The effect of the detergent on microfibre release during the washing process of polyester textiles

Microplastics are defined as plastic fragments with dimensions lower than 5 mm, which are gaining much attention due to their ubiquitous and possibly dangerous presence in marine environment, representing a threat for marine ecosystems, and potentially for humans. Although many studies warn about the quantity and danger of microplastic pollution, it is possible that the extent of the phenomenon has been greatly underestimated. Washing processes of synthetic fabrics have been lately identified as responsible for about 35% of primary microplastic release in oceans and seas, indeed, the number of microfibres released from a typical 2-2.5 kg wash load of synthetic fabrics was estimated to be ranged from 640,000 to 1,500,000 [1]. In such scenario, it is important to identify the causes of the release and to evaluate the role of washing program, detergent, and load. The aim of the present work is to evaluate the amount of microfibres released from polyester textiles during washing process, by varying the type of used detergent. For this aim, washing tests were performed on single T-shirt made of 100% polyester with a household washing machine, employing different liquid detergents. The obtained quantity of microfibres released during the washing of the T-shirt ranges from 401 +/- 17 to 437 +/- 35 mg per kg of washed fabric, that corresponds to an average number of microfibres released around 4,000,000. The obtained results allow to conclude that the washing of a single T-shirt releases a great amount of microfibres. This can be explained considering that the higher water ratio per washed fabric and the higher mechanical action due to the lower washing load, has a negative impact on the release improving fibres mobility.