Identification and Elimination of Fluorinated Methylsiloxanes in Environmental Matrices near a Manufacturing Plant in Eastern China

Abstract

Fluorinated methylsiloxanes are modified methylsiloxanes and include tris(trifluoropropyl)trimethylcyclotrisiloxane (D3F) and tetrakis(trifluoropropyl)tetramethylcyclotetrasiloxane (D4F). Here, we report fluorinated methylsiloxanes (D3F and D4F) in surface water and sediment samples collected near a fluorinated methylsiloxane manufacturing plant in Weihai, China. The concentrations of D3F and D4F in surface water ranged from 3.29–291 ng/L and from 7.02–168 ng/L, respectively. The concentrations of D3F and D4F in sediment ranged from 11.8–5478 ng/g and from 17.2–6277 ng/g, respectively. In simulation experiment, the half-lives of D3F and D4F at different pH values (5.2, 6.4, 7.2, 8.3, and 9.2) varied from 80.6–154 h and from 267–533 h, respectively. CF3(CH2)2MeSi(OH)2 was identified as one of the main hydrolysis products of fluorinated methylsiloxanes. It was also detected in the river samples at concentrations of 72.1–182.9 ng/L. In addition, the slow rearrangement of D3F (spiked concentration = 500 ng/L) to D4F (concentration = 11.0–22.7 ng/L) was also found during 336h hydrolysis experiment.