Abstract
The growing concern with environmental issues in tanneries and the search for a technological solution to their wastes are evaluated in this study. The leather shaving was chemically treated aiming the immobilization of the chromium ion on ordinary Portland cement (OPC) matrix. Cementitious mortars were obtained by adding different proportions of waste treated solutions (5 and 10% compared to the cement mass) and after 28 days, the samples were evaluated in relation to their physical properties, axial compressive strength and, for the most promising compositions, microstructural characterization analyses tests were realized. Results showed that the alternatives used for the pretreatment were effective for the leather shaving dissolution; but the results analysis describes little change in pH values when the treated waste is added in three different media. The best axial compressive strength after 28 days age were obtained by addition of diluted phosphoric acid solution at low concentration, although this addition minimize the Portlandite formation and favor the calcium phosphate formation.
Highlights
The Leather industry is responsible for a large generation of wastes during the skin tanning process to produce leather products to supply shoes, automotive and furniture markets
The mortars were prepared with Portland cement 32.5, which is equivalent to ASTM C 596 (Pozzolan-modified Portland cement)
The pretreatment was performed before adding the solid waste in the mortars, to prevent the decomposition of organic matter over time that can lead to the formation of large voids in the Portland cement matrix, and significantly affect its mechanical strength
Summary
The Leather industry is responsible for a large generation of wastes during the skin tanning process to produce leather products to supply shoes, automotive and furniture markets. Brazil, according to the Center of Tannery Industries of Brazil (CICB), is the second largest producer of leather in the world and the fourth largest exporter of leather[1]. Chromium sulfate is the most widely used reagent in mineral tanning process with a concentration in the tanning bath of roughly 1.5 to 5.0% of the total gross weight of salty skin. The oxidation states of chromium can vary from –2 to +6, but only the states 0, +3 and +6 are relatively stable in the environment. A simple transfer of electrons in change of oxidation implies a modification in its geometry, and the chromate anion (CrO )–2 has the same tetrahedral geometry of the sulfates and phosphate ions (with an easy penetration in cell membranes), contrary to Cr (III), with octahedral complex structure, difficult to penetrate the skin[2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
