Journal of Hazardous Materials 165 (2009) 604–611 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Vitrification: An alternative to minimize environmental impact caused by leather industry wastes T. Basegio ∗ , A.P. Beck Leão, A.M. Bernardes, C.P. Bergmann PPGEM - Programa de Pós-Graduac ¸ão em Engenharia de Minas, Metalúrgica e de Materiais, Escola de Engenharia, Universidade Federal do Rio Grande do Sul, LACER - Laboratório de Materiais Cerâmicos, Av. Osvaldo Aranha, 99/705, 90035-190 Porto Alegre-RS, Brazil article info Article history: Received 3 June 2008 Received in revised form 7 October 2008 Accepted 8 October 2008 Available online 19 October 2008 Keywords: Immobilization Chromium Vitrification Leather Wastes abstract The main purpose of this work was the investigation of the immobilization of chromium ion present in the ash from the incineration of chromium-tanned leather shavings (ACS) by means of vitrified ceramic bodies. To achieve the immobilization samples were initially produced adding soda-lime glass to ACS. After that, new formulations were produced with the addition of pure oxides, TiO 2 and MgO, to the soda- lime glass and ACS sample. These samples were conformed by pressing and fired in an eletrical furnace, at temperatures of 750, 800, 950 and 1000 ◦ C. The ceramic bodies were evaluated with respect to their physical properties and mineralogical composition by X-ray diffraction and energy dispersive spectroscopy (EDS) mapping. The chromium immobilization was characterized by leaching tests according to Brazilian Regulations (NBR 10005). The results confirmed the immobilization of the chromium ion within the allowed limits of Brazilian Regu- lations, NBR 10004 (5 mg/L), with the use of glass and vitrification/densification agents such as titanium and magnesium oxides. © 2008 Elsevier B.V. All rights reserved. 1. Introduction The industrial development in the last two centuries has also led to serious environmental problems. The preoccupation and concern for the environment resulted in the adoption of systematic treat- ment processes for solid, liquid and gaseous waste during industrial production, in spite of the fact that the preservation of the envi- ronment and ecology are sometimes still considered as additional production costs and expenditure. Undoubtedly, at present there is a general awareness related to the environment and inspection, and law enforcement by environ- mental protection agencies has become wide spread worldwide. The exportation of pollution is no longer permitted by means of environmentally unsafe technology or by the exportation of ecolog- ically aggressive products. Motivated by such thoughts and vision, the industry now seeks new routes to control and reduce envi- ronmentally unsafe procedures by developing new appropriate technology aimed to eliminate/or treat industrial wastes in order to minimize risks to mankind and the environment. The leather industry is inserted into this context. The major leather production centers in the world are found in Mexico, Brazil, Japan, South Korea, China, India and Pakistan. Korea, Japan ∗ Corresponding author. Tel.: +55 51 3308 3637; fax: +55 51 3308 3405. E-mail address: basegio@ufrgs.br (T. Basegio). and Italy import hides from countries which have a large meat production industry, that is, the United States, Australia, and the European countries, whereas the South American countries, for example, Argentina and Brazil, process their own hides [1]. The leather industry is prevalent in Brazil, especially in the South, in the State Rio Grande do Sul, where more than 50% of Brazilian leather is produced [1]. According to the European Commission (EC) the quantities of solid waste produced by tanneries depend on the type of leather processed, the source of hides and skins, and the techniques applied [2]. On an average, at the end of the process, about 20% of the weight of the raw hides is (grain side) leather [2]. On the other hand, in Rio Grande do Sul, approximately 40% of the initial raw material is transformed into solid and liquid wastes [3]. In the tanning industry, raw skin is transformed into leather by means of a series of chemical and mechanical operations [4,5]. Chromium salts (in particular, chromium sulfate) are the most widely used tanning substances today. Hides that have been tanned with chromium salts have a good mechanical resistance, an extraor- dinary dyeing suitability and a better hydrothermal resistance in comparison with hides treated with plant substances. Chromium salts also have a high rate of penetration into the interfibrillar spaces of the skin, what represents a saving in terms of production time and a better control of the process [6]. In Brazil, approximately 90% of the leather industry uses chromium in hide processing, resulting in hazardous chromium 0304-3894/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2008.10.045