‘’THE BUSY COMPOUNDS” - TENSIDES, WHAT ARE THEY ?

The high efficacity of the "ECS" Dust Suppression System is the result of the drastic reduction of the surface tension of water by use of the tenside "ECS 89"

Tensides are ecologically relevant substances. All requirements for the complete protection of the environment must be fulfilled before they can be used. Our society has become justifiably sensitive in matters of environmental damage caused by human agency. Therefore, it is imperative that we use criteria for testing and comparing products which can be repeated at will in experiments and which can give us objective information on all possible risks. Only thus can an emotion-free evaluation of products be achieved. Such test results are usually summarized in "Safety Data Sheets", for example according to Euro Norms, or in DIN or as US Standard safety sheets. Their contents are binding on all parties.

The interpretation of the contents of such data sheets is often unclear; as is the correct classification of the highly useful tenside in the confusing mass of chemical products.

In this LINGENBERG INFORMATION SHEET we aim to describe

... why a tenside is used in our system

... what happens to the tenside after spraying

... what the term "bio-degradable" means

... how safety data sheets should be interpreted.

Furthermore we wish to point out that the VDI GUIDELINE 2584 mentions only our tenside ECS 89 when discussing the reduction of the surface tension of water.

As is well known, dust particles and naturally occurring water do not form a stable bond with each other. From experience and observation we know that dust floats on water. Wind, sudden impact and waves result in the movement of the dust particles on the surface of the water.This observation makes it clear that the two media (water and dust) remain separate.

Physics has a simple explanation for the prevention of the desired bond:

The effective cohesive powers of both elements are considerably greater than their adhesive powers.

When the surface-tension reduction agent ECS 89 is dissolved in water, the cohesive powers of the water are practically eliminated. The adhesive powers now dominate and this results in a long.term, stable bond.

A simple experiment demonstrates this:

if a little dust is sprinkled on the surface of water in a glass, it remains there , floating.

If the experiment is then repeated, using a glass of water to which a few drops of detergent have been added, the dust then sinks immediately.

The well-known water strider - a water beetle with extra-long legs - enjoys his walk across the surface of the water. The poor guy would drown if sufficient surfactant were added to the water.

How can this phenomenon be explained?

"Surfactants"* or "surface active agents"*,for example household detergents, are substances which affect a "boundary layer" and are generally known to chemists and physicists as TENSIDES.*

A boundary layer is a surface that separates two (condensed) phases.

In connection with the "ECS Dust Suppression System" the boundary layer between dust particles (solid phase) and the liquid sprayed onto them (liquid phase) will be studied more closely.

At this boundary layer "liquid/solid phase" the laws of physics which describe the intermolecular forces of water still apply for the smallest obtainable size for nozzle exit droplets of 1 to 5µ.Even these tiny droplets contain a very large number of water molecules.(This size of droplet forms an aerosol which, because of atomization, is extremely damaging to health. It is, therefore, absent from all ECS systems.**)

While the molecules inside the droplet interact with all their neighbours, the molecules on the droplet surface are subject only to forces directed towards the inside.In simple terms, there is a tension on the droplet surface which causes the liquid surface to contract to its minimum. The result is a spherical droplet because, of all possible shapes with the same volume, the sphere has the smallest surface.Cohesive forces among the molecules give rise to "surface tension." It is this surface tension which prevents dust particles from sinking in the above experiment and enables the beetle to walk across the water surface.On the other hand surface tension prevents the binding of water and dust.

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n.b.* apart from the designations mentioned here, a further designation is sometimes to be found on the market, namely that of "water condensor" which is said to improve the "hydrophile properties of mist." We do not use this term, as we consider it to be confusing and unscientific - it cannot be explained how mist-i.e. water dispersed in air can possibly become more hydrophile.

n.b.** c.f. Lingenberg Info. "Euronorm DIN En 481 and its significance for dust suppression by water.

	The molecules inside the fluid interact on
	all sides. Those on the surface interact only
	towards the inside.

