Determination of boiling point distribution and speciation of organic chlorinated compounds in pyrolysis oil from waste plastics and tires.

The study employed gas chromatography coupled with triple quadrupole inductively coupled plasma mass spectrometry (GC-ICP-MS/MS) to determine the boiling point distribution of organic chlorinated compounds and quantify 58 organic chlorinated compounds in pyrolysis oil from waste plastics and tires. The method used helium as the collision gas, optimized collision gas flow rate, inlet temperature, and investigated interference from hydrocarbons, oxides and sulfides to ensure selectivity and sensitivity for chlorine detection. In the range of 1.0 mg/L to 50.0 mg/L, the calibration curves of 16 organic chlorinated compounds in n-hexane exhibited excellent linearity, with correlation coefficients above 0.999. The slope ratios of the calibration curves of the 16 chlorinated compounds versus tetrachloroethylene were in the range of 0.84 to 1.11, indicating that compound independent calibration (CIC) method could be employed. Through testing of organic chlorinated compounds in various pyrolysis oil matrices, this method showed excellent resistance to matrix interference. Based on the n-alkane boiling point/retention time calibration curve, the chlorine chromatogram was sliced into narrow cuts, using tetrachloroethylene in n-hexane as the external calibration reference, to determine the chlorine distribution across successive boiling range fractions. The chlorine content of real samples obtained by this method was consistent with organic chlorine content. The long duration chromatographic method was used to qualify and quantify 58 organic chlorinated compounds in pyrolysis oil from waste plastics and tires. The results showed that the chlorine distribution of waste plastic pyrolysis oils significantly differed from that in tire pyrolysis oils. The organic chlorinated compounds of waste plastic pyrolysis oils was concentrated in the gasoline fraction, with 1,2-dichloroethane making up over 37.9% of total organic chlorine. Conversely, organic chlorinated compounds in tire pyrolysis oils were primarily found in the diesel fraction, and most tire pyrolysis oils did not contain high levels of individual chlorinated compounds. The methods can be applied to the development and mechanistic study of high-value utilization processes for pyrolysis oils from waste plastics and tires.