Effect of pH on the Fading Behavior of Vinylsulfonyl Azo Dyes on Cellulose in Aqueous Solutions
1994; Elsevier BV; Volume: 24; Issue: 1 Linguagem: Inglês
10.1016/0143-7208(94)87008-x
ISSN1873-3743
AutoresYasuyo Okada, Miki Sakai, Ikuko Takahashi, Zenzo Morita,
Tópico(s)Advanced Cellulose Research Studies
ResumoAbstract The effects of pH on the fading of three vinylsulfonyl azo dyes on cellulose immersed in aerobic and anaerobic aqueous solutions were investigated in the pH range between 2.5 and 9. Under anaerobic conditions, the rates of reductive fading for C.I. Reactive Red 22 and Black 5 increased with a decrease in pH only in the acid region, whereas those for a copper-complex azo dye (Blue-Cu) were almost negligible over all the pH range examined. The rates of fading for Black 5 and Blue-Cu in aerobic water decreased with increasing pH in the acid region and increased in the alkaline region. Black 5 on cellulose underwent simultaneous oxidative and reductive fading on exposure in aerated water, although greater oxidative fading was observed at pH ⩾ 8. Vinylsulfonyl azo dyes on cellulose have a tendency to show increased fading at both extreme pHs on exposure under wet conditions.
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