Low Temperature Decomposition of Polystyrene

Abstract

Styrene oligomers (SOs), of styrene (styrene monomer, SM), 1,3-diphenylpropane (styrene dimer, SD1), 2,4-diphenyl-1-butene (styrene dimer, SD2) and 2,4,6-triphenyl-1-hexene (styrene trimer, ST), had been detected in the natural environments far from industrial area. To confirm SOs formation through thermal decomposition of polystyrene (PS) wastes in the nature, purified polystyrene (SO-free PS) has been shown to decompose at 30 to 150 °C. The SO ratio of SM:SD:ST was about 1:1:5 with ST as the main product. Mass spectrometry with selected ion monitoring was used for the quantitative analysis of the trace amounts of SOs. The rate of PS decomposition was obtained as k ( year − 1 ) = 5.177 e x p ( − 5029 / T ( K ) ) based on the amount of ST. Decomposition kinetics indicated that not only does drifting lump PS break up into micro/nano pieces in the ocean, but that it also subsequently undergoes degradation into basic structure units SO. According to the simulation at 30 °C, the amounts of SOs in the ocean will be over 400 MT in 2050.

Waste Polystyrene Degradation in the World Oceans: Newly identified sources of Contamination

“…The amount of waste PS in ow in oceans from 1950 to 2015 has been estimated as 1.5 × 10 7 MT, based on the assumption PS constitutes 7 % total global plastic production (4.8 × 10 8 MT) 2 and that 3% of this plastic ow into the world's oceans 15 and SOs (mixture of styrene monomer: SM, 2,4-diphenyl-1-butene:styrene dimer, SD and 2,4,6-triphenyl-1-hexene:styrene trimer, ST) were detected. 10 SM has been shown a breakdown product formed by cinnamon mold ora and possibly may be present in oceans as a single contaminant. 16 But SOs with constant composition ratio (puri ed PS decomposition, SM1: SD1: ST5 and eld survey in this study, SM1: SD1: ST8) is not naturally present in ocean.…”

“…10,17 Using 2.5 L water and 5.0 g sand dichloromethane extracts, SOs were analyzed in detail by Gas Chromatograph equipped with Mass Spectrometry (GC/MS). [10][11][12][13][14] Mean SO value from coastal surveys worldwide were found to be 1613.4 µg kg -1 for sand samples and 2.7 µg L -1 for water samples. SO contamination of sand was 600 times higher than that of water.…”

Waste Polystyrene Degradation in the World Oceans: Newly identified sources of Contamination

“…10,17 Using 2.5 L water and 5.0 g sand dichloromethane extracts, SOs were analyzed in detail by Gas Chromatograph equipped with Mass Spectrometry (GC/MS). [10][11][12][13][14] Mean SO value from coastal surveys worldwide were found to be 1613.4 µg kg -1 for sand samples and 2.7 µg L -1 for water samples. SO contamination of sand was 600 times higher than that of water.…”

“…Based on SO-free PS decomposition, one MT of purified PS was found to degrade at a rate of 0.3g per year at 30 °C, at an activation energy of 42.0 kJ mol -1 . 10,17 The careful decomposition of other thermoplastics at natural temperature range kinetically are generate into the monomers: the heat resistant plastics PC and EPX22 generate BPA, PET and PVC generate PAE and polyurethane (PU) generate diisocyanate.…”

“…Simulation results at PS degradation at 30°C indicated the total amount of degraded PS in oceans will come to 90 MT by 2015 (t = 65 year), this amount in excess of 400 MT by 2050 (t = 100 year). 10 On the other hand, the amounts of floating/drifting PS [2] are estimated based on SOs surveys [3] and inflow [1] into oceans throughout the world. Using SO values of 0.1 μg L -1 which may reflect the sedimentation (deep) and 0.2 μg L -1 may reflect the drifting (surface) and total water volume in oceans' of 1.4 × L, generated SOs was calculated as 1.4 to 2.8 × 9 total 4.2 × 9 MT into water columns of oceans between to 2015(Supplementary Information Section II).…”