The Application of Liquid Marbles in the Removal of Pollutants and Contaminants from the Environment and Within Industrial Processes
Lead Research Organisation:
Newcastle University
Department Name: Sch of Engineering
Abstract
This doctoral research will focus on liquid marbles and more specifically the way in which the particles coating the droplet dictate its abilities and size. It will try and answer the question; how can liquid marbles be used to remove pollutants from liquids? With the end objective being the formation of a liquid marble capable of removing plastic particles from water and. Several aims will be used, the first is how the morphology of the particles coating the droplet impacts the maximum marble size. Secondly, how do the particles used alter the rate at which vapour leaves the liquid marble. Both need to be answered before the final design of a plastic removal liquid marble can be achieved.
Plastic pollution is prevalent in all of the world's oceans and the use of filtration to remove nano particles is not possible. Therefore, a method to tackle this issue is becoming more necessary - liquid marbles could do this. The phenomena of liquid marbles have generated much interest in the past 20 years and are described as a completely non-wetting soft solid, with reduced adhesion to a solid surface. This occurs upon addition of hydrophobic particles which coat the liquid droplet, preventing contact between the internal liquid and the external surface. Numerous combinations of powders and liquids is possible, allowing for use in different environments.
I will be breaking this project into several areas. My preliminary research will examine how the critical size of a water liquid marble changes with different coatings. The existing literature on liquid marbles looks at a size range of 5-20uL with few instances of larger marbles, 1000uL, being formed. Little description about this relationship exists, with current literature focusing on liquid marbles as miniaturised reactors. It has been shown that the size and structure of particles have a key role in the lifetime of a liquid marble, but not on maximum marble size. Using a liquid marble with a large volume will allow for the capture of more plastic, meaning removal of the marble from the process will be less frequent. The second aim looks at the rate of vapour loss from the marble and its dependence on the particle. This is important for two reasons. Firstly, if a marble evaporates too quickly it will not retain its size, therefore, less pollutants are extracted. Secondly, liquid marbles containing an aqueous alcohol solution can self-propel on water due to the Marangoni effect, caused by a surface tension gradient between the two fluids. Harnessing this motion will be useful in positioning droplets quickly. The arrangement of the particles around the liquid will change based on the particles used, this means how closely packed the particles will differ, larger gaps between them should mean a higher evaporation rate. Understanding this behaviour will allow for management of vapour loss. Moreover, it is possible to coat the droplet in two particle types, coating in this manner could add directionality and control of the marbles.
I will then look into the mechanism of microplastic capture. The main driving force behind this project is the way in which microplastics move from water to oil when the two are in contact. This allows for the separation of plastic from water without requiring excessive energy input. The challenge lies in being able to easily remove the oil-plastic solution and is where liquid marbles will be beneficial. This section will be the most time intensive as lots of factors are to be considered. With the main question, is it better to form the marble before or after plastic uptake? The best type of liquid for plastic removal will be selected and the types of plastics to remove; it may be beneficial to target the most abundant. Once identified it will be easy to select the particles to coat with from previous investigations. The remaining factor that needs to be considered is then how the coating will hinder the movement of plastic into the marble.
Plastic pollution is prevalent in all of the world's oceans and the use of filtration to remove nano particles is not possible. Therefore, a method to tackle this issue is becoming more necessary - liquid marbles could do this. The phenomena of liquid marbles have generated much interest in the past 20 years and are described as a completely non-wetting soft solid, with reduced adhesion to a solid surface. This occurs upon addition of hydrophobic particles which coat the liquid droplet, preventing contact between the internal liquid and the external surface. Numerous combinations of powders and liquids is possible, allowing for use in different environments.
I will be breaking this project into several areas. My preliminary research will examine how the critical size of a water liquid marble changes with different coatings. The existing literature on liquid marbles looks at a size range of 5-20uL with few instances of larger marbles, 1000uL, being formed. Little description about this relationship exists, with current literature focusing on liquid marbles as miniaturised reactors. It has been shown that the size and structure of particles have a key role in the lifetime of a liquid marble, but not on maximum marble size. Using a liquid marble with a large volume will allow for the capture of more plastic, meaning removal of the marble from the process will be less frequent. The second aim looks at the rate of vapour loss from the marble and its dependence on the particle. This is important for two reasons. Firstly, if a marble evaporates too quickly it will not retain its size, therefore, less pollutants are extracted. Secondly, liquid marbles containing an aqueous alcohol solution can self-propel on water due to the Marangoni effect, caused by a surface tension gradient between the two fluids. Harnessing this motion will be useful in positioning droplets quickly. The arrangement of the particles around the liquid will change based on the particles used, this means how closely packed the particles will differ, larger gaps between them should mean a higher evaporation rate. Understanding this behaviour will allow for management of vapour loss. Moreover, it is possible to coat the droplet in two particle types, coating in this manner could add directionality and control of the marbles.
I will then look into the mechanism of microplastic capture. The main driving force behind this project is the way in which microplastics move from water to oil when the two are in contact. This allows for the separation of plastic from water without requiring excessive energy input. The challenge lies in being able to easily remove the oil-plastic solution and is where liquid marbles will be beneficial. This section will be the most time intensive as lots of factors are to be considered. With the main question, is it better to form the marble before or after plastic uptake? The best type of liquid for plastic removal will be selected and the types of plastics to remove; it may be beneficial to target the most abundant. Once identified it will be easy to select the particles to coat with from previous investigations. The remaining factor that needs to be considered is then how the coating will hinder the movement of plastic into the marble.