Solubility of a coal tar pitch and distribution of polycyclic aromatic hydrocarbons in soluble portion

In this study,the coal tar pitch (CTP) from a coking factory of Shanxi was extracted with nine organic sol- vents including petroleum ether,methanol and carbon disulfide under ultrasonic wave condition. Comparing the extract yield and solubility parameter of solvents,it could be found that the solvent with solubility parameter of 9 -10( cal /cm3 )1 / 2 have a good solubility for CTP. Polycyclic aromatic hydrocarbons (PAHs) in the extracts were quantitatively analyzed using gas chromatography ( GC). Furthermore,the extracts were examined by FTIR spectrometry,and the spectra were fitted,in order to investigate the dissolution characteristics of coal tar pitch in organic solvents. The results indicated that toxic PAHs except acenaphthylene preferentially monitored by Environmental Protection Agency (EPA) were detected in each extract. Moreover,the content of fluoranthene was the highest,and petroleum ether and hexane had a good extraction selectivity for fluoranthene,suggesting that pure fluoranthene may be obtained by next separa- tion. PAHs in each extract mainly consisted of highly carcinogenic PAHs with 4 -5 rings,such as benzopyrene and dibenzanthracene,and cyclohexane could extract these PAHs with high selectivity,indicating that cyclohexane could be used as the solvent for achieving the effective detoxification of CTP. According to the fitted peaks of the FTIR spec- tra,the aromaticity of each extract,and the condensed degrees of aromatic rings were compared,respectively,and it could be concluded that the carbon disulfide and toluene extracts have a high aromaticity and these aromatic rings have a high condensed degree,suggesting these extracts may be a good precursor for producing carbon materials.