Application of low temperature plasma environment for reduction of selected carcinogenic compounds in asphalt industry off-gases

摘要

Bitumen, a by-product of oil-refining, is mainly used in paving and roofing. In paving operations, bitumen is heated and mixed with mineral aggregates. The use of recycled materials and industrial byproducts in asphalt mixtures is increasing. Hot bitumen (130-200 °C) emits vapours and aerosols (fumes) that contain various compounds, including polycyclic aromatic hydrocarbons (PAHs) and sulphur-containing organochemicals. Bitumen fumes contain 1-5-ring unsubstituted PAHs, alkylated PAHs, heterocyclic PAHs and terpenoids which may have mutagenic and carcinogenic activities. Additionally some of these compounds are odour causing compounds. One of the effective ways of biochemical and chemical deactivation of odour causing and carcinogenic compounds is application of ozone and low temperature plasma environment. In these conditions the most stable organic compounds including monoaromatic and polyaromatic compounds can be oxidized. In the experiment degradation of volatile organic compounds from asphalt industry, including odour causing compounds, was conducted. With this end in view a special plasmachemical reactor was developed. In analytical part solid phase microextraction and GC-MS was applied for identification and quantitative measurements. It was observed that compounds containing heteroatoms were easily degradable than compounds containing condensed rings and aliphatic substituted benzene rings. The preliminary results of our investigations showed that methods utilizing ozone and/or low temperature plasma environment could be successfully applied for degradation of odour causing and carcinogenic compounds emitted in off-gases originating from asphalt industry. These methods can be however applied in specific conditions, after precise determination of process parameters and identification of the formed products.