Content:
The toxicity and unpleasant smell of hydrogen sulphide (H2S) gas is an issue for the leather industry that has been contained rather than eliminated in tannery practice. Completely eliminating H2S from tanneries while maintaining practical and economically feasible processing is still a big challenge to be addressed. Significant progress has, though, been made by introducing robust and reliable low sulphide unhairing systems based on selective soaking and specific enzymatic liming auxiliaries. These systems allow the reduction of sodium sulphide offers from the typical 2.5% to 1% of pelt weight. These lower levels reduce the amount of hydrogen sulphide gas released into the environment from the liming float, as well as the amount of sulphide that is carried over in the hide to subsequent processing steps. Overall, the H2S problem is not eliminated, but significantly reduced with this technology.
In a further evolution of the technology, organic thio compounds can be used to fully or partially replace the already low levels of sulphide required, and thus allow to operate with offers well below 1%, or even completely without inorganic sulphide. Due to their reductive power, the organic thio compounds react with keratin in a similar way as inorganic sulphides, but they are oxidized much faster, which is
advantageous for the effluent load.
Alternatively to, or in combination with organic thio compounds, H2S scavengers can be used to reduce or eliminate hyrogen sulphide released from liming floats. Different types of scavengers are available, but the selection is limited for technical and economic reasons. The paper on hand shows how the release of hydrogen sulphide from beamhouse operations can be effectively controlled by a combination of technologies involving more effective unhairing with lower amounts of reductive agents, replacement of inorganic sulphide by organic thio compound and the use of H2S scavengers.
Take-Away:
- The release of toxic H2S from Beamhouse operations can be effectively controlled using modern unhairing technologies allowing to use no or low sulphide.
- These modern unhairing systems are based on a combination of selective soaking, unhairing assisted by enzymes with specific activity and the use of organic thio compounds.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:34335 |
| Date | 25 June 2019 |
| Creators | Gabagnou, Catherine, Fennen, Jens, Herta, Daniel |
| Contributors | International Union of Leather Technologists and Chemists Societies |
| Publisher | Verein für Gerberei-Chemie und -Technik e. V., Forschungsinstitut für Leder und Kunststoffbahnen (FILK) gGmbH |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:conferenceObject, info:eu-repo/semantics/conferenceObject, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | urn:nbn:de:bsz:14-qucosa2-340872, qucosa:34087 |
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