Surfachem Limited supply a series of polyaminopolycarboxylic acids and their salts which are usually known by the name ‘Chelates’.
The products will complex most polyvalent metal ions and in some cases show a specific action in complexing some metals in preference to others. The metal ion in the chelate no longer shows it’s characteristic chemical properties and is not precipitated by reagents which would normally cause precipitation of the uncomplexed ion.

The extent to which chelation occurs depends on a number of factors such as the nature and valency of the metal ion, pH of the solution, presence of anions and other metals, stability of the metal chelate, temperature etc.

We offer the following groups of chelating agents -

• NTA - Nitrilotriacetate
• EDTA - Ethylenediaminetetracetate
• DTPA - Diethylenetriaminepentacetate
• HE EDTA - N-hydroxyethylethylenediaminetriacetate
• D HEG - N, N-Di-(hydroxyethyl)-glycine

Chelating agents are important in a wide range of industrial fields. The major areas of use are as follows.

Detergent Industry
Chelates are widely used in detergent formulations to combat water hardness, because the softer water improves washing action. Chelates are also used as bleach stabilizers in perborate systems. SURFAC NTA NA3 is used as a replacement for polyphosphates in detergents in places when phosphate levels are required to be reduced.

Water Treatment
Both EDTA and NTA are extensively used in the treatment of water in boiler systems and for the cleaning of systems in preference to acid cleaning.

Cosmetic Industry
Discolouration and rancid odours in cosmetics are usually caused by traces of metal ions such as iron, copper and manganese. These can be rendered inactive by the use of chelates to form soluble metal complexes e.g. Disodium EDTA.

Paper and Pulp Industry
EDTA and DTPA based chelates are widely used in the industry to complex heavy metal ions which are present in the wood pulp. The effect is to improve the efficiency of the bleaching process.

Industrial Cleaning
The complexing power of chelates particularly for calcium and iron lead to their widespread use in industrial cleaning compounds.

Agriculture
Metal salts of chelating agents are widely used as micronutrients in many areas of agriculture and horticulture.

Copper, Iron, Magnesium, Manganese and Zinc in chelate form are largely unaffected by soil condition or it’s pH value. They are thus readily available to the plant root system for the promotion of growth and maximisation of yield.

Photographic Industry
A range of chelating agents are used in the photographic industry. For the prevention of heavy metals contamination and enhancement of photo sensitivity EDTA’s are used:

Polymerisation
EDTA is used as an additive in polymerisation of Styrene and butadiene.

Sugar Industry
Chelating agents are widely used for the removal of scale in process plant.

Surface Treatment
Preparation of metal surfaces especially for use in the electronics industry can be assisted by the use of various chelating agents. This depends on the action of the chelate on the oxide film present on the metal surface.

Textile Industry
The use of chelates to combat water hardness and remove heavy metals in the processes in the textile industry is a long established practice.

General Rules For Efficient Chelation
Iron is best complexed in acid solutions by EDTA, NTA or DPTA. In alkaline solutions, iron is best complexed by chelating agents containing both acetic acid and ethanol groups (HE EDTA, DHEGN).

When chelating common metal ions in alkaline solutions use a chelating agent that is fully substituted with acetic acid groups (EDTA, NTA, DPTA).

Although chelating agents for common metal ions work in acid solutions, they perform best and most economically in alkaline solutions. Therefore whenever possible, use the chelating agent at the highest pH that the system will tolerate except when chelating iron.

For maximum efficiency and minimum cost use EDTA or NTA to complex calcium, magnesium and other common metal ions.

Products Surfachem Ltd Supply

 

Product	Chelate Group
Surfac NTA NA3/Versene NTA Crystal	NTA Na3.H2O
Surfac PD38	NTA Na3
Surfac EDTA Acid/Versene Acid	EDTA H4
Surfac EDTA Na4 Pdr/Versene Pdr	EDTA Na4
Surfac EDTA Na4 Liq/Versene 100E	EDTA Na4
Versene NA2 Crystal	EDTA H2 Na2.2H2O
Versene Na	ETDA H2 Na.2H2O
Versenex DTPA Acid	DTPA ACID
Versenol 120	HE EDTA Na3
Versene DEG	DHEGNa
Versene F	DHEGNa + EDTA Na4

 

PHOSPHATES
Alkali phosphates are well established in many detergent processes covering a wide range of cleaning operations for both industrial and domestic uses. Phosphates aid detergency by a combination of properties of which sequestration, dispersion and buffering power are the most important.

The phosphates can be conveniently divided into two classes, the orthophosphates and the polyphosphates.

• The orthophosphates we supply are SURFAC TSP, SURFAC DSP, CHLORINATED TSP AND SURFAC KTP.
• The polyphosphates we supply are SURFAC TSPP, SURFAC 4KP, SURFAC STPP, SURFAC SHMPPT, SURFAC SHMPS, SURFAC Na20, SURFAC K18 AND SURFAC K21.

