adjustment is only possible through the manufacturer, since the latter is able to control the consumer’s behaviour with the instructions for use on the package.
TAED in denture cleaners
The ingredients of modern denture cleaners are largely substances with cleansing, oxidizing and disinfectant properties.
In most cases a complex bleaching system is used consisting of caroate, perborate or percarbonate as well as TAED.
TAED provides for the necessary hygiene and the fast and complete removal of bleachable soil on the teeth.
The cleaning performance is assisted by a mixture of acid components (citric acid or amidosulphonic acid) with sodium carbonate or hydrogen carbonate, which produce an effervescent effect and support the mechanical release of food remains.
At temperatures of 30–40°C and reaction times between 10 and 20 minutes the use of a disintegration aid is recommended for faster solubility.
The use of granulated TAED is recommended for use in denture cleaners to guarantee optimum stability in storage.
The typical pH value of the cleaning tablets is in the range of 6–8.
TAED does not display the optimum bleaching action, but particularly in this range the peracetic acid formed proves to be highly reactive towards microorganisms and therefore makes TAED an indispensable constituent of modern denture cleaning tablets.
Sodium perborate x 1 H2O 25–35%
Potassium peroxomonosulphate 10–25%
TAED 2–5%
Sodium hydrogen carbonate 10–20%
Sodium carbonate 5–10%
Trisodium citrate 5–10%
Surfactant 0.5–1%
Others (polyethylene glycol,
fillers, preservatives, flavouring
and colouring matter etc.) ad 100%
TAED in dishwashing detergents
The ingredients of modern cleaners are builders (silicates, citrates or phosphates), alkali sources (soda, bicarbonate, silicates), dispersing agents, low foaming surfactants, enzymes and the bleaching agent.
The pH value is lowered to 9–11.
It is therefore an ideal field of application for the environmentally friendly TAED system with the usual washing temperatures today of 45–65°C.
At the same time it enables highly active proteases and amylases to be used, which assist in removing food containing protein and starch from the dishes being washed.
TAED is compatible with the ingredients of modern dishwashing detergents.
It can be used in formulations both with and without phosphates.
It is stable in powder and also in tablet form.
2–6% TAED are preferably used combined with 5–15 % perborate monohydrate or percarbonate to achieve the optimum bleaching result even on stubborn stains such as tea for example.
At the same time TAED suppresses the discolouration of plastic parts, caused by natural dyes in ketchup and food containing curry or paprika.
The peracetic acid formed destroys the microorganisms adhering to the remains of the food and ensures that the dishes being washed up are hygienically clean.
The use of TAED does not have a negative effect on the formation of a coating or glass corrosion.
Under certain circumstances however the presence of active oxygen may result in the discolouration of silver cutlery.
This involves the formation of layers of silver oxide (possibly also sulphides or chlorides), which are difficult to remove.
In this case the optimum formulation of the TAED system (concentration, ratio TAED : persalt) as well as the use of silver protective agents (e.g. triazoles or redox systems on an organic or inorganic base) are recommended.
Optimized dishwashing formulations
The TAED system has proved to be the bleaching system of choice in chlorine-free dishwashing detergents.
Optimum cleanliness even with stubborn tea stains is achieved whilst safeguarding the environment in the best possible manner.
At the same time active oxygen bleaching enables enzymatic systems to be used for optimal stain removal.
Sodium disilicate 20–30%
Trisodium citrate dihydrate 25–35%
Sodium carbonate 5–15%
Sodium percarbonate 5–15%
TAED 2–6%
Surfactant 1–2%
Polyacrylate 6–8%
Protease 1–2%
Amylase 1–2%
TAED [%]
Optimized dishwashing formulations
TAED has proved to be the bleaching system of choice in chlorine-free dishwashing detergents.
Optimum cleanliness even with stubborn tea stains is achieved whilst safeguarding the environment in the best possible manner.
At the same time active oxygen bleaching enables enzymatic systems to be used for optimal stain removal.
High cleaning performance due to TAED
The TAED system displays optimum activity in the temperature range of 45–65°C.
TAED concentrations of at least 2% are recommended.
Parallel to the bleaching performance, the reactivity of the dishwashing detergent towards microorganisms is increased as the TAED concentrations increase.
TAED in anhydrous liquid detergents
Conventional liquid detergents (heavy-duty liquids, HDL) have several advantages compared to products in powder form.
