Evaluation of Antioxidant Performance in Chromium Oxidation Prevention

The tanning of hides is a practice deeply rooted in ancient times, but in the early 20th century, transitioning to an industrial model of leather and hide production, chrome tanning expanded globally due to its practicality, quality, and versatility. However, in recent decades, there has been a growing attention paid to the potential oxidation of the free chromium present in tanned leather, which could transform from an unharmful trivalent status into its carcinogenic hexavalent status. This phenomenon occurs in a very small fraction of hides, which is yet sufficient to exhibit significant activity. Hence, there is an evident need to explore further alternatives that allow avoiding oxidation. In this work, the performance of a sequence of selected antioxidants is evaluated in different oxidation conditions: simple stirring, UV-Vis-IR irradiation, and heating up to 75 °C. The official diphenylcarbazide-UV tool norm was used to quantify the hexavalent chromium amount. The results underline the effectiveness of 2,6-di-tert-butylphenol, and that its greatest preventative method of addition during the tanning process is together with the tanning agent. This approach will pave the way for researching alternative concepts and exploring perspectives to inhibit chromium issues.