Leather products are almost everywhere ranging from jackets and handbags to car interiors. However, a lot of potentially harmful pollution is created by processing the leather for these luxury items. One group recently reported in ACS Sustainable Chemistry & Engineering about a new method for processing leather that is more eco-friendly.
According to Rolls Royce, 12 cow hides are used for upholstering the interior of one of their automobiles. The journey from cow to a leather seat is a long one, including a number of steps. One of the more established steps is known as tanning, but prior to this process, it is necessary to remove hair from the hides, and the fibers must be swollen or “opened” up. Currently, manufacturers use sodium sulfide and lime to complete these steps, but this creates toxic gas and sludge waste, and then it needs ammonium salts in order to remove the lime. Ionic liquids are referred to as molten salts at room temperature and are not extremely volatile, making them attractive alternatives to substances that are harsh. These liquids have been examined for use in leather-making, but they have only been employed to a single process. Jaya Prakash Alla, Jonnalagadda Raghava Rao and Nishter Nishad Fathima wanted to examine whether they could totally eliminate the requirement for sodium sulfide and lime by using ionic liquids in steps involving both hair removal and fiber opening.
Three different treatments on goat skins were carryout by the team. The researchers used traditional methods for the control. A hybrid method, known as E1, was used for processing the second set of skins. This method involved an enzyme for hair removal and lime for opening fibers. E2, which is the third treatment, involved the enzyme and an ionic liquid for hair removal, then the ionic liquid again for fiber opening. The ionic-liquid-treated skins were not quite as strong as the control after tanning, however they had the right appearance and coloration. The E2 treatment eradicated the use of lime, ammonium salts and sodium sulfide, and it reduced treatment time and pollution output.
The Council of Scientific & Industrial Research funded this research.