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10.6 The Impact of Silicones on The Environment
10.6.1 Impact on Air, Soil and Water
A large number of studies have been carried out to measure the fate and effect of
silicones in the environment throughout their life cycle (Graiver et al. 2003). The
synthesis of PDMSs is strictly controlled and environment emissions from this
phase are very small. The environmental effects of silicones depend largely on the
physical form of the material and the method of disposal. PDMSs are used as the
component in consumer products, in many industrial processes. Solid and liquid
silicones enter the environment as a component of waste materials, such as air conditioners, domestic, municipal waste, shampoos, silicone antifoams, etc. Silicone is
also used as antiflatulents in pharmaceuticals (Schalau and Aliyar 2015). Most common silicones are very poorly soluble in water and are retained in mud that settles
quickly (Pellenbarg 1979; Watts et al. 1995). In small-scale field studies, Tolle et al.
(1995) showed that the application of sludge bound PDMSs to soil did not cause
adverse effects on crops growth. Lehmann et al. (1994) and Griessbach and Lehmann
(1999) also observed that high Mw PDMSs are too large to pass through the biological membrane of plants or animals. Extensive studies have shown that sewagesludge bound PDMSs degrade in soils contact with clay minerals (Lehmann et al.
1996). The clay acts as a catalyst to depolymerize the siloxanes backbone
(Griessbach and Lehmann 1999). The main degradation product of PDMSs is
dimethyldisilanol (Me 2 Si(OH) 2 ) (Lehmann et al. 1994). PDMS is even more
degraded in the soil via biodegradation (Lehmann et al. 1998) or evaporated into the
atmosphere via reaction with hydroxyl radicals (Lehmann et al. 1996). Due to the
chemical structure of silicone, it does not cause any depletion of the ozone layer or
nor does it contribute significantly to global warming (Verbiese 1993).
10.6.2 Recycling
Most silicones are easily disposed and recycled. Silicones elastomers are used as
fillers in new elastomers when ground. Depolymerized silicones in the presence of
a catalyst to give cyclic silicones (Weidauer et al. 2015). In this way, we can reduce
the amount of silicone polymer that is fed to the environment.
10.7 Conclusions
By virtue of its structure, the polymethylhydrosiloxane is most commonly used
because it exhibits unique properties, especially at the surface and the interface
levels. Polyethylhydrosiloxane imparts not only water repellent but also shows
10 Reactive Silicones as Multifacetic Materials
10.6 The Impact of Silicones on The Environment
10.6.1 Impact on Air, Soil and Water
A large number of studies have been carried out to measure the fate and effect of
silicones in the environment throughout their life cycle (Graiver et al. 2003). The
synthesis of PDMSs is strictly controlled and environment emissions from this
phase are very small. The environmental effects of silicones depend largely on the
physical form of the material and the method of disposal. PDMSs are used as the
component in consumer products, in many industrial processes. Solid and liquid
silicones enter the environment as a component of waste materials, such as air conditioners, domestic, municipal waste, shampoos, silicone antifoams, etc. Silicone is
also used as antiflatulents in pharmaceuticals (Schalau and Aliyar 2015). Most common silicones are very poorly soluble in water and are retained in mud that settles
quickly (Pellenbarg 1979; Watts et al. 1995). In small-scale field studies, Tolle et al.
(1995) showed that the application of sludge bound PDMSs to soil did not cause
adverse effects on crops growth. Lehmann et al. (1994) and Griessbach and Lehmann
(1999) also observed that high Mw PDMSs are too large to pass through the biological membrane of plants or animals. Extensive studies have shown that sewagesludge bound PDMSs degrade in soils contact with clay minerals (Lehmann et al.
1996). The clay acts as a catalyst to depolymerize the siloxanes backbone
(Griessbach and Lehmann 1999). The main degradation product of PDMSs is
dimethyldisilanol (Me 2 Si(OH) 2 ) (Lehmann et al. 1994). PDMS is even more
degraded in the soil via biodegradation (Lehmann et al. 1998) or evaporated into the
atmosphere via reaction with hydroxyl radicals (Lehmann et al. 1996). Due to the
chemical structure of silicone, it does not cause any depletion of the ozone layer or
nor does it contribute significantly to global warming (Verbiese 1993).
10.6.2 Recycling
Most silicones are easily disposed and recycled. Silicones elastomers are used as
fillers in new elastomers when ground. Depolymerized silicones in the presence of
a catalyst to give cyclic silicones (Weidauer et al. 2015). In this way, we can reduce
the amount of silicone polymer that is fed to the environment.
10.7 Conclusions
By virtue of its structure, the polymethylhydrosiloxane is most commonly used
because it exhibits unique properties, especially at the surface and the interface
levels. Polyethylhydrosiloxane imparts not only water repellent but also shows
10 Reactive Silicones as Multifacetic Materials