They are simpler to dispense, they do not produce dust when handling, and they dissolve quickly and entirely at the beginning of the washing process.
As a result of the high surfactant content, they are particularly effective against stains containing oil and at low temperatures.
Since they do not contain any bleaching system, they have disadvantages, however, with certain types of stains, which can only be counterbalanced in part by the use of enzymes or sequestering agents.
TAED is unstable in storage in aqueous formulations, but appropriate stability can be achieved in anhydrous liquid formulations.
The new type of anhydrous liquid detergents contains citrate or phosphate as the builder system.
This is suspended with 3–7% TAED and 8–15 % of a persalt in finely dispersed form in mixtures of surfactants and polyethylene glycols.
Additives to suppress the gel formation and to ensure flowability is recommended.
TAED granules can be obtained commercially for this application.
The high surfactant concentration makes a lower dosage of the product possible, and its high density reduces the packaging.
The bleaching results of anhydrous heavy-duty liquids containing TAED are comparable to those of compact detergents in powder form and superior to conventional heavy-duty liquids.
Anhydrous formulations enable the use of the TAED system.
TAED is only stable in anhydrous HDL formulations since i n the presence of water, hydrolysis or per hydrolysis occurs immediately with the decomposition of the bleaching system.
There is good stability in storage in anhydrous formulations.
Good washing results with low dosages
Liquid detergents with TAED bleaching system are comparable in performance to conventional powder heavy duty detergents and clearly superior to conventional liquid detergents. Their highly concentrated ingredients contribute in addition towards safeguarding the environment.
TAED in textile bleaching
Sodium hypochlorite and sodium chlorite are important bleaching agents in the textile industry.
They are coming increasingly under discussion, however, in connection with the growing AOX problems.
Neither the use of peracetic acid –because of technical problems (instability, odor) –nor its production in situ from acetic anhydride and hydrogen peroxide in the presence of an acid catalyst were successful alternatives.
The heat of the reaction, which is released, and the formation of diacyl peroxide as a byproduct make the reaction challenging to control.
The choice of TAED / hydrogen peroxide as the bleaching system is offered as an alternative.
It can be used in the pad batch impregnating bleaching and pad steam process.
Although bleaching is possible in an acid medium, the best results are obtained in the neutral to weakly alkaline range.
The TAED system offers the following advantages compared to conventional textile bleaching processes:
The fibers are only damaged insignificantly due to the gentle pH value.
Catalytic damage to the fibers only plays a secondary role.
The cotton has a supple, soft feel since waxes and fats remain on the fiber.
The use of colored fabrics is possible, as many dyes have less tendency to fade and bleed under these conditions.
The gentle process is also suitable for bleaching regenerated cellulose.
Bleaching temperatures <60°C make it possible to save energy.
With pad batch bleaching the maximum bleaching performance of the TAED / hydrogen peroxide system is in the neutral to the weakly alkaline range, preferably between pH 7 and 8.5 at temperatures of 50°C.
The cellulose fiber is swollen only a little under these conditions and can be damaged only minimally by the bleaching system.
Impregnating bleaching can be carried out both for a longer period (18 hours) at room temperature and also by steaming for a short time (15 min. / 99.5°C).
While an optimum pH value of 7.5 is shown for cold bleaching, a maximum degree of whiteness is obtained at pH 10 with hot bleaching.
With the two-stage pad steam process, an optimum between the degree of whiteness and damage to the fibers has to be found.
Here the TAED system can replace the hypochlorite completely.
So in the first stage, for example, the textiles can be padded and steamed with TAED / hydrogen peroxide, and subsequently, the peroxide bleaching can be carried out in an alkaline medium (pH 11.5–12.5).
Because TAED is partly used in high concentrations for textile bleaching, it should be remembered that the activator is only moderately soluble in water at room temperature. However, the solubility increases in the range between 40 and 50°C.
One part by weight of hydrogen peroxide (100%) can activate 3.4 parts by weight TAED.
In practice, it is advisable to work with an excess of hydrogen peroxide.
The TAED system in the pad batch
bleaching
Pad batch bleaching can be carried out under
both acid and alkaline conditions. Optimum bleaching
results with minimal fiber damage are observed
at 50°C in the neutral to weakly alkaline range.
The TAED system in impregnating bleaching
The use of the TAED system proves advantageous both for cold bleaching and also for hot bleaching.
The pH value, which influences both the degree of whiteness and also the fiber damage, is of particular importance in this case.
