Removal of benzopyrene from coal tar asphalt by chemical method

For the friendly environmental application of coal tar pitch, the benzoic acid, polyethylene glycol, solid coumarone resin (S) or liquid coumarone resin (L) were selected as a modifier to lower the content of harmful benzopyrene in coal tar pitch by chemical reaction in a tube furnace. The benzopyrene content was detected by an ultraviolet-visible spectrophotometer, and the influence of reaction temperature, reaction time, modifier contents and catalyst types on the benzopyrene content was investigated. The results show that the technical condition has an intimate relationship with the decrease of benzopyrene content owing to the electrophilic substitutive reaction at the existence of acidic catalyst. All modifiers tested have obvious effects on the decrease of benzopyrene content. Under the optimum conditions, the removal rates of benzopyrene by different additives decrease in proper sequence of liquid coumarone resin, polyethylene glycol, benzoic acid and solid coumarone resin. The highest benzopyrene removal rate of 73.0% is obtained by using liquid coumarone resin, showing a promising application prospect.