REMOVAL OF AROMATIC AMINES DERIVED FROM AZO DYES IN LINING LEATHERS BY OXIDATIVE BLEACHES.

Environmental aspects and ecological production has become a great challenge for leather industry. In this study, the possibility to regain of leathers consisting highly rate of harmful azo colorants were investigated. Sodium perborate, sodium percarbonate and hydrogen peroxide as oxidative bleaches were used for the removal of azo dyes in leather. Leathers were firstly bleached at the pilot scale. Color measurements of the leathers were carried out with spectrophotometric method following the bleaching processes. As a result of the calculation of color differences (ΔE), 7% sodium perborate were elicited as optimum parameter on the bleaching effect. After determining the optimal bleach at the pilot scale, bleaching and re-dyeing processes were performed on the batch production. With the bleaching process, 35 ppm of azo dye content in leather according to ISO 17234-1 standard method was reduced under 5 ppm. Chromium( VI) formation on bleached leather samples have been examined with UV-Visible spectrophotometer at 540 nm according to EN ISO 17075 standard. Textural changes on the leathers after bleaching process were also observed by strength tests and scanning electron microscope (SEM) analysis. According to the findings of the research, Cr(VI) contents were detected under 3 ppm and strength properties of leathers showed slightly decreases not in the statistically remarkable levels. By this practically applicable way in the industrial scale, resellability of the leathers was ensured and thus, the potential danger of banned arylamine compounds which are an important problem in ecological production and eco-labeling of leather has been eliminated. [ABSTRACT FROM AUTHOR]