The increase in world production of plastics that we see today is linked to the packaging, construction, automotive, electrical and electronics industries, among others. Giving rise to microplastics, an anthropogenic pollutant with great impact in recent years.
An issue that has been becoming important worldwide is the presence of microplastics in marine ecosystems , freshwater, even industrially with water treatments for re-use and how they directly affect our health.
As we mentioned at the beginning, microplastics (small pieces of plastic with diameters that vary from a few micrometers to a couple of millimeters) come from plastic items that we use and that we do not recycle or incinerate after use, ending in landfills, rivers and oceans , where they gradually break down into smaller and smaller particles. Once released, they can be ingested by marine species that eventually reach humans causing a biological impact due to the intake of these microplastics.
Nowadays there are few works focused on the quantification of microplastics in wastewater , however, these few works have shown that wastewater treatment stations , together with the urban runoff process, are the main routes of emission of this pollutant to the environment . It is for all this that we must focus on examining, eliminating and releasing the microplastics of each of the wastewater treatment plants, as well as identifying their source of origin.
Today there are several methods for the identification of polymers , among which FTIR spectroscopy and Raman spectroscopy are the most commonly used.
The FTIR spectroscopy and Raman techniques are complementary and their accuracy is similar. They are easy to use and allow fast and accurate results since plastic polymers have highly specific infrared (IR) spectra with different band patterns, which makes IR spectroscopy an optimal technique for the identification of microplastics. The basic principle of the energy of IR radiation is that it excites a specific molecular vibration when it interacts with the sample, which allows the measurement of characteristic IR spectra. In the same way, FTIR spectroscopy can provide additional information on particles, such as oxidation intensity and degradation level.
While the ATR-FTIR is suitable for the chemical identification of larger particles (> 0.5 mm), the ATR-FTIR micro spectroscopy can provide information on the chemical structure of particles smaller than 0.5 mm, since it combines the function of a Microscope and an infrared spectrometer.
We must bear in mind that when analyzing the microplastics we must properly treat the samples, for example, the separation of microplastics through visual and chemical identification of selected particles are processes that require time, precision and therefore costs.