Azo dyes are prepared in a two step reaction the first being the synthesis of an aromatic diazonium ion from an aniline derivative. The next step is coupling
Structurally they may be considered as being derived from sodium salts of anionic azo dyes containing sulphonate and ? or carboxylate groups by replacement of
The safety of these four azo-dyes has been questioned. The rationale for this review is on the basis that these colorants form carcinogenic amines during
lying the structures synthesis and technical performance of azo pigments
dyes are released into the environment in effluents. More than 800000 tons of dyes are annually produced worldwide
Les colorants azoïques à base de benzidine et les amines aromatiques désignés Accès : www.gazette.gc.ca/archives/p3/1999/g3-02203.pdf. Canada. 2000.
of azo dyes. • Physico-chemical properties toxicity
Originality/value – Lignin-based azo pigment has great potential to replace metal oxide pigment and provide strategy for utilisation of lingo- cellulosic
du textile et des colorants où la prévalence est net- tement plus faible. pements chromophores azo (-N=N-) permettant l'as- ... 156_en.pdf).
19 In general the rate constant of the azo dye decolorization increases until a certain. TiO2 concentration and decreases due to the agglomeration of these.