Surface Properties of Coal
Coal is a combustible sedimentary rock composed mostly of combustible material known as carbon. It is mostly naturally occurring with some portions of it being manufactured by humans. As the major source of energy in the world, coal is used to generate electricity, make steel and manufacture cement among many other uses. Coal has many advantages over traditional fossil fuels such as oil and gas for instance, when it comes to production and storage, as it’s easier to produce, store and is available in a much larger quantities compared to other fossil fuels. Despite its advantages, studies show that coal has certain repercussions on the environment, such as air pollution and global warming due to its release of certain dangerous vapours and emissions.
In order to prevent these impacts, it is essential to understand the nature of coal and its physical characteristics such as its surface properties. Surface properties of coal refer to those features which are involved in the interaction between coal and other surfaces. These properties allow us to compare the behavior of different types of coal, as the surface properties vary according to the type and size of the coal. For instance, the texture or roughness of the coal surface plays an important role in how the coal responds to different chemicals and how it is affected by other solids.
The surface properties of coal are further classified according to the kind of coal being studied. Brown coal, for example, consists of small particles which can easily be broken down by mechanical means and is therefore less porous, meaning that it does not react to various chemicals as much as the other types of coal. Anthracite coal, on the other hand, is a compact and hard form of coal which is rich in carbon and is least reactive. Bituminous coal, meanwhile, is a more porous type of coal with a higher reactivity level due to its larger surface area. The reactivity of coal is determined by its structure and surface properties, which is why it is important to understand the different forms of coal in order to make the most effective use of the fuel.
The surface properties of coal are primarily studied by means of techniques such as scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). These techniques allow scholars to study the shape and size of the particles, as well as their composition, by analysing the electron emission and energy spectrum that each particle emits as it is under the microscope.
Numerous other techniques such as surface area analysis, porosimetry, surface tension and leaching tests, are used to study the surface properties of coal in further detail. Surface area analysers are used to measure the total surface area of coal particles, while porosimetry analyses the size and distribution of pores within the coal. These measurements can be used to determine the reactivity of the coal particles, as pores can be a major factor in its reactivity. Surface tension and leaching tests can be used to measure the wettability, capillary properties and leaching properties of the coal.
In order to make the most effective use of coal and to minimise its environmental impact, it is essential that we understand and analyse the surface properties of coal. Various physical and chemical techniques, as described above, are used to study the surface properties of coal and their differences between different types of coal. This knowledge can be used to identify the best use of coal and to design the most applicable technologies to limit its environmental impact.
