polypropylene (Hidalgo-Ruz et al. 2012). In the density separation, sodium chloride
is present. The wet peroxide oxidation mixture is added to isolate the plastic debris
by the process of floatation. Density separator helps to separate the denser
undigested mineral components from the floating solids, by using a custom
0.3 mm filter. The plastic material, after separation, is then weighed to calculate
the microplastic concentration. To determine the weight of the separating material,
the gravimetric analysis can be used.
For chemical method, the plastic waste in the sample is collected as suspended
particles in water. These plastic wastes can be hard plastics and soft plastics like
foam, sheets, fibers, lines, and films. Solids can be filtered using 0.335 mm surface
sampling net to collect the material of suitable sizes. The separated material is then
dried to identify the solid mass, and the microscopic examination is performed with
the stereomicroscope (normally with magnification of 40X). Many common plastics
can be determined using this technique as a preliminary identification including
polyvinylchloride, polyethylene, polystyrene, and polypropylene. The type of
microplastics examined normally are in the range 0.3–5 mm, as illustrated in
Fig. 2.10 (Nudo 2017). The wet peroxide oxidation is carried out on the dried
sample, in the presence of Fe(II) catalyst, to digest the organic matter. There will
be no change to the plastic debris, which is collected and analyzed. The physical and
chemical methods are simple and easy to execute, but the major limitations are that
they can be time consuming and a lot more samples may be wasted than is necessary,
whilst the accuracy of the interpretation may be compromised. Advanced technique
is a necessity to yield better and accurate analyses, in a shorter period of time (Lehner
et al. 2019).
2.2.2 Advanced Instruments
Raman spectroscopy has been used to identify microplastics in microfibers.
The monochromatic laser is applied as a source of light, where the sample is
illuminated at 500 and 800 nm wavelength. The light interacts with the sample
molecules and atoms (low-frequency interactions) and is backscattered, resulting in
the frequency differences as compared to the incident light. This is called Raman
shift, which is easily identified, and generates the Raman spectra. The large
microplastic polymer spectra can be easily identified by comparing with the reference one, called “surface technique.” When Raman spectroscopy is coupled to the
microscopy, the particle size of few micrometers can also be determined (i.e., below
1 μm) (Cole et al. 2015; Löder and Gerdts 2015).
Microplastics from different packaging released into mineral water have been
analyzed by micro-Raman spectroscopy. The spectra obtained from the blue nitrile
gloves, halogen blue, and polypropylene blue bottle cap exhibit almost the same
spectra. The main polymers identified are polyethylene terephthalate, polyethylene,
polystyrene, and polypropylene. Some of these particles also decompose and disappear due to the high-energy laser. The plastic particles are present at different
2 Identification and Remediation of Plastics as Water Contaminant
65
is present. The wet peroxide oxidation mixture is added to isolate the plastic debris
by the process of floatation. Density separator helps to separate the denser
undigested mineral components from the floating solids, by using a custom
0.3 mm filter. The plastic material, after separation, is then weighed to calculate
the microplastic concentration. To determine the weight of the separating material,
the gravimetric analysis can be used.
For chemical method, the plastic waste in the sample is collected as suspended
particles in water. These plastic wastes can be hard plastics and soft plastics like
foam, sheets, fibers, lines, and films. Solids can be filtered using 0.335 mm surface
sampling net to collect the material of suitable sizes. The separated material is then
dried to identify the solid mass, and the microscopic examination is performed with
the stereomicroscope (normally with magnification of 40X). Many common plastics
can be determined using this technique as a preliminary identification including
polyvinylchloride, polyethylene, polystyrene, and polypropylene. The type of
microplastics examined normally are in the range 0.3–5 mm, as illustrated in
Fig. 2.10 (Nudo 2017). The wet peroxide oxidation is carried out on the dried
sample, in the presence of Fe(II) catalyst, to digest the organic matter. There will
be no change to the plastic debris, which is collected and analyzed. The physical and
chemical methods are simple and easy to execute, but the major limitations are that
they can be time consuming and a lot more samples may be wasted than is necessary,
whilst the accuracy of the interpretation may be compromised. Advanced technique
is a necessity to yield better and accurate analyses, in a shorter period of time (Lehner
et al. 2019).
2.2.2 Advanced Instruments
Raman spectroscopy has been used to identify microplastics in microfibers.
The monochromatic laser is applied as a source of light, where the sample is
illuminated at 500 and 800 nm wavelength. The light interacts with the sample
molecules and atoms (low-frequency interactions) and is backscattered, resulting in
the frequency differences as compared to the incident light. This is called Raman
shift, which is easily identified, and generates the Raman spectra. The large
microplastic polymer spectra can be easily identified by comparing with the reference one, called “surface technique.” When Raman spectroscopy is coupled to the
microscopy, the particle size of few micrometers can also be determined (i.e., below
1 μm) (Cole et al. 2015; Löder and Gerdts 2015).
Microplastics from different packaging released into mineral water have been
analyzed by micro-Raman spectroscopy. The spectra obtained from the blue nitrile
gloves, halogen blue, and polypropylene blue bottle cap exhibit almost the same
spectra. The main polymers identified are polyethylene terephthalate, polyethylene,
polystyrene, and polypropylene. Some of these particles also decompose and disappear due to the high-energy laser. The plastic particles are present at different
2 Identification and Remediation of Plastics as Water Contaminant
65