Solid-Oil Separation of Coal Tar Residue to Reduce Polycyclic Aromatic Hydrocarbons Via Microwave-Assisted Extraction

Coal tar residue (CTR) is acknowledged as hazardous industrial wastes with high contents of carbon and toxic polycyclic aromatic hydrocarbons (PAHs). Separating residue and tar to remove the contents of PAHs in CTR via microwave-assisted extraction. Influences of solvent type, solvent addition amount, radiation temperature, and radiation time were evaluated. Furthermore, the possible resource utilization pathways of extracted residue (MCTR) and extracted coal tar (MCT) under optimized experimental conditions were discussed. Extreme extraction performance in the solvent with cyclic structure was attained, and an enhancement in extraction efficiency was achieved in elevated solvent addition amount, radiation temperature, or radiation time in a certain range. The most excellent extraction efficiency of CTR (28.70%) and reduction efficiency of 16 priority control PAHs (92.82%) was achieved under optimized microwave-assisted extraction conditions (benzene was used as the extractant, the solvent-solid ratio was 5:1 mL/g, radiation temperature was 75°C, and radiation time was 10 min). MCTR was a promising raw material for the production of carbon material and solid fuels. In addition, MCT was a commercially valuable feedstock to extract organic chemicals (naphthalene, phenanthrene, and acenaphthylene) and an excellent precursor to synthesize functional carbon materials