Yoichi Kodera

Global styrene oligomers monitoring as new chemical contamination from polystyrene plastic marine pollution

Polystyrene (PS) plastic marine pollution is an environmental concern. However, a reliable and objective assessment of the scope of this problem, which can lead to persistent organic contaminants, has yet to be performed. Here, we show that anthropogenic styrene oligomers (SOs), a possible indicator of PS pollution in the ocean, are found globally at concentrations that are higher than those expected based on the stability of PS. SOs appear to persist to varying degrees in the seawater and sand samples collected from beaches around the world. The most persistent forms are styrene monomer, styrene dimer, and styrene trimer. Sand samples from beaches, which are commonly recreation sites, are particularly polluted with these high SOs concentrations. This finding is of interest from both scientific and public perspectives because SOs may pose potential long-term risks to the environment in combination with other endocrine disrupting chemicals. From SOs monitoring results, this study proposes a flow diagram for SOs leaching from PS cycle. Using this flow diagram, we conclude that SOs are global contaminants in sandy beaches around the world due to their broad spatial distribution.

New analytical method for the determination of styrene oligomers formed from polystyrene decomposition and its application at the coastlines of the North-West Pacific ocean.

The pollution caused by plastic debris is an environmental problem with increasing concern in the oceans. Among the plastic polymers, polystyrene (PS) is one of the most problematic plastics due to the direct public health risk associated with their dispersion, as well as the numerous adverse environmental impacts which arise both directly from the plastics and from their degradation products. Little is known about their potential distribution characteristics throughout the oceans. For the first time, we report here on the regional distribution of styrene monomer (SM), styrene dimers (SD; 2,4-diphenyl-1-butene, SD1; 1,3-diphenyl propane, SD2), and styrene trimer (2,4,6-triphenyl-1-hexene: ST1), as products of PS decomposition determined from samples of sand and seawater from the shorelines of the North-West Pacific ocean. In order to quantitatively determine SM, SD (=SD1+SD2), and ST1, a new analytical method was developed. The detection limit was 3.3 μg L(-1), based on a signal-to-noise ratio of three, which was well-suited to quantify levels of SM, SD, and ST1 in samples. Surprisingly, the concentrations of SM, SD, and ST1 in sand samples from the shorelines were consistently greater than those in seawater samples from the same location. The results of this study suggest that SM, SD, and ST1 can be widely dispersed throughout the North-West Pacific oceans.

Novel Method for Polystyrene Reactions at Low Temperature

Thermal decomposition reactions of polystyrene using a new heating medium were carried out by a batch system at 190∼280 °C to clarify the manner in which decomposition is initiated. Polystyrene obtained from a commercial source and low molecular weight compounds obtained from the thermal decomposition were analyzed by GC, GPC, IR,13C-NMR and GC-MS. The main chain underwent virtually no change by heat application. Polystyrene underwent decomposition below its molding temperature and the major decomposition products were 2,4,6-triphenyl-1-hexene (trimer), 2,4-diphenyl-1-butene (dimer) and styrene (monomer). Ethylbenzene, propylbenzene, naphthalene, benzaldehyde, biphenyl and 1,3-diphenylpropane were detected as minor products. This paper presents a new method for examining the decomposition of polystyrene at low temperature into volatile low molecular weight compounds.

Methanol-mediated extraction for coal liquid (2) — the effect of phase separation caused by methanol on naphtha fraction derived from Wyoming coal

Abstract Methanol-mediated extraction, which the authors have developed, was conducted on the naphtha fraction derived from Wyoming coal. When 0.4–1.5 times methanol was added to the feed oil, the mixture formed a two-phase system. The extraction yield of phenol ranged from 86.3% to 99.2% and that of oil fraction ranged from 65.5% to 91.0%. This indicates that the extraction of phenol by methanol only was ineffective. Two extraction methods, extraction with water regardless of the presence of phase separation (method A), and that after separating the formed phase (method B), were conducted to compare the effect of phase separation on the extraction yield and selectivity of phenol. They had no significant differences between two extraction methods. From these results, we concluded that method A is applicable even if phase separation may occur by adding methanol.

Low-Temperature Decomposition of Epoxy Resin

We report a new method using a heating medium for the thermal decomposition of epoxy resin (EP) at temperatures ranging from 50 to 200°C. EP decomposition also occurred below 50°C during a 6-day period to generate bisphenol A (BPA) at concentrations as high as 5 ppm. When polyethylene glycol was used as a heating medium, we determined the kinetics of the EP decomposition at low temperature. We determined the apparent activation energy of the overall decomposition to be 40.8 kJ/mol and the frequency factor to be 2.3 × 103 by monitoring the rate of BPA formation. Thus, EP is clearly unstable upon the application of heat.