title: Total control of chromium in tanneries - thermal decomposition of filtration cake from enzymatic hydrolysis of chrome shavings.
abstract: This paper deals with the problem of chromium recovery from chrome-tanned waste and thus with reducing the environmental impact of the leather industry. Chrome-tanned waste was transformed by alkaline enzymatic hydrolysis promoted by magnesium oxide into practically chromium-free, commercially applicable collagen hydrolysate and filtration cake containing a high portion of chromium. The crude and magnesium-deprived chromium cakes were subjected to a process of thermal decomposition at 650°C under oxygen-free conditions to reduce the amount of this waste and to study the effect of magnesium removal on the resulting products. Oxygen-free conditions were applied in order to prevent the oxidation of trivalent chromium into the hazardous hexavalent form. Thermal decomposition products from both crude and magnesium-deprived chrome cakes were characterized by high chromium content over 50%, which occurred as eskolaite (Cr2O3) and magnesiochromite (MgCr2O4) crystal phases, respectively. Thermal decomposition decreased the amount of chrome cake dry feed by 90%. Based on the performed experiments, a scheme for the total control of chromium in the leather industry was designed.
authors.affiliation: 1 Department of Automation and Control Engineering, Faculty of Applied Informatics, Tomas Bata University in Zlín, Nad Stráněmi 4511, 76005 Zlín, Czech Republic.
authors.forename: P
authors.initials: P
authors.lastname: Kocurek
authors.affiliation: 1 Department of Automation and Control Engineering, Faculty of Applied Informatics, Tomas Bata University in Zlín, Nad Stráněmi 4511, 76005 Zlín, Czech Republic.
authors.forename: K
authors.initials: K
authors.lastname: Kolomazník
authors.affiliation: 1 Department of Automation and Control Engineering, Faculty of Applied Informatics, Tomas Bata University in Zlín, Nad Stráněmi 4511, 76005 Zlín, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Bařinová
authors.affiliation: 2 Department of Environmental Chemistry, Faculty of Environmental Technology, University of Chemistry and Technology, Prague, Technická 5, 16628, Prague 6, Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Hendrych
mesh_terms: D002857:Chromium / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007220:Industrial Waste; D013052:Spectrometry, X-Ray Emission; D013633:Tanning / Q000379:methods*; D018505:Waste Management / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D007220:Industrial Waste; D002857:Chromium
keywords: Leather waste; alkaline enzymatic hydrolysis; chrome shavings; chromium filtration cake; chromium recycling; thermal decomposition