Selime MENTE ÇOLAK, Urana DANDAR, Eylem KILIÇ

TANNİK ASİDİN DERİDE SERBEST FORMALDEHİT VE ALTI DEĞERLİKLİ KROM BİLEŞİKLERİNİN OLUŞUMUNUN ÜZERİNE ANTİOKSİDAN ETKİSİ

Deri ürünlerinde serbest formaldehit ve altı değerlikli krom bileşiklerinin varlığı, formaldehitin endüstriyel kimyasalların üretim proseslerinde kullanılması ve deri endüstrisinde tabaklama maddesi olarak kullanılan krom (III)’ün belirli koşullar altında krom (VI)’ya okside olmasından kaynaklanmaktadır. Bu çalışmada kromla tabaklanmış deriler retenaj işleminde 0,1, 0,5, 1, 2 ve %3 oranlarında tannik asit ile muamele edilerek, tannik asidin antioksidan etkisinin altı değerlikli krom ve serbest formaldehit oluşumu üzerine etkisi araştırılmıştır. Bu amaçla retenaj işlemi sonrasında derilerin serbest formaldehit içerikleri ISO TS 17226 metoduna göre HPLC cihazı kullanılarak analiz edilmiştir. Deri örnekleri yüksek sıcaklık ve UV gibi hızlandırılmış yaşlandırma koşullarına maruz bırakılarak derilerde altı değerlikli krom oluşumu sağlanmıştır. Deri örneklerindeki krom (VI) miktarları TS EN ISO 17075 standardına göre belirlenmiştir. Mamul derilerin fiziksel özellikleri üzerine olan etkisi de incelenmiştir. Tannik asidin altı değerlikli krom ve formaldehit oluşumu üzerine engelleyici etkisi, %1 tannik asit konsantrasyonunun üzerindeki değerlerde gözlenmiştir. %3 tannik asit kullanımı ile krom (VI) değerleri 3 ppm’in altında elde edilmiş ve ayakkabı için eko etiket kriterlerini sağlamıştır. Bunun yanında uygulanan tüm tannik asit konsantrasyonları formaldehit miktarını kısıtlanan limit değerlerinin altında elde edilmesini sağlamıştır. Tannik asidin artan konsantrasyonları mamul derilerin fiziksel özellikleri üzerine olumlu bir etki göstermiştir. Çalışmadan elde edilen sonuçlar tannik asidin derideki krom (VI) ve serbest formaldehit oluşumu üzerine etkin bir antioksidan etkisinin olduğunu göstermektedir

Anahtar Kelimeler:

Cr (VI), Formaldehit, Hızlandırılmış yaşlandırma, Tannik asit, Deri

ANTIOXIDANT EFFECT OF TANNIC ACID ON FORMATION OF FORMALDEHYDE AND HEXAVALENT CHROMIUM COMPOUNDS IN LEATHER

The presence of formaldehyde and hexavalent chromium in leather products, results from the inclusion of formaldehyde in chemical manufacturing process of industrial chemicals, and the oxidation of Cr (III), which is used as tanning agent in leather tanning industry, to Cr (VI) under certain conditions. In this study, wet-blue sheep skins were treated with different concentrations of tannic acid such as 0.1, 0.5, 1, 2 and 3% at retanning process in order to investigate the antioxidant effect of tannic acid on chromium (VI) and free formaldehyde formation in leather. For this purpose following the retanning process, formaldehyde content of leathers were analyzed according to ISO TS 17226 method with HPLC device. Hexavalent chromium formation was forced by exposing leather samples to accelerated ageing conditions, such as high temperature and UV. The chromium (VI) content on leather samples were determined in accordance with TS EN ISO 17075 standard procedure. The physical properties of final leathers were also investigated. Inhibitory efficiency of tannic acid both on hexavalent chromium and formaldehyde was attained at concentrations above 1% tannic acid. The offer of 3% tannic acid fulfilled the Eco-label criteria for footwear and provided lower chromium (VI) values than 3 ppm. Besides, all four tested concentrations of tannic acid maintained the formaldehyde concentrations under restricted limits. The improvement effect on the physical characteristics of leathers was observed in direct proportion of increasing tannic acid concentrations. The results indicated that tannic acid has a remarkable antioxidant effect on chromium (VI) and free formaldehyde formation in leather

Keywords:

Cr (VI), Formaldehyde, Accelerated ageing, Tannic acid, Leather,

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