Prediction of nanoplastics aggregation in wastewaters

Discarded plastic wastes are slowly degrading into smaller parts, namely microplastics, that can be easily transported to oceans by water streams. In vast, salty, and sunny environments, they degrade even faster and are subject to come back in the water network used for drinking or industrial water in the form of nearly indetectable objects: nanoplastics. Once in busy buffers such as wastewaters, nanoplastics will tend to aggregate to form tertiary microplastics formed of single or multiple types of plastics and potentially host other materials ranging from organics and metals to bacteria and viruses. Their nature, random shape, and various size are at the origin of nuclei merging together or with other objects. Two particles at a close distance from each other can either attract or repulse themselves depending on their nature and constitution. At very short distances, Van der Waals forces are predominant and a measure of them is given by the so-called Hamaker constant. We propose to predict this aggregation by estimating the Hamaker’s constant.