Sustainable removal of nano/microplastics in water by solar energy

Plastic pollution in water is of increasing scientific and public concern due to the increasing plastic production, slow degradation rate and low recycling efficiency. However, the present methods for the removal of plastic particles in water are either inefficient or expensive, which limit their wide application. In this work, we propose a new strategy for the efficient removal of plastic particles in water that is driven by solar energy. Sunlight was focused through a glass ball with high power density, which could induce convection and form a microbubble at the interface. The plastic particles were driven into the bubble by convection and subsequently fused in the microbubble, as the temperature in the bubble was much higher than that in the solution due to the significantly different densities. Such a hot microbubble acts as a 'furnace', which can collect and fuse plastic particles into large bulks in the microbubble, facilitating the sustainable removal of plastic particles in water without the use of any chemical or biological reagents or filters. Moreover, this method is quite simple and can effectively utilize free sunlight without requiring extra energy or causing secondary pollution, implying its promising application in dealing with plastic pollution in aquatic ecosystems.