Aerosol is a word that many people are familiar with. In many countries some items described commonly as aerosols have been banned as they themselves emit what is really the aerosol. The most technical definition of an aerosol is very similar to that of colloid, a suspension of particles in a fluid (normally air). Aerosols are notorious for their ability to rise into the upper atmosphere and interfere with incoming light from the Sun. It is for this reason, as well as chemical reasons related to chlorine’s catalytic abilities, that some man made aerosols have been made illegal. Of course not all of these particles necessarily have to come from a human source and even if they do they can be more advanced than simple molecules. Organic aerosols have their role to play as well with a great number of aerosols falling into the organic category.
It is a well known fact that materials acquire completely new properties when they are reduced to the nanoscale. Some notable examples include nanoparticles of silver gaining antibacterial properties; zinc oxide nanoparticles being able to absorb ultraviolet light, a property not seen in the bulk zinc oxide; and gold nanoparticles having an absorption band which turns them red (although citation may be needed as I can’t remember where I learnt this fact). Many of these properties derive from the fact that on a nanoscale the surface to volume of these particles is such an extreme with a corresponding higher surface energy (easier to stick to things). Of course the shape of nanoparticles is very important as this one of the main ways of changing the surface area to volume ratio.
A lot of focus has been given, and for good reason, towards understanding how individual atoms arrange physically in a space (not outer space but a space) to form a molecule. Many mechanisms have been proposed and many experiments done with the result that our quantitative knowledge about how molecules arrange is quite high. A place where we know no where near as much, would be the topic of how colloidal systems (solutions but with the solute being formed from much larger particles up to 1000 nm in diamter) manage to arrange to create useful materials.
Activated carbon is just the fancy way of talking about carbon which has been designed for purification. Carbon is quite good at adsorbing various chemicals onto it and so in order to optimise this feature we want the carbon to have the greatest surface area possible to let more material stick to it. Normally produced by thermal decomposition under controlled conditions the result is a piece of carbon riddles with pores and networks which maximise the surface area to the point that one gram of activated carbon could easily have 4,000 m2 of surface area. This optimises it for activities such as cleaning drinking water.
Transition metals are defined as any metal with an incomplete d-subshell. In other words one particular electron layer isn’t quite complete which opens a wide range of properties granted by variable electron configurations mostly focused on in chemistry through the three Cs of catalyst, colour and complex. For physics we love looking at the properties of transition metal oxides due to an increased stability which makes working with them easier. The cuprates, all the metal oxides containing copper, are particularly interesting as they have shown superconductivity and other electronic properties. Of course when we want to study what gives cuprates their properties it is best to study something very similar in many ways but with one clear distinct difference.
It is a common concern of the day that the world is running out of oil. Although partly this worry is caused by the oil producing countries not wishing to overextract oil as this would significantly lower the price and therefore the income they rely on there are still genuine supply concerns out there. Petroleum reservoirs are subterranean pits full of crude oil and are considered the most common source of our oil. It is can be considered worrying, therefore, when we can only extract 30% of the oil contained on average from any give reservoir. Apparently an extraction of just 50% or 60% is considered exceptionally lucky. To aid this, new technology is constantly being developed to assist the oil industry in their extraction plans.
Trying to produce metallic and metallic oxide nanoparticles is a challenge. To do so in expensive, laborious, time consuming, produces hazardous waste and after all that the product may not even be uniform enough for use. Clean methods for producing nanoparticles are passed off onto biological production methods. If bacteria, fungi or algae could be convinced to produce the nanoparticles it would circumvent some of the issues or we can simply remove whatever enzyme allows them to perform the feat and create the nanoparticles extracellulary. Although some metallic nanoparticles are antibiotic there has been success when using cyanobacteria. Unfortunately very little work has been done on the production of noble metals like gold, platinum and silver.