The TAED system in the two-stage pad steam bleaching
In the two-stage pad steam bleaching process, the stage of the chlorine bleaching can be replaced without any problems by activated TAED bleaching.
Advantages regarding the fiber damage result if peroxide bleaching is carried out first, followed by TAED bleaching.
TAED under cold wash conditions
Washing processes and washing conditions differ throughout the world.
Whereas washing by hand in the river with the aid of soap is common in many countries, automatic washing machines with multifunctional programs and built-in dryers are used in highly industrialized countries. Habits typical for a particular country are the temperature and length of a washing process.
In many regions, such as North America and the Far East, much lower temperatures and shorter washing times are used in comparison to Europe.
In order to obtain an optimum result, the laundry is often soaked over night and not washed until the next day.
The lower washing temperatures make it impossible in many countries to replace the ecologically harmful chlorine bleaching liquor by a persalt alone.
The reactivity of hydrogen peroxide is not sufficiently effective under these conditions.
On the other hand persalts have the advantage that they can be incorporated directly into a washing powder and the separate dosing stage can therefore be omitted.
The use of a persalt activator is essential to activate the bleach.
In this case TAED can be used either alone or combined with other low temperature activators.
Under cold wash conditions visible improvements in the bleaching results are possible over the whole temperature range between 10 and 40°C by using the TAED.
4–8% TAED combined with 6–12% perborate monohydrate or percarbonate have proved effective in compact detergents, whilst 10–15% TAED are expedient in bleach boosters.
The perhydrolysis of the TAED system is very fast even at 20°C, however the reactivity of the peracetic acid formed depends on the washing temperature and the reaction time. The bleaching result can be improved significantly, if TAED is already added in the soaking stage.
It is able to develop its full bleaching power as a result of the length of time.
Reference is made to the section on bleach boosters regarding the optimization of the bleach booster formulations.
The TAED system can be used in all powder detergents, irrespective of the type of builder system used, in bleach boosters and pre-soaking powders.
Incorporation in synthetic bar soaps is possible.
TAED granules have proved successful in many countries of the world.
Even under extreme climatic conditions they ensure good stability in storage and compatibility with other detergent ingredients and guarantee optimum bleaching combined with maximum sterilization.
TAED in all purpose cleaners
The incorporation of the TAED system in all kinds of anhydrous all-purpose cleaners in powder form does not present any problems.
In this field of application in particular, the antimicrobial effectiveness towards numerous germs is valued in addition to the excellent bleaching action.
TAED Production, toxicology, and environmental behavior
TAED has been produced from acetic anhydride and ethylenediamine since 1978 according to a method making economical use of resources.
By recycling all the partial streams, the plant guarantees integrated environmental protection and the uniformly high quality of the product with purity >99%.
The continuous, computer-controlled process makes the optimum use of both raw materials possible.
Direct coupling products are not produced.
The reaction water formed during the reaction – contaminated with traces of acetic acid – can be taken to the biological wastewater treatment plant without any problems. Organic distillation residue obtained in small amounts is burned and used to produce energy.
Numerous toxicological studies and decades of consumer experience emphasize the toxicological safety of raw materials in processing and use.
TAED does not have any labeling requirements.
By contrast with other detergent raw materials, such as surfactants, TAED changes during the washing process.
According to the reaction mechanism, it is converted into diacetyl ethylenediamine (DAED) with the release of peracetic acid and reaches the effluent in this form.
The tests conducted on both TAED and DAED prove that the two substances are not expected to cause any harm to humans or nature.
Both are readily biodegradable, compatible with water organisms, and were classified as harmless by the “Hauptausschuß Detergentien.”
In particular, when combined with sodium percarbonate, TAED represents an ecologically friendly bleaching system, the constituents of which are mineralized wholly and quickly.
The occurrence of stable metabolites was not observed during the degradation of TAED and DAED.
Industrial production of TAED
TAED is produced in a two-stage process from ethylenediamine (ED) and acetic anhydride (Ac2O).
Ethylenediamine is first reacted with acetic acid (AcOH) to form diacetyl ethylenediamine (DAED).
The reaction water formed is taken to the biological wastewater treatment plant.
In the second stage, DAED is subsequently converted with Ac2O via the stage of triacetylethylenediamine (TriAED) into TAED.
This is crystallized out of the reaction mixture, filtered, washed, dried, and granulated if necessary.
