We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Numerical simulations of bursting bubbles: effects of contamination on droplet ejection and micro- and nanoplastics transport
Summary
Scientists used computer simulations to study how tiny plastic particles get launched into the air when bubbles pop at water surfaces, like in oceans or wastewater treatment plants. They found that contaminants in the water change how bubbles burst and affect how many droplets containing microplastics are released into the air we breathe. This research helps us better understand how microplastics from polluted water can end up in the atmosphere and potentially impact human health through inhalation.
As air is entrained (e.g. surface wave breaking, waterfalls) or injected (e.g. wastewater aeration) into water, bubbles are formed and either dissolve or rise back to the surface, collapse, and eject droplets. These bubbles that burst at the water surface represent a key contribution to aerosol formation and facilitate the exchange of mass, momentum and energy between water bodies and the atmosphere with significant implications for weather and climate. In addition, environmental and industrial water bodies contain a large number of suspended materials, such as micro- and nanoplastics, pollutants and diverse microorganisms, which can be entrained in the ejected droplet and thereby pose major environmental and health risks.While recent numerical studies have focused primarily on clean interfaces, the contaminants present in natural and industrial settings affect both the bubble size distribution and droplet ejection mechanisms through Marangoni stresses. The present work aims to characterise drop ejection dynamics in the presence of contaminants, with a focus on Marangoni stresses that lower surface tension and rigidify the interface. Numerical simulations of bubbles bursting at a free surface are performed with the open source finite volume solver Basilisk. The mass and momentum conservation equations are solved on a Cartesian grid, using a Volume of Fluid method to capture the air-liquid interface while Adaptive Mesh Refinement allows to capture the jet dynamics. The effects of surface active agents or contaminants, often overlooked until recently in numerical simulations of bursting bubbles, are implemented and validated against experiments. Droplet ejection mechanism and the number of drops produced are analysed through regime maps spanning a wide range of Bond, Ohnesorge and Marangoni numbers, which characterise the bubble size, the fluid properties and the contamination effects. In the jetting regime, drops dynamics are characterised in terms of size, velocity, and maximum height. Initial results highlight the crucial damping effects of contaminants on capillary waves and the resulting jet during cavity collapse. The entrainment of micro- and nanoplastics is discussed as a function of particle sizes and concentration, providing insight into the coupling between interfacial physics and aerosol generation.
Sign in to start a discussion.
More Papers Like This
The rise and rupture of bubbles: applications to biofouling, microplastic pollution, and sea spray aerosols
Researchers studied how rising air bubbles in water collect microplastics and bacteria on their surfaces and transport them to the liquid surface, and how bubble bursting then launches these particles into the air as sea spray — with implications for both aquatic contamination and airborne microplastic exposure.
Examination of the ocean as a source for atmospheric microplastics
Researchers assessed whether the ocean can be a net source of atmospheric microplastics (rather than just a sink), finding evidence that bubble bursting and sea spray can eject plastic particles from ocean surface waters into the atmosphere.
Quantification of the Emission of Atmospheric Microplastics and Nanoplastics via Sea Spray
Researchers conducted lab experiments to measure how microplastics and nanoplastics in the ocean get launched into the atmosphere through sea spray bubbles. They found that plastic particles smaller than 10 micrometers can become airborne this way, with smaller and less dense particles being emitted more easily. This reveals an important but underappreciated pathway by which ocean plastic pollution can reach inland areas and be inhaled by people.
New insights into the role of marine plastic-gels in microplastic transfer from water to the atmosphere via bubble bursting
Researchers identified a three-step mechanism by which microplastics are transferred from ocean surface water to the atmosphere during bubble bursting, finding that marine gel particles play a critical role by concentrating MPs at the air-sea interface before aerosol ejection. The results help explain how MPs reach remote terrestrial environments through atmospheric deposition from the ocean.
Experimental evidence of plastic particles transfer at the water-air interface through bubble bursting
Experimental evidence showed that bubble bursting at the sea surface can transfer plastic particles from bulk water to sea spray aerosols, providing a mechanism for microplastics to be transported from ocean surface waters into the atmosphere.