Mitigating the Formation of Hexavalent Chromium in Leather by Using Aloe Barbadensis Miller Mixed with Carrageenan

Abstract

Aloe barbadensis miller (Abm) mixed with carrageenan has been investigated as an alternative eco benign ingredient in mitigating hexavalent chromium Cr (VI) formation in thermally and photoaged wet blue and leather crust. The effect of post-tanning operations on the formation of Cr (VI) in wet blue and leather crusts due to spontaneous and accelerated ageing caused by exposure to the temperature of 80 °C and UV radiations for 132 hours is also presented. The Cr (VI) content was analysed according to ISO 17075 standard procedure of Diphenyl carbazide and UV-VIS spectrophotometer at 540 nm. The levels of Cr (VI) in retanned wet blue leather were detectably high, while for tanned, dyed and fatliquored crusts, the levels were below detection limit of 0.2247 mg/kg. After ageing, the Cr (VI) content increased to a detectable level, the highest recorded in retanned wet blue, followed by fatliquored crust and with the lowest levels recorded in dyed wet blue leather. In all the aged samples, the levels were remarkably higher than the recommended 3 mg/kg. The levels of Cr (VI) in wet blue leathers processed with Abm/carrageenan were below detection limit of 3.587 mg/kg, even after exposing the samples to accelerated ageing conditions. Abm/carrageenan completely inhibits formation of Cr (VI) in wet blue and leather crusts. Abm/carrageenan will contribute to the eco benign and sustainable production of leather under the superior chrome-tanning technology.