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APPLICATION OF ULTRASONICS IN THE PHYSICO CHEMICAL CLEANING OF TEXTILES IN DOMESTIC WASHING MACHINES.

Objective

It is known that the acoustic phenomenal associated with the application of ultrasonics, i.e. cavitation and acoustic streaming, strongly promote the loosening of soil from solid, rigid substrates. Very little is known, however, on the effect of US on the cleaning of textiles dispersed in a detergent-water mixture.

To achieve this objective, the following research elements have been defined:
-study of the linear and nonlinear propagation of ultrasonic waves in an inhomogeneous medium consisting of textile substrates in a liquid;
-determination of the effects of ultrasound on the basic phenomena of any cleaning process, soil loosening and mass transfer;
-study of the effect of ultrasonics on chemical reactions involved in, or potentially applicable to the wash process;
-development of design principles and experimental set-ups for an integrated flexible washing system using ultrasonics.
At this stage of the project, 3 main results have been demonstrated.
Ultrasonic (US) radiation leads to an increased rate of emulsification at the oil/water interface. This effect is accelerated in presence of detergents.
Improved fluid flow inside yarns in presence of US was demonstrated. This showed that US waves contribute to the detergency process by the induced improved transport process.
The interaction between US waves and cotton fibres was shown to be a 2 stage process: first, the fibres become rounded and more resistant. Then, enhanced by improved chemical access, the depolymerisation process takes over the fibres become damaged.

Applying ultrasonic (US) radiation in the cleaning of textiles can yield a highly improved wash result in terms of effectiveness as well as efficiency, ie a better cleaning in a shorter time, at a reduced energy consumption. The presence of a minimum amount of detergent (at least 1 gramme per litre), however, remains indispensable, since in its absence no detectable wash effects are obtained.

The improved cleaning must be attributed to mechanistic (enhanced loosening of soil) as well as kinetic (increased transport of loosened soil) effects. Apart from that, enzyme performance is increased chemically by an increased reaction rate as well as by a faster removal of reaction products.

To obtain the full benefit of US radiation, partial deaeration of the wash liquid is an essential prerequisite. A detergent formulation has been developed providing this deaeration in a 2 step process on the basis of a carbon dioxide gas stripping technique.

For the development of a commercially viable option, the key problem to be solved is that of the inhomogeneity of the US effect at realistic liquid to cloth ratios. This requires a completely new machine concept, comprizing a US system ensuring a homogeneous acoustic field, and means to ensure a controlled exposure of the textiles.

Some concrete ideas have been considered for the application of US washing on a semiindustrial scale aimed at the use of US as a complementary tool in tunnel type washers. The possibility of using US in dish washing machines of medium size is also being explored.
It is known that the acoustic phenomenal associated with the application of ultrasonics, i.e. cavitation and acoustic streaming, strongly promote the loosening of soil from solid, rigid substrates. Very little is known, however, on the effect of US on the cleaning of textiles dispersed in a detergent-water mixture.

To achieve this objective, the following research elements have been defined:
-study of the linear and nonlinear propagation of ultrasonic waves in an inhomogeneous medium consisting of textile substrates in a liquid;
-determination of the effects of ultrasound on the basic phenomena of any cleaning process, soil loosening and mass transfer;
-study of the effect of ultrasonics on chemical reactions involved in, or potentially applicable to the wash process;
-development of design principles and experimental set-ups for an integrated flexible washing system using ultrasonics.

Coordinator

Ciapem SA
Address
137 Rue De Gerland
69363 Lyon
France

Participants (2)

CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS
Spain
Address
Avenida Astrofisico Francisco Sanchez S/n
38206 La Laguna
Nederlandse Unilever Bedrijven BV
Netherlands
Address

3000 Rotterdam