Ultrasonic cleaning of highly soiled apparel

Abstract

Concern for the environment is a major driver in the present day technological developments. With pressure building globally for consumers, to cut down both on water usage and greenhouse emissions, the time is right to develop sustainable textile cleaning system which will help reduce the environmental impact of washing without compromising the cleaning efficiency. From the consumers point of view these new technologies should be compatible with the existing laundry practices and are both user and fabric friendly. Currently available methods of cleaning highly soiled areas of apparel are labor intensive, harsh on the fabric and not necessarily environment friendly. These involve use of strong chemicals, enhancement in agitation like brushing of soiled areas or washing at high rotor speed for longer durations at higher temperatures. This affects the appearance and serviceable life of the garment, negatively. Use of high frequency sound waves or ultrasonic offers an effective and fiber gentle alternative. In the present work, an effort was made to use ultrasonic energy as an alternative to mechanical agitation to enhance laundry process effectiveness and thereby efficaciously clean heavily soiled areas of the garment. The cleaning action of ultrasonic energy is mainly due to the phenomenon of cavitation which is the nucleation, growth and collapse of small gas or vapor bubbles inside the cleaning liquid and near the surface to be cleaned. This is responsible for laundry process intensification by enhancement in mass transfer in textiles. The washing process parameters were optimized for ultrasonic washing in terms of type and concentration of detergent, time and temperature. Effect of this optimized ultrasonic washing method on fabric properties as well as appearance was studied and compared to conventional washing method with reference to repeated soiling and washing. To meet the specific requirement of cleaning highly soiled apparel, factors affecting system efficiency were studied.