17:15 〜 19:15
[HCG19-P03] Elution of plasticizers from plastic products in water and sediment slurry
Plastic pollution is one of the most serious environmental problems. Plasticizer is one of plastic additive that gives plastic products flexibility and facilitates processing. PVC products contain plasticizers at a ratio of about 10~80 %. Since plasticizers are not chemically bound to plastic products, it is said that plasticizers are leached from plastic products in water. Previous studies modeling plasticizer leaching under different aquatic environmental conditions (temperature, agitation, salinity, pH) have reported that plasticizer leaching is dependent on environmental conditions. However, the amount of plasticizer leached from plastic products in an aqueous environment not only depends on environmental conditions, but may also depend on the surface condition of the plastic product. Plastic products discharged into aquatic environment are likely to have their surface condition altered by sunlight exposure and collisions with stones and sand. Damaged plastic products have a larger surface area, which may allow more plasticizers to leach from the surface. In this study, we reproduced in the laboratory how plastic products are damaged by stones and sand in an aqueous environment, observed the surface condition of plastic products, and quantified the amount of plasticizer eluted into the water. The plasticizers targeted were DEHP (Diethylhexyl phthalate), DIBA (Diisobutyl adipate), ATBC (Acetyl tributyl citrate), DEHA (Di-(2-ethylhexyl) adipate), DEHS (Di-(2-ethylhexyl) sebacate) and TOTM (Trioctyl trimellitate).
A pot mill was used for the experiment. 10 g of PVC products cut into 1 cm × 1 cm pieces, dacites (2-4 mm) collected from the Unzen volcano, and 400 mL of ultrapure water were placed in the mill and rotated 48 h at a speed of 0.94 m/min. The temperature was 24 ℃. PVC product pieces and water in the mill were collected over time. PVC product pieces were sputtered with gold on the surface and observed with a scanning electron microscope. The water sample was centrifuged to separate water and particles, and plasticizers in the supernatant was extracted and concentrated using an Oasis Max Plus Short cartridge. The concentration of plasticizers in concentrated samples was quantified by LC/MS (Liquid Chromatography / Mass Spectrometry). The analysis of plasticizer concentration in water was repeated three times by processing three water samples taken at each time point. The experiment was conducted using a malleable PVC balloon. On the surface of the product, craters with a long diameter of about 30 µm were observed. DEHP, ATBC, and DEHA were detected in water samples at 0.9 µg/L~5.1 µg/L. Concentrations of DEHP and ATBC increased in water over 360 minutes after the start of the experiment. The concentration of DEHA in water reached 1.6 µg/L at 2 hours after the start of the experiment and then showed a decreasing trend until 480 minutes. The amount of plasticizer contained in different PVC products varies, and the surface structure of PVC products is expected to vary depending on the hardness of the product. Therefore, the shape of the scratches caused by damage by the particles and the amount of plasticizer eluted from them are also expected to vary among the products.
A pot mill was used for the experiment. 10 g of PVC products cut into 1 cm × 1 cm pieces, dacites (2-4 mm) collected from the Unzen volcano, and 400 mL of ultrapure water were placed in the mill and rotated 48 h at a speed of 0.94 m/min. The temperature was 24 ℃. PVC product pieces and water in the mill were collected over time. PVC product pieces were sputtered with gold on the surface and observed with a scanning electron microscope. The water sample was centrifuged to separate water and particles, and plasticizers in the supernatant was extracted and concentrated using an Oasis Max Plus Short cartridge. The concentration of plasticizers in concentrated samples was quantified by LC/MS (Liquid Chromatography / Mass Spectrometry). The analysis of plasticizer concentration in water was repeated three times by processing three water samples taken at each time point. The experiment was conducted using a malleable PVC balloon. On the surface of the product, craters with a long diameter of about 30 µm were observed. DEHP, ATBC, and DEHA were detected in water samples at 0.9 µg/L~5.1 µg/L. Concentrations of DEHP and ATBC increased in water over 360 minutes after the start of the experiment. The concentration of DEHA in water reached 1.6 µg/L at 2 hours after the start of the experiment and then showed a decreasing trend until 480 minutes. The amount of plasticizer contained in different PVC products varies, and the surface structure of PVC products is expected to vary depending on the hardness of the product. Therefore, the shape of the scratches caused by damage by the particles and the amount of plasticizer eluted from them are also expected to vary among the products.