The Nanotechnology in Environment
At present we can find in the market applications of nanotechnologies for the environment, such as recovery processes, water treatment, and ecological packaging and oil absorbers.
Devices for Water Treatment
Water purification using nanotechnologies is achieved by using nanomaterials such as carbon nanotubes and alumina fibers for Nano-filtration. The main advantage of using Nano-filters instead of conventional systems is that less pressure is required to pass water through the filter: although the pores are smaller, the interior of the nanotubes is smoother and water can flow more ease. In addition, they are more efficient, have incredibly large areas and can be cleaned more easily.
Nano-filters can remove sediment, chemical waste, charged particles, bacteria and other pathogens, such as viruses. They can also remove traces of toxic substances, such as arsenic, and impurities in the form of viscous liquids, such as oil.
Oil leaks in marine areas are very worrying and have serious consequences for the environment. A new approach is being investigated through the use of aerogels (a nanomaterial), modified with molecules that repel the water, to improve the interaction with the petroleum. These aerogels have a very wide surface so that they can absorb sixteen times their weight. They act like a sponge: when the fossil fuel has been absorbed, the “oil-soaked sponge” can be easily removed.
The widespread use of plastic packaging has a negative ecological impact. It is necessary to have ecological packaging materials. The current solutions use some natural polymers called biopolymers; however, many of them have numerous limitations, for example, low moisture barrier properties and poor mechanical properties. A possible solution would be to include nanoparticles in the biopolymer to create a “bionanocomposite”, with better mechanical properties and barrier, and also completely degradable.
There are some doubts regarding the use of nanomaterials in the treatment of water and soil: when they have been dispersed in a contaminated place, will the nanoparticles be mobile enough to be absorbed by plants or animals and cause harmful effects in them? Biodegradable nanoparticles (such as those used in biodegradable plastics) are probably less problematic; in spite of this, it is necessary to investigate these aspects of security and this is the objective of many international research programs.
These concerns pertain to the wider field of environmental impact assessments of nanoparticle use, which includes both risk assessments and life cycle analysis, in order to understand short- and long-term effects.