Each water droplet that has bonded to a solid phase e.g. dust while surface tension was present can only maintain this contact for a very short time, if at all. The slightest impact can displace it ;as happens, for example when an umbrella is shaken to remove rain drops. This comparison also shows us that, of all the rain drops on the umbrella's surface, only an infinately small number make real contact with the umbrella. It is therefore obvious why the spraying of naturally occurring water on a tranfer point for the materials to be conveyed will lead to operational problems. The separation of the water from the material to be conveyed will lead to wetting of the belt covers, to soiling of the return belts with the result that the belts will not run straight, the crushers and sieves will become too wet etc. The desired binding of emissions will, however, not take place.

The spraying of water with naturally occurring surface tension remains ineffective for purely physical reasons.

"ECS" modifies the surface tension of the water through addition of a substance that acts specifically on the boundary layer: a TENSIDE.

The unit of surface tension is N pro m.

The definition of the surface tension is s_o = DW / DA

This surface will be extended as a consequence of the work W added to the system. This leads to the quotient

where s_o is defined as the tension required to extend the surface by 1 m².

The above definitions can be made clear by the following system:

	If the shaded area is taken up by a - very thin - film of water and this film is extended by a - very small - work DW = F Dl the area is then extended by a minimal amount. The bar B moves in the range of Dl and the area extends by DA = 2a Dl
	(2a because of the fact that the area extends at front and back)
	It follows
	so = DW / DA=F Dl / 2a Dl = F / 2a [N / m]

Naturally occurring water has a surface tension of 72,5 x 10 ^-3 [N/m]

"ECS" systems use the tenside ECS 89 which was specifically developed for processing plants. It is a highly effective, environmentally safe substance, that is used in extremely low concentrations of

1 : 3750 = 1 liter "ECS 89" to 3750 liters of water.

"ECS 89" reduces tension to 15 x 10 ^-3 [N/m]

	REDUCTION OF SURFACE TENSION.

The highly effective tenside ECS 89 works by reducing the cohesive forces between water molecules to a minimum. As a result the adhesive forces WATER/DUST predominate. Thus the short-lived, instable water/dust bond is replaced by an effective, permanent moistening of the dust particles through the encapsulation of the said particles. This , in turn, leads to an increase in particle size.

INSTABLE, SHORT-LIVED BOND IN NATURALLY OCCURING SURFACE TENSION OF WATER	STABLE, ADEQUATELY LONG ENCAPSULATION WITH WATER OF REDUCED SURFACE TENSION:

What is "Tenside"?

We are not often conciously aware of tenside in our daily life. However, not for nothing are they called

THE BUSY COMPOUNDS

We use TENSIDE daily, whether we are aware of it or not.

Margarine cannot be produced without tenside.

Tensides are present in toothpaste.

Ointments, creams, lotions and medications all require tenside in their manufacture.

We employ tenside every time we use a soap or a detergent.

Industry also relies heavily on these "busy compounds"

... they are used to enhance the flowing properties of concrete

... as dispergents they are a component in varnishes

... they are used for bitumen processing in road construction

... pesticides, fire-extinguisher foam and countless other substances all contain tensides.

Tensides are invaluable in so many industries; the petrol and mineral oil industry, the mining industry, the metal-processing, plastics, cellulose and paper industries . Even gastronomy, the beverage industry , to say nothing of the private household -all are in tenside's debt.

IMPORTANT: THEY DISAPPEAR AFTER THEIR TASK IS COMPLETE!

Tensides are frequently criticized-usually groundlessly by those who do not fully understand their function. They are indispensible. Nevertheless, they must disappear from the environment after their task has been completed.

Tensides are of ecological significance, because they are disposed of through the waste water system. We must be able to guarantee that they are ENVIRONMENTALLY SAFE. The most important factor,when considering whether a substance can remain in the environment without causing damage is its

BIODEGRADABILITY

The degradability of anonic and non-ionic (e.g. ECS 89) tensides is laid down in the tenside regulation.

According to this regulation tensides must be "on average at least 90% biodegradable."

