Beating Worthington jet by surfactants

Worthington jet generated by a drop impacting onto an aqueous pool will make the secondary droplets and aerosols splash into the air, causing air pollution, bodily injury, pathogen transmission, and other hazards. Previous studies inhibited Worthington jet by significantly increasing viscosity or reducing droplet impact velocity, which cannot be applied in most practical cases. Herein, we demonstrate that surfactant solutions of tiny concentrations can effectively inhibit the Worthington jet. The nonequilibrium surface adsorption of surfactants at the liquid-gas interface during the impact process produces a strong surface tension gradient, which weakens the energy of the rebound jet and inhibits the generation of secondary droplets. This convenient and efficient method for inhibiting the Worthington jet can be applied to eliminate the aerosol spread of pathogens and pollutants, as well as the damage and waste caused by liquid splashes.