Лако-красочные материалы — производство

4.8.1

Carbon Black, Soot, and Black Carbon

Carbon black is not soot or black carbon, which are the two most common, generic terms applied to various unwanted carbonaceous by-products resulting from the in­complete combustion of carbon-containing materials, such as oil, fuel oils or gasoline, coal, paper, rubber, plastics and waste material. Most soot and black carbon species are ubiquitous in the environment as aerosols, sediments, and soils and have low

available surface areas due to their large particle size and small carbon content. They also contain large quantities of dichloromethane and toluene extractable materials and can exhibit an ash content of 50% or more.

Carbon black is chemically and physically different from soot and black carbon, with greater than 97% of carbon black consisting of elemental carbon arranged as aciniform (grape-like cluster) particles. On the contrary, less than 60% of the total particle mass of soot or black carbon is composed of carbon, depending on the type of soot or black carbon, the relative amount and type of carbon, and the characteristics of the particles (shape, size, and heterogeneity).

In the case of commercial carbon blacks, organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) can only be extracted under very rigorous laboratory analytical procedures (soxlet extraction using organic solvents and high tempera­tures). These extracts are similar to those derived from soot. Both extracted mixtures demonstrate mutagenic and carcinogenic activity. In the case of carbon black, how­ever, extracts exist only in extremely small quantities for transient time periods in laboratories. Water and body fluids are ineffective in removing them from the sur­face of carbon black and, therefore, they are not considered to be biologically available. There is no scientific evidence that normal exposures to manufactured carbon blacks share the same potential adverse effects for humans, that is, mutagenesis and car­cinogenesis, as with soot or black carbon.

Two other commercial carbonaceous products often confused with carbon black are activated carbon and bone black. Each is produced by processes different from commercial carbon black and possesses unique physical and chemical properties.

4.8.2