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

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.

Pseudo-Laminarization of Mixed Microbubble Water and Complex Fluids in Capillary Flows

Symmetry in fluid flow is determined by external factors such as magnetic or electric fields. Owing to the electrical properties of fluids, liquids containing fine bubble or ionic surfactant molecules differ from the normal fluid flow. Therefore, the pressure drop and frictional coefficient in a pipe are measured and estimated for water alone, for mixed microbubble water (MB), and for complex fluids (anionic surfactant solution and polymer solution) in capillary flow with constant flow rate. For water alone, good agreement is obtained between the experimental and theoretical values for laminar Hagen–Poiseuille flow and the Blasius expression in turbulent flow. For the MB, pseudo-laminarization is suggested up to a Reynolds number of 4.2×103. Both the anionic surfactant solution and the polymer solution exhibit the same tendency as that of the MB. In explaining these behaviors, elasticity and electrical interaction are discussed, and electrical interaction on the capillary wall is strongly suggested to be a contributing factor. Additionally, surface tension is investigated and supports the discussion.