An Eco-Benign Approach for Unhairing Goat Skin Using Ozone

Unhairing or hair removal is an important step in leather processing. The conventional lime-sulfide process used for unhairing operation generates considerable waste and toxic hydrogen sulfide in the effluent when mixed with acidic effluent. Oxidative chemicals offer an alternative to the use of sodium sulfide in a rapid unhairing reaction. Oxidative unhairing was investigated using hydrogen peroxide, chlorine dioxide, and calcium peroxide, with unsatisfactory results. Ozone being a good oxidative agent was tried in this work in unhairing goat skin. Experiments on the use of ozone with oxygen/air as feed gas were carried out to study the unhairing effect on different regions of a goat skin. Unhairing was done in a static reactor. The wet blue produced from the skin underwent physical testing and was compared with the conventional operation. COD of the spent liquors were tested for comparison. The experimental results indicate that ozone as an oxidative agent could be used for depilation without affecting the physical and chemical characteristics of the resulting leather. The use of ozone for unhairing operation in place of sodium sulfide results in hair recovery and reduction of pollution loads.