These alkali metal phosphates are used in alkaline or near neutral detergents while for acid cleaners orthophosphates acid can be used.

POLYPHOSPHATES
Polyphosphates possess a number of important properties which contribute to detergency.

a) Soften water by sequestering calcium and magnesium hardness ions.

• This is where the precipitation of metal cations by an anion is prevented by the formation of soluble metal/polyphosphate complexes. In detergency, polyphosphates prevent the deposition of insoluble soap and surfactant salts, leading to more satisfactory cleaning. By means of this sequestering power polyphosphates are also capable of redisolving insoluble metallic soaps and surfactants. This improves cleaning results and regenerates active detergent for further use.

b) Remove heavy metal ions (Fe, Mn) by sequestration. Trace heavy metals present in the water supply can cause discolouration in the washed materials due to the insolubility of certain metal salts in alkaline conditions. This problem is averted when the metals are sequestered by polyphosphates.

c) Prevent redeposition of dirt by dispersion and suspension.

• That polyphosphates are good deflocculates and dispersants of clays, pigments and the usual household and clotting soils is attributable to the adsorption of polyphosphate anions on particles of soil or dirt to produce negatively charged particles which are mutually repulsive.
  
  This causes dispersion of the soil so preventing agglomerations which are likely to deposit on the material being cleaned. In addition, polyphosphates adsorption on the cleaned substrate also reduces redeposition of soils by similar repulsive interactions.

Choice of Polyphosphate
The selection of the most suitable polyphosphate for any particular application depends on both chemical and physical properties as well as compatibility with other ingredients.

SURFAC TSPP, SURFAC TKPP and SURFAC STPP
These solids are very useful polyphosphate builders in detergent powders, where STPP in particular has very good anti-caking properties. Clothes washing powders, floor cleaners and mechanical dishwashing powders are major areas of application for these polyphosphates.

The pyrophosphates (SURFAC TSPP and SURFAC TKPP) have the better buffering capacity while SURFAC STPP has the greater sequestering power. With the pyrophosphate there is a risk of precipitating calcium pyrophosphate when the calcium/pyrophosphate ratio is too high. As a result mixtures of SURFAC TSPP or SURFAC 4KP with SURFAC STPP are sometimes used.

SURFAC SHMPPT, SHMPS and SURFAC Na20
These liquid polyphosphate concentrates are ideally suited to incorporation in liquid detergents as polyphosphate builders.

SURFAC K18, K21 and SURFAC Na20 are recommended for use in highly alkaline formulations where good sequestering and dispersion properties are required. Such detergents include mechanical dishwashing, food equipment cleaning, bottle washing and metal cleaning products in which the high alkalinity is provided by the presence of caustic alkalis and silicates.

For the more moderately alkaline liquid detergents, such as hard surface cleaners, textile laundering detergents and abrasive cleaners Surfac K18 and K21 are preferred. This is because the potassium products are more compatible in systems where relatively large amounts of anionic surfactants are present, SURFAC K21 has a shorter average chain length than SURFAC K18 and so has better buffering capacity, while SURFAC K18 has superior sequestering properties.

Choice of Orthophosphate
SURFAC TSP is by far the most popular orthophosphate used in detergents, being important because of its emulsifying and degreasing power, high alkalinity, free rinsing properties and dispersive action. TSP is most used where high alkalinity is required. It is able to soften water by precipitation of metal ions (e.g. Ca, Mg) as non-adherent gelatinous precipitates in addition it can remove fatty residues by saponification and disperse suspended soils to a certain extent.

SURFAC TSP is also useful for degreasing plant and machine parts. A hot solution of about 5% anhydrous or 10% crystalline is recommended for use by immersion or pressure spray.

Disodium Phosphate is less often used in detergent applications but is found where lower alkalinity is required, as a source of phosphate and as a buffer in moderately alkaline formulations.

Chlorinated Trisodium Phosphate
Chlorinated trisodium phosphate which combines the bleaching and sterilising properties of chlorine with the detergent properties of TSP.

It contains about 3% valuable chlorine which becomes active immediately when dissolved in water.

Chlorinated TSP is a valuable constituent of detergent sterilisers which find application in certain household products and predominantly in the food industry for cleaning process equipment where powerful bacteriocidal properties are required.

It is also used for its deodorising and stain-removing ability.


All quantities unless otherwise shown are stated as weight for weight.

Endeavours have been made to ensure that the information given is reliable, but notwithstanding this, and except for those obligations and liabilities that cannot be excluded by operation of law, neither Surfachem Group Ltd nor any of its subsidiary or associated companies assume any obligation or liability arising from the information given, the recommendations made or the use of their respective products. You are referred to the standard terms and conditions of the supplying company which apply. Certain applications may have the benefit of patent registration and you are therefore recommended in your own interest to take appropriate steps to avoid the infringement of such.

SURFAC, SURFACARE and SURQUEST are registered trade marks to Surfachem Group Ltd. Material sold under the Surfachem Group Ltd trade marks are manufactured by 3rd party suppliers.