Effect of the pre-treatment of stains with ultrasound in household laundry cleaning

Abstract

The effect of three handheld ultrasonic devices for the pretreatment of stains on textiles was evaluated under household conditions. Twenty soiled textiles were treated and the mean increase of lightness ΔL* of the soiled textiles was used as a measure for the cleaning effect. It was shown that the combination of a pretreatment and a washing cycle at 20 °C yields a higher mean increase of lightness, ΔL* = 19.5, compared to a 40 °C washing cycle without pretreatment, ΔL* = 15.3. The effect is most pronounced for mixtures consisting of oily soils with pigments, ΔL* = 25.1. During the pretreatment, the soil was soaked in a detergent solution and the effect of soaking was measured separately.

Potential of ultrasonics for energy saving in the household washing process

“…For comparison with other technologies that use ultrasonics, a manual treatment was performed with device 3 (Fig. 1, number 3) analogous to the procedure in Kimmel et al (2022). The difference between the approach in this study and in Kimmel et al (2022) was that in this study the cleaning performance was assessed directly after the treatment and a manual rinsing step with tap water.…”

“…1, number 3) analogous to the procedure in Kimmel et al (2022). The difference between the approach in this study and in Kimmel et al (2022) was that in this study the cleaning performance was assessed directly after the treatment and a manual rinsing step with tap water. In (Kimmel et al, 2022), the cleaning performance was assessed after a pretreatment in combination with a consecutive washing cycle in a conventional washing machine.…”

“…To measure washing performance, two stains made on cotton textiles, either with sebum/pigment (10D) or olive oil/pigment (10B), were obtained from wfk-Testgewebe GmbH. The stain olive oil/pigment was chosen as it responded very well to ultrasonics, according to Kimmel et al (2022). Sebum/pigment was used because sebum is a typical stain found in textiles that have contact with human skin.…”

“…For device 3, stains with the size 5 × 5 cm 2 were used similar to the procedure in Kimmel et al (2022). During the treatment of stains with device 3, the textile is not submerged under water but wetted with the detergent solution.…”

“…In Kimmel et al (2022), devices for the pretreatment of stains were examined. If a pencil-shaped ultrasonic device is used for a manual 30 s pretreatment of 20 different consumer-relevant stains of 5 × 5 cm 2 each, followed by a 20 °C cotton program, the In wool programs, the energy-efficient cleaning effect due to the drum rotation cannot be used.…”