Study on distribution features of polycyclic aromatic hydrocarbons in bituminous

The release of polycyclic aromatic hydrocarbons(PAHs)from unburnt and transported coal may cause negative impacts on human health and the environment.In order to understand the distribution of PAHs in different rank bituminous and provide the basic data for the efficient and clean utilization of coal，the 16 polycyclic aromatic hydrocarbons(PAHs)priority controlled by U.S.Environmental Protection Agency(USEPA)from Yunnan Fuyuan bituminous were determinated by microwave assisted extraction coupled with gas chromatography-mass spectrometry(GC-MS).The optimum conditions for extraction, such as extraction solvent, solvent volume and temperature of extraction were studied in detail, and the determination parameters of PAHs by GC-MS were optimized too.The relationship between PAHs distribution and coal type and coal quality parameters were discussed.The results showed that the optimum extraction conditions were as follows: carbon disulfide(CS2)and dichloromethane(CH2Cl2)mixed solvent(volume ratio was 1∶1), solvent volume was 20 mL, extraction temperature was 110 ℃.After being separated by column chromatography and concentrated, the qualitative and quantitative analysis of PAHs in coal could be realized by the combination of GC-MS full scan mode and selective ion scanning mode.PAHs in seven kinds of raw coal were mainly three ring, four ring and five ring aromatic hydrocarbons, among which five ring aromatic hydrocarbons were the most.With the increase of carbon content, the total content of PAHs in bituminous first increased and then decreased.When the carbon content was 81.32%, the total content of PAHs reached the maximum of 36.77 mg/kg.With the increase of the ratio of H/C and O/C, the total content of PAHs first increased and then decreased.When the molar ratio of H/C and O/C was 0.347 and 0.069, the total amount of PAHs was the highest.