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烟煤中多环芳烃分布特征研究

Study on distribution features of polycyclic aromatic hydrocarbons in bituminous

  • 摘要: 煤在不充分燃烧和运输过程中都会释放出多环芳烃,给人类健康和环境造成危害。为了解不同变质程度烟煤中多环芳烃的分布规律,为煤的清洁化利用提供基础资料,采用微波萃取技术提取了7种云南富源烟煤煤样中的可溶有机物,并利用气相色谱质谱联用仪(GC-MS)测定提取液中美国环境保护局(USEPA)优控的16种多环芳烃(PAHs)的含量,通过试验优化了萃取溶剂、溶质比、萃取温度等微波萃取条件和PAHs的GC-MS测定条件,并研究了PAHs的分布与煤种、煤质参数之间的关系。研究结果表明:在萃取溶剂为二硫化碳(CS2)和二氯甲烷(CH2Cl2),混合溶剂体积比1∶1,溶剂体积为20 mL,萃取温度为110 ℃条件下可获得理想的萃取效果。萃取物经柱层析分离、浓缩后,采用GC-MS的全扫描方式和选择离子扫描方式相结合的方法可以准确实现煤中多环芳烃的定性定量分析。7种原煤中PAHs分布均以3环、4环、5环芳烃为主,其中5环芳烃最多。随碳质量分数的增加,烟煤中PAHs总含量呈现先增加后降低趋势,当碳质量分数为81.32%时,PAHs总含量达到最大值36.77 mg/kg。随着H/C和O/C物质的量比的增加,PAHs总含量先增加后减小,在H/C物质的量比为0.347,O/C物质的量比为0.069时,PAHs总含量最高。

     

    Abstract: 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.

     

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