This requirement is met if a single check shows a result of at least 80%

The required methods of testing and analysis are laid down in detail. In most cases, biodegradability is checked using the SCREENING TEST. This is a statistical test where a mineral medium is used together with tensides as the only organic nutrient.When waste water bacteria are added to the medium the tensides must have broken down by 80% within 19 days. <If this limit has not been indisputably reached, tenside break-down is further studied by means of a decisive "waste water treatment plant simulation test",- the so-called OECD CONFIRMATORY TEST. In this test, the experimental conditions are continuous and the tenside is studied in the presence of a large excess of easily degradable compounds. Such experimental conditions reflect, therefore, an absolutely realistic competitive situation. Biological degradation is measured using analytic methods that are specific for each substance group and allow quantification of the remaining tenside.

Tensides used on a large scale generally consist of many homologous individual compounds. Due to their differing structures, the individual compounds differ also in their primary degradation and toxicity. Thus we can detect an inverse effect: compounds that degrade slowly are more toxic than those which degrade rapidly.

The level of degradability of modern tensides considerably exceeds that required by law.

"ECS 89" provides especially good results:

.

The toxicological data available for the concentrate show that the aqueous solution can be used without reservation and can be considered safe by environmental health standards.

Test results and data on the degradation process are available for all tenside groups.

Generally speaking, the total degradation of compounds is studied in comparative tests like the ones described above; i.e.simple discontinuous screening tests. (Test of Ready Biodegradability)and waste water treatment plant simulation tests. /e.g.Coupled Unit Test)The main difference, however, is that criteria of final biological degradation are used to assess the results i.e. the mineralization of the substance tested to yield carbon dioxide, water and possibly salts, as well as the assimilation of biomass.

The analytical methods to measure the extent of final degradation include determination of the mineralization parameters CO₂ production and chemical oxygen requirement, as well as the measurement of the totals of mineralization and assimilation by studying the decrease in the amount of organic carbon in solution (DOC).*

Usually, the final degradability of the test substance is studied using one of five "Tests of Biodegradability" that were recommended by the OECD and are integrated into EC legislation on chemical substances. Duration of the test is 28 days. Again in these tests, the test substance is the only carbon source for the bacteria originating from waste water, rivers and soil. According to OECD criteria, compounds with a mineralization rate (CO₂ ,CSB) of more than 60% or a DOC decrease of more than 70% are considered to be degraded rapidly and completely under environmental conditions.

Comparing the data for primary and final degradation of tensides, it can be said that tensides with a high rate of primary degradation are further degraded extensively to their natural end products, so there is no accumulation of lasting waste products in the environment.

The extensive degradability of tensides and their ecological safety are also stated in the latest report on the aquatic compatibility of tensides in cleaning agents and detergents issued by the Detergents Committee. This committee consists of representatives from administration, water industry manufacturers, industry and universities, and serves as a consulting body to the German government.

According to this report, all major tensides in cleaning agents and detergents clearly exceed the primary degradation rate of 80 % specified by law. In addition to this, their total degradation of more than 60% fulfills the requirements of the OECD for readily biodegradable substances.

Acute aquatic toxicity of tensides, measured as LC₅₀ **/EC₅₀ (concentration where 50% of the organisms survive in the fish- and daphnia test) is higher than 1 mg/l. - Compare with numbers for "ECS 89" listed above-!

As mentioned above, the tenside concentration used in the "ECS Dust Suppression System" is 1:3750 - 1 : 4200, i.e. 1 liter of tenside is dissolved in 3750 (4200) liters of water.

Consequently, each liter of the ECS mixture: raw water and "ECS 89" contains 0.27 g of tenside. Tenside concentrations of 0.5 g/l drinking water are considered safe by the health authorities

Our safety sheets (DIN - US STANDARDS) list all relevant data for the concentrate and the concentration used in the system.

It is obvious that the tenside "ECS 89" used in the "ECS Dust Suppression System" meets and even exceeds all requirements with regard to environmental protection, toxicology, ecology and biodegradability. There have been and can be no objections raised against its correct use, in Germany or abroad.

More than 300 systems are in use world-wide but there have been and can be no objections raised against its correct use anywhere.

The tenside ECS 89 was developed specifically for the "ECS Dust Suppression System" Applied concentration, compatibility with installed seals, tubes, pipes and other materials, flow properties and especially gauging and control instrumentation have been designed and tested specifically for our system. For these reasons and also because of the environmental considerations, exhaustively listed above, our warranty expires immediately and completely if another tenside is used.

"ECS 89" is available in many countries and on all continents.