Preparation of Low Toxicity Pitches by Thermal Oxidative Condensation of Anthracene Oil

Abstract

This article describes a novel industrial procedure for producing new pitches of low toxicity from anthracene oil, a byproduct of coal tar distillation. The procedure involves oxidative treatment in order to polymerize and condense the anthracene oil components followed by thermal treatment and distillation in order to obtain a pitch with the desired parameters. This sequence (oxidative treatment/thermal treatment/distillation) was repeated four times under reaction conditions of increasing severity in four cycles of anthracene oil processing to obtain the four pitches. The pitches had similar characteristics to those of standard binder coal tar pitches (e.g., softening point and wetting capacity). Because of the inherent composition of the parent anthracene oil, the pitches were found to be totally free of solid particles, i.e., primary quinoline insolubles and metals. The gas chromatography and gas chromatography/mass spectroscopy results revealed a consecutive decrease in toxicity with successive cycles of anthracene oil processing. Thus, the benzo[a]pyrene content decreased from 11.2 mg/g for the pitch in cycle one to 1.5 mg/g for the pitch with four processing cycles. The carcinogenicity of the pitches, evaluated on the basis of benzo[a]pyrene toxic equivalency factors, also followed the same tendency. The final carcinogenity values are nearly all lower than those of standard binder coal tar pitches.

Sequential assessment via daphnia and zebrafish for systematic toxicity screening of heterogeneous substances

“…Most evaluation methods are based on an individual substance's toxicity rather than on a whole mixture of various substances (Abdelraheem et al, 2015;Backhaus and Faust, 2012;Buckley and Farraj, 2015;Herzog et al, 2013;Marcone et al, 2012;Nabeshi et al, 2011;Nazarenko et al, 2012;Rider et al, 2013). Pesticides for agriculture (Bussy et al, 2015;Jang et al, 2014b;Seiber et al, 2014), industrial products for consumers ( Alvarez et al, 2009;El-Didamony et al, 2013;Mastella et al, 2014;Misik et al, 2014), and by-products from the automobile and electronic industries (Feng et al, 2015;Snow et al, 2014) are introduced into ecosystems in mixture forms. Besides toxic effects caused by single substances, there are toxic effects caused by a culmination of heterogeneous substances that eventually affect people.…”

Reducing the carcinogenic impact of pitch processing

“…For eign researchers obtained a similar result in the ther mooxidation of the anthracene fraction of pitch by air. That fraction has a benz[a]pyrene content an order of magnitude smaller than for pitch obtained from the same anthracene fraction by thermal preparation [33].…”

Characterisation and feasibility as carbon fibre precursors of isotropic pitches derived from anthracene oil

“…Variations in pitch MW distributions are a consequence of the conditions during the thermal treatment/distillation step, which is used in pitch production to adjust the softening point. It is clear that this adjustment gives rise to complex changes in compositions [7].…”

“…Anthracene oil-derived pitches can be obtained by a multistep sequential procedure that involves oxidative thermal condensation of anthracene oil and subsequent thermal treatment/distillation to reach the desired softening point of the pitch [7]. This type of pitch exhibits a consistency of quality and has a chemical composition free from solid particles, i.e., primary quinoline insolubles (QIs) and metals, which is guaranteed by the distilling technology employed in anthracene oil production [7].…”

“…This type of pitch exhibits a consistency of quality and has a chemical composition free from solid particles, i.e., primary quinoline insolubles (QIs) and metals, which is guaranteed by the distilling technology employed in anthracene oil production [7]. Their highly aromatic composition makes them a promising raw material for obtaining carbon fibres.…”