Avoiding the Production of Polluting and Toxic Chemicals in the Tanning Process

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Josep M. Morera
Esther Bartolí
Patricia Rojas
Luisa F. Cabeza


Polluting and potentially toxic chemicals are used in tanning. Sodium sulfide/hydrosulfide are used when the hides are unhaired. These chemicals can be transformed into hydrogen sulfide with a simple change of pH. This gas is highly toxic and is the recurring cause of many deaths and accidents due to suffocation of workers in tanneries around the world. The basic salts of chromium III are the most used chemical to tan. The chromium III used can be transformed by oxidation, even once the leather transformed into a consumer good (shoes, for example), in chromium VI, which is carcinogenic. Both chemicals are present in process floats, in residual floats and in solid waste generated. Chromium III is also present in manufactured leathers. This article aims to describe the problems associated with the use of the aforementioned hazardous materials and deepen the possibility of using less toxic alternative processes to tan. The designed process allows to significantly reduce the pollutant load of the discharged wastewater, facilitates the reuse of the solid waste generated and clearly improve the safety of people at work.

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